[ACP-282]  Calibrated guider images cause "impossibly clean image" error
Type Limitation
Priority Medium
Severity Minor
Component AcquireSupport library
Fixed In Version [5.1.10] 5.1 HotFix 10
Versions Affected [5.1.10] 5.1 HotFix 10
Severity Closed
Resolution Complete
Reported By Bob Denny
Resources Bob Denny
Start Date 11/4/2009

Description 
Under as yet undetermined conditions, full-calibration on guider images cause ACP's guiding exposure calculations to fail with the "impossibly clean" error. I have tested calibrated guiding on an ST-237 and found that it does nicely clean up hot pixels and removes the common high pedestal on the ST-237. Guiding works better. The problem comes when calibration removes the camera noise from the guider image, preventing calculation of SNR.

Comments
11/4/2009 6:49:13 PM   Bob Denny 

 

  SVN Comment
 

 

  Author
  rbdenny
 

 

  Repository
  svn+ssh://rbdenny@a2_svn_dc3/home/rbdenny/svn/astro/acp
 

 

  SVN Revision
  34
 

 

  Affected files
  /trunk/ACP Help/relnotes.htm (Modified)
/trunk/AcquireSupport.wsc (Modified)
/trunk/Script Components Master/AcquireSupport.wsc (Modified)

 

 

  Check-in comment
  Remove test for "impossibly clean" guider images. 
GEM:282
11/4/2009 6:41:02 PM   Bob Denny 
Code tested for ImageBackgroundMean < 1 and the image had ImageBackgroundMean = 0! There is plenty of noise in the image for SNR calculation. I should have been testing for ImageBackgroundSigma. But what the heck, I'll remove the test completely. The SNR calculations have a safety against division by zero, and that will clamp the guiding exposure at the user's minimum guide exposure interval anyway.