Goldstone Radar Observations Planning: 2018 XR and 2022 GU6


Background


2018 XR
2018 XR was discovered on December 3, 2018 by ATLAS-Haleakala in Hawai'i.  
This is an Apollo-class object with a relatively slow rotation period of 15.27+-0.03 hours,
a lightcurve amplitude of 0.53 mag (Warner et al. 2019), and
an absolute magnitude of 18.3, which suggests a diameter in the realm of 0.6 km.
The lightcurve amplitude probably indicates a shape with moderate elongation.

2018 XR will approach within 0.06 au on June 13 when it will be a moderately strong
radar target suitable for CW observations, ranging, and coarse-resolution delay-Doppler imaging. 
Time is scheduled at Goldstone on June 10 and 12. 

2018 XR is designated as a "Potentially Hazardous Asteroid" by the Minor Planet Center.


2022 GU6 2022 GU6 was discovered by Pan-STARRS 2 on April 9, 2022. This asteroid will approach within 3.1 lunar distances (0.0081 au) on June 12 when it should be a very strong radar target at Goldstone. Its absolute magnitude of 23.0 suggests a diameter within a factor of two of 80 meters but otherwise nothing is known about its physical properties. The view periods for this asteroid overlap time already scheduled for 2018 XR on June 10 and 12, and of these two targets, the signal-to-noise ratios (SNRs) for 2022 GU6 are likely to be much stronger. We anticipate SNRs that may be strong enough for 40 MHz chirp imaging (3.75 m/pixel resolution). 2022 GU6 is not classified as a "Potentially Hazardous Asteroid" as defined by the Minor Planet Center due to an absolute magnitude of 23 and a diameter of only about 80 meters.
Orbital and Physical Characteristics  
Name                     2018 XR                 2022 GU6
Number                   not numbered            not numbered
Discoverer               ATLAS-Haleakala         Pan-STARRS 2
Discovery date           2018 Dec  3             2022 Apr  9
Orbit type               Apollo                  Amor
Close approach dist.     0.0595 au               0.00808 au
Close approach dist.     23.2 lunar distances    3.1 lunar distances
Close approach date      2022 Jun 13             2022 Jun 12

semimajor axis           2.153 au                2.314 au
eccentricity             0.668                   0.562
inclination             20.5 deg                 5.7 deg
Orbital period           3.16 y                  3.52 y
perihelion distance      0.715 au                1.0135 au
aphelion distance        3.591 au                3.614 au
MOID                     0.049 au                0.00251 au

absolute magnitude (H)   18.6                    23.0
Diameter                ~0.6 km                 ~0.08 km         
optical albedo           unknown                 unknown
Rotation period          15.27 h                 unknown
lightcurve amplitude     0.5 mag                 unknown
spectral class           unknown                 unknown
                         PHA                                    

Last update: 2022 June 23


Goldstone Radar Echoes from Asteroid 2018 XR


Echo power spectrum from 2018 XR obtained on June 10.
Echo power in standard deviations is plotted as a function of Doppler frequency.
Solid and dashed curves denote opposite-sense circular and same-sense circular polarizations.
The frequency resolution is 0.1 Hz and the bandwidth of the echo is about 3 Hz.
The bandwidth and rotation period place a lower bound on the maximum pole-on extent
of about 0.46 km.  The width of the echo is also consistent with the 15.3 h rotation
period estimated from lightcurves. 




Delay-Doppler image of 2018 XR obtained on June 12. Resolution is 37.5 m x 0.3 Hz.
Range increases down and Doppler frequency increases to the right.  The visible extent 
places a lower bound on the long axis of about 450 meters.  The image suggests an 
asymmetric shape.


Goldstone Radar Echoes from Asteroid 2022 GU6

Echo power spectrum obtained from 2022 GU6 on June 10.  This is a weighted sum
of 35 transmit-receive cycles shown at a frequency resolution of 0.11 Hz.  
The echo is narrow and suggests a slow rotation period.  The ~3 Hz offset in 
Doppler frequency was used to estimate a new orbital solution for the asteroid.



Delay-Doppler image of 2022 GU6 obtained on June 12.  Resolution is 18.75 m x 0.2 Hz.
The frequency resolution is limited by the short round-trip light travel time of 8 seconds 
and by the slow rotation of the asteroid.  The echo is not resolved in 
in Doppler frequency.  

The fact that the bandwidth was narrow on both June 10 and 12, even though the asteroid 
moved nearly 50 degrees, establishes that the subradar latitude was
not close to a pole on both days and that the rotation period is slow.

