My First Telescope: the Hadley on Hill's Space

Mars Observations

hillexed@email.com (hillexed) — Sat, 09 Nov 2024 04:54:16 +0000

I looked at mars with my 4.5" telescope. Previously it just looked like a big circle, but adding a 2x barlow lens to get to 150x zoom made it big enough I could make out a tiny line of slightly darker area on Mars! That’s the first time that I saw any detail on mars! That’s neat, but also wow my standards are so low.

Comet Tsuchinshan-Atlas

hillexed@email.com (hillexed) — Thu, 17 Oct 2024 12:49:09 +0000

Cell phone pic of Comet Tsuchinshan-Atlas!

It was visible faintly in the sky by eye too!

Weridly it seemed brighter by eye than through the telescope. That could be because my telescope wasn’t shielded from a nearby streetlight and stray light created a brighter background?

A Partial Lunar Eclipse

hillexed@email.com (hillexed) — Wed, 18 Sep 2024 04:40:01 +0000

Partialest of partial lunar eclipses

The planets... There's two of them

hillexed@email.com (hillexed) — Tue, 13 Aug 2024 14:46:32 +0000

Taken using my 4.5" telescope and phone! Both Mars and Jupiter fit into telescope view!

Very annoying observing session. Tried to take photos of the ring nebula but missed; planet conjunction was extremely slightly out of focus and I didn’t see until morning, and I looked for but still couldn’t see M33. Couldn’t see any detail on mars by eye either; that should change as we get closer to opposition. I think I need to finish my bigger telescope.

It's M42!

hillexed@email.com (hillexed) — Sat, 17 Feb 2024 00:15:58 +0000

Since Orion was so high in the sky compared to my last photo I was curious if photos would look better… and they do!

This is one 1/2s phone pic, scaled to hell and back to bring out the “bat wings”: big dark edges that go from bottom left to top right. Now I know there’s many ways to make this better, such as motorizing or a bigger telescope or stacking multiple pictures - but for just one phone pic this isn’t that bad!

Half Moon

hillexed@email.com (hillexed) — Thu, 18 Jan 2024 06:08:43 +0000

A quick moon pic from my 3D printed telescope and phone cam. Some out of focus tree branches snuck into the top and traced some faint dark lines!

Observing amongst the salt thieves

hillexed@email.com (hillexed) — Wed, 03 Jan 2024 04:30:22 +0000

I drove out to what Google maps said was a park and then saw a sign saying “state property no trespassing” and a second sign saying “don’t steal road salt or gravel from here, if we catch you you’ll be prosecuted”. I guess that’s what some silly rural fellows get up to in their free time? So I parked right in front of the entrance off the side of the road, since it was pretty dark. Eventually someone did drive up in a truck and ask if I was lost before driving in and then out a few minutes later (to I imagine check for salt thieves)!

Astronomy: it was so dark. I could see mountains and trees silhouetted against the sky once my dark vision adapted. I could see a naked eye slight fuzzy patch, point my scope, and it was M44! Lots of stars in one place. Everything had a slight bloom to it, like the sky some haze, and eventually a high cloud came in and reduced visibility to “only” a bortle 6 or so. Wow.

I also saw a dim fuzzy near Auriga - maybe M37? Pleiades looked as good as ever. Jupiter had four nice moons.

The pifinder didn’t get a GPS lock, and then shut down from lack of battery pretty quickly. I think the battery pack might be having more issues from when the scope fell off the mount a week ago?

The galaxies are aligned!!

hillexed@email.com (hillexed) — Tue, 02 Jan 2024 00:11:06 +0000

This is the best photo I’ve made of the Andromeda galaxy!

It’s my second time stacking pictures to bring out faint details. You’re looking at 20 phone pics taken through my 3D printed telescope, each 1/2s exposure so the Earth didn’t rotate as much during the photo and smear the stars. I tried the program deepskystacker, but it failed to stack my pictures (maybe my phone camera’s pics had too much noise?) so over 3 days I wrote some custom python code using astropy and astroalign to stack them myself!

Look at all those dim stars! That’s so many stars! In the bottom right that slightly fuzzy star is actually the core of M31’s satellite galaxy M110! I was hoping to see some dust lines or spiral arms, but I guess I’ll need more data for that.

THE STARS ARE ALIGNED

hillexed@email.com (hillexed) — Fri, 29 Dec 2023 21:18:14 +0000

BEHOLD, MY FIRST STACKED ASTROPHOTOGRAPHY IMAGE!

This combines 20 1/2sec exposures taken with my phone through my 3D printed 4.5" telescope. You can see stars down to magnitude 12!! This is so cool.

Turns out I didn’t see a galaxy in my photos because… I was looking at photos of a non-galaxy. This is the ring nebula, M57. Oops.

The stars are not aligned

hillexed@email.com (hillexed) — Fri, 29 Dec 2023 17:50:51 +0000

I took many 1/2s exposures of the galaxy M33 but it wasn’t visible. I’m trying to combine them in python to see if together it can simulate a long exposure. It’s not going too well

(The lines are from stars moving as the earth rotates!)

Those galaxies are just too darn faint

hillexed@email.com (hillexed) — Wed, 13 Dec 2023 05:35:50 +0000

There’s a galaxy (named M33) in most of this picture

but it’s so faint I couldn’t see it by eye or by camera :(

The pifinder helped me find this place, so I took like 30 exposures in the hopes that I can stack them and see it

Oops, pifinder actually wasn't done

hillexed@email.com (hillexed) — Sun, 10 Dec 2023 17:07:33 +0000

Oops. NOW my Sliced PiFinder is done.

The original PiFinder uses a $50 USB GPS module. To avoid spending $50, I wrote some code to fake a GPS. Eventually the dev brickbots switched PiFinders to a $10 solderable GPS module that uses UART instead of USB, and $10 felt reasonable, so I bought one and soldered it in. I thought I was done and that all I had to do was edit the software to remove my fake GPS code and use the regular GPS code! I was wrong - the GPS didn’t connect.

My Sliced PiFinder uses a raspberry pi 3 but the PiFinder was designed for a raspberry pi 4. I thought the only difference was CPU speed, but there’s more: the instructions asked me to solder the GPS to two pins which couldn’t speak UART on a pi 3 but could on a pi 4. Oops.

The Pi 3 has only one pair of GPIO pins that can speak UART: 14 and 15. By default it’s used for a “linux serial console”, but you can configure it for custom use (like listening to GPS) by adding enable_uart=1 in /boot/config.txt.

So I desoldered my GPS, attached it to pins 14 and 15 with some truly janky soldering (pic above), fixed a “NMEA unknown msg” problem by turning off echo according to comments here, edited gpsd.conf, and now GPS is finally working.

PIFINDER: COMPLETE!
...for real this time

Pifinder: complete!

hillexed@email.com (hillexed) — Sat, 09 Dec 2023 20:13:06 +0000

I’m building the Sliced PiFinder, a device to help my telescope find things! Previously, I tried using a cheaper IMU but gave up and bought a $30 fancy chip.

Originally I didn’t want to buy a $50 GPS USB stick but the PiFinder creator found a $10 solderable GPS unit for a v2, so I bought one and soldered it in.

After soldering in the GPS chip, dubiously electrical taping it in place, dropping it and cracking my 3D printed parts, printing new parts, using a soldering iron to remove heat inserts out of the old parts so I can place them into the new parts, printing the case, discovering the case wasn’t designed for my battery and blocks access to the on/off switch and USB ports, melting holes in case with soldering iron, putting on a cover plate over the screen and LEDs… I finally put it on my telescope!

PIFINDER: COMPLETE!

Testing on the telescope went well. The printed dovetail mount was slightly too thin and sagged slightly under gravity, but the field of view was wide enough it wasn’t a problem. And even when I couldn’t see any stars through my finderscope, the pifinder’s camera still got a lock.

Eventually I tried using the find-objects feature, and it successfully pointed me towards M31! I tried pifinding to M33, but I didn’t see it by eye. Maybe the streetlight 30 feet away was just too bright? Perhaps it’ll show up on a long exposure phone cam.

