Clusters by the Light of the Moon

by Tom Campbell


STARLOG

April 26, 2004

ObserverTom Campbell
LocationIola, Kansas (Long: 95°24'W Lat: 37°55'N)
EquipmentDiscovery 8" DHQ dob
Time9:00pm - 10:30pm CDT (02:00-03:30 UT)
TransparencyClear (8/10)
SeeingMostly Stable (7/10)
WeatherTemperatures in the lower 50s. There was little or no breeze.

Observing Summary
GEMININGC2129, NGC2395, NGC2420
VIRGOM104

I've been wanting to view a few Herschel open clusters in Gemini, but the weather and my schedule hasn't been cooperating. Tonight, the nearly First Quarter moon was in Gemini, but the sky was so clear, I decided to give it a try anyway.

NGC 2129GeminiOpen Cluster9:00pm CDT
RA: 06h 00m 42sDec: +23° 19'Mag: 6.7

This cluster contained two bright stars and several fainter ones. The brightest star had a slight yellowish color. The overall shape of the cluster reminded me of the letter D, and was best viewed at 122x. Most of the stars were along the border of the cluster.

NGC 2395GeminiOpen Cluster9:15pm CDT
RA: 07h 27m 12sDec: +13° 37'Mag: 8.0

The overall shape of this cluster was triangular, with faint stars scattered randomly throughout. Perhaps a dozen stars were seen with averted vision. Perhaps due to its faintness (or the brightness of the nearby Moon), this cluster was disappointing.

NGC 2420GeminiOpen Cluster9:30pm CDT
RA: 07h 38m 24sDec: +21° 34'Mag: 8.3

This cluster appeared rich, with several stars packed into a rather small area. I have added this to my list of things to observe when I have a darker sky. The shape was fairly circular.

M 104VirgoGalaxy10:00pm CDT
SombreroRA: 12h 39m 59sDec: -11° 37'Mag: 9.0

I saw Corvus peeking above the tree line, and decided that before I headed back inside, I'd take a look at M104. Tonight, I noticed on my star charts that there was a chain of bright stars leading from Gamma Corvi to M104, so I thought I'd try this new route of starhopping tonight. Sure enough, at low power, each star along this "Sombrero Highway" was just about one FOV away from each other. The last "star" in the chain was actually a Sagitta-shaped asterism which pointed right to the galaxy.

The galaxy's dust lane was very noticeable, as usual, but the seeing was getting worse so that the galactic core "below" the dust lane was only visible occasionally with averted vision. Regardless, this galaxy always impresses me. The best view tonight was 81x.

A few weeks ago, somebody on one of the Internet astronomy boards stated that he mounted an indoor/outdoor thermometer to his telescope, to determine when his mirror had cooled down sufficiently. I did the same thing, and it was fascinating. The seeing started out pretty decent, but worsened as the night wore on. Checking my thermometer, I noticed that the outdoor temperatures were dropping faster than my mirror was cooling. What started out as only a 2° temperature difference when I started had increased to about 6° when I finished up! Add to that the fact that the relative humidity (my thermometer shows that, too) had climbed to 76%, and it was little wonder that the seeing was getting worse.


Posted on starrynights Apr 27, 2004 20:29:13 PT
Converted by report.pm 1.1 Jul 10, 2004 22:48:16 PT