2012 TC4 Goldstone Radar Observations Planning
2012 TC4 was discovered by Pan-STARRS 1 on October 5, 2012. 2012 TC4 will approach Earth within 0.25 lunar distances (LD) on Oct 12, 2012 when it will be an outstanding radar target at Goldstone. The current orbital solution (solution 11) indicates that 2012 TC4 approached Earth within five lunar distances (and possibly much closer) in October of 1996 and that it may approach within about 0.37 lunar distances in October of 2017. 2012 TC4 is on NASA's Near-Earth Object Risk Page (http://neo.jpl.nasa.gov/risk/). There are 60 potential impacts between 2020-2106 for a cumulative impact probability of 3.7x10^-5. That's a small number, but it's large enough that radar astrometry will be of considerable interest and it could improve the orbit sufficiently to rule out many potential impact trajectories. That said, it is still much more dangerous to walk across the street. Not much is known about this object, except that its absolute magnitude of 26.5 suggests a a diameter within a factor of two of about 15 meters. J. Briggs, P. Wiggins, R. Miles, A. Carbognani, W. Ryan, and P. Bacci (pers. comm.) have reported a rotation period of 0.2 h and a large lightcurve amplitude of nearly one magnitude. This indicates that 2012 TC4 is an elongated and rapidly rotating object. In addition, a second period is present in the lightcurves that hints that the object could be a non-principal axis rotator (i.e., a tumbler). Due to the rotation period and our guess about its size, we expect a bandwidth of 5-10 Hz. Due to the short notice, there is only one track scheduled on Oct 11 when the object is inbound at a range of about 1.4 lunar distances. As a result of the very short RTT (~3.6 sec), the observations will be bistatic with DSS-14 transmiting and DSS-13 receiving. We are planning to obtain CW and 10 and 11 usec ranging data, and if SNRs are significantly stronger than we expect, we *hope* to utilize the highest resolution available from the chirp system (3.75 m) and obtain some delay-Doppler images. The S-band radar at Arecibo is undergoing a receiver upgrade and will not be available to observe 2012 TC4. 2012 TC4 brightens below 14th magnitude on the day of the closest approach, after which it moves too close to the Sun for optical observations. The astrometry and lightcurves that have been provided by observers around the world have been invaluable: Thank you very much!
Orbital and Physical Characteristics orbit type Apollo semimajor axis 1.284 AU eccentricity 0.294 inclination 1.4 deg perihelion distance 0.907 AU aphelion distance 1.662 AU absolute magnitude (H) 26.5 diameter ~0.014 km (within a factor of two) rotation period ~0.2 h (J. Briggs, P.Wiggins, R. Miles, A. Carbognani, W. Ryan, P. Bacci, pers. comm.) pole direction unknown lightcurve amplitude ~1 mag spectral class unknown Last update: 2012 October 10