Total cost, including the pi and battery pack I scavenged for free: $118. Much better than $550!

hillexed@email.com (hillexed) — Thu, 07 Dec 2023 04:59:55 +0000

Perseus double cluster

Equipment used: my 3D printed 4.5" telescope, custom mount, Pico pic-taker button, my phone

I have a raw version of this where some stars are noticeably blue or orange but it has more camera noise than this

hillexed@email.com (hillexed) — Wed, 06 Dec 2023 05:50:35 +0000

hey rememer that pinfinder I made a longpost about? I dropped it. 3d printed parts cracked and have to reprint em

Pifinder Perils

hillexed@email.com (hillexed) — Mon, 04 Dec 2023 15:29:08 +0000

I’m building a PiFinder! It uses a camera to take pictures of the sky, connected to a raspberry pi which uses a database of stars to tell you where in the sky your telescope is pointing. But a PiFinder is $550 new. A stock pifinder uses the newest and most expensive options for pis and cameras, and when I looked at the parts list, I thought: I can build something similar for a fifth of the price! And so began the quest to create the Sliced PiFinder: a DIY PiFinder made from an used raspberry pi for a small slice of the cost. Previously, I bought a $33 camera and 3D printed a custom enclosure for it.

On the one hand, if I can successfully modify this project so I don’t need expensive parts, I save $400! On the other hand, my hubris has led to consequences.

This is a longpost about those consequences and the shenanigans I found to work around them.

(None of this would be possible if the pifinder wasn’t open source, so thanks to the creator brickbots, who has given me tons of help!)

Problem 1: Camera FoV

We live in a world where I use software written by a space agency across the ocean for free. What a world we live in.

Once the PiFinder takes a picture of the sky, it needs to use a database of stars to figure out where in the sky the camera was looking when the picture was taken. That process is called “plate solving” because we used to take star pictures on photographic plates.

How do you plate solve? Amazingly, that’s the easy part! The European Space Agency released an open source python library called “tetra3” that does it all for you! All you need to know is… hmmmm… the exact position of every single star in the sky your camera can see.

Amazingly, you can just download a database of every single bright star in the sky! Astronomers have been making star catalogs for thousands of years, including launching space telescopes like Gaia devoted to doing nothing but star cataloging. The PiFinder software downloads a database of stars automatically!

However, for tetra3 to plate solve, it needs to know your camera’s field of view (FoV), so it knows how far apart various stars will look to the camera. Different lenses change FoV. The PiFinder software expects you to have a Raspberry pi HQ Camera ($50) and 25mm lens ($20), which has a FoV of 10.2. I’m using an IMX462 camera ($33) and 12mm lens from a different camera ($10), so how do I figure out my FoV?

One option is math. I tried pointing the camera at Orion, taking a picture of the screen, measuring the distance in pixels between stars in orion, and comparing that to the known angular distance. That gave me an estimate of 15 degrees of FoV. Unfortunately, I didn’t know at the time that the the picture was wider than the screen.

Then I realized I was using a raspberry pi and could access the raw hardware. I SSHed in, used the command line to take a picture, then downloaded the raw .png. Now I knew what the software was looking at. I uploaded it to nova.astrometry.net, which plate solved my image and told me not just the exact coordinates of where I was looking (and the constellation!) but also the image’s FoV.

(Also, just for fun, I used it to take my first ever long exposure shot of 30s, and was blown away by the number of stars visible. Image above!)

Another complication: images are 2D. Does tetra3’s FoV input mean horizontal FoV or vertical FoV or diagonal FoV? I didn’t see it anywhere in the documentation. (It was horizontal)

In the end, my new IMX462 camera with 12mm lens had about 26deg of horizontal FoV. I could buy a new lens to reduce that down to the PiFinder software’s expected 10.2 degrees… but instead brickbots helped me write software to crop the image down to 10.2 degrees. Now plate solving works!

Problem 2: Alt/Az

Let’s say you want to see the andromeda galaxy. How do you know if it’s is visible in your night sky right now or not? Should you look north or east or south to find it?

Since the earth is a sphere, “down” changes from place to place. Since north is perpendicular to down, that means north/south/east/west look at different parts of the sky based on your place on earth.

Thankfully, if you know your location on Earth and the time, since Earth rotates once per 24 hours you can do some math to figure out where to look relative to your local north and down directions. Those coordinates are called “altitude” and “azimuth”.

The PiFinder gets your location on Earth and the time from a $50 GPS USB dongle. But that’s expensive and my phone already has a GPS. If I can modify the software so I can enter my coordinates and the time, I save $50.

It turns out parts of the software don’t work unless it knows your coordinates, but instead of showing an error message some features simply do nothing. I edited the software’s config file to add my GPS coordinates… but coordinates in the config file are never used, since all previous pifinders have had GPSes and got coordinates from there. So I had to modify the existing “GPS_fake.py” (which previously did nothing) to actually send fake GPS and time messages.

And because computing altitude and azimuth isn’t complicated enough: the raspberry pi has no internal clock, so every time it starts up the time is wrong (unless it can connect to wifi and download the time using NTP). This works for me at home, but if I want to take this to dark places, I eventually need to program a screen that lets you enter the coordinates and time on the device itself!

Problem 3: Gyroscope Fusion Failures

If you move a telescope with a PiFinder left or right, changing your azimuth, its screen should move the star display left or right quickly. That’s hard for a few reasons.

First, the Pifinder needs long exposures to capture dim stars. If it moves during a long exposure, the image it captures will have stars that look like smeared lines instead of dots and it can’t plate solve. That means if you bump the device, there’s a few seconds of delay before the camera can lock on to the sky again.

To get quicker feedback during unsuccessful pictures, the PiFinder uses an intertial measurement unit (IMU) chip, which combines a gyroscope (measures changes in angle), an accelerometer (measures acceleration, including gravity), and a magnetometer (measures Earth’s magnetic field). The PiFinder uses a fancy $30 IMU chip called the BNO055, which has a tiny processor that computes the chip’s current altitude and azimuth 100+ times a second.

However, I scavenged an LSM6DS3TR-C + LIS3MDL IMU from a different project with the exact same sensors: magnetometer, gyroscope, accelerometer. Surely, I thought, I could write some code to compute altitude/azimuth from those sensors and save $30!

Combining data from the 3 sensors is called “sensor fusion”. It’s incredibly hard. Thankfully, I’m not the first to study sensor fusion (drone builders want it too) and there’s two main sensor fusion algorithms which already exist, named mahony and madgwick. Adafruit has an AHRS library which implements both… in C++, but I was using python. Eventually I found an implementation of both and downloaded it, loaded in my sensor readings… and spinning the device 90 degrees didn’t change the output by 90 degrees. Why?

Problem #1: Axis remapping!

In my PiFinder, the IMU is oriented so the sensor’s +Y direction is the one the camera is pointing towards, but I had a hard time figuring that out because the chip was buried inside a circuit board and the code has many options to switch coordinates based on how a PiFinder is mounted on a telescope.

Problem #2: Units

The Madgwick filter expected the gyro’s inputs to be in degrees/second when they were in radians per second. No problem, I can just multiply them by 180/pi. Then I took a look at the Madgwick code, and it requests degrees because it multiplies the numbers by pi/180 to turn them back into radians. Aaargh.

Problem #3: Calibration!

Magnetometers and gyroscopes will drift - if they output a range, say, 4 units wide, instead of getting sensor readings from -2 to 2, your actual readings might be shifted so you read values from 0.5 to 3.5. Magnetometer readings shift in a similar way for a different reason: Earth’s magnetic field is different everywhere. You can take many many readings and average them to find the true zero point, then subtract that from all future readings to make zero the middle point.

For a gyroscope, those readings need to be taken while the gyroscope isn’t moving. I realized I could use the accelerometer for that - if the accelerometer’s gravity direction isn’t changing, I can use that to know I’m not moving and grab some gyroscope readings. Once you integrate the gyroscope over time, it looked pretty stable, with only around 0.3 degrees of error.

For a magnetometer, spin it around as much as possible, and the unchanging 3D vector of earth’s magnetic field, as measured by the magnetometer’s 3 axes, should trace out a sphere! Then you can use the center of that sphere as your reference zero point.

Engineers did what engineers do in overly specific fields and made up magnetometer calibration number jargon. The values for center of the sphere (which should be at (0,0,0) but usually isn’t) are called the “hard-iron offsets”. But you can get fancier: if you have a magnet (or some other electrical device) near the magnetometer, it might make its own magnetic field and skew one axis at a time, and that skew is called the “soft-iron offset”. They’re just coefficients in a calibration matrix!

The simplest way to calibrate a magnetometer is to ignore soft-iron entirely, keep track of maximum and minimum values in all 3 magnetometer axes as you spin the device around every which way, assume the hard-iron offset is the average of the max and min, and subtract that calibrated value every time you read from the magnetometer in the future.

