by Marek Cichanski
Henry Coe State Park Thu Feb 23 - Fri Feb 24, 2006 18" f/4.5 Obsession, ParaCorr Seeing: 3 to 4 (out of 5), intervals of 4+ Sky darkness: Approx. 20.3 to 20.7 mags / sq. arcsec (Unihedron meter)
Note: The formatting on this post might be funny, because I had to write parts of it at various different times, and patch it together from a series of messages that I forwarded to myself...long story...
As I was driving down the 101 to join the gang at Coyote, I couldn't help noticing the thick haze that filled the southern part of the Santa Clara valley. I exited the freeway at East Dunne, ate a quick fast-food dinner and bought gas, and decided to make an impromptu switch to Coe. I'm not sure how much of the haze I was able to get above, but it looked more 'layered' or 'structured' from Coe than it had from the valley floor, making me think that I had ascended to somewhere in the vicinity of the top of the layer.
There were two observers there when I arrived, one whose voice I recognized but whose name escapes me, and a fellow named John who was working on the Herschel 400 list. Once I was all set up at around 20:30, I noted that the air was almost completely still, 'cool but not cold', 6 stars in the Trapezium easily visible with the 9mm Nagler, and 20.35 magnitudes/arcsec on the Unihedron meter. The sky below about 30 degrees altitude was characterized by serious extinction, but it looked pretty good above about 30 degrees.
I continued my experiment with the Astrocards, starting with card B 10h UMa. It was really nice to be able to look to the northeast and see a dark sky. I don't get that at Montebello, and I made a mental note to go to Coe and Coyote more often, so as to greet the rising constellations.
The galaxy-hopping began with the 17mm type 4 Nagler, for a magnification of 139x and a true field of about 0.6 degrees. As always in my log entries, I use a shorthand system to describe the sizes of objects. I record the maximum linear dimension using an adjectival term that describes the fraction of the diameter of the field of view subtended. These 'field sizes' increase in the order "tiny field", "small field", "1/4 field", "central field", "3/4 field", and "full field". The idea is that I will make myself a lookup table so that I can translate these adjectival terms into actual sizes in arcminutes or arcseconds.
Maybe one of these decades I'll get around to actually making the table...
NGC 3184: Pretty faint to pretty bright, quarter field, elliptical N-S, concentrated nucleus with a stellar nucleus within, very diffuse edge.
NGC 3179: Small field to tiny field, round, faint, stellar nucleus. Challenging-ish.
NGC 3237: Tiny field, round, pretty faint to faint, concentrated nucleus. Tough-ish. It's looking like these 'B' series cards have some non-trivial objects on them.
NGC 3319: Considerably faint to faint, much elongated north-south, only a slight trace of a nucleus. Man, these suckers are tough!
NGC 3468: Considerably faint, small field, possibly pretty much elongated north-south, concentrated nucleus. Another toughie.
Lalande 21258: I think I've I.D.'d this star - looks orange - I wonder what's special about it? (Answer: If the data in this table is to be believed, it looks like it's a red dwarf about 8 light-years away, with two planets. Neat! http://www.johnstonsarchive.net/astro/nearstar.html)
NGC 3415: Pretty bright, small field, round, nearly stellar nucleus, next to a triangle of field stars.
NGC 3478: Small field to quarter field, pretty faint to considerably faint, elliptical to pretty much elongated northwest-southeast, slightly concentrated nucleus.
NGC 3320: Small field, pretty faint to pretty bright, much elongated north-south, slightly concentrated elongated nucleus, more concentrated at southwest end.
NGC 3198: Central field, considerably bright, much elongated north-northeast - south-southwest, concentrated nucleus. Finally, something brightish! I wonder if this is an H400 galaxy?
NGC 3191: Small field to tiny field, round, pretty faint, concentrated nucleus. It helps to put the bright field star to the north out of the field of view.
NGC 3135: Considerably faint to faint, tiny field, round. Tough! Whew!
And that was the end of the first Astrocard. One down, and I don't know how many to go... At 21:27 it was 48 degrees F, still calm, still only the tiniest bit of dew, and only on the infamously dew-attracting seat of the observing chair. A very nice winter evening so far. It's what northern California winter observing is supposed to be, I'd say.
