Residual Bulk Image Examples

Examples of RBI are shown below.

Download FITS files of these two images to see actual ADU counts

RBI example number 1: Dark exposure taken immediately after a sequence of 10 unfiltered exposures of 10 minutes each binned 2x2 (KAF3200ME sensor, no cover slip, -25C operating temperature). None of the image saturated during the preceeding exposures prior to taking this dark frame.

The dark frame above was dark-subtracted to better reveal the latent image. The dark used for subtraction had no bias so the bias offset remains in the RBI image above.

RBI example number 2: Dark exposure taken immediately after a sequence of 10 unfiltered exposures of 10 minutes each binned 2x2 (KAF3200ME sensor, no cover slip, -25C operating temperature). Several of the stars in the image saturated during the preceeding exposures prior to taking this dark frame.

The dark frame above was dark-subtracted to better reveal the latent image. The dark used for subtraction had no bias so the bias offset remains in the RBI image above.

 

------April 27, 2007 Update-----

The fix for RBI was tested. The fix consists of preflashing the array with a strong light and then flushing just prior to exposure (light or dark). The unstretched raw FIT data is available for download below. The images shown are stretched JPEGs to make viewing convenient.

The fix is 100% effective.

download FITS files

30 sec exposure, unfiltered, last of four consecutive exposures

First dark after sequence of four exposures above: RBI is apparent

30 sec exposure, fourth of sequence of four: preflashed and flushed prior to exposure

First dark after sequence of four, preflashed and flushed prior to dark, preceeding images preflashed and flushed prior to exposure. RBI is eliminated.

 

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