The visible extent of three rows places a lower bound of ~60 meters
on the long axis.  We obtained the same result using other data obtained 
at 3.75 meter resolution.

The fainter pixels at positive and negative frequencies adjacent to the echo result 
from the impulse response function due to very high signal-to-noise ratios.


Discovery Minor Planet Electronic Circulars

2018 XR
https://www.minorplanetcenter.net/mpec/K18/K18X51.html

2022 GU6
https://www.minorplanetcenter.net/mpec/K22/K22H57.html


SNR Calculations


2018 XR
GOLDSTONE SNRs
2018 XR:  D = 0.63 km,  P = 15.27 h,  OC albedo = 0.1

 start date    window       RA, dec   dist   runs      SNR/day   SNR/run
2022 Jun  4  13:30-01:14    67, +34  0.115    185         20         2
2022 Jun  5  13:29-00:56    66, +31  0.105    198         29         2
2022 Jun  6  13:27-00:35    64, +28  0.095    212         41         3
2022 Jun  7  13:27-00:12    62, +23  0.086    226         61         4
2022 Jun  8  13:29-23:45    60, +18  0.078    239         89         6
2022 Jun  9  13:33-23:14    58, +11  0.071    248        130         9
2022 Jun 10  13:40-22:36    55,  +3  0.065    250        170        12 Scheduled
2022 Jun 11  13:52-21:50    52,  -6  0.061    238        210        15
2022 Jun 12  14:13-20:50    49, -16  0.059    206        200        16 Scheduled
2022 Jun 13  14:54-19:28    45, -26  0.058    143        150        14


2022 GU6 Goldstone SNRs 2022 GU6: D = 0.08 km, P = 0.5 h, OC albedo = 0.1 JPL/Horizons solution 26, so rise-set times are firm. start date window RA, dec dist runs SNR/day SNR/run 2022 Jun 6- 7 21:28-10:02 194, +42 0.027 840 55 2 2022 Jun 7- 8 21:20-10:18 196, +45 0.022 1041 120 4 2022 Jun 8- 9 21:11-10:51 199, +51 0.018 1360 290 8 2022 Jun 9-10 20:57-12:20 205, +59 0.014 1945 870 22 2022 Jun 10-11 20:34-21:40 233, +73 0.010 3610 3400 65 Scheduled: overlaps 2018 XR. Visible for > 24 hours. 2022 Jun 12 01:39-20:04 337, +60 0.008 3364 7600 140 Scheduled: overlaps 2018 XR 2022 Jun 13 07:47-19:27 353, +30 0.010 2152 3273 77 2022 Jun 14 09:06-19:00 358, +12 0.013 1376 940 27 2022 Jun 15 09:45-18:39 1, +2 0.017 945 290 10 2022 Jun 16 10:08-18:23 2, -4 0.021 697 110 5 2022 Jun 17 10:23-18:10 3, -8 0.026 543 49 2

Track Assignments


Goldstone tracks:
         UT         UT                      PDT                          RTT  SNR/
DOY      Date       TX Window  Target       TX Window            Dur'n   sec  run      
161      Jun 10     1610-2235  2018 XR      0910-1535 Jun 10      6:25    65   12
161      Jun 10     2035-2235  2022 GU6     1335-1535 Jun 10      2:00    10   63   

163      Jun 12     1415-1805  2018 XR      0715-1105 Jun 10      3:50    59   16
163      Jun 12     1415-1805  2022 GU6     0715-1105 Jun 10      3:50     8  140


Uncertainties


2018 XR
JPL/Horizons solution 35, # obs: 239 (2014-2022)
2022 June 6
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.             delta  POS_3sigma   DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2022-Jun-07 00:00 *m   62.14597  25.99386  0.09262481110299      11.527        11.08       40.26       0.001141
 2022-Jun-08 00:00 *m   60.14965  21.24978  0.08398936793996      12.816        13.05       47.43       0.000776
 2022-Jun-09 00:00 *m   57.90180  15.45358  0.07620929648013      14.148        15.29       55.56       0.000504
 2022-Jun-10 00:00 *m   55.36056   8.42789  0.06954441727066      15.360        17.50       63.62       0.000704
 2022-Jun-11 00:00 *m   52.47603   0.08827  0.06431494757379      16.181        19.08       69.36       0.001264 *
 2022-Jun-12 00:00 *    49.18962  -9.43222  0.06086588764019      16.284        19.15       69.58       0.001924 *
 2022-Jun-13 00:00 *    45.43429 -19.67692  0.05948399436994      15.479        17.07       62.03       0.002568
 2022-Jun-14 00:00 *    41.13671 -29.91150  0.06029112970791      13.933        13.18       47.89       0.003110
 2022-Jun-15 00:00 *    36.22289 -39.37171  0.06318687258243      12.110         8.69       31.59       0.003498
 2022-Jun-16 00:00 *    30.62956 -47.53487  0.06789183724487      10.449         4.82       17.53       0.003730


