The ritention problem
CCD Camera: SBIG ST7E nabg (January 2002), Kodak Kaf-401e chip.


6 min exposure near Gamma Cyg, Meade 127ED f/9, chip temperature= -19°C.

6 min dark frame
Author of images: Alberto Brunati


Comet Ikeya-Zhang, March 23, 2002, 20 sec exposure, brightest part of coma: 8400 ADU (saturation at 50,000 ADU). Chip temperature= -20°C. [star shapes are big because the comet was only 2-3° above horizon!]

20 sec dark frame, captured after 2 min from the previous image. Mean of central part of the dark= 109,8 ADU, mean of adiacent parts= 107,0 ADU.
Author of images: Alberto Brunati, Lorenzo Comolli

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