J. L. Margot, P. A. Taylor, M. Nolan, E. Howell, S. J. Ostro, L. A. M. Benner, J. D. Giorgini, C. Magri, L. Carter
Observations of (35107) 1991 VH in 2008 provide an exceptional opportunity to characterize the dynamics, morphology, and physical properties of a binary (or multiple) system. High resolution images obtained over a suitable range of aspect angles will provide detailed information on the regolith, size, shape, and spin of the components and on their mutual orbit and dynamical interactions. Unless the secondary is exceptionally symmetric (equatorial radii within 10% of each other), we expect it to be attitude unstable and therefore a challenge for shape reconstruction efforts. But we like challenges and we will try hard to characterize the rotation of the secondary.
In conjunction with pre-existing observations, these data will probe the formation and evolution of binaries in great detail, including dynamical processes such as tidal interactions and tumbling, radiative processes such as YORP, and erosional processes such as avalanches and lofting/redeposition of material. The signal-to-noise ratio will approach 1000 per run, allowing very high quality images to be obtained down to 8 m resolution. If the observations are successful 1991 VH may become one of the very best characterized binaries in the solar system, comparable to 1999 KW4.
UT Date RTT DEC UT rise-set runs SNR/run (updated) ----------------------------------------------------------- 2008 JUL 29 86.4 37 22:18-23:22 22 101 1 x CW, 3 x 2 us, 7 x 0.1 us, azimuth arm fault 2008 AUG 01 75.8 32 21:23-23:24 48 160 2 x 3 x CW, 3 x 2 us, 34 x 0.5 us 2008 AUG 03 69.1 29 20:52-23:16 62 220 3 x 0.5 us in last 6 minutes (vacion interlock missing, no radar technician on site, both drove in) 2008 AUG 05 62.8 24 20:23-23:02 76 306 2008 AUG 07 57.1 19 19:58-22:42 86 425 2008 AUG 09 52.3 12 19:39-22:11 87 577 2008 AUG 10 50.3 8 19:34-21:50 81 660 2008 AUG 11 48.6 4 19:34-21:22 66 743 2008 AUG 12 47.2 0 19:49-20:38 31 818
DOY UT date --- UT window --- RTT SNR/run 219 2008 AUG 06 0125 0255 0625 0655 62 31 220 2008 AUG 07 0125 0255 0545 0615 59 37 224 2008 AUG 11 2300 0030 0415 0510 48 64 Radiation clearance grantedRadiation clearance
219 AUG-06-08 0255Z 0625Z (LOCAL AUG. 05, 7:55PM TO 11:25PM PDT) 220 AUG-07-08 0255Z 0545Z (LOCAL AUG. 06, 7:55PM TO 10:45PM PDT) !225 AUG-12-08 0030Z 0415Z (LOCAL AUG. 11, 5:30PM TO 9:15PM PDT) ! = conflict to be resolved
/share/obs4/usr/radar/1991VHData reduction scripts are stored in :
/proj/radar/1991VH
Ephemerides are available in:
/share/trabuco4/jplephem/osod/ops/a35107 aardvark:/export/data3/osod/ops/a35107Jon prepared solution 157, which we used on 2008 July 29. Jean-Luc obtained three range measurements on July 29 and generated solution 159, which we used on 2008 August 1. We found the object within a few us of the expected location. We will continue to use solution 159 on August 3, 5, and possibly longer, depending on how much drift we observe in upcoming tracks.
Relevant 3-sigma uncertainties are listed below:
Date__(UT)__HR:MN POS (asec) Doppler (Hz) RTT (seconds) 2008-Jul-29 00:00 .524 0.10 0.000337 Based on soln 157. 2008-Aug-01 00:00 .493 0.08 0.000012 Based on soln 159. 2008-Aug-03 00:00 .548 0.08 0.000021 Based on soln 159.
The secondary is likely ~500 m in diameter and may spin with 12.84 hours period (Pravec et al., 2006), so the limb-to-limb bandwidth would be ~1 Hz.
1. We will start with one CW run to confirm detection.
2. A single run with 8191 code at 2 us baud and 2 samples per baud (10 Hz tx offset, 61 Hz bandwidth, 32-point FFT) will allow us to compute a preliminary range measurement and determine whether the system is double or triple.
3. A single run with 1023 code at 2 us baud and 2 samples per baud (10 Hz tx offset, 489 Hz bandwidth, 32-point FFT) will confirm the range measurement above, at which point one observer will update the ephemeris and the other will recable for PFS sampling.
4. The rest of the track will be conducted with 65535 code at 0.1 us baud.
1. We will start with three CW runs to verify echo strength, measure primary and secondary bandwidths, and estimate cross-sections.
2. We will then acquire three runs with 1023 code at 2 us baud and 2 samples per baud (10 Hz tx offset, 61 Hz bandwidth, 128-point FFT) to confirm ephemeris solution 159.
3. We will acquire plenty of imaging data at 0.5 us baud. (8191 code, 1 sample per baud, 2 Hz tx offset, 244 Hz bandwidth, 512-point FFT).
4. We will end with three CW runs to verify echo strength, measure primary and secondary bandwidths, and estimate cross-sections.