M.P.E.C. 2012-T18 Issued 2012 Oct. 7, 14:42 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Commission 20 of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network MPC@CFA.HARVARD.EDU URL http://www.minorplanetcenter.net/ ISSN 1523-6714 2012 TC4 Observations: K12T04C* C2012 10 04.46767323 32 31.445+04 13 34.66 20.1 iLET018F51 K12T04C C2012 10 04.47999623 32 29.747+04 13 29.02 20.2 iLET018F51 K12T04C C2012 10 06.17441 23 31 27.98 +03 58 15.4 18.8 VrET018703 K12T04C C2012 10 06.18227 23 31 26.61 +03 58 10.8 19.0 VrET018703 K12T04C C2012 10 06.19686 23 31 23.91 +03 58 03.3 19.0 VrET018703 K12T04C KC2012 10 06.82657 23 30 47.49 +03 48 25.7 uET018J95 K12T04C KC2012 10 06.82879 23 30 47.13 +03 48 23.8 uET018J95 K12T04C KC2012 10 06.83069 23 30 46.85 +03 48 22.3 18.9 RuET018J95 K12T04C KC2012 10 06.91007 23 30 32.94 +03 47 21.3 18.7 VtET018J84 K12T04C KC2012 10 06.91735 23 30 31.58 +03 47 15.3 18.5 VtET018J84 K12T04C KC2012 10 06.92464 23 30 30.16 +03 47 09.2 18.7 VtET018J84 K12T04C KC2012 10 07.18949 23 30 09.38 +03 44 19.4 17.9 RuET018H36 K12T04C KC2012 10 07.20168 23 30 06.54 +03 44 08.0 17.9 RuET018H36 K12T04C KC2012 10 07.21581 23 30 03.30 +03 43 54.5 18.4 RuET018H36 K12T04C KC2012 10 07.22407 23 29 53.00 +03 43 25.9 19.7 VuET018932 K12T04C KC2012 10 07.22588 23 29 52.61 +03 43 24.0 19.1 VuET018932 K12T04C C2012 10 07.50398 23 29 48.85 +03 39 27.2 19.2 VuET018900 K12T04C C2012 10 07.51112 23 29 47.07 +03 39 19.6 18.9 VuET018900 K12T04C C2012 10 07.51826 23 29 45.22 +03 39 12.0 19.2 VuET018900 Observer details: 703 Catalina Sky Survey. Observer A. Boattini. Measurers A. Boattini, E. J. Christensen, A. R. Gibbs, A. D. Grauer, R. E. Hill, R. A. Kowalski, S. M. Larson, R. H. McNaught. 0.68-m Schmidt + CCD. 900 Moriyama. Observer Y. Ikari. 0.26-m f/7.0 reflector + CCD. 932 John J. McCarthy Obs., New Milford. Observer M. Polansky. 0.4-m f/6.3 Schmidt-Cassegrain + CCD. F51 Pan-STARRS 1, Haleakala. Observers N. Primak, A. Schultz, S. Watters, J. Thiel, T. Goggia. Measurer PS1 Science Consortium. 1.8-m Ritchey-Chretien + CCD. H36 Sandlot Observatory, Scranton. Observer G. Hug. 0.56-m reflector + CCD. J84 South Observatory, Clanfield. Observer D. Briggs. 0.61-m f/4.75 reflector + CCD. J95 Great Shefford. Observer P. Birtwhistle. 0.40-m f/6.0 Schmidt-Cassegrain + CCD. Orbital elements: 2012 TC4 Earth MOID = 0.0001 AU Epoch 2012 Sept. 30.0 TT = JDT 2456200.5 MPC M 322.00810 (2000.0) P Q n 0.67724540 Peri. 233.68736 +0.30233884 -0.95316785 a 1.2842178 Node 198.71920 +0.88223745 +0.28295573 e 0.2940961 Incl. 1.40910 +0.36089930 +0.10680409 P 1.46 H 26.6 G 0.15 U 7 Residuals in seconds of arc 121004 F51 0.1+ 0.1+ 121006 J95 0.2+ 0.0 121007 932 0.2- 0.2+ 121004 F51 0.2+ 0.1+ 121006 J84 0.3+ 0.1+ 121007 932 0.4- 0.2+ 121006 703 0.9- 0.5+ 121006 J84 0.5+ 0.3+ 121007 900 0.2+ 0.5+ 121006 703 0.0 0.5+ 121006 J84 0.0 0.4+ 121007 900 0.5+ 0.2+ 121006 703 0.3+ 1.9+ 121007 H36 0.3- 0.2- 121007 900 0.2+ 0.0 121006 J95 0.1+ 0.3+ 121007 H36 0.2- 0.0 121006 J95 0.1- 0.1+ 121007 H36 0.9+ 0.1+ Ephemeris: 2012 TC4 a,e,i = 1.28, 0.29, 1 q = 0.9065 Date TT R. A. (2000) Decl. Delta r Elong. Phase V 2012 09 07 23 39 53.0 +04 18 05 0.1469 1.1509 166.2 12.1 23.5 ... 