David's Astronomy Pages Notes - Session 310 (2008-10-04) Notes (S306)   Notes (Main)   Home Page   Notes (S316)

Goto Images from 2008-10-04

Analysis of automated guiding performance - HD 209458

Automated guiding between frames was active during a time series run from HD 209458, involving run of 100 frames (20s exposures) over a 82 minute period. 

Routines automatically selected the brightest star in the image as the guide star, this was HD 209458 itself (Mag +7.6) 
An position error threshold of 0.5 pixels relative to the first image was used to make trigger guide corrections.

Analysis of 100 frames over the time series showed that the average pointing error from the mean star position was 1.56 pixels   This is equivalent to 3.8 arc secs. This contrasts with an average FWHM of 4.9 arc secs over the run. 

Qualitative Analysis of autoguiding performance

Image below shows simple stacking of 100 frames from a 54 min time series run No alignment of images has been performed.  The image shows some bloating of stars and impact of some rogue seeing/guiding miscorrection/failures  but there is clearly no major star drift (Unguided there would be noticeable star drift over an interval of 54 minutes)

Stacked CCD Image (Non-Aligned) 100 x 20s exposure (average combine), 2x2 binning, V filter,   2008-10-04 23:53h UT (#310222-321)

Image below shows aligned image stacking of the 100 frames  Alignment of images has been performed.  The stars are sharper in this image compared to the non-aligned image above. but the difference is not that great and shows the obvious success  of autoguiding between frames

Stacked CCD Image (Aligned before stacking) Image details as above

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Automated Slew & Jog Positioning Performance (S306) 

Analysis of data from session S310 shows that Pointing Error after slews was generally less than 5 arc minutes  mean 2.4 arc mins), with final pointing error after jog positioning consistently less than 0.6 arc minutes (mean 0.5 arc mins).

See earlier analysis of Slew and Jog Positioning performance from session S297-S305

Graph showing analysis of Automated Slew/Locate Positioning performance (2008-10-04, S310)

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