Telescope Reviews: *Driveway Fun (going DEEP)*

DS063008 ***RECENT OBSERVATIONS***
by David Knisely

DATE: June 30th, 2008, 0530 to 0805 hrs UTC.
LOCATION: Beatrice, Nebraska, 40.283N 96.736W, elev. 1322 ft (403m)
INSTRUMENTS: NexStar 9.25 inch f/10 SCT: 98x, 168x, 235x, 297x, 480x, 743x, 1199x.
CONDITIONS: Clear, Temp 63 deg. F, Wind calm.
UNAIDED-EYE ZENITH LIMITING MAGNITUDE: 5.7
SEEING (above 45 deg. altitude): 0.5" arc to 1.5" arc (Antoniadi II)

OBJECTS OBSERVED: M51, M57, M97, MCG +9-19-14?, NGC 6572, NGC 6517, NGC 6539,
IC 1276, NGC 6712, NGC 6751, Minkowski 3-34, Palomar 11, NGC 6891, NGC 7006.

OBSERVATIONS: After getting home from work and having something to eat, I got the scope out to the driveway in front of my home to get at least a little time out under the stars instead of inside at the computer. The sky seemed to be clear but perhaps not as dark as I had sometimes seen from my home. However, first impressions would definitely be deceiving this time, as it ended up to be one of the best nights ever with the NexStar. After a quick alignment, I decided to do a quick test of the pointing and sent the scope to M51. I had the 14mm Ultrawide in the scope (29.7 arc minute field of view) for when I had aligned the finderscope, but even at 168x, M51 was well-placed in the field of view, perhaps only six or seven arc minutes from the field center. I immediately dropped the power to 98x and could see it and the companion NGC 5195 fairly clearly, although the spiral structure was difficult to discern. I put in the Lumicon Deep-sky filter, and the view improved, with the arms now vaguely but fairly easily seen.

With this under my belt, it was time to get on with a few projects I had deferred. I sent the scope over to the "Owl" Nebula M97 and once again, the scope put the object fairly near the center of the field of view. Without filtration, it was just visible as a dim circular glow, as I had competition from nearby Sodium vapor streetlights, but with the DGM Optics NPB narrow-band filter, it stood out fairly well, showing both "eyes" to averted vision. I took out the filter and put in the Lumicon Deep-sky to look for some faint stars in the area which had been mentioned by one contributor on the Deep-sky section of Cloudynights, kicking up the power to 168x. I noted several faint ones near the nebula, but decided that they weren't easy enough to see, so I went to 297x and took out the filter. This improved the view of the stars to the point where 14th and possibly 15th magnitude stars were seen. Just to the southwest of the Owl was a very faint dot of light that looked just a bit fuzzy. It showed up on the thumbnail Megastar image as a star with a sort of a "plume" behind it. I judged the star to be probably close to 15th magnitude, but the plume was unknown, so I reset the magnitude limit to 18 and a galaxy appeared at that location on the chart: MCG +9-19-14. It had a listed magnitude of 16.1, but at these levels, the magnitudes are rather inaccurate and are probably blue-band anyway, so it could have been as much as a full magnitude brighter than this. The fuzzyness seemed to be similar to what the image showed, although it could just have been the effects of a seeing plume from a tube current rather than the galaxy itself. I will have to try for this one again at the Nebraska Star Party to see what can be seen.

I had the laptop out and running, so I decided to just look around for a while before hitting the calibrated star field around M57 (the main "serious" project goal I had for the night). I noted the small bright planetary nebula NGC 6572 in Ophiuchus, so I sent the NexStar over to it. It is quite small (about 11 arc seconds across), but its color is a rather striking bluish-green, and it stood out well even without a filter. The object seemed to be slightly oval north-to-south, and the middle appeared somewhat brighter even at 98x, so I bumped things up to 480x using the 5-8mm Speers Waler eyepiece. At that magnification, a sort of vague inner shell appeared with hints of detail, along with what looked like a very faint central star. This was surrounded by the outer more diffuse circular glow of the outer shell. This still didn't seem like enough power, so in went my 2.5x Powermate. I meant to slide the Speers-Waler in to get only 743x, but I accidently left it all the way out, resulting in a whopping *1199x*! The central shell at that power appeared highly elongated with the central "pip" or star winking a bit in and out as the seeing varied. Nearby brighter stars showed clear diffraction disks with rings, so the seeing was outstanding. This is a new "record" for me as far as the highest magnification I have used on a deep-sky object, although 743x would probably have served better.

I noted some globulars that I hadn't seen for a while, so I slewed the scope over to NGC 6517. This is a somewhat small object maybe three or four arc minutes in diameter and fairly faint, appearing as a small fuzzy spot with a slight concentration towards the middle. Even 297x didn't show even a hint of resolution. My next target, NGC 6539 in Serpens, was somewhat larger and maybe a hair brighter than NGC 6517, although it seemed more diffuse, especially in the middle regions. 297x showed vague hints of granularity in the outer haze along with many nearby field stars, but I could not get any confirmed members to appear (even the magnitude of the giant "tip" is only 15.9). Still, the object wasn't all that hard to see, so it was worth a look. While in the area, I noted another globular IC 1276 on the screen, so after a few more key punches, the scope stopped on that object. It appeared as a small rather faint diffuse glow just to the south of a 10th magnitude next to a 12th magnitude star. The symbol for the globular in Megastar overlapped those stars, but what I saw was noticeably smaller, perhaps only three or four arc minutes across. The cluster appeared slightly granular at 168x, with some central concentration and hints of patchyness. 297x showed perhaps a few faint stars across the glow, but these may be just field stars and not cluster members.