2012 09 22 23 37 31.9 +04 40 35 0.07892 1.0821 173.0 6.5 21.8 ... 2012 09 30 23 34 53.8 +04 32 18 0.04680 1.0471 167.1 12.3 20.8 ... 2012 10 06 23 31 28.9 +04 03 03 0.02371 1.0221 161.0 18.6 19.5 2012 10 07 23 30 22.9 +03 51 25 0.01991 1.0181 159.8 19.9 19.1 2012 10 08 23 28 49.4 +03 34 17 0.01611 1.0141 158.4 21.3 18.7 ... 2012 10 14 11 22 02.3 -02 16 56 0.0068230.9915 29.2 150.6 24.3 ... 2012 10 22 11 08 11.7 +00 33 15 0.03707 0.9676 41.2 137.4 25.9 ... 2012 11 06 11 14 43.3 +00 14 37 0.09493 0.9392 54.4 120.9 26.3 A. U. Tomatic (C) Copyright 2012 MPC M.P.E.C. 2012-T18
Target Name: 2012 TC4 D = 0.014 km Period = 0.2 hr (lightcurves) OC albedo = 0.1 Monostatic UT # max BISTATIC DOY start date window RA, dec dist runs SNR SNR/run SNR/RTT ------------------------------------------------------------------------------------------------- 284 2012 Oct 10 01:28-10:14 350, +2 0.008 2306 330 8 2 285 2012 Oct 11 01:20-09:35 346, -1 0.004 4367 4700 79 20 286 2012 Oct 12 00:59-03:14 311, -28 0.001 12540 1500000 14000 3500 287 2012 Oct 12 15:16-22:01 180, -11 0.002 6937 42000 570 140 288 2012 Oct 13 13:39-21:51 171, -3 0.006 2861 920 19 5 289 2012 Oct 14 13:18-21:45 169, -1 0.010 1775 130 3 - The round-trip time is so short that the observations must be bistatic. Goldstone SNRs assume Ptx = 435 kW
Goldstone tracks: UT UT PST Duration Round-trip Bistatic DOY Date TX Window TX Window hh:mm time (sec) SNR/RTT --- ---- --------- --------- --------- --------- ------- 285 Oct 11 0545-0935 2245-0235 Oct 10/11 03:50 3.6 ~20 NOTE: TXON is shown at the earliest time, which is only 15 min into the precal time.
From Jon Giorgini, 2012 October 10: Including the three new measurements forwarded directly by e-mail, 2012 TC4 orbit solution s11 was estimated. Data arc is 133 optical from Oct 4-10 2012. Files were updated on aardvark, .s9 moved to /OLD sub-directory. Minor noise-level update (below). 3-sigma X-band uncertainties at 4 hour steps: Date__(UT)__HR:MN POS_3sigma DOP_X_3sig RT_delay_3sig 2012-Oct-11 00:00 2.277 181.07 0.002106 2012-Oct-11 04:00 3.355 179.50 0.001838 2012-Oct-11 08:00 5.499 177.27 0.001584 2012-Oct-11 12:00 9.488 173.69 0.001350 2012-Oct-11 16:00 17.055 167.28 0.001147 2012-Oct-11 20:00 34.990 152.23 0.000986 2012-Oct-12 00:00 93.460 127.36 0.000842 2012-Oct-12 04:00 281.099 493.21 0.000469 2012-Oct-12 08:00 231.081 365.35 0.000690 2012-Oct-12 12:00 109.043 193.09 0.001100 2012-Oct-12 16:00 69.196 172.81 0.001383 2012-Oct-12 20:00 57.623 171.27 0.001642 2012-Oct-13 00:00 53.819 176.64 0.001904 Differencing old and new: RECEIVER U.T. RANGE DOPPLER LHA DEC RA EL s11: 2012 OCT 11 01:30 4.5099030821 391778.316 297.8950 -0.5111 347.766 22.089 s09: 2012 OCT 11 01:30 4.5098652318 391786.844 297.8951 -0.5112 347.766 22.089 ------------ ---------- So + 37.8 usec, -8.5 Hz .... noise levels changes in s11 relative to s9. - - - - - - - - - - - - - - - - - - - - From Jon Giorgini, 2012 Oct. 10: With the current dataset of 130 optical measurements spanning Oct 4-10, 2012 (including the data forwarded