Object of the Week April 21, 2013 - M51

[Howard B]

The Whirlpool Galaxy, NGC 5194–5195, Arp 85

Canes Venatici

RA
13h 29m 52.7s

DEC
+47° 11′ 43

Type: Interacting galaxies, B magnitudes 9.0 and 10.5

168 years ago, in April 1845, Lord Rosse discovered the spiral structure in M51 so I propose we honor Lord Rosse’s landmark discovery by not only appreciating the overall structure and beauty of M51 but to delve deeper and enjoy some of its more elusive delights, such as:
1. The dust lanes that define the inner edges of the spiral arms are much more subtle than photos suggest and require the most transparent nights to see. But not the darkest – my best view of them was on a 21.25 SQM night at 7200 feet with superb transparency.
2. The super star clusters near the core appear stellar at high power and help define the two-pronged beginning of the southern spiral arm. It takes steady seeing and high power for these tiny glimmers to sparkle into visibility.
3. HII regions help define the brightest parts of both spiral arms. I've found that high power is best even if the seeing isn't very steady.
4. The spiral arm spurs that connect the northern and southern.
5. Following both spiral arms all the way into the core is more difficult than I thought, again needing exceptional transparency.
6. How many of NGC 5195’s tidal tails can you see?
7. Has anyone seen IC 4277 as an edge on background galaxy? What magnitude is it? I've barely been able to see its core just east of NGC 5195.
8. And my new favorite, that until recently I assumed was an HII region of NGC 5195. Jimi pointed out it’s actually a distant background galaxy, 2MASXi J1330023+471654. I tried unsuccessfully for the past three years to see it with my 28 inch scope – so it’s not shown in my sketch - but Jimi, Steve Gottleib, Jim Chandler and I saw it through Jimi’s 48 inch earlier this month. Has anyone else seen this surprisingly elusive galaxy through NGC 5195?

M51 for Hawaii presentation.jpg M51 for Hawaii presentation_inverted.jpg

M51 OOTW_4-21-13.jpg

“GIVE IT A GO AND LET US KNOW”
GOOD LUCK AND GREAT VIEWING!