4 asteroids, plus an extra at 19.6 magnitude

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4 asteroids, plus an extra at 19.6 magnitude

Unread post by Pete »

Thursday, 4 Nov 2011 The afternoon sky’s cloudy but the CSC forecasts clear so I’m out opening up the dome at 17:30 under cloud. 4 asteroids have been targeted, and the plan is to be back in by 21:00 A bad camera connection results in a half-hour delay and the colder ambient temperatures prompt me to run some new dark frames as well as update my flat frames. Around 18:30 I'm giving it up due to cloud when my son points out that it's clear to the west. So I turn the scope back on and continue with setup.

The scope is carefully focused while pointing toward zenith, and then the guide system is synchronized on a star low in the south. As I slew to the first target air temp is 44°F

2005 NX44 is a 2.3km sized asteroid now 18.8 magnitude and .6AU distant. Uncertainty level is 2. Speed is 3.8’/hr. Imaged from 19:00 to 19:17 at 90 sec, 2X2, -20C, 8Hz. Being relatively dim and fast, stacking is required. Frames 1-3, 4-6 & 7-9 show dRA = -0.1’ and dDEC = +0.2’

2003 FH is s 998m sized 17.4 mag potentially hazardous Apollo. Distance is 0.17AU and speed is 4.4’/hr. Uncertainty level is 1. Imaged from 19:26 – 19:36 at 1 min, 2X2, -20C, 11Hz. Frames 1, 3 & 5 show dRA = +1.3’ and dDEC = +0.9’ (a surprisingly large variation for such an “old” asteroid).

283460 (2001 PD1) is a 1.4 km sized 17.0 mag Amor .27AU distant and moving at 1.2’/hr. Since it’s slow and since there’s another potential dim asteroid in the frame imaging from 19:50 – 20:35 is done at 3min, 2X2, -20C, 2 Hz. Images 1, 5 & 9 show dRA = +0.9’ and dDEC = +0.2’

1997 EB15 is supposed to be 19.5 mag, 5.2 km in size, 1.8 AU distant, moving at 0.47’/hr. However, there were only 8 observations made on this asteroid with an orbital arc of only 8 days, and this was back in 1997!!! This asteroid is supposed to be within the same FOV as 2001 PD1. Even with stacking as many as 6 frames (equivalent to 18 minute exposures) blinking fails to find EB15. This is truly a lost asteroid waiting to be rediscovered.

2002 QE7 is a 792m sized Amor now 18.8 mag, .36AU distant, moving 1.6’/hr. Uncertainty level is 1. Imaged starting at 20:37 hrs at 3 min, 2X2, -20C, at what I think was 2 or 3 Hz. It’s a beautifully clear night but my first image is a bit fuzzy and I suspect that focus has shifted somewhat due to the temperature having now dropped to 37°F. This being the last observation planned for the night I don’t interrupt the imaging sequence to refocus. I’m interrupted for more than an hour after the first few frames have been collected and when I get back out I’ve got a lot of long-exposure images. Which is fortunate as they’re not sharply focused, forcing me to stack a bunch of them. Frames 1-4, 8-11 & 15-18 show dRA = +0.5’ and dDEC = 0. Due to the lengthy exposures the stacked S/N is running around 10 and focused or not, the stacked images are strong.

2009 FU14 is a 3.8 km sized main belt asteroid in the QE7 FOV. Being 19.6 magnitude I’d normally give it a pass, but since I’ve more than an hour’s exposures I’ll try for it. Uncertainty level is 2. Distance is 1.5AU. Speed is 0.6’/hr. Stacking images from between 20:37 and 22:04 hrs, frames 1-7, 8-14 & 15-22 show dRA = +0.1’ and dDEC = -0.1’. Stacked S/N varies from 4.9 to 8.0 while FWHM is as fuzzy as 5.5

I’m in by 22:15 and the data is emailed to the MPC within minutes.

Conclusions & lessons learned:

I’ve been having trouble sending MPC format data with Win 7 and Outlook 2010. Hopefully this one is correctly formatted.

As winter draws closer I’m finding the new settings are allowing me to go deeper. Can’t say it’s routine now though. More like chance.

What a great night to be out under the stars.

hgp 14:06 hrs, 5 Nov 2011
Pete P.