2022 GU6 JPL/Horizons solution 28, # obs: 145 (60 days) 2022 June 8 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta POS_3sigma DOP_S_3sig DOP_X_3sig RT_delay_3sig 2022-Jun-07 00:00 *m 193.99936 41.36072 0.02768017393250 0.563 11.17 40.60 0.002894 2022-Jun-08 00:00 *m 195.58871 44.66080 0.02312848580088 0.837 10.98 39.89 0.002505 2022-Jun-09 00:00 *m 198.31629 49.50352 0.01869552096594 1.584 10.66 38.74 0.002130 2022-Jun-10 00:00 *m 204.02073 57.07115 0.01449984990451 3.432 10.17 36.97 0.001770 2022-Jun-11 00:00 *m 222.18762 69.06693 0.01083178238763 7.911 9.87 35.87 0.001420 * 2022-Jun-12 00:00 * 306.49422 72.95546 0.00842377121984 16.386 11.92 43.34 0.001053 * 2022-Jun-13 00:00 * 346.75859 45.08290 0.00844235698059 19.963 11.21 40.76 0.000790 2022-Jun-14 00:00 * 355.81773 20.97953 0.01087601894935 14.455 7.68 27.92 0.000898 2022-Jun-15 00:00 * 359.55658 7.13096 0.01455727355830 9.560 8.75 31.80 0.001181 2022-Jun-16 00:00 * 1.58963 -0.85323 0.01876154050053 6.739 9.93 36.07 0.001517 2022-Jun-17 00:00 * 2.86948 -5.84873 0.02320164271690 5.107 10.59 38.48 0.001882 2022-Jun-18 00:00 * 3.75118 -9.21850 0.02775974922385 4.098 10.95 39.82 0.002265 Pointing uncertainties are small enough for radar observations. JPL/Horizons solution 12, # obs: 59 (28 days) 2022 May 9 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta POS_3sigma DOP_S_3sig DOP_X_3sig RT_delay_3sig 2022-Jun-07 00:00 *m 194.00017 41.33816 0.02772436765921 285.352 203.33 739.00 0.172582 2022-Jun-08 00:00 *m 195.58698 44.62827 0.02317086187205 416.135 241.85 879.00 0.164806 2022-Jun-09 00:00 *m 198.30694 49.45374 0.01873551506798 647.951 325.67 1183.65 0.155031 2022-Jun-10 00:00 *m 203.98235 56.98987 0.01453615118613 1095.908 533.15 1937.69 0.140553 2022-Jun-11 00:00 *m 221.95529 68.94036 0.01086098187191 2000.418 1089.59 3960.08 0.113707 2022-Jun-12 00:00 * 305.71568 73.06661 0.00843773794093 3383.531 2186.94 7948.35 0.057022 2022-Jun-13 00:00 * 346.58780 45.30893 0.00843411502300 3466.841 2142.48 7786.75 0.026297 2022-Jun-14 00:00 * 355.74526 21.12152 0.01085349291673 2151.474 941.45 3421.67 0.079551 2022-Jun-15 00:00 * 359.51355 7.21009 0.01452924996523 1239.454 313.38 1138.95 0.099741 2022-Jun-16 00:00 * 1.55956 -0.80624 0.01873178364847 773.622 71.17 258.66 0.105562 2022-Jun-17 00:00 * 2.84641 -5.81862 0.02317164869704 527.110 45.33 164.74 0.105633 2022-Jun-18 00:00 * 3.73240 -9.19799 0.02773018459356 385.592 91.72 333.35 0.103132 JPL/Horizons solution 1, # obs: 17 (16 days) 2022 Apr 25 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta POS_3sigma DOP_S_3sig DOP_X_3sig RT_delay_3sig 2022-Jun-07 00:00 *m 193.94863 41.39316 0.02781860132395 3054.591 1586.91 5767.56 1.498432 2022-Jun-08 00:00 *m 195.51973 44.69309 0.02325541001999 4325.006 1943.94 7065.18 1.438765 2022-Jun-09 00:00 *m 198.21296 49.53100 0.01881112286889 6541.047 2742.89 9968.90 1.359553 2022-Jun-10 00:00 *m 203.83442 57.08278 0.01460396488010 10755.289 4736.22 17213.56 1.234916 2022-Jun-11 00:00 *m 221.67355 69.06138 0.01092241270056 19117.610 10019.75 36416.33 0.992925 2022-Jun-12 00:00 * 305.88840 73.28110 0.00849241541792 31612.714 20239.54 73559.69 0.476654 2022-Jun-13 00:00 * 346.77694 45.56393 0.00847781494195 31957.589 19844.87 72125.25 0.322171 2022-Jun-14 00:00 * 355.86727 21.35141 0.01088931425551 19709.040 8881.93 32280.98 0.806860 2022-Jun-15 00:00 * 359.60300 7.38937 0.01456519059882 11337.370 3198.11 11623.38 1.000791 2022-Jun-16 00:00 * 1.63055 -0.66470 0.01877283134228 7108.001 1084.90 3943.01 1.066825 2022-Jun-17 00:00 * 2.90562 -5.70255 0.02322035866677 4894.625 556.90 2024.04 1.082482 2022-Jun-18 00:00 * 3.78349 -9.09949 0.02778792393312 3637.699 719.56 2615.19 1.076221
Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: 2018 XR Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-brt S-O-T /r T-O-M/MN_Illu% 2022-Jun-07 00:00 62.16921 26.00526 0.09264298150361 27. n.a. 12.1988 /L 93.5/ 43.9163 2022-Jun-09 00:00 57.92870 15.47046 0.07622020650820 23. n.a. 19.5880 /L 125.8/ 64.3137 2022-Jun-11 00:00 52.50702 0.11017 0.06431503324671 20. n.a. 34.6490 /L 155.7/ 83.4103 2022-Jun-13 00:00 45.46945 -19.65635 0.05947063186782 17. n.a. 55.2905 /L 137.3/ 96.6629 2022-Jun-15 00:00 36.26124 -39.36132 0.06316203202492 16.223 n.a. 76.5527 /L 96.4/ 99.5259 2022-Jun-17 00:00 24.36124 -54.20853 0.07402168641091 15.864 n.a. 93.5635 /L 64.3/ 90.5530 2022-Jun-19 00:00 9.77132 -63.40994 0.08942597616251 15.887 n.a. 105.5598 /L 53.2/ 72.8201 2022-Jun-21 00:00 353.69299 -68.34219 0.10742587148064 16.054 n.a. 113.8607 /L 63.8/ 51.5428 2022-Jun-23 00:00 338.31509 -70.52726 0.12693764338773 16.271 n.a. 119.7471 /L 83.0/ 31.2027 2022-Jun-25 00:00 325.35110 -71.13906 0.14739667653045 16.500 n.a. 124.0588 /L 103.1/ 14.7570 2022-Jun-27 00:00 315.21611 -70.94130 0.16850571181003 16.727 n.a. 127.3062 /L 120.9/ 4.0374 2022-Jun-29 00:00 307.51074 -70.36173 0.19010436863229 16.946 n.a. 129.8012 /L 133.1/ 0.1110 2022-Jul-01 00:00 301.65392 -69.61743 0.21210472754230 17.156 n.a. 131.7404 /L 135.2/ 3.3457 2022-Jul-03 00:00 297.15141 -68.81313 0.23445872483032 17.357 n.a. 133.2519 /L 126.2/ 13.3932 2022-Jul-05 00:00 293.64052 -67.99798 0.25714092762813 17.550 n.a. 134.4226 /L 110.0/ 29.2314
2022 GU6 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-brt S-O-T /r T-O-M/MN_Illu% 2022-Jun-01 00:00 190.71983 33.00554 0.05568926767477 19.430 n.a. 101.8627 /T 86.5/ 2.1667 2022-Jun-02 00:00 190.95873 33.77677 0.05100790950338 19.280 n.a. 100.7855 /T 76.1/ 5.7750 2022-Jun-03 00:00 191.26436 34.69612 0.04632530423988 19.114 n.a. 99.6750 /T 66.1/ 10.9678 2022-Jun-04 00:00 191.66023 35.81468 0.04164577415670 18.929 n.a. 98.5180 /T 56.8/ 17.5789 2022-Jun-05 00:00 192.18380 37.20868 0.03697571390376 18.720 n.a. 97.2945 /T 48.5/ 25.4196 2022-Jun-06 00:00 192.89847 38.99664 0.03232499052229 18.483 n.a. 95.9736 /T 42.3/ 34.2790 2022-Jun-07 00:00 193.92055 41.37224 0.02770971552477 18.210 n.a. 94.5048 /T 39.5/ 43.9163 2022-Jun-08 00:00 195.48858 44.67077 0.02315819496757 17.893 n.a. 92.8010 /T 41.5/ 54.0455 2022-Jun-09 00:00 198.17812 49.51000 0.01872500014431 17.522 n.a. 90.7033 /T 49.0/ 64.3137 2022-Jun-10 00:00 203.79821 57.07196 0.01452811572528 17.094 n.a. 87.9125 /T 61.6/ 74.2811 2022-Jun-11 00:00 221.68771 69.08415 0.01085610298189 16.642 n.a. 83.9437 /T 79.9/ 83.4103 2022-Jun-12 00:00 306.27110 73.21709 0.00843706915825 16.337 n.a. 78.9428 /L 103.3/ 91.0837 2022-Jun-13 00:00 346.88893 45.34982 0.00843709420619 16.452 n.a. 76.6629 /L 117.5/ 96.6629 2022-Jun-14 00:00 355.91827 21.15357 0.01085710880240 16.890 n.a. 78.6870 /L 108.6/ 99.5927 2022-Jun-15 00:00 359.63267 7.23912 0.01453177440934 17.382 n.a. 81.4107 /L 91.8/ 99.5259 2022-Jun-16 00:00 1.64976 -0.78083 0.01873271268707 17.819 n.a. 83.6593 /L 74.8/ 96.4192 2022-Jun-17 00:00 2.91868 -5.79651 0.02317084600284 18.190 n.a. 85.4807 /L 58.7/ 90.5530 2022-Jun-18 00:00 3.79249 -9.17863 0.02772761203727 18.504 n.a. 87.0209 /L 43.5/ 82.4632 2022-Jun-19 00:00 4.43176 -11.59782 0.03234785751674 18.773 n.a. 88.3798 /L 29.4/ 72.8201 2022-Jun-20 00:00 4.91972 -13.40895 0.03700271641733 19.006 n.a. 89.6188 /L 17.2/ 62.3079 2022-Jun-21 00:00 5.30372 -14.81428 0.04167554579547 19.210 n.a. 90.7760 /L 11.5/ 51.5428 2022-Jun-22 00:00 5.61259 -15.93653 0.04635597004425 19.391 n.a. 91.8759 /L 18.1/ 41.0380 2022-Jun-23 00:00 5.86484 -16.85411 0.05103709834515 19.552 n.a. 92.9348 /L 29.2/ 31.2027 2022-Jun-24 00:00 6.07287 -17.61929 0.05571411458051 19.698 n.a. 93.9638 /L 40.9/ 22.3581 2022-Jun-25 00:00 6.24525 -18.26823 0.06038351384749 19.829 n.a. 94.9710 /L 52.7/ 14.7570 2022-Jun-26 00:00 6.38810 -18.82665 0.06504266599262 19.950 n.a. 95.9621 /L 64.4/ 8.5987

