ScopeDog mk3 edges closer

The digital finder is now working very nicely on my 18” Dobsonian. Celestron have a range of telescopes that use the technology to control their scopes, without the need for initial user alignments on reference stars. Would this work on my 18”?

A few quick experiments showed the concept is very viable. Without any initial alignment of my Dobsonian, I can push or drive the scope to a position, and within seconds the digital finder has worked out where it is pointing and sent the result to the ScopeDog drive to start tracking. This was done with some quick and dirty hack code. A proper solution is more difficult.

Currently ScopeDog uses Java but the plate-solving is most easily done with Python. Converting the java to python is proving to be fairly straightforward, and I am taking the opportunity to review some routines and make better use of ‘off the shelf’ astronomy code (PyEphem). Debugging is so much easier in Python too!

For now I am leaving the eFinder in its own box with dedicated Raspberry Pi. Eventually the eFinder code would go into the ScopeDog box - I’ve checked the Pi in there can cope with the extra workload. No Nexus DSC is needed (no encoders). Without a Nexus DSC, my ScopeDog needs its own gps dongle, and a direct connection to SkySafari running on a tablet or pc. These changes were easy although talking via code to SkySafari was a learning experience!

Anyone building their own ScopeDog (instructions start here) will be relieved to hear that the mk3 will be a firmware upgrade to a mk2. Realistically I need a year to fully complete and test the mk3, but if anyone wants to get involved early, contact me. (email on the first ScopeDog instructions page)

© AstroKeith 2022