Assault on the Beehive

by Randy Muller

On Saturday evening, February 9, 2002, I went up to my usual winter observing haunt in the Sierra Nevada foothills, about 90 minutes away by very scenic and historic highways and byways.

I decided to get up there a bit earlier than my customary time, to take some photographs during the day and give my mirror a little more time to cool down. The views later on were worth it!

Dennis Beckley (18") with his Significant Other and Gary Manning (16") were already there when I arrived. I was followed closely by Alvin Huey (22")and his friend Steve (16"). A short time later, Jane Smith (12.5") showed up, followed by Allan Keller (17.5") and eventually by Dave White (16"), Bruce Burke (10" SCT) and my coworker Francis Lau (10").

The photos Alvin and I took of us setting up are located at

http://groups.yahoo.com/group/tac-sac/files/MemberPhotos/FTown020209/

I began observing with a very abbreviated look at Jupiter. I could see several dark belts and the Great Red Spot was present, although the Great Red Spot Hollow was much more obvious than the Spot itself.

Assault on the Supernova

Dave White had a chart of supernova SN 2002ap in M74, and was looking at it in his 16" Starmaster telescope. It was easy to see the "Guest Star" in the field with some other mag 12 and 13 stars. It was a bit brighter (but not much) than most of these other stars, and it lay well outside the visible part of the diffuse spiral disk of the galaxy. It did not look unusual in any way, except that there had never been a star at that position in any photographs of that galaxy before, and there won't be a few months hence. But for now, there is.

Someone in the group questioned whether it was really part of M74, or whether it was simply superimposed on top of it (and actually in our own galaxy). I pointed out that if that were the case, it would be a LOT brighter than mag 13.

Although it looked exactly like a star, I think it's always interesting to look at supernovae, as transitory objects are typically limited to the solar system. It's also mind boggling to resolve a star that far away: The brightness and energy release are incomprehensibly enormous.

Later, I looked at it in my own 18" Starmaster. The view was noticeably brighter and easier to make out. The same was true for many other views I shared with Gary and his 16" Starmaster. They are of equal quality, and the only difference is the size of the main mirror. The secondaries are the same size.

The view in the 18" was always noticeably, but not significantly brighter and better. It's a clear tradeoff between bulk, weight and expense on the one side, versus slightly better views on the other side.

Assault on the Beehive

After finding only the brightest member of Hickson 22 (see below), I decided that atmospheric conditions did not warrant further searches for such faint galaxies, so I began discussing with Gary alternative plans. My primary plan is always to look for Hickson Compact Galaxy Groups, which are mostly extremely faint, and I never have a good backup plan when sky conditions go south.

I mentioned that I had Miles Paul's Webb Society monograph "Atlas of Galaxy Triples", but I felt that would be as challenging as the Hickson list. Gary mentioned that he had seen people mention finding galaxies in the Beehive Cluster (M44 = NGC 2632 = Praesepe = the Manger = "Gary's Cluster"). I also vaguely remembered some discussion of this somewhere.

We also discussed searching for galaxies in the Zone of Avoidance (perhaps more commonly known as "The Milky Way").

I finally settled on finding galaxies in the Beehive as an amusing pasttime, and pulled up a chart on my laptop. Setting the galaxy limiting magnitude to a somewhat conservative 15, I immediately noticed 4 galaxies that looked promising.

Since most open clusters are near the Milky Way, and since most galaxies are well away from the Milky Way (hence the term, "Zone of Avoidance"), it is unusual to find them near or overlapping each other. But M44 is well away from the plane of the galaxy (being relatively near to the solar system) and is located in a galaxy-rich area of the sky. In fact, all regions of the sky other than the Zone of Avoidance are "galaxy-rich", if you go faint enough.

The Beehive is so big that I cannot fit the whole thing in the field of view of my 26mm plossl, so I pointed into the center.

I based all my searches on a cute little house-shaped asterism near the middle of the Beehive consisting of two triple stars, a double and two singles. This asterism is visible in Burnham's Celestial Handbook on pages 344 and 346 of the 1978 hardback edition, and also in figure 4.5 on page 85 of Stephen O'Meara's wonderful adaptation of Walter Scott Houston's "Deep-Sky Wonders" articles. The wide double is epsilon Cancri (aka Tycho 1395-2733-1, Hipparcos 42556 and SAO 98024 for those keeping score at home).

The asterism looks like a house on its side, with the roof on the right side, consisting of the 3 double and triple star groups.

I began at the eastern edge of M44, and at 266x found a small, faint (B magnitude 15) diffuse galaxy, NGC 2647. As I found this, Gary beside me was reporting seeing a nice galaxy pair on the western side. It turned out we were looking at opposite ends of the Beehive.

I noticed a couple of other fainter galaxies in the immediate vicinity, so I decided to try for them. I failed to detect NGC 2643, but I did see NGC 2637 21 arcminutes nearly due west from NGC 2647. It was extremely faint (B magnitude 15.4) and barely detectable.

After observing these two galaxies, I star-hopped my way across the cluster to the nice pair that Gary had reported. I went back to the "house", and made my way to the western side of M44.

NGC 2624 (small, diffuse, fairly bright, somewhat concentrated in the center) was the brightest galaxy seen so far. Only 3 and a half arminutes to the east was NGC 2625 (small, diffuse and fainter than 2624). Together, these galaxies made a lovely pair in the same 226x field of view.

Finally, I observed a faint galaxy (UGC 4526 = PGC 24400) about 13 arcminutes to the south east of epsilon Cancri, anchoring my starhop once again on the house asterism.

This turned out to be a very rewarding, entertaining and spontaneous project, borne of idle conversion during bad atmospheric conditions.

By this time (about 9:30pm local time), I realized that sky conditions had improved quite a bit. The moisture in the air was dropping, dew was drying up and it was becoming much clearer. So it was time to renew my hunt for Hickson Compact Galaxy Groups.

Assault on the Hicksons

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