After all this, I noted NGC 6712 sitting all by its lonesome, so over to it the scope went. WOW!!! After reaching for all this faint stuff, this one was a real gem. I had forgotten that I had called this cluster the "Wierd Globular", many years ago during my Herschel 400 hunt due to its unusual shape and detail. At 97x, the cluster appeared noticeably oval east-to-west, with granularity as well as many of the brighter cluster members appearing easily. The core seems a bit off-center, and at 168x, the cluster showed an almost triangular core with a rich envelope of stars in a more irregular mass than I was used to seeing with many of the richer globulars. The overall brightness profile across the cluster reminds me a little of M22, although the members are much fainter.

I noted a few planetary nebulae along the way, so I stopped on NGC 6751 in Aquila. This was another little guy (26" arc across) but not terribly difficult, appearing as a small faint slightly oval fuzzy patch. 480x showed what appeared to be a very small central condensation with perhaps a very faint central star and hints of a slightly annular overall form. After that, I saw Minkowski 3-34 on my Megastar screen, so over I went to it. This was one of those tiny faint guys which are very hard to pick up (about six arc seconds across), but it blinked with the OIII filter. It was stellar up to about 168x, and at 297x showed a slight brightening of the tiny disk towards the center. I kicked up the power to 480x and occasionally saw what I thought was a tiny pip of brightening near the middle, but not a confirmed central star.

I also saw the globular Palomar 11 on the screen, and I almost never turn down a chance to really push myself. What I saw was *very* faint and diffuse, but was definitely there, just to the southeast of a 9th magnitude star. It was maybe 4 arc minutes across and visible as just a very faint glow with little central concentration and no component stars visible.

I went back to at least one more planetary, NGC 6891 in Delphinus. This one was basically a rather small "dot" at 98x, and it took about 297x to bring out much detail on it. It is basically round (21" arc) with a small slightly brighter middle and a rather dominating 12th magnitude central star. Indeed, to see much detail in the interior required that I put in the DGM Optics NPB filter to "tame down" that star. There appeared to be something of an inner shell surrounding that central star, but it was fairly diffuse.

Someone on Cloudynights had asked about the globular NGC 7006 in Delphinus, so I slewed over to it. It was fairly easy, appearing as a roughly round small fuzzy spot with only a slight concentration towards the core. 297x made the core stand out a bit more, but did not even begin to resolve the cluster.

Finally, I went to the Ring Nebula M57 which was nearly overhead. I had wanted mainly to see how much the local skyglow would compromise my ability to detect really faint stars, and as it turned out, it didn't hurt nearly as much as I had thought it would. I briefly observed the nice ring form of the nebula for a minute or two before "getting serious" with my 5-8mm Speers Waler eyepiece and my photometric chart of the stars in the area of the nebula. I put the eyepiece in and my jaw just dropped because there, right in the middle at only 297x, was the central star! It wasn't even all that hard, as it shone steadily for several seconds to my unbelieving eye. Then, as if the star suddenly thought, "Oh Goodness! I AM BEING WATCHED!!", it instantly vanished as the seeing declined slightly. My thoughts at the time went about like this:

"You are on your driveway *in town*!"
"There is a sodium vapor light 150 feet from you." (full-cutoff though)
"You are using a 9.25 inch SCT with a 36% central obstruction."
"You are using *only* 297x!"

"YOU SHOULDN'T BE ABLE TO DO THIS!!!"

I just sat there on my observing chair dumbfounded. Seeing M57's central star had always been HARD in my 10 inch, but this "little" 9.25 inch scope just nailed it as if it were an old friend! Oh, yea, it was pretty darn faint and required averted vision, but the fact that it just appeared so quickly at the very first glance in the eyepiece just had me stunned. I watched the center for a while (the central star stayed gone) and then moved the slide on the Speers-Waler out to give me 480x so I could examine the area around the ring. The magnitude 14.6 star just north of the Ring was visible pretty much constantly, while the magnitude 15.3 star to its west was visible maybe a bit over half the time. As I watched, the magnitude 15.7 star just off the west edge of the ring began to appear, perhaps only 20% to 30% of the time, so that seemed to be about the limit for the night. I have *never* gone that faint with the old 10 inch, so this little SCT still continues to surprise me years after I reviewed it. Every once in a while, I would glance back to the center of the ring and the central star would pop out for a second or so before vanishing again, so it was playing "tag" with my eye a bit more than it had when I first sighted it at only 297x.

After a while, I glanced up to see a pair of satellites (probably in the NOSS group) flying in close formation as they flared and then faded in their flight to the southeast, while high in the south, Jupiter beckoned. I slewed the scope over to it and watched as Ganymede did a nice transit with its disk clearly visible against the cloudtops of the planet, but my thoughts still kept going back to that remarkable view of M57 and one of the most elusive "challenges" in amateur astronomy which had fallen to my lowly little 9.25 inch scope, all from the comfort of my driveway.

Clear skies to you.

--------------------
David W. Knisely
Hyde Memorial Observatory
http://www.hydeobservatory.info