What Isaac Roberts Saw Without A Space Telescope

January 20, 2026 by Al Williams 44 Comments

Space telescopes are all the rage, and rightfully so. The images they take are spectacular, and they’ve greatly increased what we know about the universe. Surely, any picture taken of, say, the Andromeda galaxy before space telescopes would be little more than a smudge compared to modern photos, right? Maybe not.

One of the most famous pictures of our galactic neighbor was taken in — no kidding — 1888. The astronomer/photographer was Isaac Roberts, a Welsh engineer with a keen interest in astrophotography. Around 1878, he began using a 180 mm refracting telescope for observations, and in 1883, he began taking photographs.

He was so pleased with the results that he ordered a reflecting telescope with a 510 mm first-surface mirror and built an observatory around it in 1885. Photography and optics back then weren’t what they are now, so adding more mirrors to the setup made it more challenging to take pictures. Roberts instead mounted the photographic plates directly at the prime focus of the mirror.

Andromeda

Because it took hours to capture good images, he developed techniques to keep the camera moving in sync with the telescope to track objects in the night sky. On December 29th, 1888 he used his 510 mm scope to take a long exposure of Andromeda (or M31, if you prefer). His photos showed the galaxy had a spiral structure, which was news in 1888.

Of course, it’s not as good as the Hubble’s shots. In all fairness, though, the Hubble’s is hard to appreciate without the interactive zoom tool. And 100 years of technological progress separate the two.

Roberts also invented a machine that could engrave stellar positions on copper plates. The Science Museum in London has the telescope in its collection.

Your Turn

Roberts did a great job with very modest equipment. These days, at least half of astrophotography is in post-processing, which you can learn. Want time on a big telescope? Consider taking an online class. You might not match the James Webb or the Hubble, but neither did Roberts, yet we still look at his plates with admiration.

Cold Sensor, Hot Results: Upgrading A DSLR For Astrophotography

October 3, 2025 by Matt Varian 14 Comments

When taking pictures of the night sky, any noise picked up by the sensor can obscure the desired result. One major cause of noise in CMOS sensors is heat—even small amounts can degrade the final image. To combat this, [Francisco C] of Deep SkyLab retrofitted an old Canon T1i DSLR with an external cooler to reduce thermal noise, which introduces random pixel variations that can hide faint stars.

While dedicated astrophotography cameras exist—and [Francisco C] even owns one—he wanted to see if he could improve an old DSLR by actively cooling its image sensor. He began with minor surgery, removing the rear panel and screen to expose the back of the sensor. Using a sub-$20 Peltier cooler (also called a TEC, or Thermoelectric Cooler), he placed its cold side against the sensor, creating a path to draw heat away.

Reassembling the camera required some compromises, such as leaving off the LCD screen due to space constraints. To prevent light leaks, [Francisco C] covered the exposed PCBs and viewfinder with tape. He then tested the setup, taking photos with the TEC disabled and enabled. Without cooling, the sensor started at 67°F but quickly rose to 88°F in sequential shots. With the TEC enabled, the sensor remained steady at 67°F across all shots, yielding a 2.8x improvement in the signal-to-noise ratio. Thanks to [Francisco C] for sharing this project! Check out his project page for more details, and explore our other astrophotography hacks for inspiration.

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Learning The Basics Of Astrophotography Editing

June 12, 2025 by Bryan Cockfield 13 Comments

Astrophotography isn’t easy. Even with good equipment, simply snapping a picture of the night sky won’t produce anything particularly impressive. You’ll likely just get a black void with a few pinpricks of light for your troubles. It takes some editing magic to create stunning images of the cosmos, and luckily [Karl Perera] has a guide to help get you started.

The guide demonstrates a number of editing techniques specifically geared to bring the extremely dim lights of the stars into view, using Photoshop and additionally a free software tool called Siril specifically designed for astrophotograpy needs. The first step on an image is to “stretch” it, essentially expanding the histogram by increasing the image’s contrast. A second technique called curve adjustment performs a similar procedure for smaller parts of the image. A number of other processes are performed as well, which reduce noise, sharpen details, and make sure the image is polished.

While the guide does show some features of non-free software like Photoshop, it’s not too hard to extrapolate these tasks into free software like Gimp. It’s an excellent primer for bringing out the best of your astrophotography skills once the pictures have been captured, though. And although astrophotography itself might have a reputation as being incredibly expensive just to capture those pictures in the first place, it can be much more accessible by using this Pi-based setup as a starting point.

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Tracking Deep-Sky Objects

March 13, 2025 by Bryan Cockfield 2 Comments

Astrophotography, and astronomy in general, takes some fairly specialized tools and a high amount of precision. Setting up the equipment can also take a lot of time, especially for amateurs traveling to various locations with their equipment, so anything that can reduce the amount of time spent looking for objects and increasing the amount of time looking at them is a welcome addition, especially since nights where conditions are ideal for these activities can be rare. [Anton] developed this real-time tracking tool for deep sky objects (DSOs) to keep tabs on most of the interesting things out there a telescope can be pointed at.

