Astrometry.net Pointing Corrections

For a while it has been a little mystery on how RTS2 handles telescope corrections. With the help of Wildi it is actually pretty simple.

1. RTS2 takes an exposure, when complete imgprocess.py processes the image
2. This fires up Astrometry.net which begins calculations on the exposure to determine the center of the exposure
3. Once Astrometry.net finds the position a correction is generated by looking at the RA and DEC on the exposure header and calculated the difference from what Astrometry got. Think of it as a delta.
4. RTS2 reads this correction and stores it as WCORR (waiting corrections)
5. During next pointing (between exposures) RTS2 add WCORR  to the target coordinates and tell the telescope to slew to the new position thus correcting the telescope pointing.

RTS2 also has a correction threshold to ensure if the correction is extreme it will simply ignore the corrections. This would only happen if the RA and DEC of the exposure is wrong or if Astrometry.net matches the wrong coordinates (haven't experienced this yet).

In other news Astrometry.net solving in RTS2 now supports the use of Sextractor which seems to be better at selecting objects. (svn up people!)

On a more sour note reviewing the LX200 and LX200GPS driver show the LX200 driver *may* have outdated protocols. Especially for the parking commands. The LX200GPS drivers looks like it is a partial implementation.

With this being said our LX200GPS may still support older protocol commands which would be nice. If not will have to update the LX200 or finish the LX200GPS which might not be bad since the LX200GPS has extra features like sleeping and self defined home/park position.

*sigh*