Sunday, October 31, 2010
The Herschel Project Night 14
I should be on my guard when an observing run gets off on the wrong foot, muchachos. Not that I thought I was putting that wrong foot in it at first. The last new-Moon Saturday looked like it was gonna be a nice one. Dry and cloudless, as dry and cloudless as it’s been down in the swamp in a right smart spell. I gave myself plenty of time to gather up all my stuff in leisurely fashion and position it in the front parlor. Did not get all sweaty and stressed in the process of loading Celeste, my C8, and the CG5 mount in the car. Grabbed a bottle of water, hollered to Miss Dorothy “Honey, I’ll probably be pretty late,” and pointed the car west toward Tanner Williams and the PSAS dark site. What could happen?
As I said not long back, I always forget something. I know that, so I run through the equipment inventory in my head as I’m leaving. If I had half a brain, I’d use the gear checklist I made up a while back, but I yam what I yam, I reckon. About a block from home, I suddenly realized I’d forgot the Astrogizmos red filter I put over the netbook screen. When I’m doing Stellacam deep sky video, as I’d be doing on this night, my night vision doesn’t matter much, but I try to be as considerate as possible regarding spurious light so as not to disturb my fellow PSASites. I turned the car around, grabbed the filter, set out again, and all was well. But I started wondering whether this misstep might be a bad omen.
It occurred to me as I was pulling into the PSAS dark site that the red filters weren’t the only thing I had forgot. The Bahtinov mask I use for fine-tuning focus was sitting back in Chaos Manor South. Not a big hit. I love the (Farpoint) Bahtinov, since it helps ensure my focus is on the money every time, which is important with the Stellacam’s smallish chip, but I’ve focused astro-cameras for years without one, so I figured I’d endeavor to persevere. I did resolve that enough was finally enough. From here on out I go back to using my checklist.
When I was done with my disconsolate and peeved muttering about the Bahtinov mask, I focused a weather eye on the sky. Not bad, not bad at all. There was a little haze, but not much. Way down on the western horizon there were some clouds, but they were skittering off and it was evident it was gonna be a good night. Maybe a real good one. There was also a young, slim Moon in the sky, but she was following Sister Venus into the gloaming, and wouldn’t be a problem.
Everything would likely have gone like clockwork if I hadn’t got ambitious. I would, as last time out, be using my 1995 Ultima C8, Celeste, on my beloved CG5 mount under the control of NexRemote, which takes the place of the NexStar hand controller. NR allows you to select the telescope firmware version you want to use, with version 4.16 being the latest offered for the CG5 GEM in the current build of NexRemote. Not that I normally use 4.16. I’ve stuck with v4.13.
What’s so different about 4.16? Celestron redid the polar alignment routine. The old version points the scope where it assumes Polaris will be given a perfect polar alignment. You then adjust mount altitude and azimuth till the North Star is centered in the eyepiece, which yields a polar alignment more than good enough for the Stellacam’s 10-second exposures.
All-star is, however, superior, or so I’ve been told. In addition to allowing any star—well almost any star—to be used for polar alignment, it is reputedly considerably more accurate than the Polaris routine. I’ve been happy with the old software, but, hey, if that elusive More Better Gooder is available for free, why not take advantage of it? While I’d tried this new software once, briefly, down in Chiefland, I hadn’t really got comfortable with it. Since there would be neither Herschel I nor Herschel II objects available this evening, I figgered this would be the perfect time to give 4.16 another try.
I reviewed the All-Star instructions (which have still not been included in the CG5 manual) one more time as the Sun sank. Didn’t seem too hard. Main difference is that you now access polar alignment from the Align button instead of the Utility Menu. To begin the procedure, you send the scope on a go-to to a named star. This star should, according to Celestron, not be near the eastern or western horizons and should, if possible, be high in the sky near the Local Meridian.
Hmmm…lessee. Well, there was Altair shining his little heart out. He was, if not at culmination, at least near it, and since he’s almost on the Celestial Equator, I figured that qualified as "high in the sky." Despite the All-Star directive to choose a star “high in the sky,” they also caution you to avoid one “directly overhead.” Altair was high, but not right overhead, and I guessed it would be as close as I could get to complying with the somewhat ambiguous instructions.
Once I had Altair in the field and carefully centered, it was time to begin polar alignment by pressing the Align button and scrolling to and selecting “Align Mount.” When I hit Enter, the scope re-slewed to Altair, and following instructions, I centered the luminary in my finder and then in the field of my 12mm reticle eyepiece. So far, so good.