I took a break to use the 15x50 Canon IS binos a bit. I like to alternate between intensive work at the eyepiece and easier, more relaxing stuff. Orion was heading over into the west, out of the dark part of the Coe sky. Canis Major was hanging just above the tree at the south end of the lot. M41 was just visible to the naked eye. I used Deep Map 600 to identify open clusters with the binos: M41, NGC 2367, NGC 2383, M93, NGC 2482, and the Tau Canis Majoris cluster. The views of the winter Milky Way through the binos were really pleasing. Something about the way I was holding them and the action of the stabilizers conspired to make the views rock-steady, and it was a delight to cruise amongst the starfields of the Orion (Perseus?) spiral arm. I think that the Messier and brighter NGC open clusters are wonderfully matched with an instrument like this.
By 22:30 I had been looking at Saturn for a while, and I'd had some great views. Very sharp and contrasty with the 8" aperture mask. I suppose that I'm obsessing too much over trying to get "apo-like" views, but that's the way I've been judging the views I have with the mask. Whenever the seeing is good, I find myself asking "is this view like the one I'd get in a big apochromatic refractor?" A silly game, true, but somehow that's what comes to mind. These views of Saturn were getting substantially into the realm of my longed-for "apo-like" views. There were very crisp edges on the planet and the rings, the cloud bands were easily seen, and the planet looked noticeably warmer and yellower than the rings. The Cassini Division very sharp, and I felt confident that I saw the Crepe Ring and the 'Crepe Ring Band' that it forms on the planet.
I'm even going to go out on a limb here - a pretty long limb - and say that I seriously suspect that I got glimpses of the Encke Minimum. I was mostly using the 7mm and 5mm type 6 Naglers, for magnifications of 336x and 471x. (I even used the 5 Nagler with a 2x Meade shorty barlow for 943x, but my barlow had this insane amout of dust in it, for some reason.) I kept asking myself whether an effective aperture of 8 inches could allow me to see the Encke, but there were times when it seemed like I glimsped a thin dark line in the outermost part of the rings, outside the Cassini Dvision. Was it just a diffracted 'mirage' of the rings' outer limb, or of the Cassini Division? Could be. But it was tantalizing, whatever it was.
After a long session with Saturn as it transited the meridian, I decided to see if I could knock off another Astrocard. This one was A 10h Leo, which covered the M95 / M96 area.
Starting with the 17 Nagler...
M95: Quarter field, round, bright, nucleus was concentrated to stellar. Diffuse edge.
M96: Small field to quarter field, considerably bright to bright, stellar nucleus, elliptical northwest-southeast.
NGC 3389: Small field to quarter field, pretty much extended east-west, pretty bright, slightly concentrated nucleus.
NGC 3384: Considerably bright, small field, elliptical to pretty much elongated northeast-southwest, very concentrated nucleus.
NGC 3412: Small field, considerably bright, pretty much extended east-west, stellar nucleus. Nice.
At 23:15 an owl was softly hooting in a nearby tree, which gave the night a pleasant feel. Some deer wandered by, silhouetted at one point against the lights of Morgan Hill. Still calm and dry, 46 degrees F, Unihedron meter reading 20.5 to 20.6.
At this point I switched to the 9mm type 6 Nagler, just to experiment with higher magnification...
NGC 3367: Small field to quarter field, pretty bright to condiserably bright, much extended northeast-southwest, concentrated nucleus, nearly stellar.
NGC 3377: Quarter field, round, pretty bright to pretty faint, stellar nucleus, hints of mottling or spiral structure at the edge of visibility.
NGC 3391: Pretty faint to considerably faint, small field, round to irregular figure, stellar nucleus or field star.
NGC 3357: Small field, round, considerably faint to faint.
NGC 3338: Round to elliptical east-west, pretty faint, concentrated nucleus. Prominent field star preceding.
Now a switch to the 12mm type 4 Nagler...
NGC 3300: Round, small field, pretty bright to pretty faint, concentrated to stellar nucleus.
NGC 3489: Considerably bright, quarter field, much extended east-west, stellar nucleus. Nice!
NGC 3506: Small field, round, pretty bright to pretty faint, no nucleus to speak of.
Then a switch to the 17 Nagler, to make finding things easier...
NGC 3433: Small field, faint to very faint. Quite challenging.
NGC 3434: Tiny field, round, pretty faint. Another toughie.
NGC 3428: Small field, very faint. Near a small group of field stars, quite difficult.
Back to the 9 Nagler...
