The size and diversity of the cosmos produces many wonderful features, of which M51 the Whirlpool Galaxy ranks highly amongst astrophotographers and is certainly one of my favourites.  Unfortunately, it is at the limit for my equipment and location, though in 2020 I was fortunate to capture over 16-hours integration time and a reasonable image (see here).  Whilst currently in the summer doldrums of limited darkness, I chose to process M51 data previously obtained using a Takahashi FSQ 106 located at Deep Sky West in New Mexico, USA.

Seen face-on from Earth, the balanced arms of this grand design galaxy contains dark dust lanes, blue star clusters and numerous pink star-forming regions rich in hydrogen gas.  But it is the cosmic dance taking place between M51 and its companion dwarf galaxy NGC 5195 that makes this such an exciting and popular object.

The most popular theory of what’s happening, is that the smaller galaxy is passing behind M51 and the joint gravitational forces are interacting between the two, resulting in the misalignment of stars and unusually bright blue and pink areas across the M51 galaxy.  Though not certain, it seems that their fates are inextricably linked and might eventually merge.  Whatever the process taking place, it will take millions of years if not longer to play out and is likely to provide this exciting spectacle for many generations of astrophotographers yet to come!

Whilst I was satisfied with my image obtained here in Surrey at Fairvale Observatory in 2020, there’s no denying that the data set from New Mexico is in a different league and was a pleasure to process.  Given the short focal length of both telescopes, Takahashi FSQ 106 (530mm f5) and William Optics GT 81 (382mm f4.72), out of the camera both set-ups inevitably produce a wide FOV but nonetheless pleasing images (see image above).  However, the quality of the DSW data holds up much better when cropping out M51 and its dance partner, thus showing off the aforesaid details of this dynamic and colourful scene to great effect (see top of page).   

    

	IMAGING DETAILS
Object	M51 Whirlpool Galaxy & NGC 5195
Constellation	Canes Venatici
Distance	23 million light-years
Size	Approx. 77,000 light-years (M51 only) ~10 arc minutes
Apparent Magnitude	-+8.4
Scope	Takahashi FSQ 106  FL 530mm  f/5  +  Moonlight Nightcrawler focuser
Mount	Paramount MyT
Guiding	Yes
Camera	QSI 683-WSG8    KAF-8300 full frame CCD sensor   5.4nm pixels
	FOV 1.94o x 1.46o   Resolution 2.1”/pix.   Image array 3326 x 2,507 pix
Processing	Deep Sky Stacker, PixInsight v1.8.9-1
Image Location              & Orientation	Centre – RA 13:29:55.31      DEC +47:11:41.608 Top Left = North
Exposures	L x 16, R x 18, G x 16, B x 17 @ 900 sec & -20o C Total Integration Time: 16hr 45min
Calibration	48 x 900 secs Darks   x47 Bias & x20 LRGB Flats
Location & Darkness	Deep Sky West – amateur hosting facility near Rowe, New Mexico  – USA    SQM Typically >= 21.7
Date & Time	January 2018