I had to do all that calibration myself. The output still didn’t work very well. The sensor fusion algorithm’s output reported altitude and azimuth axes which didn’t measure down correctly. Why wasn’t it working?

Problem #4: EVERY SINGLE MAGDWICK FILTER EVER WAS WRONG 3 YEARS AGO

According to this research by someone named Mark Uckermann from a British bike GPS startup,, apparently almost every Magdwick library has a subtle bug in the code compared to the original paper, invisible if you use a small enough “beta” parameter. Oops. That was 3 years ago, and I think my library has fixed it? But I can’t tell since the variable names are slightly different.

Problem #5: Speed

The sensor fusion algorithms involve lots of math. Doing these calculations myself in python (along with the camera and plate solving and everything else the pifinder was doing) took up so much time that on my pi 3, the IMU code was only able to read values from the sensors around 12 times a second. The sensors were updating 104 times a second. That meant I was losing tons of info, including updates of “how much the angle shifted since the last time you checked” data from the gyroscope. I could configure the sensors to slower speed… But the gyroscope+accelerometer could only go to discrete values like 12.5 Hz while the magnetometer could only go to different discrete values, like 10 Hz. Aargh.

After all that… turning my device 90 degrees still wouldn’t make the azimuth output change by 90 degrees. Aaaaargh.

But wait. If my sensor fusion algorithm wasn’t working… maybe it was a problem in the sensor fusion algorithm code? The accelerometer tells me the direction of gravity - maybe I can compute azimuth. The IMU can tell me where magnetic north is. If I measure both… maybe there’s a way to compute altitude and azimuth directly? Maybe, just maybe, if I sat down and did a ton of galaxy brain math, I’d be able to use my own scavenged IMU instead of buying the pifinder’s recommended BNO055 for $30!

Oh yeah. The BNO055 chip is $30. It does calibration for you.

I gave up, desoldered my old IMU, bought a BNO055, and soldered it in.

It better work.

Pifinder is almost pifinding!

hillexed@email.com (hillexed) — Sun, 26 Nov 2023 01:17:31 +0000

The pifinder is a tool to help you aim a telescope. It uses a camera to take pictures of the sky, connected to a raspberry pi which uses a database of stars to tell you where in the sky your telescope is pointing. Then, if you want to find a specific object, it tells you what direction to move your telescope in.

I’m building a janky pifinder with some nonstandard parts: instead of a $60 raspi 4 and $50 HQ camera and $25 lens and $30 IMU, I’m using a $10 lens, a secondhand raspi 3, and a cheap “pi camera module v1” from 2013 that was attached to the raspi, and a $20 IMU with unpronounceable name I found lying around in a drawer of sensors. Previously, it didn’t see any stars, so I bought a better camera, an IMX462.

Turns out the two cameras are different sizes, so the enclosure for my first camera didn’t fit the second one. The IMX462 has some holes in it that fit M2 screws, but my local hardware store only sells metric screws in specific lengths like 12mm, while the pifinder wants 8mm screws.

So I designed a 3D printed enclosure for the new camera, and printed it in orange! It was too big; the screws I bought weren’t long enough.

So I designed another 3D printed enclosure for the new camera, and printed it in blue! It did fit!

Then I put it together, and took it outside… and the display showed that the camera is successfully seeing stars! This camera is definitely much better and more sensitive than the old one. Plus, because it’s connected to a raspberry pi, I can just SSH in and ask it to take pictures to see the raw camera output.

The pifinder still isn’t plate solving properly - it should be trying to compute where in the sky it’s looking and it isn’t. It could be the lens/camera combo means this image is a different FoV than it expects, meaning it’s seeing more or less of the sky and the stars are closer or farther apart than it expects. We’ll see.

Maybe this camera will make the pifinder see stars

hillexed@email.com (hillexed) — Thu, 23 Nov 2023 17:42:35 +0000

Pifinder update: the new $33 camera arrived! But it’s slightly bigger than my previous camera, so I had to design a new part to hold it. While the pifinder was designed with M2.5 screws, this camera only accepts smaller M2 screws. I had to go to the hardware store yet again.

The pifinder is designed for a raspberry pi HQ camera ($50). Originally instead I wanted to use a pi camera module V1 ($10, from 2013) because I recycled it from another project, but it didn’t work too well. I designed a custom printed mount for that. This innomaker IMX462 camera is $33 and has a big pixel size, which means it’s more sensitive to light (good for astronomy!). This means I’m on round 2 of designing custom holders for cameras the pifinder wasn’t designed for!

hillexed@email.com (hillexed) — Thu, 16 Nov 2023 05:04:39 +0000

I built enough of a pifinder to test it! This pifinder is using a pi camera v1 because I salvaged an old secondhand pi project… and it was able to see one or two stars, but not much more because of light pollution. Not enough to see the stars and plate solve to see where in the sky it was aimed at. I ordered a better $33 camera, maybe that’ll work

My first Orion nebula!

hillexed@email.com (hillexed) — Sat, 11 Nov 2023 04:00:21 +0000

The first picture is at 36x zoom, the second one at 150x zoom. The more zoomed in one is fainter because the same light is spread across more area, but you can see the four trapezium stars as four separate streaks!

This was a very frustrating night for photography because finding things in a big sky is hard. Light pollution made it hard to see M31, I couldn’t find M33, and then finally clouds rolled in and it became a race against time to photograph the Orion nebula M42. I really need a motorized mount or other device to help me find things.

hillexed@email.com (hillexed) — Mon, 06 Nov 2023 04:59:02 +0000

Today in observing I:

Tried to get a photo of the ring nebula through the 6mm lens. Realized my finderscope was misaligned, couldn’t get it aligned in time before it sank below a tree.
Tried to get a photo of Jupiter, succeeded! Tried out a new phone app named skeyecam that lets you take many many photos with the same settings, for some reason it made Jupiter green.
Then I tried taking a photo of m42 through the 6mm lens, but I couldn’t get anything on camera. Then I messed with my setup to see if it was aligned, only saw a star and not a nebula, tried to take off, then dropped and broke my openocular, and only after all that discovered I was aiming at the wrong group of 3 stars in Orion and was actually aiming at alnilan instead. Oops

M13, the great hercules cluster

hillexed@email.com (hillexed) — Wed, 18 Oct 2023 14:08:06 +0000

I found this with the help of an amateur with a huge telescope and laser pointer so bright it looked like a line pointing into the sky. Looked like a dim circular smudge to the eye. Picture taken with the 25mm eyepiece, so I bet I could get an even better picture through the more zoomed in 6mm

Annular eclipse today!

hillexed@email.com (hillexed) — Sat, 14 Oct 2023 14:21:02 +0000

Reminder to North and South Americans, there’s an eclipse today! https://www.timeanddate.com/eclipse/in/usa?iso=20231014 DON’T LOOK AT THE SUN WITHOUT SPECIAL ECLIPSE GLASSES, EVEN DURING A PARTIAL ECLIPSE! If you don’t have one, take a piece of paper, punch a hole in it, and look at the shadow. Trees or colanders with many holes will make very cool shadows!

I GOT THE RING NEBULA

hillexed@email.com (hillexed) — Wed, 11 Oct 2023 15:22:43 +0000

YEAHHHHH FINALLY

IT’S SO SMALL

FINDERSCOPE HELPED

hillexed@email.com (hillexed) — Wed, 11 Oct 2023 14:30:55 +0000

Got this used finderscope from the local astro club, designed and printed a mount for it. Took two revisions

Telescope update:

hillexed@email.com (hillexed) — Mon, 09 Oct 2023 18:13:12 +0000

I put a telescope on my telescope

hillexed@email.com (hillexed) — Mon, 25 Sep 2023 04:59:14 +0000

I took out a relative’s 8x42 binoculars today. Saw M7 as a faint sparkling of stars, but Andromeda was a much dimmer smudge compared to my telescope that if I hadn’t seen it before I wouldn’t have been able to spot. It I was able to follow a satellite though! And I got to show off Mizar and Alcor to others!

Sadly the moon was out and it was so bright it was casting shadows, stopping me from seeing any nebulae like I was hoping. Grr, how dare the moon be out there.

ANDROMEDA GALAXY CORE

hillexed@email.com (hillexed) — Wed, 20 Sep 2023 14:36:37 +0000

I got to see it with my own eyes for the first time!! It looked like a gray oval-ish but slightly pointy smudge. But it’s a cool smudge in the sky!!

