A new processing of M109

My previous processing of M109 – 360x60s – did not turn out well. Serious issues with noise, most likely calibration files that were not ok.

So I did a complete re-build of the calibration files darks and bias.

The resulting stack and processed image is noticeably better:

M109, 360x60s Gain 0 Esprit120 F7 ASI2600MC Darks, Bias

M109 galaxy in Ursa Major

This galaxy lies very very close to one of the bright stars of the bowl.

An integration on several nights with 60-second subs at gain 0. This resulted in a lot of (read-?) noise. I should experiment further with Gain 100.

M109 Ursa Major Esprit 120mm F7 no flattener ASI2600MC 360x60s Gain 0 Offset 50 no flats ; darks, bias

M109 again, with the C11. With the ASI183mm

This is such a nice galaxy! Spiral arms and a central bar, beautiful! After the attempt to image it th elast nights with the C11 & Nikon, again a few nights (nights are short!!) now with the ASI183mm.

Th epixels are a bit small, and the C11 ‘s output is oversampled. In that respect the Nikon’s larger pixels (5µ) make more sense. However, this really worked out more acceptable then the previous attempts.

Using SIMBAD, you can identify some of the smallest and faintest patches in this image. SDSS J115703.88+532414.6 was about the faintest one with a listed green band magnitude of 20,893! The image itself measure 20′ x13′ end has a resolution of 0,6″ per pixel. Seeing was rather bad these nights, with nortwest sea air blowing over. Very clear however, with SQM 20,40 on average.

The C11 was guided with a 8×50 finderscope, using an ASI290MM. Autofocus was done using an Esatto 2″ focuser.

M109 3,8 hours LRGB C11 ASI183 Meldert May 2020
Searching the limiting magnitude
Astrometry from nova.astrometry.net