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Followup on possible discovery

Posted: Fri Oct 26, 2012 10:57 am
by Pete
Thursday, 25 Oct 2012

This exercise is focused upon reacquiring the unidentified 20th magnitude asteroid from Monday night (Oct 22/23). The sky on the 24th was overcast, but at just before midnight it turned crystal clear. Dressing quickly I powered up the dome and ran the focusing & tracking calibrations. Just as I was preparing to slew to target cloud came in from the NW so I was back in bed by 00:30. Because of the very short 2-hour track, I figured that any ephemeris calculated would be pretty poor, so my working assumption is that this is a reacquisition of 2008 ON12, and it’s path is traveling very closely with 77738.

Woke again at 04:15 hrs to find the sky clear. Tossed & turned in my warm bed before deciding that my night was already bitched and I might as well give it another try. Wish I hadn’t completely shut the dome down as I wasn’t imaging on the spot where 2008 ON12 should be until 05:12. Using reductions that were available images were 3 min, 2X2, -25C, 3 Hz. I’ve waited too long though as the target’s quite low in the west and I’m viewing through miles of atmosphere. Asteroid 77738’s visible (18.8 magnitude) in the individual frames but it’s weak even in 2X stacks. Each successive image deteriorates a bit more. After 11 frames I’m losing my 9th mag guide star and change down to 1 Hz guiding. By 06:00 S/N is down 3-fold. Even with stacking the first (and best) 11 images there’s no hint of the target.

Ran astrometry on 77738. Frames 1-3, 4-6 & 7-11 show DRA = -0.1’, dDEC = 0. Same as the other night.

Imaging stopped at 06:23 and I’m back in bed by 06:30. Data on 77738 forwarded to the MPC later in the day.

At time of this logging, have received no feedback from the MPC and can find no indication of their posting on my one-nighter. Working a 20th mag object is probably beyond the capabilities of my setup, given my skies, but those were good numbers.

hgp 10:51 hrs, 26 Oct 2012

Re: Followup on possible discovery

Posted: Fri Oct 26, 2012 11:43 am
by AndyG
So the hunt continues... I hope you get another chance tonight before we start getting the clouds and rain from Hurricane Sandy. Looks like tonight there might be a small chance of some clear spots, especially earlier in the evening.

Re: Followup on possible discovery

Posted: Fri Oct 26, 2012 1:42 pm
by Pete
There are many problems Andy. First I need a couple of hours of cloud free highly transparent sky, at a time that I can manage. But the second is that I'm only guessing at where this asteroid will next turn up (and the longer the delay the higher the uncertainty). And the third, of course, is my inability to understand the MPC's setup. Think I'll just give up on this one as too much bother.

Pete

Re: Followup on possible discovery

Posted: Sat Oct 27, 2012 12:26 am
by AndyG
Pete, thanks for sharing your observing reports. It's fun to hear about what you are up to and share in the excitement of a potential discovery or re-acquisition of a lost object.

Re: Followup on possible discovery

Posted: Sat Oct 27, 2012 11:12 am
by Apollo XX
I agree. This has been fun to follow. Thanks for putting it all up for us to see, Pete.

Mike M.