Observing on 19 Feb 06 - asteroids + an attempt on SN 2006X

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Observing on 19 Feb 06 - asteroids + an attempt on SN 2006X

Unread post by Pete » Mon Feb 20, 2006 2:37 pm

Pete's observing log of 19 Feb 06

I was hoping to observe with the regular ASSNE crew tonight, but since it looks like the cold temperatures are keeping everybody close to home Dave and I set the 14” out on the tripod around 16:00 hrs. There’s a stretch of very clear weather right through Tuesday night’s scheduled Backyard Astronomy class, so I went with the bigger scope, and plan on leaving it out under cover for the 3 day stretch.

Tonight’s game plan is to observe some asteroids, duck in to warm up, and come out later to try to observe the super nova in M100.

19:00 hrs. The scope ran an auto alignment using Rigel and Dubhe. The temperature’s down to 23°F, but there’s no wind. The sky is 100% clear, the transparency looks very good, and the seeing isn’t all that bad either. I just did a crude alignment – centering the stars by eye in the Nagler 31, but recent experience shows this to be sufficient. My alignment check was on M42. I could see all 6 stars in the Triangulum readily at 115X, and the star grouping was just a hair high of center. Quite workable.

My sister-in-law has been visiting, and as she’s on her way out I gave her a brief sky tour – M42, Saturn & its planets, Andromeda (NG – it was just below the roof ridgeline), M45, M44 and M82.

20:10 hrs. After about 45 minutes of trying to view asteroid 286 Iclea (14.2 magnitude) I give up on it. I can usually go this deep with the 12”, and I went all the way to my 6.4mm Plossl (556X) without seeing Iclea.

For a clear night, the sky isn’t as black as I’d hoped for. Temp’s down to 22°F, and its still calm.

19 Feb 06; 20:22 hrs. 456 Abnoba is shining at 13.7 magnitude tonight. The scope’s go-to is right on and I’m centered on the star group around Abnoba, but it takes about 5 minutes of straining my viewing eye through the 17mm (209X) before I’m viewing Abnoba thru the 14” with averted vision. This 27 mile sized asteroid orbits Sol at 2.9 AU, and it is presently 2.0 AU from Earth. Normally I’d be viewing this bright an object easily at 115X. What’s wrong? There’s no dew.

20:28 hrs. I slew to the Horse Head nebula, but can’t see a thing with the Hbeta equipped Nagler 31. Perhaps there’s a high thin haze that’s catching the light pollution.

19 Feb 06; 20:43 hrs. 790 Pretoria is a 109 mile sized asteroid shining at 13.9 mag this evening. Star-hopping in from an 8th mag star to the W, I have to push the 14” all the way to 395X (9mm Plossl) before I’ve got Pretoria as well as two 14.4 mag stars to either side of it. Pretoria orbits the sun at 3.9 AU, and it now lies a distant 3.1 AU from Earth.

19 Feb 06; 20:47 hrs. 135 Hertha is a bright 12.7 mag tonight. The 14” go-to is right on and I’ve got Hertha immediately at 115X. This 51-mile sized asteroid orbits 2.9 AU from the sun, and is presently 2.0 AU from Earth.

19 Feb 06; 20:54 hrs. 534 Nassovia is 14.0 mag tonight. Star hopping from a 5th mag star to the SE, I’ve got it in the 14” at 209X (Nagler 17mm). Nassovia is 23 miles in size. It orbits Sol at 2.8 AU, and is presently 1.9 AU from Earth.

I’ve also got a dim star a bit N of Nassovia that’s not on my chart at location 08h 42m 39.53s, +21° 37m 060s. The dim star shows on my imported Deep Sky Survey image, but its far too dim to be normally seen. Could we have another Nova here?

19 Feb 06; 21:03 hrs. 642 Clara is a 25-mile size asteroid that’s at 14.2 mag tonight. Star hopping in from the W, I’ve got it in the 14” with the Nagler 17mm (209X). Clara orbits the sun at 2.8 AU, and is presently 1.9 AU from Earth.

19 Feb 06; 21:18 hrs. 700 Auravictrix is shining at 13.6 mag. I’ve got it in the 14” at 209X. This 10½ mile sized minor planet orbits the sun at 2.1 AU, and it is now 1.1 AU from Earth.

19 Feb 06; 21:24 hrs. 596 Scheila is a relatively bright 13.5 magnitude tonight. It’s bracketed by some 9th mag stars, and I’ve got it in the 14” at 115X. This 73-mile sized asteroid orbits the sun at 3.0 AU, and its now 2.1 AU from Earth.

19 Feb 06; 21:38 hrs. 1078 Mentha is an 18-mile sized minor planet shining at 13.8 mag this evening. It’s moved a bit since my 20:00 hour plot was generated, and I must regenerate an up-to-the-minute plot to confirm viewing Mentha thru the 14’ at 296X (Nagler 12mm). Mentha orbits Sol at 2.0 AU, and is presently 0.99 AU from Earth.