This is a phone pic with a 2s exposure and ISO cranked up to it’s max, 3200. The rainbow snow is random noise from my sensor magnified by turning the sensitivity up very high. You can even see M32 as a slightly fuzzy star almost directly above Andromeda’s core!

I’m really glad I found it. Aiming the telescope was annoying, but rubber bands on the mount helped it keep its aim. I guess that means when I tried and failed to find the ring nebula, it’s just too faint to see in my light polluted sky.

I took many 1s exposures, too. I need to figure out how to stack them and use astronomy software but that’s a process for another time

Dumb telescope idea: liquid mirrors

hillexed@email.com (hillexed) — Mon, 18 Sep 2023 17:27:56 +0000

I’ve been thinking about https://www.space.com/liquid-telescope-construction-in-space-ax-1 . I wonder if you could take a circular baking tray, spin it on a pottery wheel, and then pour SLA 3D printing resin into it so the resin would form a liquid mirror, then shine UV light on it to cure it and make a telescope mirror

I think I figured out why the pifinder recommends you use a beefy raspberry pi 3.

hillexed@email.com (hillexed) — Mon, 11 Sep 2023 04:28:35 +0000

The code’s open source, so I looked through it. Turns out every time it tries to draw a map of the sky, it loops through every single star in the sky down to magnitude 7.5. Every frame. Sigh

At least it’s open source, so I can probably add some caching and massively speed it up.

oh yeah, I'm making a pifinder

hillexed@email.com (hillexed) — Sun, 10 Sep 2023 01:01:27 +0000

The sky is too big. I went out telescoping looking for M13 and there were too many stars and it’s too big and I don’t know where I’m aimed. When you’re so zoomed in, there’s so many stars you don’t know where you are or where to look.

Enter the pifinder! I’m going to make one.

I went to my local makerspace, known for having too many donated bits and bobs they actively try to get rid of (what a wonderful problem to have). I found an old project involving a pi, a decade old pi camera v1, and a battery pack that I was allowed to take and cannibalize on the condition that I show off the final product. Thank you!

Pifinders are normally sold for $600 fully assembled because that’s what similar units cost, because the astronomy market is nuts. The creator sells cheaper DIY kits, thankfully. I’ll be able to save even more DIYing because unlike a normal pifinder, my janky secondhand pifinder will have:

A different battery No GPS module (those are $50!!!), instead I’ll mod the code to input my GPS coordinates from the GPS in my phone A slightly different IMU chip A much smaller and older camera, compared to the $50 raspberry pi HD camera twice the size with a convenient screw-on lens interface

Surely none of this will hassle me and I can save money without any consequences!

Progress so far

First, I needed to buy a lens for my camera!

Looking at what’s written on the ribbon cable of the camera, I have a pi camera v1. According to https://www.raspberrypi.com/documentation/accessories/camera.html the sensor is 3.76 × 2.74 mm big, so I can use FoV = 2 * math.atan((2.74/2)/22) * 180/math.pi

Turns out lenses are tricky. The official pifinder uses a 25mm lens. Why? It uses the “tetra3” library by the European Space Agency to go from pictures of stars to figure out where in space you are. You also need to pass in the FoV of the image. Pifinder expects a 10.2 degree FoV, and it has a database that works with FoVs from 10 to 20 degrees. I looked up the formula, and my smaller camera’s smaller sensor size would give me a TINY FoV with the same 25mm lens. Oops! I ended up buying a 12mm lens for a 13deg focal length.

Next, getting it on the board. I lost one of two screws holding it on. Following this video, I printed a M12 lens adapter, which had screw holes too small but otherwise fit perfectly. However, I also needed to remove the existing lens. There are printed tools for that, but many are a + shape for the pi camera v2, and the pi camera v1’s lens is a different shape with 3 spokes. Eventually I found one, printed it, unscrewed it, finished the job with pliers, and put on the lens. It does seem more zoomed!

Configuring the raspberry pi was a bit annoying. Running “libcamera-vid” shows a video, but for 5 seconds. You need to pass “-t 0” to get the preview to keep running. And after all that… when I turned off the lights, the video was pitch black. I need to figure out how to increase the exposure time if I want it to see stars.

I’ve spent $30 on electronics and the lens so far. I joined the pifinder discord and the creator was incredibly nice, willing to bundle multiple DIY components if I bought them at once instead of charging double shipping from the webstore price. PCBs and some hardware and LEDs will be arriving soon for another $15. The case is 3D printed, which will cost $little in filament. I have a lot of code work ahead of me to save that money, but it’ll be very cool if I can pull this off, with the help of that amazing makerspace.

Possible telescope upgrades

hillexed@email.com (hillexed) — Wed, 06 Sep 2023 20:39:46 +0000

My telescope is pretty good, but now that I have one I’ve been thinking about how to get even better. Here’s what I’ve been thinking about:

#1: Bigger telescope.

Bigger telescopes with bigger mirrors both capture more light and allow you to resolve tinier details. I saw someone made a “Leavitt” telescope, also 3D printed, designed to fit an 8" mirror! My telescope has a 4.5" mirror right now. It cost $30.

An 8" mirror, double the diameter, costs…

$360. Oof.

Another way to do it is to grind the mirror yourself. There’s a long tradition of amateur telescope makers doing that, but it takes lots of time grinding and polishing. The raw materials are still expensive-ish - an 8" circle of glass 1" thick is around $55, and there’s $50 extra of grits and powders you need. For making ultra-big mirrors, there’s some insane people who have started using kilns to take glass circles of normal plate glass and soften them over a mold, so they fall down and make a meniscus shape. It’s a rabbit hole I’ve already gone very very far down researching.

#2: Motorize the mount.

Stepper motors are decently cheap. With some gearboxes to reduce their speed, you could give your telescope the ability to automatically point itself at a target.

There are two kinds of mounts: Alt/Az and Equatorial. Alt/az involve one axis which rotates left/right along the ground, changing “azimuth”, and one axis which rotates up/down to change “altitude”, like a cannon. They’re the simplest to design, and someone has already made one for my Hadley telescope! But I’d need wood-cutting tools and $100 or so for just the wood alone, not to mention electronics.

Equatorial mounts are angled so one axis points towards the north pole, and rotates along the same axis that planet earth does to counteract the rotation of the planets. These are the ideal kind of mount. They’re much harder to design because they have to carry all the weight on those axes and geraboxes, and earth’s spin axis isn’t at all aligned with gravity.

Once you’ve set up motors, you can add “goto” functionality, which lets you press a button and watch as the telescope automatically figures out how to point at something. There’s software called “onstep” for that. I’d love goto someday!

Either type of motorized mount would also let me start taking long exposures to photograph very dim things out in space. An alt/az mount would let me take long exposures of up to a minute. Expose for too long with an alt/az mount and you’ll notice the thing you’re staring at starts rotating in your field of view, called “field rotation”. An equatorial mount doesn’t have that problem, but they’re expensive: a commercial entry-level one is around $700.

Surprisingly, there are people 3D printing decent equatorial mounts! Not many, though - it’s hard to design gearboxes without “backlash” to avoid tiny wobbles. Most are designed to hold DSLR cameras, not heavier telescopes.

#3: Pi-finder

https://www.pifinder.io/ is a neat raspberry pi powered device that looks at the sky and tells you where you’re pointed. It uses a high quality camera to take pictures of the sky, does some magic to figure out where you are, and then uses an accelerometer to track slight nudges. You still need to point and aim the telescope, but it would let me know where I’m aiming.

The most expensive components are a $50 high quality raspberry pi camera, a $20 lens, a $50 GPS USB stick, and an out-of-stock-everywhere raspberry pi 4. Ouch. But I do have a pi 1 lying around… maybe it’ll work? Plus, if I mod the software so I can input my coordinates from the GPS I carry around in my phone, I can save $100 or so.

Will I do any of these? I don’t know!

JUPITER BELTS JUPITER BELTS

hillexed@email.com (hillexed) — Thu, 31 Aug 2023 14:52:05 +0000

THE NEW TELESCOPE MIRROR IS GREAT

BEST $20 I’VE SPENT

Uploaded my telescope mount to Printables

hillexed@email.com (hillexed) — Sun, 27 Aug 2023 18:43:33 +0000

Now anyone can have a sturdy 3D printed telescope! https://www.printables.com/model/565412-hill-mount-for-hadley-telescope

On the Night of the True Enemy, I tried to find the ring nebula!

hillexed@email.com (hillexed) — Thu, 24 Aug 2023 23:28:28 +0000

For the record, past me was wrong. That’s not the ring nebula. There aren’t two bright stars aligned like that near the ring nebula. But that’s the prettiest Jupiter I’ve ever taken!