directly), 2012 TC4 orbit solution #9 was estimated and OSOD w/nominal radar predicts established on aardvark in the /2012tc4 sub-directory. Formal 3-sigma X-band uncertainties for .s9 at 4 hour intervals: Date__(UT)__HR:MN POS_3sigma DOP_X_3sig RT_delay_3sig 2012-Oct-11 00:00 3.194 200.81 0.002149 2012-Oct-11 04:00 4.815 198.93 0.001872 2012-Oct-11 08:00 7.842 196.21 0.001618 2012-Oct-11 12:00 13.409 191.94 0.001399 2012-Oct-11 16:00 24.019 184.11 0.001228 2012-Oct-11 20:00 48.903 163.99 0.001114 2012-Oct-12 00:00 129.091 133.30 0.001003 2012-Oct-12 04:00 381.490 668.30 0.000513 2012-Oct-12 08:00 304.256 496.48 0.000916 2012-Oct-12 12:00 134.199 243.41 0.001463 2012-Oct-12 16:00 76.439 202.75 0.001810 2012-Oct-12 20:00 59.462 194.58 0.002113 2012-Oct-13 00:00 54.843 197.58 0.002409 There is some questionable astrometry which has been deweighted, but there remains the potential for bias larger than the formal statistics above. - - - - - - - - - - Uncertainties based on 127 optical observations (6 day data arc), JPL Horizons sol. #7, Oct 10, 2012 Date__(UT)__HR:MN POS_3sigma DOP_S_3sig DOP_X_3sig RT_delay_3sig 2012-Oct-09 00:00 * 0.518 59.66 216.82 0.006299 2012-Oct-10 00:00 * 0.713 59.28 215.45 0.004292 2012-Oct-11 00:00 * 5.441 58.19 211.48 0.002567 2012-Oct-12 00:00 * 217.734 56.01 203.57 0.001731 2012-Oct-13 00:00 * 67.012 57.68 209.65 0.003118 2012-Oct-14 00:00 * 57.591 59.22 215.23 0.005002 2012-Oct-15 00:00 *m 57.927 59.85 217.51 0.007046 2012-Oct-16 00:00 *m 58.269 60.24 218.96 0.009158 2012-Oct-17 00:00 *m 58.498 60.58 220.17 0.011303 ********************************************************************************************** Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: Date__(UT)__HR:MN R.A._(J2000.0)_DEC. APmag delta S-O-T /r T-O-M/Illu% 2012-Oct-09 00:00 351.59314 3.11045 18.09 0.01232825962405 156.7981 /T 120.4/ 43.4 2012-Oct-10 00:00 350.45706 2.24106 17.36 0.00854721488741 154.5769 /T 134.2/ 33.7 2012-Oct-11 00:00 347.54759 -0.00760 16.21 0.00477094120664 150.2789 /T 150.6/ 24.3 2012-Oct-12 00:00 323.42399 -17.58309 13.84 0.00109824337336 121.1159 /T 165.2/ 15.8 2012-Oct-13 00:00 176.26647 -6.69283 n.a. 0.00305192311159 21.9380 /L 13.3/ 8.6 2012-Oct-14 00:00 170.51187 -2.28420 n.a. 0.00681428435744 29.2301 /L 8.333/ 3.3 2012-Oct-15 00:00 168.87627 -1.01074 n.a. 0.01058488177640 32.0916 /L 24.8/ 0.5 2012-Oct-16 00:00 168.11436 -0.40923 n.a. 0.01435532506468 33.9609 /L 40.5/ 0.4 2012-Oct-17 00:00 167.68449 -0.06173 n.a. 0.01812675220229 35.4495 /L 56.0/ 3.3
We're going to attempt 20 MHz chirping. If the SNRs are sufficiently strong, we hope to try 40 MHz chirping. We're going to start with unhopped CW, update the ephemeris, do more CW to verify the new solution, and then decide what do do next depending on the SNRs. If the SNRs are stronger than we expect, we may try imaging. Regardless, we plan to do a block of at least 45 minutes of CW with the updated solution at some point in order to cover multiple rotations by the asteroid. 