1. Four CW runs (10 min).
2. Twelve runs (28 min) at 0.5 us baud. (8191 code, 1 sample per baud, 2 Hz tx offset, 244 Hz bandwidth, 1024-point FFT).
1. Five CW runs (10 min).
2. Twelve runs (25 min) at 0.5 us baud. (8191 code, 1 sample per baud, 2 Hz tx offset, 244 Hz bandwidth, 1024-point FFT).
Instructions for this track will be provided on the basis of the Arecibo results.
We will be doing mostly CW in a fixed configuration: no hopping, 2000 Hz receive offset. PFS will sample at 2 MHz with 0.5 MHz Faraday filter. What is critical is to measure limb-to-limb bandwidths with quasi continuous sampling to establish the rotation state of the secondary.
We will also obtain a few images for primary-secondary delay-Doppler separation measurements. We will use a 1 us baud, 4095 code, no coherent averaging, 245 Hz bandwidth, 256 FFT.
We will alternate between the following setups:
1. Twenty CW runs (40 min).
2. Ten imaging runs (20 min).
Pointing macros:
UT RA DEC dRA dDEC
(deg) (deg) (mdeg) (mdeg)
2008 AUG 06 03:00 213.317 23.5950 1.3 -1.9
2008 AUG 06 05:00 213.156 23.3763 1.3 -1.9
2008 AUG 06 07:00 213.003 23.1540 1.2 -1.9
Same configuration as DOY 219.
Pointing macros:
UT RA DEC dRA dDEC
(deg) (deg) (mdeg) (mdeg)
2008 AUG 07 02:00 211.576 21.0204 1.5 -2.0
2008 AUG 07 04:00 211.403 20.7810 1.4 -2.0
2008 AUG 07 06:00 211.236 20.5374 1.4 -2.0
1. Five CW runs (10 min).
2. Twelve runs (23 min) at 0.2 us baud. (65535 code, 2 samples per baud, 2 Hz tx offset, 76 Hz bandwidth, 1024-point FFT).
1. Two CW runs.
2. Twelve runs (19 min) at 0.1 us baud. (65535 code, 2 Hz tx offset, 152 Hz bandwidth, 256-point FFT).
Same configuration as DOY 219. If there are any uncertainties about pointing, shift the balance to more CW and monitor signal strength carefully in real-time.
We will alternate between the following setups:
1. Twenty CW runs (32 min).
2. Ten imaging runs (16 min).
Pointing macros:
UT RA DEC dRA dDEC
(deg) (deg) (mdeg) (mdeg)
2008 AUG 12 00:00 200.671 3.4258 1.6 -2.4
2008 AUG 12 02:00 200.435 3.0639 1.5 -2.4
2008 AUG 12 04:00 200.203 2.6998 1.5 -2.4
Name Institution Work phone Cell phone Email
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PI Jean-Luc Margot Cornell 607 255 1810 607 229 5015 jlm@astro.cornell.edu
Rising star Patrick Taylor Cornell 607 255 2727 ptaylor@astro.cornell.edu
AO guru/friend Mike Nolan NAIC 787 878 2612 x 334 nolan@naic.edu
DSN guru/friend Lance Benner JPL 818 354 7412 626 319 4369 lance.benner@jpl.nasa.gov
TX clearance Reid Drummond GDSCC 760 255 8218 rdrummond@jgld.gdscc.nasa.gov
TX clearance Larry Sturgis GDSCC 760 255 8071 LSturgis@jgld.gdscc.nasa.gov
DSN operator J. Van Brimmer RARG/ADVDEV 760 255 8469 JVanbrimmer@gdscc.nasa.gov
DSN operator M. Silva RARG/ADVDEV 760 255 8469 masilva@gdscc.nasa.gov
DSN L. Juare RARG/ADVDEV 760 255 8469 LJuare@gdscc.nasa.gov
Ephemerides Jon Giorgini JPL 818 393 3107 jdg@tycho.jpl.nasa.gov
GSSR support Joseph Jao JPL 818 354 2102 818 640 5802 Joseph.S.Jao@jpl.nasa.gov
JLM in Arecibo Control Room 787 878 2612 x 229 JLM VSQ 787 878 2612 x 374 Patrick VSQ 787 878 2612 x 379 JPL radar central 818 354 2877 Goldstone Pedestal 760 255 8470,8469,8259
Arecibo Cornell Goldstone JPL
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2008 JUL 29 Jean-Luc/Mike Patrick
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2008 AUG 01 Jean-Luc/Mike
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2008 AUG 03 Jean-Luc
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2008 AUG 05 Patrick/Mike Jean-Luc
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2008 AUG 06 G Jerry/Marc Lance/Joseph
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2008 AUG 07 G Jerry/Marc Lance/Joseph
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2008 AUG 07 Patrick/Mike Jean-Luc
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2008 AUG 09 Patrick/Mike Jean-Luc
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2008 AUG 10 Patrick/Mike Jean-Luc
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2008 AUG 11 Patrick/Mike Jean-Luc
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2008 AUG 12 Patrick/Mike Jean-Luc
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jlm@astro.cornell.edu