Pi Zero Gives Amateur Astronomer Affordable Control Of Telescope

Like many other hobbies, astronomy can be pursued on many levels, with equipment costs ranging from the affordable to the – well, astronomical. Thankfully, there are lots of entry-level telescopes on the market, some that even come with mounts that automatically find and track heavenly bodies. Finding a feature is as easy as aligning to a few known stars and looking up the object in the database embedded in the remote.

Few of the affordable mounts are WiFi-accessible, though, which is a gap [Dane Gardner]’s Raspberry Pi interface for Celestron telescopes aims to fill. For the price of a $10 Pi Zero W and a little know-how, [Dane] was able to gain full control over his ‘scope. His instrument is a Celestron NexStar, a Schmidt-Cassegrain reflector with a 150-mm aperture, has a motorized altitude-azimuth mount. The handheld remote had enough room for him to add the Zero, powering it from the mount’s battery pack. The handset has an RS-232 serial port built-in, but with the level differences [Dane] just connected the Pi directly to the handset before the UART. Running INDI, a cross-platform astronomical instrument control library, he now has total control of the scope, and he can use open source astronomy software rather than the limited database within the handset. As a neat side trick, the telescope can now be controlled with a Bluetooth gamepad.

Astronomy and electronics go hand in hand, whether in the optical or radio part of the spectrum. We like the way [Dane] was able to gain control of his telescope, and we’d like to hear about what he sees with his new tool. Assuming the Seattle weather ever cooperates.

18 thoughts on “Pi Zero Gives Amateur Astronomer Affordable Control Of Telescope

  1. I was just looking around for something live this, I’m in the market for a telescope and was thinking of getting to to track satellites. Not sure if something like that exists yet, but need to get the telescope first

    1. I have the same mount, and mounted an antenna on it with a 2×4. At the time I just used it for GOES, but it also worked for meteor and the NOAA polar-orbiting weather sats

    2. GPredict claims to offer antenna rotation control, which I imagine could be hacked to control this sort of setup. I’ve never heard of anyone trying to track satellites optically!

      It seems like most scopes on the market these days are motorized. I’m not quite sure why people want to take the hands-on (fun) part of astronomy out of the equation, but at the last astronomy-themed events I’ve been to I didn’t see a single planisphere about, so I guess it appeals to a different sort of crowd to the traditional amateur astronomer.

      1. The reason most people want them motorized is for taking pictures. If I want to take a hour long exposure of something, I need the telescope to track with that object so I am not getting any streaks or anything.

        1. No, not necessarily, I have two alt-as mounts. One of which is the same mount as I this article. This mount is not a great imaging platform, but for visual use, a really good system. Once you get this mount aligned, which on its own is quite easy, you can go to any target in its over 40k object database….and in light polluted ares where you can’t see the sky that well with your eyes, this is a big deal. Celestron like other manufactureres have allowed technology to enhance the capabilities by connecting to computers via cable, WiFi, and using as com and Indi drivers. As I said the database in this HC allows you to go to over 40k objects and even add to that database. For visual use at a dark site, I have found a lot of satisfaction with this SE mount. It is light weight, easy to setup, and go to and tracking are well within reason for this mount.

      2. Planisphere? I think you’re going to astronomy events for the wrong reasons. :-).

        Seriously though many astronomy events these days have segregated areas for different groups who are into different things. Those who look through their telescopes, and those who take photos through them. For the former group motorised mounts make things far easier, especially at longer focal lengths where objects quickly move out of the field of view when mounts aren’t motorised. For the latter crowd motorised is not only essential, it’s also only the beginning which is precisely why these hand controllers have additional ports to interface computers or other equipment in order to properly track guide stars keeping the camera on point during 10+ minute long series of exposures.

      3. GoTo mounts are appealing to those in bright sky locations. It’s difficult to use a dob in a city when you can’t see anything but a handful of stars with your naked eye. Some like the thrill of the hunt to find things, others like to actually look at the things. To each their own.

        BTW, I’m the guy who did this hack, and I own a couple planispheres and several paper-based atlases that I use regularly with the featured 6SE.

  2. I wonder how Celestron is going to take this? This guy has basically shown people how to turn their $800 scope into one of their $1300 and up scopes for a fraction of the price. Plus there’s still more functionality to come going by the build log.

    On one hand he just made their mid-level scopes worth more because of the demand a hack like this will generate. More buzz usually equals more sales.

    On the other hand, Celestron can design the next generation of their controllers with DRM or some other kind of lockout and the game of whack-a-mole begins.

    1. Why would you wonder how Celestron is going to take this? Interfacing electronics into the Celestron provided RS232 port for telescope control has been a thing since long before the Raspberry Pi has existed. This is literally using a provided function for its intended purpose. The fact that it was scaled down and hacked into the controller itself instead of simply plugged into the bottom is irrelevant.

      There are commercial products which have done similar things since telescopes had electronic control. You’re also forgetting that these interfaces are pretty damn standard and the Astronomy community doesn’t really tolerate the breaking of standards very well.

      Personally I bypass the hand controller entirely and interface directly with the port on the mount.

    2. My bet is they welcome it. There are mailing lists, and even small businesses dedicated to this type of stuff. These types of “hacks” are as old as telescopes, and I’ve never seen a manufacturer do anything but try to make these modifications easier.

  3. This is very impressive, however this will void warranty on the scope, fine to do this but of warranty.

    Would love to see this open sourced if it hasn’t been already.
    I am not good with Arduino on coding so a nice copypasta would be nice.

    I don’t think Celestron will be displeased about this mainly because if you’re a idiot like me who doesn’t know how to code then they have people like me who buy the add-ons they and other companies sell.

  4. I use a Pi3 ( more horse power) with the Celestron 8se and an avx also. The Celestron drivers for indi are kind of buggy but they do work sometimes. But if they crash or you have to stop the server you have to realign the scope. I’m sure this will be worked out in the future but for an unattended automated observatory solution it isn’t quite ready for primetime. That being said having a low power tiny box or something i could put in the hand control is a game changer in the field. I used to have to take a decent laptop and bulky battery bank sometimes even another monitor to view guiding. I run this setup and it runs on very little power, all the necessary apps are in one place and i can remote into it from a phone, tablet or laptop. I usually use the tablet to keep an eye on the guiding when im imaging.
    It is good usful for visual observing as well the built in planetarium apps and ability to synch up with sky safari on a phone for gotos is a great tool. I was thinking about mounting a touch screen on my mount to omit the laptop and tablet altogether. Just point at an object get detailed information and go-to.

  5. Dan, Dan, Dan!

    Do us a favor and grab the data sheet for a uart and a max232, and put them side by side. Notice anything interesting like the max232 has a voltage doubler and an inverter, but the uart does not. here is why. The uart converts parallel (or bus signals) to serial, but does not change voltages, provide isolation, or provide high current drivers. the max232 is a rs232 driver chip that converts the system voltage (3 or 5 volt) to the levels specified by the rs232 spec.

    Bottom line he did not bypass the uart, he bypassed the line driver.

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