by Albert Highe
|Observers||Observing by myself in very good conditions, this was my most productive night - 53 new objects|
|Weather||The CSC predicted mediocre conditions. But weather at Michelle's Plettstone usually is better than predicted, so I headed out anyway. At sunset, quite a lot of high cirrus, and some thicker clouds, caused some doubt. But sure enough, by 7:30PM, the sky cleared nicely. Temperatures quickly dropped to the low 60's and stabilized around the mid-50's during the night. The RH topped out at 79%. No wind. Seeing and transparency were very good. Seeing softened a bit during the night.|
|Observers||Michelle, Rashad, Guillermo.|
|Weather||Very similar to yesterday, but a couple of degrees warmer (high 50' s) and lower humidity (max 66% RH). No wind. Transparency continued to be very good. Seeing softened a bit from yesterday, but was still good.|
|Observers||Joined by Rob H. and Richard N.|
|Weather||Repeat of Friday except it was even drier. The RH topped out at 55%. No wind. Transparency continued to be very good. Seeing softened a bit more from yesterday, but still was adequate for 286X.|
|Scope||17.5" f/4.5 ultralight|
|Eyepieces||mostly 7mm and 5mm Nagler T6.|
This was my last chance to hunt down galaxies in the pair of galaxy clusters in Hercules - Abell 2197 and Abell 2199. As I mentioned a couple of months ago, A2197 and A2199 form a "Double Cluster" approximately 4-1/2° NW of M13 in Hercules. Uranometria indicates member galaxies lie within partially overlapping circles with diameters approximately 1.5° and lying 1.5° apart. Target lists include selected galaxies within 1° of each cluster center. My goal was to observe at least 100 galaxies in each cluster.
Few galaxies are left on the A2197 list after I added 29 new observations at
CalStar last month. I observed six new galaxies, bringing the total to 120.
I've searched for most of the remaining galaxies on the list and was not
able to see them. So this observing project is essentially complete. The
list and some details of my observations are available on my web page:
It has been interesting to me just how many "brighter" galaxies, visible to amateurs, are not included in the more commonly cited NGC, IC, UGC, MCG, CGCG, and PGC databases. The galaxy 2MASXJ16275925+4029499 is a good example. It appears in the Two Micron All Sky Survey (the 2MASX designation), the Lyon Extragalactic Database (LEDA 169659), and Arecibo General Catalog (AGC 260927). Its photographic magnitude is 13.4, although this seems anomalously bright vs. other galaxies on the list. However, I could hold it with averted vision 90% of the time. This places the galaxy in the top brightest third in A2197 or A2199 (it appears on both lists). It is brighter than a few NGC objects, and many MCG, CGCG, UGC and PGC objects, on the list.
I added 15 new observations to A2199, bringing the total to 99. I'll have to wait until next year to break 100. The list and some details of my observations are available at: http://pw2.netcom.com/~ahighe/a2199temp.htm
One of the biggest disappointments was not being able observe UGC 10433. With a photographic magnitude of 15.7, and size 1.5' x 0.3', I would have expected to see it. Unfortunately, there is a 11.6 mag star just 2" SE of the core of the galaxy. I might have glimpsed one of the elongated extensions. But even repeated attempts at 400X did not convince me that I observed it.
On the other hand, I was thrilled to be able to see MCG+7-34-104NED02. It is a small pimple just 13" west of the 14.8 mag galaxy MCG+7-34-104NED01. At 286X with averted vision, I can hold the NED01 galaxy continuously. At 400X, it is visible with direct vision. No magnitude or size data is reported for the nearby NED02 galaxy. However, at 286X, I could hold it with averted vision 15% of the time - a very challenging object.
Because of the spatial and radial velocity overlap between A2197 and A2199, there is some duplication between the two lists. Seven observed objects appear on both.
My favorite galaxy cluster, Abell 426 in Perseus, is back. I resumed my
search at CalStar, having a particularly good night on my birthday. At
Plettstone this month, I added 31 new objects, bringing the total to 271.
Although my pace has slowed since the remaining objects are increasingly
faint, reaching 300 galaxies seems inevitable. Detailed information and the
observing list is available at: http://pw2.netcom.com/~ahighe/a426.html
If you haven't visited this web page recently, you'll find I've recently added some new information in addition to updating the observing list.
One particularly satisfying observation in A426 was of galaxy MCG+7-8-4. This galaxy has eluded me during several observing sessions. NED and Uranometria list its magnitude as 14.9. Uranometria indicates its surface brightness is 13.3. I usually have little difficulty with such galaxies. However, there is a 10.7 mag star at its eastern edge, 18" from its core. I was finally able to see this galaxy as a faint hazy patch next to the star and hold it with averted vision 15% of the time at 286X.
Here is another one of those "brighter" galaxies that doesn't appear in the more common databases. Apparently, galaxy 2MASX J03080440+4258478 has been discovered only within the past couple of years. It only appears in the 2MASS database. Since the 2MASS survey focused on the infrared, there is no relevant visual magnitude. However, the galaxy was very easy to see. At 286X, I could hold this galaxy continuously with averted vision. It was easier to see than UGC 2552, 9' SW and just as easy as UGC 2559, 14' W.
