Back in the saddle again

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Back in the saddle again

Unread post by Pete »

Monday, 10 Nov 2014

The Backyard Astronomy class ended last week and it’s time to remount the camera and get back to chasing down some asteroids. The scope had been disassembled and cleaned a few weeks back, and since the sun’s shining (allowing critical inspection of glass) a couple of hours are spent doing the same with the camera train optics.
The camera was mounted mid-day and the rather damp observatory was left open to dry. I’m out at 19:00 plugging in cables and firing up electronics that’s been unused since Oct 2nd. Various actions such as squaring the camera and forgetting to reset software to Eastern Standard Time slow down the process but it still feels comfortable sitting out in the dome going through the familiar startup routine.

At 20:00 the sky’s clear and air temp’s down to 43°F. Due to the setup sequence it wasn’t possible to run optical flats for this session. Tonight’s work will be done using the camera’s autodark function so that at least darks are factored into the astrometry. Some stars seemed to bloom when shifted to the edge of the camera’s field of view, suggestion that the regenerated desiccant hadn’t fully dried the camera interior and frost was forming. So rather than attempt than cool to the normal -20 or -30°C the cooling was kept to just above freezing.

2014 VQ is a 548 meter Amor now 9 million miles distant and a bright 16.4 magnitude. Discovered 5 days ago, uncertainty level is 7. Motion is a brisk 8.7’/hr. Imaged from 20:08 – 20:37 hrs. at 30 seconds, 2X2 binning, +1°C cooling, 5 Hz guiding. Frames 1, 4 & 7 show dRA = -0.3’ and dDEC = +0.5’, with magnitude reported at 15.8R, 16.0R and 16.1R for the 3 frames. S/N averaged 22, while FWHM averaged 3.8”.

2014 TX57 is a 363 meter Amor now 10 million miles distant and 17.7 magnitude. Discovered 34 days ago, uncertainty level is 5. Apparent motion is 3.6’/hr. Imaging started at 20:48 hrs. 90 sec exposures binned 2X2, cooled to +1°C and guided at 2 Hz. The scope’s pointed high in the SE but the rising full moon is hurting image contrast. Frames 2, 5 & 8 show dRA = -0.9 are minutes from calculated orbit and dDEC = +1.0’ from established ephemeris. S/N ranges from 12.4 to 9.7 while FWHM stays tight between 4.1 and 3.6”

There are two other asteroids in the camera’s FOV.

2001 QB282 (55182) is a 12.6 km sized main belt asteroid now 1.6 AU distant and 17.3 magnitude. Apparent motion is only 42”/hour. Frames 2, 8 & 16 show dRA & dDEC = 0’ while S/N ranges from 16 to 11 and FWHM hangs tight at around 3.3”

1994 WW12 is a 5.7 km sized main belt asteroid now 1.8 AU distant and a dim 19.4 magnitude. Motion is 31”/hr. Stacking frames 2-8, 9-15 & 16-22 shows dRA & dDEC = 0’, with S/N strong at 12.5 and FWHM very tight at 3.1 Imaging finished at 21:33 hrs.

Although the transparency’s great, the moon’s rising and that’s it for the night. In at 21:41 hrs. Air temp now 41°F.

Conclusions & Lessons Learned:

12 observations were forwarded to the Minor Planet Center a bit belatedly as my desktop PC’s down and I’m working off of a borrowed laptop.

There’s an amazing amount of effort (won’t call it work ‘cuz I enjoy it as a hobby) that goes into a complete system cleaning and after sitting out in an unheated dome for years some traces of mold/mildew were present. The cleaning was needed. Perhaps a 60W light should be left under the scope cover to keep things dryer.
The cleaned optics looked good on the camera so the flats weren’t critical. But to go deep flats are needed – preferably twilight/Tee-shirt flats the next time out.

Didn’t intend to go 19.4 mag as this was just a test run of sorts, but we’re getting into clear winter sky conditions and it just happened to work without full reductions.
Classes are fun but it’s nice to be back to routine.

hgp logged 10:54 hrs., 11 November 2014
Pete P.