(Why is there a double saturn? I know why now!)

hillexed@email.com (hillexed) — Wed, 23 Aug 2023 03:24:01 +0000

Huh. I installed the front truss addon, I’m observing now and finally noticed the direction of the wobble. After a transient big vibration period of 3s or so it settles down… and stars look like two points right next to each other instead of a big glob of light. Progress! I looked at a low-altitude object… And the direction of the two stars was up and down. I think I’ve finally defeated side to side wobble only to find my true opponent was altitude wobble

Attacking vibration in Hill Mount v3

hillexed@email.com (hillexed) — Tue, 22 Aug 2023 16:56:49 +0000

Telescope mount v3 is pretty good, but it still wobbles slightly. If I touch or move the telescope, it wobbles a bit before settling down in 2-3 seconds. Before it settles down, Saturn turns into two images of Saturn next to each other.

I can use that picture and do the math to see how much it's wobbling:

https://www.timeanddate.com/astronomy/planets/distance says Saturn is 18.96" right now. That's a second of arc, 1/60 of a minute of arc, which is 1/60 of a degree. That means it wobbles 2 saturns * 18.96 arcseconds/saturn * 1/60 * 1/60 * 2π/360 radians/arcsecond = .0001838 radians. My telescope is about 1.75 feet long from the center point, so since sin θ = o/h, the tip of the telescope is moving side-to-side a distance of h * sin θ ≈ 1.5ft * .00009192 = 0.08403 mm in that picture. Wow, that's about one printed layer line.

How do I stop that?

Right now my telescope mount looks like this. It has a C-shaped top, so the telescope can rotate in and out.

It’s not a full truss - I can’t put a bar between the two tips of the C because that’s where the telescope goes. As a result, the tips of the C are only supported at one side, so they can move in and outwards. Experimentally, if I put pressure on the top part I can make the top part shift slightly in the xy plane.

I tried designing a tiny truss add-on to the front to help resist sideways force for mount v2:

I tried remaking it for mount v3! This time, here’s what mount v3 looks like. The rectangle in the center marks the telescope Bonk Zone, where I can’t put anything without hitting the telescope.

I printed it out, put it together, and noticed it was a very tight fit. Looks like I forgot to add tolerance to the hole sizes. I tried forcing it in anyways to see if it would work, and…

oh well. let’s see if it works once I reprint with bigger holes.

Oh my god there's so many stars in this galaxy

hillexed@email.com (hillexed) — Sun, 20 Aug 2023 06:27:52 +0000

I drove a few hours to visit friends and a bortle 4 sky. wow there were so many stars. You could barely make out an arc slightly lighter in the sky than the rest of it! The Milky Way! Through a telescope, there were much more stars than before and they just kept going and going if you moved the telescope. Saw the plediades too wow many bright stars near each other

No photos of nebulae, my goal, because my openocular malfunctioned and didn’t hold the phone to the camera well. No eye sightings of nebulae like m57 either because oh god the sky is so big and aiming is so hard and you look into the telescope and it’s full of stars and you’re lost

This photo is a 30 second timelapse at ISO 3200, the strongest it can go, from my phone camera placed on a concrete block. Edited to increase contrast and saturation. THAT’S A GALAXY

hillexed@email.com (hillexed) — Sat, 19 Aug 2023 22:26:14 +0000

Jupiter, four Galilean moons, and a blue star!

It could be improved if I was better collimated, but I’m happy I got all 4 of them with the high power eyepiece!

Brightnesses are cursed

hillexed@email.com (hillexed) — Tue, 15 Aug 2023 20:46:47 +0000

Today I learned that astronomers measure star brightnesses in the modern AB system, using (logarithmic) units of Janskys, where one Jansky is 10⁻²⁶ W⋅m⁻²⋅Hz⁻¹. Why is there the extremely cursed Hz⁻¹? Hz is already s⁻¹. Why is it like that. Astronomers, why is it like that. s^−1⁻¹ is just seconds

If you cancel all the units, you get… 1 Jy = 10⁻²⁶ kg m² s⁻³m⁻² s^−1⁻¹ = 10^-26 kg s⁻². …so we measure starlight in the same units as surface tension. If you really wanted to, you could talk about how bright a star is by how much its light would stretch a soap bubble.

Which 3D model takes less material to print?

hillexed@email.com (hillexed) — Sat, 12 Aug 2023 19:02:19 +0000

turns out it’s…

click to reveal

the first one?? 3D printers fill the inside of objects with really lightweight infill, and it's so light compared to 100% filled walls that it takes both less time and ends up being less weight than the fancy truss on the right. Which sucks because I spent such a long time designing that fancy truss only to be outdone by a brick.

I saw a meteor!

hillexed@email.com (hillexed) — Sat, 12 Aug 2023 04:30:41 +0000

I heard there was a meteor shower tomorrow! So naturally I went out today to see it. First I treated it like any other target and tried to find a good gap in the trees to see Perseus, but then I read online that meteors appear in the full sky, not just at the radiant.

So I lay down on the sidewalk, and 30 minutes later… zoop!

The meteor was super underwhelming compared to the time I spent waiting. A blink-and-you’ll miss it streak of a little bit of light. I wish they had a sound like in fiction.

Only bad space today, said the sky

hillexed@email.com (hillexed) — Mon, 07 Aug 2023 14:17:42 +0000

Everything was very blurry today and I kept wondering why focusing didn’t seem to fix it before realizing it was cloudy.

My custom Pico Bluetooth picture taking button worked great though!

A rabbit hole of bluetooth

hillexed@email.com (hillexed) — Fri, 04 Aug 2023 02:25:25 +0000

It all started with an idea for better telescope images.

I take photos using my phone. My telescope shakes when I press the capture button. I have a raspberry pi pico W, which recently added bluetooth. I wonder if I can connect the pico to my phone as a bluetooth device so I could press a button on the pico and remotely take a snapshot.

Bluetooth is a nightmare

the C++ standard is a mess of inscrutable acronyms. Apparently there’s multiple types of bluetooth services, keyboards and mice are called “HID” for human input device, I think bluetooth audio is called HSP for HeadSet Profile. Will that do what I want? Hope so, because I don’t know how to test yet! I found https://github.com/raspberrypi/pico-examples#pico-w-bluetooth, but clicking the links just takes you to some inscrutable C examples from the BTstack library. On the plus side, maybe that means things made for the BTstack library will simply work.

I found a micropython UART example, but my phone wouldn’t connect to it, possibly because it only supports specific services? sigh

I start to get it

okay, I’m starting to get this. bluetooth is many protcols in one, GATT is the meta-protocol that tells you what protocol you should use, each protocol has a number assigned to it like 0x180F for “telling you how much battery I have”, you can only find the numbers by searching a giant inscrutable PDF which doesn’t tell you what anything means.

Oh gosh which service will let me press volume down

Do I want… 0x1812 Human Interface Device (which I know is for keyboards and mice) 0x1843 Audio Input Control 0x1849 Generic Media Control 0x1848 Media Control 0x1855 Telephony and Media Audio 0x1844 Volume Control

Good question! Apparently the list of magic service numbers on https://www.bluetooth.com/specifications/assigned-numbers/ doesn’t actually say what each service does, and you need to go to https://www.bluetooth.com/specifications/specs/ and read a giant specification to find out! Yay!!

Unable to find image voldown.png

This image is all you get for “how to reduce the volume”. It doesn’t even say what Opcode or Change_Counter stand for. To do that I need to go to another paragraph which says “Change_Counter is read from Volume State”??? aargh

A page from the bluetooth HeadSet Protocol dscribing cases where this newfangled bluetooth technology might be used

Unable to find image bluetoothexamples.png

every single one of these 3 pictures is glorious

Pain

Unable to find image volcontrol.png

Ah, of course, the Volume Control Service is 0x1844 in the Assigned Numbers document, but you need to read the Volume Control Service document to learn that you also need Volume State and Volume Control Point characteristics. Naturally now that you know what characteristic names you need, their magic numbers (which are the true things you need) aren’t kept in this document, and you need to go back to the first one into this table. I wish it was sorted by “numbers you need for this service” instead of ALPHABETICALLY

A computer update

My computer can see what bluetooth services my phone supports.

It doesn’t support any of the 18xx fancy Bluetooth Low Energy profiles. NONE of them! There goes my work understanding Volume Control Service.

