Wednesday, March 3, 2010

The other Leo Triplet

Tonight was a spectacular night at the Lost Pleaid Observatory.  A very mild day with little change predicted in the weather over the next few days (due to a high pressure system) resulted in skies that were steadier than they have been in some time.  On a scale of 1-5 with 5 being perfectly stable, tonight was a 4 at the worst moments and at times the seeing ranged to an almost perfect 5/5.  With several hours of dark skies before moonrise, I decided that I would push the limits of my 5.5 inch refractor a bit and observe some galaxies.

Before the serioius hunting started, Ian joined me in the observatory which is a rare pleasure for me.  I showed him the great orion nebula (M42) and the trapezium stars, and he remarked that the A through D stars were in the shape of a butterfly- I have looked at this group of stars countless times yet I have never noticed this.  Maybe we should observe with kids more often!  I also showed him M82 (the Cigar galaxy) as well as the very pretty open cluster M46 which has a planetary nebula (NGC 2438) superimposed on the cluster.

The constellation Leo (The Lion) is home to many galaxies.  So many in fact, that under dark skies one can literally get lost observing them!  Observing galaxies in this constellation requires a good star chart and the one that I prefer to use in the observatory is Sky and Telescope's Pocket Sky Atlas.  It is spiral bound, easy to read under a red light, and contains just enough objects to keep one busy for years.  It is also cheap, which is a rarity in this hobby.  Copies can be found for approximately $15.  I like this atlas so much I have actually purchased additional copies to give to other amateurs as gifts.  Certainly one needs a star atlas that goes deeper, however this atlas is suffiecient for 95% of my observing.

Leo is home to a famous grouping of galaxies called the Leo Triplet.  The triplet consists of M65, M66 and NGC 3628 and can be seen in the photo to the left.  I was observing these galaxies tonight and decided to take a look in the atlas and see what other targets may be nearby.  I turned to the page where I would find Leo and started to look near Regulus (the brightest star in Leo) and the famous sickle pattern of bright stars.  I immediately noticed NGC 3190 and NGC 3193 sitting just east of Algieba, the third brightest star in Leo.  As these galaxies are approximately 11th magnitude I knew that they would be a challenge in my refractor, but as they were not large, they should be visible.  I pointed the scope at the coordinates and was rewarded with a view of these interacting galaxies.  After observing them for a few minutes I decided to make a sketch.

Instrument: TEC 140 APO        Eyepiece: 8mm (122x)
Time of sketch 0350 UT, March 4, 2010

                   NGC 3190             NGC 3193
RA:             10h 18.1m              10h 18.4m
Dec:            +21 deg 50 min      +21 deg 50 min
Mag:           11.2                       10.9
Size:            3.5' x 1.4'               2.2'
Distance:     53 million LY          56 million LY

After making the sketch, I decided to take a look on the internet to see what was out there on these galaxies.  To the right is a photograph of the galaxies from the Sloan digital Sky Survey.  Not that interesting, I'll admit.  However, I did turn up the image below (credit: Adam Block/NOAO/AURA/NSF ) which is absoultely stunning.  Not only are NGC 3190 and 3193 featured, but a third galaxy, NGC 3187 is in the field.  Hence, the title of this post, the "other Leo Triplet."  I would highly recommend you visit the source of this photo where you can view a high resolution version of this image.  And if you own a large scope, you can observe all three of these galaxies!

No comments:

Post a Comment