Friday, October 11, 2013

More Calibration from Calstar 2013

With the past week, I've been working on calibrating the data from the starparty.  I've run into a few roadblocks.  Either there's not enough data, not enough good data, or bad data was gathered in the first place.

As noted in the earlier post, there are some star flares that appear and make for havoc in subexposures.  Removing these flares requires more good data -- there's just not enough good frames to balance out the bad ones.  For IC59, this means that I'll need to get up to Montebello and image at least 6 frames on the target. 

For other targets, like the horsehead, there's no content other than the flared data.  This means that at least 9 or more frames will be needed to fix it.  I've worked on the HH before, so I might toss this data in with that set for refinement. 

For targets like the Triple Cave, there are hot pixels that have made it past the calibration phase.  This is probably because the bad pixel map isn't robust enough to catch them.  I've tried to boost the strength of the DSS detection to catch them but it sucks out the inside of bright stars instead.  Now that I've fixed flexure to the level where it is now, hot pixels are being reinforced and without dithering it's hard to control them automatically.  I believe that the only way to remove them at this point is with a stronger bad pixel map during calibration.

And then there's focus.  Some pictures are so out of focus that they are unusable.  Temperatures were dropping so quickly during the evening that focus didn't settle.  Not much I can do about that problem!