Perseus is well positioned during the next several months. Be sure to have a look at Abell 426.
At this point I'd like to mention a useful observing technique I discovered this weekend. It allowed me to better observe some of the ultra-faint galaxies I was hunting down. The technique is to move your eye away from the eyepiece so that you observe your target object within a much narrower field of view. The approach is similar to placing a nearby bright object outside the f.o.v. However, there are a number of advantages to restricting the f.o.v. vs. moving the brightest object.
Placing a bright star outside the f.o.v. usually moves the object near the edge of the eyepiece field. Eyepieces don't perform as well at the edge. Placing an offending star outside the f.o.v. may also place the object where one's averted vision is not the most sensitive. Also, you are usually limited to placing only one bright object outside the f.o.v. at a time. Finally, even when the brightest object is placed outside the f.o.v., the integrated brightness of the surrounding fainter stars and background sky still makes it more difficult to see very faint objects. Wide field eyepieces, such as the Naglers I use, allow more light into the eye, obscuring faint objects more than narrower field eyepieces.
I found I could place my target object near the center of the field, yet adjust my head so that I could narrow the f.o.v. while maintaining the object at one of my more sensitive averted vision locations. When a large fraction of the background light was excluded, the object popped into view. The technique does require some practice, and you have to use a hood or cup your hands around your face and eyepiece so no other light can enter your eyes. However, it did make a difference. Has anyone heard about or used this technique before?
The above technique was particularly helpful on IC 1296, a small galaxy approximately 4' NW of M57. I used a labeled DSS image as my finder chart to locate the field. At 400X, I could hold it with averted vision 20% of the time. On another night that weekend, I was able to see it 15-20% of the time at 286X. It appeared as a very small dim oval.
Perseus is a wonderful area to troll for groups of galaxies. While waiting for Abell 426 to rise high enough, I explored the region around NGC 1129. I noticed a tight clump of galaxies on page 43 of Uranometria. Experience has taught me to prepare detailed finder charts for these areas. In addition to the six galaxies plotted in Uranometria, I found and labeled an additional eight likely candidates in a DSS image 15' x 15'. I was able to observe 12 out of the 14 galaxies.
Uranometria shows a label M+7-7-5 (for MCG+7-7-5) associated with this clump of galaxies. NED says this is another designation for NGC 1131. So the "M+7-7-5" printed in Uranometria is an error. The coordinates the Field Guide gives for M+7-7-5 correspond to 2MASX J02542748+4130490, a very small, faint galaxy that I was not able to see.
Page 140 in Uranometria shows an interesting area in Cetus near NGC 327. Four NGC galaxies form a close group arranged in a "V" less than 6' across.
Within the same 15' x 15' field are two moderately bright galaxies approximately 6' north of the "V". These are:
Both were rather easy oval galaxies to observe. I could hold them with averted vision 90-95% of the time. It is interesting that they weren't discovered earlier since they are considerably brighter than NGC 325.
Almost exactly 9° due south of the above group is another set of four galaxies whose relationship to each other is almost identical. The "V" is rotated 45° so that it looks like an "L".
However, the brightness of these galaxies is more nearly equal. All can be held continuously with averted vision. Their visibility with direct vision varies a bit. NGC 284 is the dimmest, while NGC 285 and NGC 286 are somewhat brighter.
While hunting galaxies in the vicinity of NGC 349, I came across one of the most obscure designations I've ever seen. I noticed the galaxy on a DSS image near the mag 7.5 star 4' west of NGC 349. The NED web site identified it as:
What struck me as most unusual is that this rather "bright" galaxy has not been catalogued elsewhere. Even the 2MASS survey missed it. Although only 75" away from a bright star, I could hold it with averted vision 25% of the time.
In case you are wondering, APMUKS(BJ) = Automated Plate Measurement United Kingdom Schmidt (B J )
This is a survey published in 1990 that focused on an area covering the southern galactic cap.
Cetus also holds one of the most bizarre-looking irregular galaxies I have ever seen - NGC 520. In images, it looks like a whale. It has a blunt bright end whose shape is remarkably like the head of a sperm whale. The body of the galaxy is straight and undulates near the other end. This other end turns a right angle to the body and sports a tail complete with a nearly symmetrical pair of flukes! Visually, the bright blunt head is easy to see. The body looks like a thick dash and dims gradually as one moves away from the head. Unfortunately, I couldn't see the dimmer tail. Oh how we wished the 30" were there.
As you can tell from reading my observing highlights, I like to observe galaxies, especially when they occur in tight groups. Structures I find particularly intriguing are galaxy chains. A nice chain of 11 brighter galaxies appears in Pisces near the Cetus border. The chain runs N-S and spa ns less than 1°. From north to south, the group consists of:
Galaxies appearing on the same line are roughly E-W of each other. All were rather easy to see. With the exception of NGC 208, I was able to hold all with averted vision continuously. A few were also visible with direct vision. I was able to hold NGC 208 with averted vision about 70% of the time.
As usual, I had some wonderfully productive observing sessions at Michelle' s. The above observations are only a sample.
The company was likewise enjoyable. Thanks again to Michelle and fellow observers.