NGC 3938 is one of my favourite galaxies since I first imaged it in 2002 (at
that time with an 8" Meade LX200 and MX516 camera, 2x20m exposure, to be
found at http://www.slilge.de/MX512_img/3938-40gut.jpg.html ).
I imaged it in three nights in April, of which only the first had good
conditions (but I started late that night), the second had bad transparency
and the third had clouds which eventually made the autoguider lose the
guidestar.
After processing the new frames I had to find that my previous attempts from
2009 and 2007 were deeper, so I added them to the stack. That cost sharpness
and stars are not perfectly round any more, but the result is much deeper.
Taken from the middle of Berlin with a Meade 10" ACF/ C8 on a G11 mount,
Atik 383 and SXV-H9 cameras, 27x10m and 65x5m for Lum, 12x10m for RGB each.
http://ccd-astronomy.de/temp7/3938colourgut.jpg
Stefan