The final step is to press the Align button, which first syncs on the star and then slews the scope to the place it believes the star should be given a perfect polar alignment. Then, just as in the old Polaris alignment procedure, you recenter the star in the main scope using the mount altitude and azimuth adjusters (never the R.A. and declination buttons). That’s when doubt began to creep in. I did not like what I was seeing.
The place the mount slewed to was a good ways from Altair. By Herculean effort, I got it in the field with the alt/az screws. Sure seemed like I was lowering the polar axis a whole lot, though. Wouldn’t have thought that would be necessary, since I’d put Polaris smack in the hollow bore of the polar axis before I began my go-to alignment. Maybe with Altair high in the sky it just seemed as if I were having to move the star a long ways due to my uncomfortable perspective. The NexStar ought to know what it was doing, oughtn’t it?
What next? I’ve been told that if you do the All-Star procedure correctly, there should be no need to re-do your go-to alignment. In line with my usual thinking, though, “trust but verify,” I decided to check the mount on one object before setting up the Stellacam. Off to M13. Nope. Nada. Zip. Zilch.
Hokay. The instructions caution that this can happen, and suggest unsyncing the All-Star star, replacing alignment stars, yadda-yadda-yadda. I just hit the big switch and redid my go-to alignment, adding Calibration Stars until one (the third one) was in the field of the main scope when the slew stopped. Alrighty then, “M13.” There she was near the center of the field. I was good to go with 4.16, right? Hah!
Got the Stellacam II hooked up, SkyTools 3 running, and focused as best I could on M13. Why “as best I could”? It’s a little hard to focus on a moving target. No, the CG5 is not an AP1200, but with the HC polar align procedure done, you get round stars with the video camera’s short exposures. Except I wasn’t getting that. Even if the stars were near-round on a single frame/exposure, I could see something was wrong, since they moved a considerable distance on the screen when the Stellacam’s image was refreshed with the next exposure.
Hmmm… What to do? Well, maybe it was just that I was pointing fairly high in the West to get at M13. Perhaps poor balance was making the CG5 tracking a little less good than it usually is. There is no doubt balance is important with a GEM in this class. But… What I was seeing looked a heck of a lot worse than that. It looked like bad declination drift, an artifact of poor polar alignment. Nevertheless, I pushed on to the first object of the evening. I’d already wasted too much darkness fiddling around with the scope.
Yeah, I decided to just put up with the mis-tracking if I could. After a few objects, I decided I couldn’t. Hell, the progress of stars and DSOs across my monitor was making me dizzy. I’d already wasted a lot of time and didn’t relish wasting more, but it looked like the whole run would be a waste if I didn’t do something. I returned to NexRemote’s settings screen and cycled power on the mount.
At the NR settings display, I used the pull-down menu to choose my software build—one of the beauties of NexRemote. You can bet I didn’t pick 4.16; I went back to the tried and true 4.13. Yeah, it was a pain: do a go-to alignment, complete the old-fashioned Polaris polar alignment routine, and redo the go-to alignment (mandatory with the old software). I’d probably burned close to an hour with little to show for my work. What was done was done, though, and at least now when I sent the scope to M13 it was not only centered, it stayed centered exposure to exposure.
So what was the deal? Was it the software or was it Unk? I’m guessing we all know the answer to that one. All-Star has, from what I can tell, gotten rave reviews from all and sundry. It obviously works at least as well as the old polar alignment utility. Then how did your silly old Uncle screw it up? I don’t know. Altair was a little close to being straight overhead, but I really don’t think that was it. I’ve gone back over the instructions a couple of times and tried to review in my mind what I did. I suspect—suspect—that I messed up the step where you press Align following the mount’s initial re-slew to the star. It is possible I, out of habit, pressed Enter instead of Align. I am not giving up on All-Star, and intend to give it another chance some evening “soon.”
As per usual, “POSS” is the Palomar Observatory Sky Survey, galaxy morphological types are where possible given according to the de Vaucoleurs system, matter in italics was transcribed from my log audio recordings, and images (except Hartley 2) are from the POSS. There are a couple of references below to NED. Who or what is “NED”? I’m a-talking about the NASA Extragalactic Database. If you are a galaxy hound, you owe it to yourself to try this wonderful tool. Just about any island universe in the sky is there, and there are reams of data and images for every fuzzy. Best of all? IT’S FREE!
Pegasus was high up and out of the light dome, so to his awesome Great Square I went. I’m just amazed, y’all, at how the summer observing season has flown by. It hardly seems possible the fall constellations are riding high and the winter ones on the rise before a night is out. Sigh. I must be getting old.