Setups




CW setup:
TX polarization     RCP
RCV polarization    LCP & RCP
Frequency hops:     no hopping
Bandwidth:          5000 Hz 
TXoffset            +500 Hz
FFT                 5000 for 1 Hz resolution 


Ranging setups:
---------------------------------------------------------------------------
10-usec
baud             10 usec
code            127
PRP            1270 usec
FFT              64
ncoh              1 
bandwidth       787 Hz   
resolution       12.3 Hz
TXOFF          +100 Hz  (echo in bin 32 + 8 = 40)
---------------------------------------------------------------------------
11-usec 
baud             11 usec
code            127
PRP            1397 usec
FFT              64  
ncoh              1 
bandwidth       716 Hz   
resolution       11.2 Hz
TXOFF          +100 Hz  (echo in bin 32 + 9 = 41) 
-------------------------------------------------------------------------
1-usec 
baud              1 usec
code            255
FFT             256
ncoh             16
bandwidth       245 Hz   
resolution        0.96 Hz
TXOFF           +50 Hz 

---------------------------------------------------------------------


Instructions

NOTE: Data should be moved to the appropriate subdirectories in aardvark:/export/data0/2018xr/raw/

POINTING:

  OSOD and predicts will be on aardvark:

...not available yet...


POINTING  
                                                          TX Offsets    
Date (UTC)   DOY  hhmmss    RA        Dec         Macro   LHA     Dec    RTT    OSOD

... to be added ...

Transmit offsets are given in millidegrees.  


PRDX.OUT.14f-14-14.?? TRANSMITTER: STATION #14, RECEIVER: STATION #14 RECEIVER U.T. RANGE DOPPLER LHA DEC RA EL

2018 XR 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 https://echo.jpl.nasa.gov/asteroids/2018XR/2018XR.2022.goldstone.planning.html

Asteroid Radar Astronomy
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