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On a more sour note reviewing the LX200 and LX200GPS driver show the LX200 driver *may* have outdated protocols.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*

Success With Astrometry.net

For some uknown reason Astrometry's image2xy doesn't like the images that we are producing from our CCD.

Finally a bit of success, we are now extracting RA and DEC from our exposures using Sextractor. YAY!

Our Image (Smaller FOV)

SDSS Image

Problems as of 7/22/12

 Currently things don't seem to be so bright. We are still having issues and have spent a lot of time yet it seems little progress has been made.

There are two main issues that are really bugging me that we are working on.

1. Astrometry.net

Currently it seems that astrometry.net will pick up on any noise generated via the CCD. This leads to astrometry.net finding 10,000+ points of interest and taking forever to find a match between all those points.

Wildi thinks it is something to do with sextractor, which I agree. Will be tweaking this.

The significance of this is without astrometry.net we have no pointing feedback/correction loop and are at the mercy of our Meade fork, which is already giving us problems.

2. Autofocus

This is the last software piece preventing out fully autonomous setup. Currently we do have a convergence in determining the optimal focus position. There is a problem with the autofocus software communicating with the focuser via RTS2 xmlrpc helper library. Attempts to make the driver fail via direct xmlrpc or scripting lead to perfect behavior.

Also another issue is currently in play with what Wildi thinks is something to do with the python environment and using python 2.6.6, which I am in the process of updating.

Software

• Add user friendly GUI to control primitive features of the system - Website in progress
• Nagios setup to point to new devices- BORAT online, other devices still need work - Later when stuff is working
• FWHM minima calculations - TESTING, thanks Wildi
• Focus Driver doesn't update status while focusing, always displays idle.- FIXED

Hardware

• Serial card doesn't work, maybe setting in kernel- FIXED
• Motion sensor wiring done, just need to connect each sensor via breadboard/connectors - On Hold
• Boltwood sensor reporting clear skies as cloudy - In progress
• Fan need to be added to focuser/fan controller box - Ordered

 Security - ON HOLD

• Motion detectors need to be wired in and fully tested
• Need some minor integration with IR+ZM+Lights work in combination
• Bluecherry Capture Card module causing kernel panics, need to grab new version and compile 

FML :)