Making do with brighter objects

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Pete
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Making do with brighter objects

Unread post by Pete » Mon Dec 16, 2013 2:36 pm

131215 log

There’s a full moon rising in the east but the sky’s clear and it’s a night for at least some observing. The next Osiris (exoplanet HD209458b) transit isn’t until 03:47 hrs on Dec 17th, and besides which I’ve not had a chance to study my setup test results. So even though Pegasus is high in the west the targets will be asteroids.

Air temp’s 28°F with a light breeze. Between the moon and the Christmas lights reflecting off of the 2” deep snow the sky’s not really dark. Consequently, I won’t be working dimmer objects.

163696 is a 3½ km sized Apollo now .3 AU distant and 16.6 magnitude. Motion is 6.3’/hr, Uncertainty level is 2, and ephemeris RMS residual is 0.54” Imaged from 17:39 – 17:54 hrs at 45 sec exposure, 2X2 binning, -30C cooling, 3 Hz guiding. A-ha! There are 3 bright galaxies in the field of view (FOV) as well as a second bright asteroid  Frames 1, 4 & 7 show a slight error in the calculated orbit as dRA = -0.1’ and dDEC = +0.1’ S/N is strong (12.6, 12.6, 15.2) with tight FWHM so the numbers are good.

2442 Corbett is a 19 km sized main belt asteroid now 2 AU distant and 17.3 magnitude. Discovered in 1942 it’s surprising that its RMS residual is still 0.54” Using the images from 163696, frames 1, 6 & 12 show dRA & dDEC = 0’

2013 TB80 is a 2.1 km sized Amor discovered 54 days ago. It’s .5 AU distant, 18.0 magnitude, with apparent motion of 1.7’/hr. Uncertainty level is 3. Imaged from 18:05 – 18:25 hrs at 3 min, 2X2, -30C, 2 Hz. Frames 1, 3 & 5 show dRA & dDEC = 0’.

138095 is a 4.4 km sized Amor now .7 AU distant and 17.4 magnitude. RMS is high at 0.58’ Imaged from 18:37 – 19:05 hrs at 5 min, 2X2, -30C, 10 Hz. Motion is a very slow 49”/hr allowing an unnecessarily long exposure taken in the hope of a discovery. This is the Cygnus area of the Milky Way and I usually avoid dense star areas. Although there are over 1000 stars in the FOV this asteroid is in the clear. Frames 1, 2 & 3 show dRA = -0.1’ and dDEC = +0.1’ S/N runs from 13.8 to 17.4 (and the FWHM from 3.6” to 4.3” so the numbers are firm.

2013 UR3 is a 2.6 km sized Amor now .4 AU distant and 17.4 mag. Motion is 2.3’/hr. Imaged from 19:17 – 19:50 hrs at 2 min, 2X2, -30C, 1 Hz. The sky’s pretty wiped out from the moon on the snow and doing visual DSOs would be out tonight. Frames 1, 5 & 9 show dRA & dDEC = 0

251346 is a 2.7 km sized Apollo now .2 AU distant and 15.7 mag. Motion is 1.3’/hr and uncertainty level is 1. Imaged from 19:59 – 20:22 hrs at 4 min, 2X2, -30C, 2 Hz. Once again I’m getting maximum shutter time to enable blinking for dimmer asteroids. Frames 1, 3 & 5 show dRA = -0.’1 and dDEC = 0’ With unusually high S/N between 60 & 70, the magnitude is reported with some confidence to be 15.4 R.

2007 YK1 is a 5.2 km sized main belt asteroid now 2 AU distant and (given tonight’s conditions) a relatively dim 18.9 mag. Uncertainty level is 1 and motion is 1’/hr. Imaged from 20:30 – 21:05 hrs at 4 min, 2X2, -30C, 3 Hz. Usually I’d capture this easily with a single 3-min exposure but since the 4 minute exposures are weak tonight stacking is necessary for higher accuracy. Frames 1-2, 3-4 & 5-6 show dRA & dDEC = 0

Two nights ago I was chasing the moon across the sky, working from W to E. Tonight the moon has been chasing me, and it’s near the meridian. I’m in at 22:10 hrs. Air temp’s 26°F

Conclusions & lessons learned:

It was, as expected, a short night. But it is lovely when the sun sets early and one can be up and running early in the evening. None of tonight’s objects were challenging but they were on the MPC critical object list and therefore fair game.

hgp logged 14:36 hrs, 16 Dec 2013
Pete P.
Bruce D
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Re: Making do with brighter objects

Unread post by Bruce D » Mon Dec 16, 2013 4:44 pm

Great report Pete, interesting as always, thanks!
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Pete
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Re: Making do with brighter objects

Unread post by Pete » Mon Dec 16, 2013 7:03 pm

Thanks Bruce,

This is where things were at on Saturday, January 28, 2005 - back when I was collecting asteroids visually with the old 12".
Image

Looking back at the log, it fell from 12° down to 7° while observing that night.

I was out most clear nights then, just as now. But given my advancing years and the increased complexity of setup and observations, these days I'd be pretty much out of business without the dome.

Pete
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Re: Making do with brighter objects

Unread post by Bruce D » Mon Dec 16, 2013 7:35 pm

Dome or no, you are out there a heck of a lot more than I am, good man!
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