Wednesday, May 9, 2001

14.5" backyard report.

Last night Nilesh Shah came over to do some backyard observing. I had the 14.5" f/5.6 set up on La Caja, and a great light-blind placed between us, my house and the neighbors. Everything worked perfectly. This was essentially the real first use of a larger aperture scope in my backyard, as we had at least a few hours of dark sky.

Conditions were not the best as there was significantly more sky brightening from the north than on the really good nights out back. Still, we had very good success using both 20mm and 12mm Nagler two eyepieces. Nilesh had his laptop set up running TheSky, which we used to peruse Herschel objects and some NGCs that appeared near by or were well placed.

Our first target was NGC 3610, a small galaxy in the bowl of the Big Dipper. It is nicely placed almost equadistant into the bowl between Dubhe and Merak, the famous "pointer" stars in the Dipper. It is funny how perception and assumption are easily proven wrong under certain conditions. I had thought all the stars in the Dipper were about equal in brightness. It is such a landmark asterism that little thought is given to the individual components, it is kind of "known" subconsciously as an entity. But earlier last night, as the sky was beginning to darken, there was Dubhe, standing out very plainly, while none of the other stars of the Dipper were visible. Turns out Dubhe is 0.5 mag brighter than two and 1.5 brighter than the third other bowl stars.

But back to NGC 3610. A line of mag 8 stars arcs gently from ESE to WNW next to the galaxy. Nice small groups of dimmer stars cluster at the east and west ends of the arc. This makes a recognizable landmark in the eyepiece, taking up nearly all 47 minutes of the 20mm. Just south of the middle mag 8 star is a small smudge, at first dim and non-descript, but with some study detail emerged. Really, adding the 12mm provided some detail. With the 12 in, we could see a nearly stellar core, bright, and a halo of what might be a dim disk or halo surrounding the bright center. The galaxy seemed slightly elongated north to south, and maybe 2.5' in diameter. The listed magnitude is 10.8, but it appeared significantly dimmer, which its surface brightness of 12.8 correctly tells us.

Following the line of stars back ESE you run into a tight group of three bright stars, with another pair to their SW. By continuing perhaps 50 minutes past the pair of stars you will find NGC 3613. This sits a short distance away from a dimmer galaxy, NGC 3619. I first noticed NGC 3613, situated between a pair of roughly mag 10 stars. The stars sat about 5 minutes NNW and SSE of the galaxy, while the galaxy galaxy appeared elongated E/W. The elongation was quite evident. Off to thw SE beyond one of the pair of stars, NGC 3619 shown itself unexpectedly, since I didn't know where to look for it at the time. I described the scene to Nilesh who confirmed everything at the computer (although my direction in the eyepiece still needs some brushing up). 3619 was much dimmer than 3613. 3619 seemed round and perhaps a bit small than its neighbor, with a very slight elongation N/S. 3613 is 3.9'x1.9' at mag 10.9 and surface brightness of 13. 3619 is 2.7'x2.3', 11.5 and 13.4 respectively. This was a fun group to find and observe.

Nilesh mentioned another galaxy back across the pair of stars at the south end of the three that comprised the mag 8 chain. So we went after NGC 3690. This one was tough. The best I can say is we saw a brightening in the field. There was nothing conclusive, or at least "galactic" about the view. It was in the right place. I don't think my eyes or Nilesh's were tricking us, but it was "kind-of" at best. In a good dark sky with some aperture this object would be fun to view. Located in nearly the same position is IC 694, nearly the same magnitude as 3690. Very close by to the NE is MCG-10-17-5, and again almost in an identical position to the NGC and IC galaxy is the very dim MCG-10-17-2A. The washed out DSS image of the two brightest members shows a very disrupted shape. Oddly, NGC 3690 is smaller, has a higher magnitude and surface brightness than some of the earlier object we did see. Perhaps it was a moment of poor transparency?

Another "ain't there" object for the night was NGC 3642, a large galaxy NE and across the line of bright stars from NGC 3610. We looked for some time but only suspected some brightening in the correct location. 3642 is almost 5' in size and mag 11.2 with about a 14 surface brightness. This was pushing it on a rather bright night in town.

Next we moved out of the bowl of the Dipper, SSW from Merak to two degrees to the mag 5 star 44 Ursae-Majoris. The target was NGC 3448, an elongated galaxy, 1.2'x0.8' and mag 12.6, but a slightly higher surface brightness at 12.5. Finding the star in my 11x70 finder was easy. I knew two stars sat NNW of 44, and on the other side was a mirror image, but instead of two stars it was one and a galaxy. The galaxy was an easy pick. Its elongation was very evident, with brightness increasing evenly from its extemities to the core. Its position was ENE/WSW, and was about 20' SE of 44 Ursae. Nice view.

Since we were already out away from the Dipper, Nilesh spotted another galaxy on the laptop that was just about 1/2 a Telrad away from where we were. If I kept our current position and thought of Merak as 6 o'clock on the Telrad, 44 as the middle of the clock, then the next star I needed was at 10. That method dropped me right on the star, mag 5.5 SAO 27724. Sitting 11' S of the star in the 20 Nagler was NGC 3310, a nice round galaxy at mag 10.8 and surface brightness 12.8. It is roundish, but has noticeable elongation N/S. It is also listed as Arp 217. The DSS shows an interesting image of a rather face-on looking galaxy, stubby spiral arms. But I could not see such detail in the eyepiece.

By this time it was getting late. We started looking for a few other objects, and in fact tried one (NGC 5466 in Bootes), but it was time to just poke around a bit and finish up. Instead of dim galaxies, we looked at a few doubles. Izar looked gold and blue to me. Nilesh felt the companion was a bit green. Then I shot over to Xi Bootis, a nice wider double with red and gold components. After that it was over to Pi Bootis, a whilte pair of near equal magnitude, and finally over to another white pair - Zeta Bootis. These were all fun, but Xi is always my favorite in this area.

`The night finished up on M3 and M13. Globulars are to me the most fantastic celestial entities around. Don't know why, but the view of M3 was more pleasing the M13. I guess I was looking for NGC 6207 around M13, which may have slightly detracted from the showpiece itself.

All in all, a fine night in the backyard. The 14.5" will be even more fun as sky conditions improve.

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