I gave up trying to use micropython and now I’ll just use C++

turns out, the official bluetooth examples https://github.com/raspberrypi/pico-examples are missing the actual bluetooth examples. you need to build these examples using make to generate the actual example code. of course they also give no instructions for building those examples.

I tried: cmake pico_sdk_import.cmake? Nope, CMake Error: The source directory is a file, not a directory.

cmake .? CMake Error at pico_sdk_import.cmake:55 (message): SDK location was not specified. Please set PICO_SDK_PATH or set PICO_SDK_FETCH_FROM_GIT to on to fetch from git.`

cmake . PICO_SDK_FETCH_FROM_GIT=1? CMake Warning: Ignoring extra path from command line:

“PICO_SDK_FETCH_FROM_GIT=1”

Turns out PARTIAL instructions are in https://github.com/raspberrypi/pico-sdk, and the implication is: they want me to edit the file CMakeLists.txt to add the line set(PICO_SDK_FETCH_FROM_GIT on). WHY WOULD YOU NOT WRITE THIS DOWN

Not all keyboards are made equal

I got an example working! Turns out the unofficial code that lets you code a Pico from the Arduino IDE has its own example classes for acting as a bluetooth keyboard or mouse. You can’t actually see their sample code without going here and looking for a library with BLE at the end of its name, but they work!

I tried sending the HID_KEY_VOLUME_DOWN key and it… did nothing.

After many hours of banging head against wall: I think not all keyboards are made equal, and as part of the bluetooth protocol a device send a “HID report descriptor” which says what buttons it has on it. Of course, HID_KEY_VOLUME_DOWN naturally isn’t part of the keyboard, it’s a completely separate thing called CONSUMER_CONTROL and the arduino-pico’s keyboard class doesn’t include the arcane hex constants that say “I can do consumer control device things like volume down” in its report descriptor. aaaaargh

Protocols all the way down

HID (Human Interface Device, the protocol for Bluetooth keyboards and mice) is a nightmare. It’s ALSO a protocol made of protocols. In fact, at the start of a HID connection the device needs to define its protocol by sending some arcane constants called the device descriptor which says what format all the future messages (called “reports”) will be in. And, of course, there can be multiple types of reports in the same device, with different formats. Turns out you can’t push Volume Down unless the device descriptor says “I have both a keyboard and a consumer control device”. Then you have two types of reports, and you send a report ID with each report to say whether you’re sending a keyboard type report or a consumer control type report. So you define your own custom protocol on top of HID on top of GATT on top of BLE! I’m four protocols down!

Remember, I want to take a picture on my phone. I thought the best way to do that is to press the volume down key.

The Arduino IDE for the Pico has a BLE keyboard library hidden in the examples. No BLE Consumer Control example library. Other people have Consumer Control libraries, so I spent a long time trying to modify the device description from “I am a keyboard” to “I am both a keyboard and a consumer device” and trying to figure out how to send the right report format.

Remember that report ID? That’s how normal Bluetooth works. Turns out all my effort was for naught because the BLE functions physically didn’t have a place to put that report ID. Turns out HID with BLE handles multiple report formats in a slightly different way compared to HID over normal bluetooth. And that’s when I realized something.

The end

I embarked on this quest to press the volume down button. But I don’t need to press the volume down button. I realized I could just click the take picture button with a mouse instead!

So I looked at the Bluetooth mouse library, and successfully used it to make the mouse move!

Sure, the “move to absolute position” didn’t work, and packets kept dropping if I sent them too quickly, and you can only move 128 pixels in a single move, and I can’t know where I am on the screen without moving to the bottom left repeatedly to reset the mouse position…

But I can finally press a button on my Pico, and watch the mouse move to the corner, then move to and click the “take picture” button! I declare: ABYSS SUCCESSFULLY GAZED

An idea for better images

hillexed@email.com (hillexed) — Thu, 03 Aug 2023 22:59:32 +0000

Welcome! Welcome, new galaxy!

hillexed@email.com (hillexed) — Wed, 02 Aug 2023 18:43:00 +0000

I got the Andromeda galaxy!!!

Aiming the telescope was a nightmare. “I’ll use a star app to aim!” I thought. I tried downloading Stellarium, it complained about a Google Play error. I downloaded SkEye, and it had some weird gyro issues because it expected the phone to be pointing in the same direction as the telescope, but I use my phone camera to take pics so it was mounted sideways looking at the telescope’s eyepiece. I didn’t really know my constellations, so it was hard to figure out what stars I could see in the light polluted sky were which stars on the app, and the part of the sky where it was seemed perfectly dark with no landmarks to aim at. I ended up pointing my telescope at a bright star, aiming upwards to what I thought was the right altitude using my mount v3’s degree markers, then rotating left/right at random patches of dark sky, shooting some four second long exposures, and hoping it would appear out of the gloom.

And somehow, looking through my pictures, I got it.

And then I immediately lost the telescope’s aim trying to see Andromeda with my eye and despite like 10 tries never managed to find it again.

I tried stacking my 3 exposures in Krita in Addition mode, but it didn’t seem to work well, so you’re looking at the best 4s exposure lightly edited to increase contrast.

hillexed@email.com (hillexed) — Sat, 29 Jul 2023 19:13:51 +0000

oh my god I think I can see multiple moons of saturn in my pictures if you turn the brightness up

Pictures from My 3D Printed Telescope, with Mount v3

hillexed@email.com (hillexed) — Sat, 29 Jul 2023 18:12:59 +0000

I finally finished Hill Mount v3, so I put it to the test. I got the clearest phone-cam Saturn I’ve ever seen! Wobbles still exist if you touch the telescope, but the wobbles are much smaller now and go away if I wait a few seconds or use a short exposure time.

Before the wobbles settle down, if you take a picture with a big exposure time, the wobbles cause the image to have two Saturns.

I think that confirms my theory that the long stretched out Saturn I saw with Mount V2 was caused by a tiny wobble. Overall, it's not wobble-free and could use some damping, but I declare Mount v3 a success!

I also got Jupiter again, and I could see two Galilean moons by eye but I couldn’t capture any using camera. I couldn’t see any of the stripes, though. Jupiter is way more featureless than I expected; I wonder if there are any cheap filters I can use to see more of the stripes.

In the last picture, I took a very long 4s exposure of Saturn. The earth’s rotation meant, Saturn blurred into a streak, but take a close look - there’s a smaller streak right next to it following Saturn! I think that’s one of its moons, possibly Titan! It’s so cool that I can see it from my backyard.

Things to improve:

Make the mount even stiffer?
How do I add damping, to make vibrations decay over time?
Just as I was writing this, I discovered some smudges on my eyepiece. Oops! Maybe that’s adding some glare. Hopefully once I clean that I can get even sharper images!
Try image stacking?

Telescope mount v3: Complete!

hillexed@email.com (hillexed) — Sat, 29 Jul 2023 01:19:05 +0000

This mount is my stiffest one yet!

Changes from last time:

uses steel EMT instead of wooden dowels, for extra stiffness
flat sides so you can see the degree markings
deeper and more visible degree markings

It feels pretty darn stiff! Unfortunately, tapping the side still makes the telescope wobble. It’s definitely much less wobble than before, though. Maybe it’ll be enough for clear pictures!

Maybe it wasn't the cheap filament's fault

hillexed@email.com (hillexed) — Fri, 28 Jul 2023 17:22:10 +0000

maybe this orange filament just likes to warp. Anyway, all parts printed!

Telescope mount v3 is half printed

hillexed@email.com (hillexed) — Thu, 27 Jul 2023 18:35:50 +0000

Just need one more big part to print!

Telescope mount v3 is printing!

hillexed@email.com (hillexed) — Wed, 26 Jul 2023 18:47:58 +0000

comment “safe printing mx mount” to lend it your energy

Here's a cool cutaway of how I'm holding the rods in place

hillexed@email.com (hillexed) — Wed, 26 Jul 2023 18:21:33 +0000

Here’s a cutaway view of my telescope’s 3D printed bases to hold rods in place. The rods go into the giant cylinders, but how do you stop them from slipping out? Insert a nut in on one side of the hole, and then screw it in from the other side. The cut in the top means the entire piece bends to hold the rod in tightly! This is so annoying to design because my rods are so close together you need to make sure that the cutaway for the nuts and screws don’t accidentally cut a hole in the wall of the places where the rods go.

Hope it works.

