Thursday, October 25, 2007


After the comet cleared the tree branches, at 10:50 p.m., I took a good look.

It is somewhat brighter, and a bit bigger. I don't think it has increased a lot in size, but some. With a 7mm Nagler in the 10" f/5.7 CPT, I was running 207X and the overall comet took about a quarter of the field of view. That would put it at 6 arcminutes. I also looked with a 12 Nagler giving 120X.

The brighter portion of the comet is still around 2 arcminutes. The nucleus is a bright golden yellow stellar point, offset slightly SSW. A bright yellow/cream colored fan of ejecta extends SSW from the nucleus. At times I felt the southern edge of the fan would show some movement, as if a pinpoint of brightening was occurring - extending into the edge of the fan, and perhaps feeding the fan itself.

Around the nucleus and ejecta fan was a bright circular glow, more pronounced on the fan side. Outside that was a darkened ring, which on the fan side was mostly interrupted. This darkened ring was enclosed by a bright soft outer ring, and that defined the end of the "bright" portion of the comet. If not for the fan and bright inner glow, the bright outer ring would have made the view as annular, maybe it could still be called that though. The darker part inside the bright outer ring appeared to be gray tinged with red to me.

Beginning at the outside edge of the bright outer ring, a very dim glow extended away from the comet. It appeared to extend an additional 2 arcminutes around the bright "outer" ring. The dim glow was easier to view at 120X than at 207X.

I hope this comet is still putting on a show in a few more days. It would be great to see it under dark skies.

More tomorrow... this is a really unusual comet!

More Comet Holmes 17P

Just came in from observing the comet in a 10" f/5;7 with a 7mm Nagler. The nucleus is very bright, nothing competes with it in the field of view. Somewhat yellow/cream colored. The inner coma fans out to the WSE, tight. The outer halo is slightly elongated NW to SE, approx, from memory. Very unusual comet! I agree with the size, estimated at 1.5' to 2.0'. If I didn't know what it was, I'd guess this was a very bright planetary nebula with an off-center central star.

I had to laugh, after doing a bit of fixing of my finder base today on the scope, I had to use the nearly full moon to align. But it works fine now. But once the fix was done, the finder aligned correctly and kept the comet centered. Smart move preparing for tonight! Simple fix, a screw head was too "tall" and throwing everything off.

I haven't seen a comet's coma like this since Hale-Bopp. I suggest we all watch this guy closely over the next week. Hale-Bopp, back in '93 or so, when the coma was incredibly distinct, was throwing off all kinds of ejecta spinakers - you could watch them spiraling off the nucleus real-time. Wouldn't that be a treat!


Sunday, October 7, 2007

A Social Night At Coe

Title translated: observing was not very good. But there was a very good turnout, and everyone seemed to be enjoying themselves.

Do I regret going? Not at all. The drive up the mountain, past Anderson Lake Reservoir at sunset, which enhances the reds of fall, is excellent. I thought I was taking it slow, but kept hearing my gear moving around in the back of the truck, at each turn. When I arrived, Turley and Cichanski were already there, at the southeast end of the lot, along with newcomer Elizabeth, a recent transplant from D.C. Mark Johnston was in his usual spot in the center of the lot, and one other observer was parked along the eastern perimeter just to my south. Some other vehicles were there, day hikers celebrating Coe's Tarantula Festival. The day hikers were gone shortly before twilight ended.

Sunset was gorgeous. Very clear skies, with golden orange over the black silhouette of the coastal mountains. More observers arrived, and by dark there must have been 15 of us, with a few stragglers arriving after dark. There were a number of first timers to Coe in the group, who unfortunately picked one of the worst night there I can recall for transparency (other than getting fogged out) in a very long time. It was actually deceiving as well before astronomical dark the Milky Way was horizon to horizon, the star clouds in Sag and Cyg showing off nicley, and the offramp heading to Oph was obvious. We thought we were in for a great night. But soon after dark the muck starting to lay in, high. Before long, the light domes of San Jose and Gilroy were blotting out the west and south. The east looked okay, but in my 18" f/4.5 Dob I could tell, showing Stephan's Quintet to others, that the transparency was way down. Just a roll of the dice, and last night it came up snake eyes.

The most fun I had, other than visiting with the TACos present, was showing eye candy to a camper who hiked from his campsite near the park headquarters (we could see his flashlight on the trail coming toward us). He was very interested... objects included decent views of M57, M15, The Veil Nebula, NGC 7008, The Double Cluster, M31 - pointing out its dust lanes, along with M32 and M110, The Blue Snowball (not blue at all last night), NGC 246, NGC 253, and M33 (enhancing NGC 604 with a UHC). Someone asked me to show Stephan's Quintet, and with the 7 Nagler (294x) we could break out all five components, but it was not a view to write home about.

Other than the eye candy and special requests, and yakking it up, I worked on the southern crumbs of my September observing list...

N7171 Aqr GX 2.6'x1.5' 12.9 22 01 01 -13 06 09
Dim, diffuse, elongated mostly e/w, slight brightening in core region otherwise even brightness throughout. Bright star 15' N, size of galaxy is about 3'x1.5'.

N7184 Aqr GX 6.0'x1.3' 11.7 22 02 39 -20 48 50
Extended edge on galaxy, mostly wwsw/eene. Pinpoint stellar core in brighter condensed central area. Approx 7'x2'. Star at eastern extremity of galaxy.

M30 Cap GC 12.0' 6.9 21 40 22 -23 10 45
Smaller Messier globular, approx 10' and uneven core. Core is rather tight and uneven. Stars in 2 chains trailing out to the N with more dim stars trailing to the E.

Arp 110 Aqr GX 1.0'x0.6' 15.9 22 54 09 -15 14 09
Possibly very fleeting view of dim patch elongated nnw/sse, but no definite sighting or any detail.

N7392 Aqr GX 2.1'x1.2' 12.6 22 51 46 -20 36 25
Elongated, brighter central region, no noticeable core. WNW/ESE about 2x1.

N7377 Aqr GX 2.9'x2.4' 12.1 22 47 47 -22 18 42
Round, about 3' diameter, brighter core about 1'.

Arp 93 Aqr GX 2.3'x1.3' 12.8 22 28 38 -24 50 27
Double galaxy, just the cores show as object is in the muck. Cores are obvious. Western galaxy has brighter core, both have dim halos and are virtually touching.

I think my favorite view was of the last target, Arp 93. The total longshot is Arp 110, which I figure there is no way I saw, but decided to track down the location and pretend. I wrote down my "impression" which was severely fleeting. I did not look at the P.A. of the lumpy darkness last night on the computer, but, interestingly, as I write this OR I called it up both in The Sky (which was crashing like crazy again last night) and Megastar. They show two very different P.A.s!

Speaking of Arps, since I'm observing quite a number of them on my monthly lists, I've begun reading a book Ray Cash sent me, entitled The Electric Sky, by Donald E. Scott, in which Halton Arp so far is featured quite regularly. Interesting reading....

All in all though, it was a fun night at Coe, and more fun coming at CalStar... hope to see you all there.