Observing note from March 14, 2004

by Mark Wagner

I was at Fiddletown over the weekend. Saturday night the sky was so-so, with intermittently good and poor transparency. The shadow transit on Jupiter early in the evening was very good, and views of Saturn at very high power were excellent. Sunday's late afternoon clouds cleared at sunset and the night was much better than Saturday in terms of transparency, although steadiness was a bit off.

My observing highlight was Sunday night when searching for NGC 4627. The galaxy is interacting with NGC 4631 (Arp 281, The Slug), a clearly disrupted edge-on spiral galaxy 15.5 x 2.7 arc minutes at PA 86 sb 13.1. Nearby is NGC 4656, also disrupted at 15.1 x 3.0 arcminutes PA 33 sb 14.5 - and also known as the Hockey Stick (or Crowbar) due to its distinctive shape.

When observing NGC 4631 I was tired from lack of sleep the night before. I could not help thinking I was seeing HII regions in two, and maybe even three or four places in the galaxy. I took the scope up from 102X to 294X and, waiting for the seeing and my eyes to settle, confirmed small knots of blue, glowing in the dark lane of the big galaxy. The thought that I can see star forming regions, similar to the Orion Nebula, in another galaxy 22.5 million light years distant amazes me. It gave the view of this galaxy a distinctly 3-D appearance.

I began wondering in which galaxies can we, in amateur telescopes, visually detect HII regions? M33, M101, M51... M82... ... NGC 6822... ...

Can anyone add to this list?

It was also astonishing that I was able to easily see NGC 4631 in my 10x70 finder. Easily.... its shape was obvious even with such small aperture.

Here is an image of the area:

http://www.ricksastro.com/DSOs/NGC4656-NGC4631_SXVH9_E160_4_5_03.jpg

Posted on sf-bay-tac Mon Mar 15 19:48:36 2004 PT
Converted by report.pm 1.0 Wed Jul 7 22:33:25 2004 PT