M99 took me 6 nights (4 weekends). I had to drop about 60% to 70% of the subs due to non-circularity of the stars and cloud cover.
M99, also known as NGC 4254, Coma Pinwheel Galaxy, or the Virgo Cluster Pinwheel (Wikipedia is the source of the names). Following the same source -Wikipedia- it is speculated that this galaxy may had an encounter with another object, maybe NGC4262 which is a compact small but bright lenticular galaxy, about 280 million years. There is the other option, that it collided with a dark galaxy (dark galaxies are hypothetical at this moment), called VIRGOHI21. There seems to be a neutral hydrogen gas bridge between M99 and VIRGOHI21. Other hypothesis about this galaxy include ram-pressure stripping because it is just entering into the virgo cluster, and seems to have a high star birth rate even if it is not starburst type galaxy.
here are the settings:
- Edge HD 9.25 on CGEM
- UnMod Sony a7s
- Light Subs (6 hours 58 minutes 20 sec) 1255 x 20 sec Subs. Data from 6 Nights
- ISO 6400
- Calibration with dark, flat and bias images
- Registering & stacking with DSS 3.34
- Post-processing in PI with pseudo luminance layer in the second case and no pseudo luminance in the first one.
- Red Zone
- Also, some of data (from two nights) I catch NGC4262, which I stitched a section to created mosaic that includes the lenticular galaxy.
PS: I had not been able to match my two computer screens, so in one the color saturation looks to high, in the other it looks good. Let me know if it looks too saturated in color.