20 MHz chirp: ------------- sample clock at 40 MHz, prp 50 us, offset +40 Hz, 2000 bins in delay, FFT=500, ncoh=40 (0.025usx1 Hz) 40 MHz chirp: ------------- sample clock at 40 MHz, prp 50 us, offset +40 Hz, 2000 bins in delay, FFT=500, ncoh=40 (0.025usx1 Hz) This object has large Doppler uncertainties, and we may see a Doppler correction of up to several hundred Hz, so we're going to start with a wider bandwidth than usual: TX polarization RCP RCV polarization LCP & RCP Frequency hops: no hops Bandwidth: 8000 Hz TX Offset: + 1kHz Sampling interval: 1250 x 0.1 usec VME FFT for PSD files: 8192 for 0.98-Hz resolution Once we improve the solution, we'll switch to: TX polarization RCP RCV polarization LCP & RCP Frequency hops: no hops Bandwidth: 4000 Hz TX Offset: + 1 kHz Sampling interval: 2500 x 0.1 usec VME FFT for PSD files: 4096 for 0.98-Hz resolution Ranging setups: --------------------------------------------------------------------------- 10-usec baud 10 usec code 127 PRP 1270 usec FFT 128 ncoh 1 bandwidth 787 Hz resolution 6.15 Hz TXOFF +100Hz (echo in bin 64+16=80) --------------------------------------------------------------------------- 11-usec baud 11 usec code 127 PRP 1397 usec FFT 128 ncoh 1 bandwidth 716 Hz resolution 5.6 Hz TXOFF +100 Hz (echo in bin 64+18=82) ------------------------------------------------------------------------- 1-usec baud 1 usec code 255 FFT 128 ncoh 6 bandwidth 654 Hz resolution 5.1 Hz TXOFF +80 Hz -> echo would be centered at 64 + 16 = 80 _____________________________________________________________________ POSSIBLE RANGING SETUPS: (code=127, FFT=64, single-pol'n) These are from JX, w/ max-band (min-acc) options from Ray Jurgens. Currently configured for 5-sec records. _______________________________________________________________________ Setup Baud RP 1-acc 1-acc usec m usec band res acc band res _______________________________________________________________________ JX1XS110 11.000 1650 1397.0 715.8 11.2 2 358 5.6 JX1XS070 7.000 1050 889.0 1124.9 17.6 3 375 5.9 JX1XS020 2.000 300 254.0 3937.0 61.5 12 328 5.1 4 984 15.4 JX1XS010 1.000 150 127.0 7874.0 123.0 41 192 3.0 8 984 15.4 JX1XS005 0.500 75 63.5 15748.0 246.1 123 128 2.0 15 1050 16.4 JX1XS002 0.250 37.5 31.75 31496.1 492.1 492 64 1.0 30 1050 16.4 JX1XS001 0.125 18.75 15.875 62992.1 984.3 1970 32 0.5 60 1050 16.4 ____________________________________________________________________
OSOD and predicts are on aardvark: Binary-phase coding: /export/data3/osod/ops/2012tc4/PRDX.OUT.14f-13-13.s11 PUNCH.OUT.14f-13-13.s11 EPH.OUT.s11 New waveform generator: /export/data3/osod/ops/2012tc4/PRDX.OUT.14v-13-13.s11 PUNCH.OUT.14v-13-13.s11 POINTING TX Offsets Date (UTC) DOY hhmmss RA Dec Macro LHA Dec RTT OSOD 2012 10 11 285 050000 346.4945 -1.3029 A 3.9 11 2012 10 11 285 060000 346.0341 -1.5705 AB 0.5 -0.3 3.8 2012 10 11 285 070000 345.5390 -1.8597 AB 0.5 -0.3 3.6 2012 10 11 285 080000 345.0156 -2.1729 BC 3.5 2012 10 11 285 090000 344.4702 -2.5129 C 0.5 -0.3 3.3 2012 10 11 285 100000 343.9084 -2.8833 C 3.2 Transmit offsets are given in millidegrees.