Gas giants, wooden wobbles

hillexed@email.com (hillexed) — Thu, 20 Jul 2023 17:07:03 +0000

I took my new wooden-dowel telescope mount for a spin, and got pictures of Jupiter and Saturn with my high-power eyepiece!

I took many pictures, and a few videos. I also figured out how to control the shutter speed on my phone’s camera, and got many photos at 1/40s shutter speed. Using a smaller shutter speed takes the planets from blinding white blurs to circular colored blurs, I assume because it lets in less light. It can make a planet go from blindingly white to almost completely disappearing into the night sky. However, my phone doesn’t let me control those settings when taking a video. The second and third images show the best raw pictures I got.

Saturn through my telescope had this weird diagonal smear to it. Since I’ve been fighting vibration issues with my wooden-dowel mount, I think it’s a very small high-frequency vibration from left to right causing that problem?

Then I tried using image processing software, Pipp plus autostakkert plus registrax, following this video tutorial. There were some shenanigans because Pipp’s site got taken down and I had to find a backup, but eventually I made the heavily processed Jupiter in the first image. Sadly, I haven’t figured out how to stack my photos because the software complained my images were different sizes (from before and after I pressed the “save as raw” button), but I was able to take a video of Jupiter without the high shutter speed setting and process that. It was a bit underwhelming - I went from dim blurry sphere to SLIGHTLY STRIPED dim blurry sphere! Wow! If there’s one thing I learned I suppose it’s that my telescope was out of focus.

I hope the pictures will be improved if I make a new mount using metal EMT pipes.

Built part of it

hillexed@email.com (hillexed) — Sat, 15 Jul 2023 20:42:24 +0000

It’s still sturdy, but wobbles when I hit it. I think it might be the springiness of the wooden dowels that’s causing the motion. I could try adding two more struts and seeing if it works but I don’t really want to. It’s also very colorful now.

Time for EMT, I guess!

Another Way Forward

hillexed@email.com (hillexed) — Sat, 15 Jul 2023 15:31:44 +0000

Last telescope update I finished mount v2 and was stuck because it wobbled. One way to try again is to make the rods out of metal EMT instead of wooden dowels. I bought a hacksaw and spent a while hacksawing my EMT to the right length before learning there were specific pipe cutting tools that were far easier to use. Oops! I’ll also need to redesign my mount to use the larger 0.706in EMT pipes.

Recently I went to my local astronomy club for the first time! It was filled with old retirees who could recognize messier objects by sight like I recognize pokemon. Incredible! As I talked about my telescope, eventually I nerd-sniped someone into helping me brainstorm how to resist the shear from the top twisting. They suggested turning the bottom part of the mount into a shear-resistant two-level truss, so that the vertical rods extend upwards to support the top part.

Apparently a truss is stable because of tension lengthwise along the rods - a theoretical truss can freely rotate at every vertex. These theoretical rods have no bending resistance. In practice of course rods do have bending resistance, and that’s what would resist my twisting. It’s worth a shot.

I designed some parts that include at least part of those truss structures to see if it would help. I have some wood left over, so I’ll test if this makes the mount any more rigid before designing an EMT mount. Hope it works.

A new rod challenger

hillexed@email.com (hillexed) — Tue, 11 Jul 2023 15:49:23 +0000

Update: I’ve learned about the existence of EMT conduit, which is steel so it’s much stiffer, cuttable with a handsaw, and most importantly way cheaper than the aluminum tubes I bought before!

The downside is it’s sized in nominal diameter, which means lying. The size “1/2 in” has an outer diameter of 0.706 in. But I’ve faced nominal diameter before and this time I’m prepared. Let’s try this.

Telescope mount v2: complete!

hillexed@email.com (hillexed) — Wed, 05 Jul 2023 21:50:20 +0000

It didn’t work. The main type of wiggling I was trying to stop is the top part twisting around the z axis compared to the bottom part. This new mount stood up well, but if I placed the telescope on the mount and gave it a sideways nudge, the telescope would wiggle from side to side at a period of about 1/4 s. It does seem less wobbly than my previous square mount, but it’s still pretty wobbly.

On the plus side, I added little degree markers so you could see what elevation your telescope is pointed at. I like them.

I’m stuck as to where to go from here. How do I change this design to make it more rigid? I’m out of ideas. Maybe the wooden dowels are too flexible and I need to buy aluminum rods? But I can’t cut aluminum to the right size. Damping exists as a theoretical idea, but how do I add some in practice?

Telescope mount V2 construction begins!

hillexed@email.com (hillexed) — Wed, 05 Jul 2023 17:22:59 +0000

Starting to build telescope mount v2! I’m using 0.5in rods, and v1 had holes 0.52in wide. This one has holes 0.51in wide, and that was a mistake, it made getting the rods in there so much more annoying.

hillexed@email.com (hillexed) — Tue, 04 Jul 2023 18:33:15 +0000

I was unsure about how to model this part to make it non-wobbly so I looked up and watched a full lecture from MIT OCW about vibration reduction. it didn’t really help but now I understand that when you bend a stick, the outer part expands and the inner part shrinks and so by making bigger areas farther from the bending (weird) you can resist shrinking and growing a bit more. how do I apply that to a complicated multi-beam twisting telescope part? unsure

Triforce of Space

hillexed@email.com (hillexed) — Tue, 04 Jul 2023 01:55:19 +0000

Telescope mount v2 has 3/4 pieces printed! The pretty colors are because I ran out of filament twice

hillexed@email.com (hillexed) — Sun, 02 Jul 2023 16:40:01 +0000

This redesigned telescope mount part is a good shape

It didn't work

hillexed@email.com (hillexed) — Sat, 01 Jul 2023 20:41:07 +0000

I put everything together for version 1 of my telescope truss mount. It stands! It was also an inch too wide for the telescope to properly rest on it. I had to rotate it the wrong way so it could fit on the stand for the picture. Aargh.

Some of the clamps did grip the rods well, some of the clamps didn’t. The base did feel pretty solid, but the top part is still pretty wobbly after full assembly. I’ve learned a few lessons:

Longer holes for more grab surface area
Add some holes to screw my mount into the floor, which will stop flexing in addition to being a requested feature
Right now I have 0.5in rods, and they’re fitting in 0.52in holes. If my mount is wobbly, maybe I should decrease the hole tolerance to 0.51in? It’s a tradeoff but may be worth it
Redesign rear base back grabber, it doesn’t grab properly
It’s 6.5 inches wide from outside to outside, not 7.5 inches. :(

Now, to design version 2!

hillexed@email.com (hillexed) — Wed, 28 Jun 2023 18:38:04 +0000

time to assemble

My telescope mount prototype is finished printing!

hillexed@email.com (hillexed) — Wed, 28 Jun 2023 18:23:59 +0000

Came out with some blobs and very stringy, which isn’t good, but they came off with some pliers. Time to go cut my dowels to size and see if it all fits

Designing a new mount

hillexed@email.com (hillexed) — Sun, 25 Jun 2023 20:53:32 +0000

My 3D printed telescope has a problem: it’s very wobbly. That means it’s hard to point the telescope at a planet and have it stay pointed at the planet. It also means I can’t focus it well, or take good pictures through my phone.

The telescope itself is fine, but the mount is the problem. There’s a 3D printed mount included in the files with the telescope, and I built that 3D printed mount (after trial and error and discovering pipe sizes are a lie ). However, the creator of the telescope doesn’t actually use the 3D printed mount - he has a mount made of solid wood. I don’t have a wood saw, so I can’t build that.

There’s another mount named Marci’s Mount, made by Marci, which involves using a vinyl record as a turntable so you can rotate the telescope along azimuth (very cool). It uses a sort of truss design with cross-braces to be even more stable, but you need a drill and a saw to use the turntable part. I don’t have either, which is a shame because it seems like a very cool mount.

I decided to try making my own mount. Halfway through studying that one, I discovered a third mount which is very clever and uses more rods to make a truss shape for extra stability. It also uses a clever screws-squeeze-the-plastic design to have more surface area grabbing the rods for more friction.

My plan now is to make my own mount, copying Ivan’s truss design but increasing the size of the bottom part for added stability. Hopefully that’ll make a more stable telescope!

hillexed@email.com (hillexed) — Fri, 23 Jun 2023 19:12:05 +0000

I woke up early and saw Jupiter and Saturn!

