Ho hum, more asteroids......

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Astro Day Coordinator
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Ho hum, more asteroids......

Unread post by Pete »

Monday, 3 December 2012

The sky’s been a bit hazy with light cloud, but the Clear Sky Charts are calling for clear sky with reasonable transparency tonight. Although I’ve downloaded asteroid data from the MPC and identified some targets I’m a bit hesitant to actually open up the dome early due to doubt. After dinner the sky is clear with dampness rendering moderate transparency. Timing the process the dome’s opened at 5:25 and between powering up the computer, scope and camera, loading target data into the computer, setting up data files, turning on software routines, calibrating the scope orientation, calibrating the adaptive optics, and focusing it takes 33 minutes before I’m ready to slew to the night’s first target. (Oh, air temp is 45°F and I’ve only got -30C reductions set up, so included in that is a 3 minute -25C reduction – as the camera wouldn’t reach -30C.)

2012 WJ4 is 1.8 km sized minor planet now 18.9 magnitude and .58 AU distant. Discovered 4 days ago, uncertainty level is 8 out of 9. Apparent motion is 2.12’/hr. Imaged from 18:18 – 18:50 at 3 minute exposure, 2X2 binning, -25°C cooling, 1 Hz guiding. Couldn’t see the asteroid in the first 2 or 3 frames so resorted to stacking 2-up, only to subsequently discover that the problem with the first few frames was the asteroid hiding in front of a star. Frames 4-5, 6-7 & 8-9 show dRA = +0.5’ and dDEC = +0.1’

2012 TA219 is a 1.6 km sized Amor now 19.1 mag and .6 Au distant. Discovered 55 days ago the uncertainty level is 4. Imaged from 19:03 – 19:41 hrs at 3 min, 2X2, -25C, 3 Hz. I’ve got it very weakly in individual frames. Stacking, frames 1-2, 3-4 & 9-10 show dRA = +0.3’ and dDEC = +0.2’

2012 TA79 is a 1.2 km sized Amor now 18.6 mag and .5 AU distant. Discovered 52 days ago, uncertainty level is 4. Apparent motion is 51”/hr. Imaged from 19:55 – 21:02 hrs at 3 min, 2X2, -25C, 3 Hz. Got it in single frames with S/N of 7+. Frames 1, 4 & 7 show dRA = +0.4’ and dDEC = +0.1’

158969 is a 4.8 main belt asteroid in the same frame as 2012 TA79. It’s presently 19.2 mag and 1.7 AU distant, moving at 40”/hr. Frames 1-2, 10-11 & 18-20 show dRA = +0.1’ and dDEC = 0’

2012 TJ146 is a 524 meter sized Apollo now.16 AU distant and 18.9 magnitude. Discovered 51 days ago, uncertainty level is 4. Apparent motion is 2.2’/hr. Imaging attempted from 21:15 – 21:22 hrs but the asteroid’s quite low in the west and the first image was very noisy, even with reduction, and unsuitable for astrometry. It’s been a very moist night, and a light layer of condensation was noted both inside and outside the corrector plate. The hair dryer was applied for a couple of minutes to clean things up, but no subsequent attempt was made to capture TJ146.

2012 VJ82 is a 757 meter sized Apollo now .36 AU distant and a dim 19.3 magnitude. Discovered 19 days ago, uncertainty level is 6. Apparent motion is 2.2’/hr. The air temp’s dropped to 38°F and VJ82’s close to zenith, so the focus is adjusted and the camera’s cooled deeper before proceeding. Imaged from 21:33 – 22:02 hrs at 2 min, 2X2, -30C, 2 Hz. Frames 1-3, 4-6 and 7-9 show dRA and dDEC = +0.2’

Shutting down is ever so much quicker than opening up, and I’m back in the house at 22:07 after noting some scattered cloud to the east. 15 observations are submitted to the MPC at 22:13 hrs.

Early darkness is a real boon, in that a decent number of observations can be taken without staying out late.

hgp logged 18:25 hrs, 4 Dec 2012
Pete P.