NGC 3425: Small field, faint to very faint, round, stellar nucleus.
NGC 3427: Small field, pretty faint, elliptical east-west, stellar nucleus.
NGC 3441: Tiny field, round, pretty faint, no nucleus discernable.
Wolf 359: I'm not sure if I I.D.'ed this star correctly, but I presume that I saw it in the field of view. Looks like it's about the third farthest star from the Sun. I thought that the name of this star sounded familiar, as though I'd heard it in a sci-fi movie or on a TV show. A quick Google search showed that it was from an episode of Star Trek.
End of Astrocard. Whew! That one worked me!
Okay, enough faint galaxies for a while, time for some eye candy. Coma B is up nice and high, and that can mean only one thing: NGC 4565. Not looking at this galaxy during an eye candy break is like buying the swimsuit issue and just reading the article about the new offensive coordinator at Notre Dame. I always forget how big NGC 4565 is. Wow! Careful study at 139x and 252x shows a soft, lambent glow coming from the more obscured side of the nucleus. The remarkably stellar nucleus peeks out from under the dust lane. Reminds me of a setting sun seen under layered clouds.
At around 1:30 am I looked at M100 to try to see the supernova. Here is a sketch that I made:
http://nebula2.deanza.edu/~marek/images/M100sn.jpg
It's interesting to compare this to Richard's image from several days ago:
http://www.narrowbandimaging.com/m100_mk1sn2_sn2006x_page.htm
I'm not sure if the supernova is still bright, but it makes me think there's a reasonable chance that I had IDed the SN correctly. Some of the field stars seem to match up if you rotate my sketch.
Then, a long eye candy stroll around Downtown Virgo. Markarian's Chain, M87, the whole magilla. This was a great moment in the observing session, when I realized that it was February and I was at play in the fields of galaxies. Life is good.
Then, as if things couldn't get any better... the first globulars of spring. That's right, it was time for M3, M5, and M13. God bless Coe for its dark east. I pointed the Telrad up between Arcturus and Cor Caroli, and there it was: M3. Always a harbinger of spring and summer. Looking at M3 through a big scope is one of the few things in life that is very nearly as good as the first time. How sweet it is! The views through the 9 Nagler and 5 Nagler were unreal, despite some wind shake that had set in. As that city of stars hove through the field of view, it reminded me of just how great it is to have the constellations come and go with the seasons. We are always away from the globs long enough to miss 'em real badly when they come back.
The view of M5 was also incredible. I found myself saying "this is one of the most perfect things I've ever seen in a telescope." It was resolved to the core, and the extra-bright stars that are superimposed on the core added that extra 'oomph' to it. Exquisitely jewel-like.
Then M13. M13 in February! It is to laugh. I started thinking about these bright northern globulars and their even bigger counterparts in the SoHem. I decided that if M5 is the mini - 47 Tuc of the north, then M3 is the mini - Omega Cen of the north.
At 2 am Jupiter was looking VERY nice, but I have to admit that it was only that good during the moments when good seeing and calm breezes coincided. And this was despite only being about 25 degrees up. It was good without the aperture mask, but better with. The GRS was coming around towards the central meridian and was showing detail. There were many bright and dark knots and festoons in the belts. At their best, the views were full-on 'apo views'. I started calling them 'Voyager Views'. I felt like it was 1979 and I was a kid looking at the incredible images coming back from Jupiter.
Finished up at 2:30 am, rolling by about 3:15. Unihedron was giving about 20.50 to 20.80. Swung by the iron ranger and paid my moolah before driving down. Cheap at twice the price.
The only downsides to the evening were the haze and the moderate northeast wind that came up after midnight, but it wasn't a big deal. Really only got noticeable after about 1 am, and it came from the east, so it didn't pick up dust from the lot. Most of the night was almost perfectly still. Ahh... perfectly still air at Coe. I savored it. Virtually no dew, either. Great seeing, and previews of the spring and summer goodies in the east. All in all, it was a very nice night.
I have to admit that I don't get to Coe all that often, but when I have good nights there, I am reminded of how nice it can be. I rather enjoy the drive, and I enjoy the quiet mountaintop solitude of a good Coe night. The weather window opened, I was lucky enough to be able to make use of it, and I ended up rollin' 7s.
Posted on sf-bay-tac Feb 24, 2006 18:46:01 PT
Converted by report.pm 1.2 Mar 01, 2006 23:52:10 PT
