This is the tale of a search for two galaxies. The stats for one indicate that it should not be too difficult for a 12" scope to locate, while the second one indicates perhaps a deeper challenge. This pair is located in Lacerta, now situated well for observing later in the evening (it's basically between Cygnus and Cassiopeia).
To a fully seasoned observer, it came as no surprise that the easier one was the most difficult to locate, and the harder one was just sitting there, no effort required. Conditions were perfect--very clear and mostly dry, and observing was done around midnight, when the objects were almost directly overhead.
The easier one is supposed to be eg 7264. It has a visual mag. of 13.8, and a surface brightness of 13.2. Averaging 13.5 mag., then, this should pose no problem for a 12" mirror in good skies. However, it was the shape that told me this one would be tricky. Its dimensions are 2'.2 x 0'.3. In other words, it's a "needle" galaxy. Due to the slender shape, the galaxy becomes much more difficult to see well, if at all. Add to the fact that two stars run alongside it and you have a potential no show. Did I mention the dark dust lane? Though invisible in the 12", it does affect the light coming our way.
It took a while, but I finally found it. I did not use a photo, just Uranometria, so at first I did not realize that the galaxy ran parallel to the two faint stars (just bright enough to make things tricky).
It took a while, but I finally found it. I did not use a photo, just Uranometria, so at first I did not realize that the galaxy ran parallel to the two faint stars (just bright enough to make things tricky).
NGC 7264, upper center; 7263 right
http://ccd-astronomy.de
At first I suspected only the central area of the galaxy, a very faint smudge that might have been a tiny third star. However, at 150x I suddenly had one of those averted vision flash epiphanies, and I saw the entire galaxy for just an instant. A seasoned fellow astronomer also took some long, careful looks, declaring that for him the object was right at the limit of what he could discern. Consider he was coming down in aperture, taking a short break from observing with his 22". I am a bit more used to searching out these really faint objects, so I had a tiny bit less difficulty, but those averted vision glimpses were few and far between. A far cry from what a 13.5 mag. galaxy should look like!
The second galaxy was eg 7263. With a visual magnitude of 14.6, and a surface brightness of 13.8, this one sounded like a challenge. It is south preceding 7264, and the first galaxy points toward it (see image, above). However, this fainter galaxy (averaging 14.2 mag.) was a veritable picnic by comparison! Why? The shape. It's size is 0'.8 x 0'.7, which is virtually round. These objects are usually much easier to view than elliptical ones. This galaxy was picked off without difficulty at 100x! 14.2 mag.! I told you I had a good sky. It forms the apex of a triangle with two faint stars, one south and one preceding. Best of all, at 150x and 187x it appears in the same field with 7264. This is where the real comparison begins. Going back and forth between a "brighter" galaxy, which is actually dimmer, and a "dimmer" galaxy which is actually much brighter, is a mind-expanding experience.
While in the area, you may wish to visit a much brighter galaxy, which is very close by. Eg 7265 is a showpiece by comparison to the other two, with a visual mag. of 12.2 and a surface brightness of 13.7. At 2'.4 x 1'.9, the shape again makes it easy to see, though its ovalness is very apparent at higher powers. There is even a very faint UGC galaxy near 7265, for those of you with even larger apertures.
NGC 7265 at bottom, with 7264 in upper center and 7263 in upper right. The faint UGC galaxy is south following 7265, and involved with a 10.8 mag. star.
http://www.webbdeepsky.com
Enjoy your clear skies!
Mapman Mike
