Asteroid 1999JM8

Arecibo Observations of 1999JM8: Proposal R1334

Abstract of the proposal

URGENT PROPOSAL FOR RADAR OBSERVATIONS OF ASTEROID 1999 JM8

S. J. Ostro, L. A. M. Benner, R. S. Hudson, M. C. Nolan, J. D. Giorgini, J.-L. Margot, D. B. Campbell, D. K. Yeomans

We propose intensive imaging observations of this recently discovered, large, Earth-crossing asteroid during its coming approach to within 0.06 AU from Earth. The expected echo strength should yield images with decameter resolution and a similarly detailed physical model.

The text of the entire proposal can be found here.

Preliminary results

The images below show partial reductions of delay-Doppler images of 1999 JM8 obtained at Arecibo Observatory on 1999 Aug 1-5. Range increases toward the bottom and Doppler frequency increases from right to left. Each image has a delay resolution of 0.1 usec (15 meters). The total range extent shown in each image is 7.68 km. The asteroid has a bandwidth of about 0.9 Hz and a maximum visible range extent of about 4 km. Updated images will be posted as soon as they become available.

AUGUST 1

Sum of 26 runs (7760 DFT, frequency resolution 0.020 Hz) out of 28 runs obtained on Aug 1. Doppler extent of image is 2.5 Hz.

Asteroid 1999JM8

AUGUST 2

Sum of 35 runs (8085 DFT, frequency resolution 0.019 Hz) obtained on Aug 2. Doppler extent of image is 2.4 Hz.

Asteroid 1999JM8

AUGUST 3

Sum of 28 runs (8192 FFT, frequency resolution 0.019 Hz) out of 30 runs obtained on Aug 3. Doppler extent of image is 2.4 Hz.

Asteroid 1999JM8

AUGUST 4

Sum of 5 runs (9000 DFT, frequency resolution 0.017 Hz) obtained on Aug 4. Doppler extent of image is 2.2 Hz.

Asteroid 1999JM8

AUGUST 5

Sum of 33 runs (9750 DFT, frequency resolution 0.016 Hz) out of 35 runs obtained on Aug 5. Doppler extent of image is 2.0 Hz.

Asteroid 1999JM8

AUGUST 6

Sum of 13 runs (10240 DFT, frequency resolution 0.015 Hz) obtained on Aug 6. Doppler extent of image is 1.9 Hz.

Asteroid 1999JM8

AUGUST 9

Sum of 22 runs (12288 DFT, frequency resolution 0.012 Hz) out of 26 runs obtained on Aug 9. Doppler extent of image is 1.6 Hz.

Asteroid 1999JM8

1999 JM8 ARECIBO OBSERVATIONS MASTERLOG

                      Bandwidth                AST            UTC    
DATE     SETUP   CODE   (Hz)    OSOD RUNS START - STOP   START - STOP
----     -----   ---- --------- ---- ---- ------------   ------------
AUG 1
DOY 213   4 us   2047  122.13    21    2  083730-084051  123730-124051
         0.1 us 65535  152.59    21   30  085104-095424  125104-135424

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AUG 2
DOY 214   CW          5000       23    1  083810-083903  123810-123903
         0.1 us 65535  152.59    23   35  084750-095751  124750-135751 last rcv incomplete

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AUG 3
DOY 215   CW          1000       23    2  081929-082235  121929-122235 levels changed during 1st run
         0.1 us 65535  152.59    23   30  084312-094600  124312-134600

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AUG 4   
DOY 216  0.1 us 65535  152.59    23    5  092600-093604  132600-133604

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AUG 5
DOY 217   CW          1000       26    1  075436-075540  115436-115540
         0.1 us 65535  152.59    26   35  075814-092054  115814-132054

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AUG 6
DOY 218  0.1 us 65535  152.59    26   13  083350-090522  123350-130522

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AUG 9
DOY 221 0.1 us 65535  152.59     26   26  064635-080350  104635-120350

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Last modified: 1999 August 9