DSOs with an ASI178MM

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Joined: Tue Jul 12, 2016 10:42 am

DSOs with an ASI178MM

Post by Coastliner » Tue Jun 30, 2020 6:08 pm


I am imaging DSO with my ASI178MM for the first time as I am trying to move away from DSLR.

Things are going reasonably well, but I am having problems with removing the amp-glow using Darks.
The ASCOM offset/gain I am using is 25/200, although the gain is reported as 90 in the FITS header.

I am using 240s exposures with temperature and exposure matched darks, but I am still left with small black areas in the two brightest corners, the "starburst" pattern in the other corner seems to be supressed quite well.

My theory is that using long exposures causes the amp-glow to saturate the sensor in the corners, this saturation not being removable with darks.

Is this correct? What would be the optimal gain/offset settings to use for long-exposure photography for this camera?

The image shows the blown out corners bottom left and right, with the starburst top right almost removed.

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