19 Feb 06; 21:44 hrs. 292 Ludovica is a 22-mile sized asteroid shining at 13.4 mag. Star hopping up from the SE, I’ve got it easily thru the 14” at 209X (Nagler 17mm). Ludovica orbits the sun at 2.6 AU, and is now 1.7 AU from Earth.

It’s down to 18°F now, but it’s still calm.

19 Feb 06; 21:54 hrs. 677 Aaltje is a 18-mile sized minor planet shining this evening at 13.7 magnitude. I’m viewing it thru the 14” at 115X but had to go to 209X to confirm the sighting. Aaltje orbits 2.8 AU from Sol, and is now positioned 1.9 AU from Earth.

19 Feb 06; 22:01 hrs. 774 Armor is a relatively bright 13.3 mag tonight. It sits in the center of a triangle formed by three 10th mag stars, and I’ve got it thru the 14” with the Nagler 31 (115X). This 35-mile sized asteroid orbits Sol at 3.3 AU, and it now lies 2.3 AU from Earth.

19 Feb 06; 22:06 hrs. 174 Phaedra is a bright 12.4 magnitude. I’ve easily got it thru the 14” at 115X (Nagler 31mm). This 44-mile sized minor planet orbits Sol at 2.9 AU and it is presently 1.9 AU from Earth.

22:34 hrs. I’m forced to give up on asteroid 1444 Pannomia. It’s supposed to be at 13.7 magnitude tonight, but I’m viewing thru the 14” with the Nagler 12mm (296X) and although I’m seeing 14.3 and 14.5 mag stars bracketing where Pannomia should be, there’s no asteroid. Hmmmm.

22:49 hrs. I’m forced to give up on asteroid 2094 Magnitka. It’s supposed to be 14.0 magnitude, and although I’ve got a 14.2 mag star in the 14” fov using the Nagler 12mm, I don’t see the asteroid. And I can’t go to the 9mm Plossl because my guide stars are too far apart to fit the smaller fov.

22:58 hrs. Coma Berenices and M100 are relatively high now, and its time to search out the supernova the club’s been talking about – SN 2006X. The 14” go-to puts M100 in the center of the fov. At 115X I have identified three nearby 10th mag stars that provide me with an initial orientation as to where to look in the galaxy. Shifting to the Nagler 17mm (209X) I can now see the two 13.9 mag stars that bracket the supernova, as well as an additional 12.9 mag orientation star 5’ to the NE from the core of the galaxy.

I’m still seeing my orientation stars when I increase to 296X with the Nagler 12mm, but this is where things start to break down. I still can’t see the three 15th mag stars that form a dog-leg about 140° around the spiral galaxy’s center from the supernova. And I can’t see the supernova or the somewhat fainter star just inside of it, where they nest in the armpit of a spiral.

The text accompanying the amateur posted article that Paul D had forwarded said that the magnitude had surpassed 11.6 mag. And there are several other SN 2006X postings all containing conflicting magnitudes. Knowing the magnitude of the “dog-leg” stars and comparing them and the 13.9 magnitude stars against the inner star and the outer supernova photos, that inner star appears to be 16th or 17th magnitude, and the supernova appears to be 14th to 15th magnitude. The 13.9 mag star on the SE side (GSC1445-2507) appears to be a bit hazy – not sharp. So I may be in error in identifying this star. But the proportions of the group are right and I don’t think I’m wrong. The galaxy itself seems to fade from nebulous to non-existent as I increase magnification.

23:55 hrs. I pack it in for the night. But first I carefully focus the scope using the Nagler 31, and I then point it toward the zenith and put it into SLEEP mode.

20 Feb 06; 08:30 hrs. I’m trying for Jupiter in the daylight, but it’s already down below the house. The go-to centers Venus however, and I check out the rather full crescent for a minute or two before powering the scope off and recovering it with the Mylar cover.

Conclusions and lessons learned:

It was a good but puzzling night. Most of these small asteroids are far from spherical, and perhaps those I couldn’t find were just at a bad angle and were too dim to view because of that. I dunno. I was able to view 12 asteroids going as dim as 14.2 mag. So why supposedly brighter ones escaped me is indeed a puzzle.

SN 2006X is probably dimmer than reported, and I believe that’s the reason I couldn’t see it. But even with a minimal CCD camera I’m sure I could have captured it.

Interestingly, I found the ASVOS chart to be completely out of sync with the Deep Sky Survey photos I downloaded during my effort to view the supernova.

Although I was out for 5 hours the average 20°F temperature wasn’t a problem as I was properly dressed.

Pete 20 Feb 06