PRDX.OUT.14f-13-13.s11 TRANSMITTER: STATION #14, RECEIVER: STATION #13 RECEIVER U.T. RANGE DOPPLER LHA DEC RA EL 2012 OCT 11 05:30 3.8657591042 371677.584 359.6524 -1.4325 346.268 53.319 2012 OCT 11 05:40 3.8397435199 370633.519 2.2366 -1.4774 346.191 53.216 2012 OCT 11 05:50 3.8138011431 369589.052 4.8218 -1.5228 346.112 52.954 2012 OCT 11 06:00 3.7879319295 368546.182 7.4080 -1.5688 346.033 52.537 2012 OCT 11 06:10 3.7621357039 367506.906 9.9952 -1.6155 345.953 51.970 2012 OCT 11 06:20 3.7364121404 366473.212 12.5833 -1.6627 345.871 51.258 2012 OCT 11 06:30 3.7107607765 365447.080 15.1723 -1.7106 345.789 50.410 2012 OCT 11 06:40 3.6851810181 364430.475 17.7622 -1.7591 345.706 49.434 2012 OCT 11 06:50 3.6596721241 363425.341 20.3529 -1.8082 345.622 48.339 2012 OCT 11 07:00 3.6342332280 362433.601 22.9445 -1.8580 345.538 47.134 2012 OCT 11 07:10 3.6088633165 361457.149 25.5368 -1.9084 345.452 45.829 2012 OCT 11 07:20 3.5835612638 360497.844 28.1299 -1.9596 345.366 44.431 2012 OCT 11 07:30 3.5583257921 359557.512 30.7237 -2.0114 345.279 42.950 2012 OCT 11 07:40 3.5331555154 358637.938 33.3182 -2.0639 345.191 41.392 2012 OCT 11 07:50 3.5080489195 357740.862 35.9134 -2.1172 345.103 39.766 2012 OCT 11 08:00 3.4830043631 356867.973 38.5092 -2.1711 345.014 38.078 2012 OCT 11 08:10 3.4580200948 356020.912 41.1056 -2.2258 344.924 36.333 2012 OCT 11 08:20 3.4330942469 355201.258 43.7026 -2.2813 344.834 34.539 2012 OCT 11 08:30 3.4082248495 354410.535 46.3001 -2.3375 344.744 32.698 2012 OCT 11 08:40 3.3834098185 353650.201 48.8982 -2.3946 344.652 30.817 2012 OCT 11 08:50 3.3586469765 352921.648 51.4967 -2.4524 344.561 28.899 2012 OCT 11 09:00 3.3339340437 352226.196 54.0957 -2.5111 344.469 26.948 2012 OCT 11 09:10 3.3092686656 351565.093 56.6952 -2.5706 344.376 24.967 2012 OCT 11 09:20 3.2846483892 350939.511 59.2951 -2.6309 344.283 22.959 2012 OCT 11 09:30 3.2600706838 350350.543 61.8954 -2.6921 344.189 20.928 2012 OCT 11 09:40 3.2355329462 349799.198 64.4961 -2.7543 344.096 18.875
2012 TC4 GOLDSTONE MASTERLOG
============================================================================== Receive TX Setup hops dwell code ncoh FFT runs start -stop OSOD offset Poln Notes ------------------------------------------------------------------------------
Dr. Lance A. M. Benner | PHONE: (818) 354-7412 Mail Stop 183-601 | FAX: (818) 393-4445 Jet Propulsion Laboratory | email: lance.benner@jpl.nasa.gov California Institute of Technology | Plan: To live long and prosper Pasadena, CA 91109-8099 http://echo.jpl.nasa.gov/asteroids/2012TC4/2012TC4_planning.html