My attempts at astro imaging

Observatory Automation

Well, I have been a busy astro imager……  This past couple of months I have been hard at work trying to automate the observatory 🙂

First up was to get the roof done, I bought a garage door opener from Ebay and somehow managed to shoe horn it into the observatory, TBH it was a lot easier than I thought it would be…. The opener has a metal track that comes in three sections, 2 sections was perfect to have the motor stuck on a shelf in the warm room and the track the full length of the cold room.  I also did a bit of work on the roof – previously the roof had some castors that rolled along a routed bit of wood, this was far from ideal, the wood was not perfectly square, neither were the castors, basically it worked but was very hard to operate. I got hold of some metal ‘V’ track used for electronic gates, such as you would have at the end of a driveway and the the rollers to go with the track. This means the rollers sit on the groove on the track. This was the hardest part, getting the track fitted but eventually with the help of one of my neighbors we managed to do it without lifting off the whole roof (which is very heavy, its a 3 man job to get it off and on). Anyway, now I can move the roof open and shut with a single finger 🙂

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So… Back to the opener, I fitted that, cut the belt that was too long as I was only using 2 lengths of track and away it went! press the button on the remote and roof opens!

This was good but not good enough, the plan was for me to be able to open, start imaging and close at the end, the remote just allowed me to open and shut the roof… I invested in an Arduino, which is basically a small computer, that has a number of inputs and outputs, all controllable by software. Now it just so happens that I moved job a couple of years ago and have been learning the art of C# programming so I set myself the task of writing a small application that would ‘talk’ to the Arduino and allow me to open/shut the roof, power on/off the mains to the scope and camera and park/unpark the mount.  I also wanted to know when the roof was open and when it was shut so that (hopefully) I could set an imaging run off, go to bed with an alarm set, waken up and close everything down, secure in the knowledge that the roof was closed.  To do this, I ordered some of those magnetic contacts you have on windows and placed them at both ends of the track, the idea being that the trolley that pulls the roof along would have a magnet stuck to it which would trigger the contacts and let the software know the roof was open/shut. This however did not work – the repeat-ability of the trolley is not 100% and often the roof would be open but the contact not triggered, another solution was required….. This time, I went for a couple of microswitches, and this works a lot better!!

Back to the software….. So I have a little bit of code in the Arduino, this sets certain outputs high or low, I have one output connected via a relay to the roof opener contact (Now I dont need to use the remote, just the button on my c# app), another via a second relay to the mains power and 2 inputs that are connected to the microswitch at each end of the track.  The inputs are read and if it detects the roof is open, a word is sent over the USB bus to the C# app, the same for the roof closed, mains on etc etc  The c# app, runs on my imaging laptop, I can manually open/shut the roof, power the mains, connect to the scope etc, or I have a couple of buttons that do it all – click a button, the roof opens, the scope unparks, click another, the scope parks, then the roof closes – nearly everything needed for remote imaging, I already have full goto with plate solving, the last piece is auto focusing…..

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Auto focusing – the final piece of the jigsaw!

So…. I bought another arduino, this time a mini one, and got a good friend to build a little plate to allow a stepper motor to be mounted on my focuser, I then connected it to the Arduino and installed the SGL Focus Software – this worked a treat, more or less straight out the box! I had to hard code the speed into it but other than that it allowed me to focus from my laptop, although…… I really wanted this automated too, so I downloaded FocusMax and after much messing about with it’s settings (Its not the easiest to understand, and I think it was more by luck than anything else that I eventually got it working) I now have auto focusing working!!!

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So… the workflow is now….

Use VNC to remote into the observatory from the warmth of the house 🙂

Power on the Telescope and CCD

Connect to the Telescope

Click the button on my app to open the roof and unpark

Start CCD Commander

enter the co-ords of a star to focus on

goto star and plate solve

focus on star

goto target

plate solve

find guide star and start guiding

Start Imaging!!!

Whats next???

Well… I want to redo the app, in fact I am in the middle of it now – basically it works but is not written well. As a training exercise I am rewriting it properly! I will also control a red light in the scope room and a white light in the observatory warm room, I also have a rain sensor that I need to wire up as well.  Finally, I would really like to try some fancy stuff, have it send me a text message if a guide star is lost or if it starts to rain – but all thats really a job for next year I think!


One response

  1. Great write up 🙂 I’d be interested in any wiring schematics you have for this….also are you making your software available 🙂

    Keep up the good work!

    July 26, 2014 at 10:35 am

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