David's Astronomy Pages Notes - Session 316 (2008-10-18) Notes (S310)   Notes (Main)   Home Page   Notes (S324)

Goto Images from 2008-10-18

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. 

Comparison of Master Darks acquired two years apart Although visually similar note how the peak dark values are 21 ADU lower in the more recent image
Master Dark 180s S151  (2006-10-31)		Master Dark 180s S316  (2006-10-15)
Comparison of result of reducing a recent 180s raw image using  an old Master Dark acquired two years apart (left) and using a new Master Dark (right)  Although visually similar note how the image that has been reduced using the old master dark (left), leads to a large number of spurious 'stars' objects when Inventory is shown. The large number of invalid objects is probably why the image fails to link using usual source extraction settings.
W And with old master dark		W And with new master dark
180s exposure, 2x2 binning, B Filter 2008-10-04 (#310206) Reduced using Old Dark		180s exposure, 2x2 binning, B Filter 2008-10-04 (#310206) Reduced using New Dark
Image (old dark) with Inventory - CCDSoft Min Number of Pixels above threshold = 4 Detection threshold = 1.25		Image (new dark) with Inventory - CCDSoft Min Number of Pixels above threshold = 4 Detection threshold = 1.25

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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

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