[Anton] calls his tool the Nova DSO Altitude Tracker and gets its information from SIMBAD, updating every minute for a given location on the planet. With that location data, the program calculates altitude and azimuth for various objects and also helps the user keep track of other important variables like moon illumination and angle above the horizon. It also allows the user to highlight specific objects of interest, making sure they are front and center throughout the session. Each DSO can be selected from a list to display detailed information about it such as its path, time visible in the sky, and other properties.

To get the program running, essentially all that’s required is a computer capable of running Python and a display of some sort. From there it provides a quick view of the best objects to point one’s telescope or camera at without any guesswork. With all of the code available it shouldn’t be too much of a leap to do other things with the underlying software, either, such as tying it into a tracker of some sort like this DIY telescope tracking device we featured a while back.

DIY Open-Source Star Tracker Gets You Those Great Night Shots

February 25, 2025 by Donald Papp 15 Comments

What does one do when frustrated at the lack of affordable, open source portable trackers? If you’re [OG-star-tech], you design your own and give it modular features that rival commercial offerings while you’re at it.

What’s a star tracker? It’s a method of determining position based on visible stars, but when it comes to astrophotography the term refers to a sort of hardware-assisted camera holder that helps one capture stable long-exposure images. This is done by moving the camera in such a way as to cancel out the effects of the Earth’s rotation. The result is long-exposure photographs without the stars smearing themselves across the image.

Interested? Learn more about the design by casting an eye over the bill of materials at the GitHub repository, browsing the 3D-printable parts, and maybe check out the assembly guide. If you like what you see, [OG-star-tech] says you should be able to build your own very affordably if you don’t mind 3D printing parts in ASA or ABS. Prefer to buy a kit or an assembled unit? [OG-star-tech] offers them for sale.

Frustration with commercial offerings (or lack thereof) is a powerful motive to design something or contribute to an existing project, and if it leads to more people enjoying taking photos of the night sky and all the wonderful things in it, so much the better.

Amateur Astronomer Images Spy Satellite

September 20, 2024 by Bryan Cockfield 14 Comments

As anyone who’s looked at the sky just before dawn or right after dusk can confirm, for the last seventy years or so there have been all kinds of artificial satellites floating around in low-Earth orbit that are visible to the naked eye. Perhaps the most famous in the last few decades is the International Space Station, but there are all kinds of others up there from amateur radio satellites, the Starlink constellation, satellite TV, and, of course, various spy satellites from a few of the world’s governments. [Felix] seems to have found one and his images of it can be found here.

[Felix] has been taking pictures of the night sky for a while now, including many different satellites. While plenty of satellites publish their paths to enable use, spy satellites aren’t generally public record but are still able to be located nonetheless. He uses a large Dobsonian telescope to resolve the images of several different satellites speculated to be spy satellites, with at least one hosting a synthetic aperture radar (SAR) system. His images are good enough to deduce the size and shape of the antennas used, as well as the size of the solar panels on board.

As far as being concerned about the ramifications of imaging top-secret technology, [Felix] is not too concerned. He states that it’s likely that most rival governments would be able to observe these satellites with much more powerful telescopes that he has, so nothing he has published so far is likely to be a surprise to anyone. Besides, these aren’t exactly hidden away, either; they’re up in the sky for anyone to see. If you want to take a shot at that yourself you can get a Dobsonian-like telescope mostly from parts at Ikea, and use a bit of off-the-shelf electronics to point them at just the right position too.

A black motion system with two stepper motors. A green circuit board is fixed in a rotating cage in the center, and the entire assembly is on a white base atop a green cutting mat. Wires wind through the assembly.

Pi-lomar Puts An Observatory In Your Hands

November 20, 2023 by Navarre Bartz 5 Comments

Humans have loved looking up at the night sky for time immemorial, and that hasn’t stopped today. [MattHh] has taken this love to the next level with the Pi-lomar Miniature Observatory.

Built with a Raspberry Pi 4, a RPi Hi Quality camera, and a Pimoroni Tiny2040, this tiny observatory does a solid job of letting you observe the night sky from the comfort of your sofa (some assembly required). The current version of Pi-lomar uses a 16mm ‘telephoto’ lens and the built-in camera libraries from Raspbian Buster. This gives a field of view of approximately 21 degrees of the sky.

While small for an observatory, there are still 4 spools of 3D printing filament in the five different assemblies: the Foundation, the Platform, the Tower, the Gearboxes and the Dome. Two NEMA 17 motors are directed by the Tiny2040 to keep the motion smoother than if the RPi 4 was running them directly. The observatory isn’t waterproof, so if you make your own, don’t leave it out in the rain.

If you’re curious how we might combat the growing spectre of light pollution to better our nighttime observations, check out how blinking can help. And if you want to build a (much) larger telescope, how about using the Sun as a gravitational lens?

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