NGC 7550 (H.III.181) is set in a lovely little field. The galaxy itself is a magnitude 13.1, 1.5’ x 1.3’ E-S0 elliptical. In addition to it, there is a nice looking barred spiral, NGC 7549 about 5’ to the North; NGC 7558, an elliptical, is a bit less than 6’ to the east; and another barred spiral, NGC 7547 is 3’ to the west. Together, this small galaxy group is known as Hickson 93. Sweet.
A magnitude 14.2, 2.2’ x .6’ edge-on Sbc spiral according to N.E.D., NGC 52 (H.III.183) is right attractive. On its POSS plate, the galaxy shows off a tiny dust lane, and I almost convince myself I’m seeing that with the C8/Stellacam tonight.
NGC 7681 (H.II.242) is a dim one, a magnitude 15.7 S0 lenticular. It’s relatively small, too, 1.5’ x .8’. A double star is 2’20” to the east and there is a faint, magnitude 16 star about 20” to the northeast of the galaxy’s center. Onscreen, the galaxy is a small, slightly elongated bright spot with slight hint of nebulosity around it.
An E type elliptical 1.7’ x .9’ in size, NGC 7647 (H.III.473) shines weakly at magnitude 14.6. With the Stellacam, it is a slightly elongated fuzzball that’s redeemed by the presence of several small galaxies in the immediate area. Collectively, this group is known as Abell 2589, or, to be exact, “ACO 2589” in recognition of the fact that the catalog of galaxy clusters done by George Abell was extended by Conwin and Olowin.
As the night aged, Triangulum began to emerge from its light pollution cocoon, so Celeste and I ventured over to this little constellation’s surprisingly extensive galaxy field…
NGC 750 (H.II.222), a magnitude 12.9 E peculiar galaxy, is weird looking. It’s immediately obvious there are two “lobes” involved. What it looks like is a galaxy with two nuclei. And that’s apparently just what it is. This 1.7’ x 1.3’ object is classified as a “dumbbell galaxy.” Supposedly, the two lobes are the centers of two interacting ellipticals contained in a common stellar envelope. NGC 750 and other dumbbell galaxies are what the N.E.D. refers to as “binary elliptical galaxies.”
Before tearing down, I did take a minute or three to have a look at this fall’s little hit of a comet, Hartley 2, as it drifted along not far from the Double Cluster. As you can see in this single-frame Stellacam snapshot, it’s a nice one. Bright little nucleus, some coma, and even hints of a tiny little tail. It was almost as outstanding visually through my buddy Jason’s NexStar 11. Be sure to get out and have a look at it this coming week, y’all. Sky & Telescope’s website has finder charts and other cool Hartley stuff for your perusal.
Takeaway this time? Obviously, I've still got some work to do with All-Star. No, I don’t really need to use it, but now it’s an ISSUE with me and I won’t be happy till it is conquered. Otherwise? I am continually amazed at how downright powerful my C8 and CG5 and Stellacam are. It’s often said a Stellacam (or Mallincam) can effectively triple the aperture of a telescope, but what I’ve learned while going through the Herschel 2500 is that the video advantage is considerably greater than that. I’ve seen detail in small, dim galaxies from our less than pristine skies the likes of which I have never seen visually in a 24-inch telescope.
Not that I eschew the visual. That is still a big part of the Herschel Project and will continue to be so. I hope to get out to the PSAS darksite this coming weekend with my 12-inch Dob, Old Betsy, and get her tuned up and ready to go for the Deep South Regional Star Gaze, which will be four nights of visual Herschel heaven.
SkyWeek from Sky & Telescope
Psst, buddy! Got 99 cents? Got an Apple handheld—an iPhone, iPod (Touch), or iPad? If the answers are “yes,” man do I have an astronomy program for you! The good folk at Sky and Telescope have just released their first app, SkyWeek. What it is is a little program that connects to the Internet and downloads all the information you need to know about the week’s observing events. It’s like the “Observing” pages from the Sky website, but better, since you can carry it around with you.
What do I like about it? There’re beautiful star charts and glitzy things like an animated Lunar phases screen and cool graphics of Jupiter’s Great Red Spot and Moons you can step forward and back in time. Best of all, it’s easy for computer ignorant old Unk to work. Just download it from the app store using either a PC and iTunes or the handheld, and tap the purty little icon. As long as you’ve got location services turned on in your device, SkyWeek sets date, time and location for you and all you have to do is enjoy.
Given that my memory ain’t what it used to be—if’n it ever was—SkyWeek will go a long way toward seeing I don’t forget upcoming astronomy events. Now, if the Sky and ‘Scope folks could just develop an app to help me remember to bring my eyepiece case along when I go observing, I’d really be in business. If you’re an Apple user, don’t ruminate on it; just get this 99 cent wonder. You’ll thank me later, muchachos.