Thoughts on the observing: I have two eyepieces, a high power 6mm and a low power 25mm. I couldn’t get a picture of the planets with my high power lens because my mount is too wobbly and I couldn’t find the planets once I mounted my phone on the telescope. I did see Jupiter through it amidst the wobbling, and it looked like a featureless white blob. I could barely make out some stripes, whichwas cool!

To get at least some pictures before the sun rose, I switched to my low power lens. Using that, I found Saturn! And as the sun began to rise, I switched back to Jupiter, and I could see it as just a big round bright circle… but also with some of the Galilean moons next to it! And then morning clouds rolled in and covered everything and I went home.

Instead of taking pictures, now I’m taking videos so I can extract the good frames afterwards. I took a video of Saturn while trying to focus the telescope, hoping I’d get a good level of focus somewhere. Turns out my phone’s autofocus didn’t like Saturn and kept trying to focus incorrectly.

What that means is: as cool as these photos are I need to aim my telescope better, I need to focus better (I did find the button to turn off phone autofocus!), and if I do that, I can get even better photos with the higher powered zoom lens! There’s a ton of potential for improvement.

hillexed@email.com (hillexed) — Tue, 20 Jun 2023 08:34:18 +0000

I woke up early to go see Jupiter and Saturn and turns out it’s still really really hard to align this telescope! I took videos in the hopes I’d catch at least one good frame, now to review them and see if that’s true. I got a decent video of Saturn in my low power lens, hope it shows up well as rings instead of fuzzy blob

Moon Nyoom

hillexed@email.com (hillexed) — Sat, 03 Jun 2023 16:42:31 +0000

With all those upgrades, I was able to mount my phone to my telescope. Recently, the moon finally reached the right phase for it to be visible, so I got great shots of the moon!

With my 6mm high power lens, the moon was super duper detailed. And I realized something amazing: the moon was moving. I was so zoomed in I could see the rotation of the earth! That’s incredible!

Now that my phone is mounted, I don’t have to manually hold it up to take a picture, meaning video became possible. To my amazement, 3 minutes was enough for the moon to enter and exit the telescope’s view. I took a video and made a timelapse:

It’s one thing to know the earth is rotating. It’s another thing to see it with your own eyes. The universe is so cool.

Telescope upgrade 2: Electrical tape and openocular phone mount

hillexed@email.com (hillexed) — Thu, 01 Jun 2023 15:05:23 +0000

(Part 3 of my adventures with my 3D printed telescope! Previous part)

I tried adding 3 upgrades, but only two of them worked. Check out an amazing moon photo below!

Upgrades

My mount is very wobbly. To reduce the wobble I had two ideas: first, place wooden dowels along the diagonals of the sides to make the mount more rigid, and second, print an openocular.com phone holder so I didn’t have to touch the telescope to take pictures with my phone and wobble it.

I bought three more wooden dowels, then I designed two versions of 3D printed pieces to hold the diagonals in place. After printing, they didn’t fit my base. I forgot to account for the fact that there were plastic parts at the top and bottom of the pipes that would stop me from attaching them there. In the end, I just taped the dowels to the mount using electrical tape. I think it worked pretty well to make the telescope rigid, but it didn’t stop the wobbling.
The openocular.com phone mount is a 3D printed piece that lets you place a phone up to an eyepiece. That works for me, because that means I can place my phone in there then step back and the telescope’s wobbles will settle down! It still wobbled, but the wobbles died down after a while. Nice.

The mount itself is very fiddly, and it doesn’t help that if I see black through my phone, I can’t tell if the mount is aligned wrong and my phone isn’t pointed in the eyepiece, or if the mount is aligned correctly and the telescope is just pointed at dark sky. It’s also hard to focus with the mount on because the phone will also try to autofocus.

The open ocular and eyepieces are heavy, and plastic on plastic is slippery. If I put the open ocular on, the entire telescope rotates down because of the weight. To fix that, I unscrewed and adjusted the position of the center piece on the rods until it balanced. But I also added some electrical tape to the curved circular rockers, to make it less slippery, and that was a massive improvement. Now the telescope stays in place much better. I wholeheartedly recommend doing this.

Using all these upgrades, I took this picture of the moon using the phone mount.

Wow! You can see so many craters!

Telescope upgrade 1: basket

hillexed@email.com (hillexed) — Fri, 26 May 2023 21:59:57 +0000

(Part 2 of my adventures with my 3D printed telescope!)

I printed a collimation helper and a basket! The collimation helper helped me find out that I thought I was collimated, but was actually misaligned. With proper collimation, I went out again and took this new picture of Venus.

To the eye, collimation didn’t seem like it did anything, because my telescope and its mount was just so wobbly it looked the same to the eye as before. But my phone pic definitely seems better - now you can see the waxing gibbous shape instead of bright dot. Don’t know why.

I also found out “open ocular” is a 3D printable mount to hook a phone up to a telescope. I’m making one now. Hopefully that’ll help make it less wobbly?

One imposter remains

hillexed@email.com (hillexed) — Sat, 13 May 2023 05:21:48 +0000

this entire journey started because I could only find 3-packs of aluminum pipes and needed a fourth. What a story this frame has

Aiming

hillexed@email.com (hillexed) — Mon, 01 Jan 0001 00:00:00 +0000

My Hadley has two upgrades that help it aim.

Finderscope

The first upgrade is an 6x50 finderscope that says “orion” on it. I found it in my local astronomy club’s shelf of spare parts, bought it for $10, and designed a 3D printed adapter for it to fit onto my Hadley. It features integrated crosshairs and helps me aim at planets at a glance!

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Sliced Pifinder

The second upgrade is the Sliced PiFinder. It’s a targeting computer that permanently lives on my telescope - which is an incredible sentence. We truly live in the future.

Unable to find image pifinder/3810526-pifinder-complete/IMG_20231208_190024848.jpg

Unable to find image pifinder/3810526-pifinder-complete/IMG_20231209_145050722_1.jpg

Unable to find image pifinder/3810526-pifinder-complete/IMG_20231208_204635840_1.jpg

The PiFinder is a device that uses a raspberry pi and a camera to take pictures of the sky and compute where in the sky your telescope is aiming, even with high light pollution. Since it knows where the telescope points, you can select a particular galaxy or nebula and it will tell you how to push the telescope to get there.

PiFinders are an open-source project that can also be bought for $500 from the designer. Mine was built for $110 - a mere slice of the cost. The stock PiFinder is designed for a Raspberry Pi 4 using the Raspberry Pi High Quality Camera ($50) with a $50 lens, but I 3D printed and assembled the parts myself, used a scavenged battery pack and previous-generation Raspberry Pi 3 from a defunct project, and a $30 IMX462 camera and $12 lens.

Fixing the Astigmatism

hillexed@email.com (hillexed) — Mon, 01 Jan 0001 00:00:00 +0000

When I tried to focus my Hadley on mars, I couldn’t see very much. It looked like a blob.

When I looked at Saturn, I noticed a sort of double-saturn effect.

The Hadley’s default telescope mount was very wobbly. I assumed that the pattern I was seeing of two saturn images was actually one Saturn image vibrating back and forth quickly.

Based on this assumption, I designed a much stiffer truss mount. Inspired by Ivan’s open-source Hadley mount which used a truss design but sized for metric screws and rods, I designed a printable Hadley mount focused on a truss design to reduce wobbling and cheap EMT steel tubing. While the Hadley used aluminum rods that cost $30 for 9 feet, one 10-foot tube of EMT cost $7! Eventually I open-sourced my design; it’s available to download for anyone who has a Hadley!

After spending a long time building my design… Every star still looked like two points close together when viewed through the Hadley.

Undeterred, I redesigned the mount to be even stiffer; going through three iterations of increasingly stiffer mounts and even adding cross-bracing.

I took a look… still double saturn.

It took looking at the double-double in Lyra to figure out the issue. I should have seen two clusters of two stars. I did see two clusters of two stars - but each cluster seemed to be aligned the same direction. That direction didn’t match the star charts - and it didn’t even match the direction that my telescope should have been wobbling in. My “extremely fast vibrating” wasn’t vibration at all.

The problem? Astigmatism in my primary mirror. The Hadley telescope relies on a $30 cheap chinese mirror, and not all mirrors are made equal. I had bought a mirror off a random vendor from Amazon, and instead of a perfectly spherical shape, my mirror focused light to two slightly different places. As confirmation, removing the lower optical assembly containing the mirror and putting it back on rotated 120 degrees rotated the abberations.

Eventually I reported my findings to the Hadley discord, and Zane Landers offered to ship me a replacement 4.5" mirror. Saturn has looked sharp ever since.