Goldstone Radar Observations Planning: 2019 UM12


Background


2019 UM12 was discovered on 2019 October 29 by the Mt. Lemmon Survey near Tucson, Arizona.
This asteroid has an absolute magnitude of 24.7 that suggests a diameter
within a factor of two of 35 meters.   J. Chatelain and T. Lister report a preliminary 
rotation period of 0.34 hours and a lightcurve amplitude of 0.3 magnitudes, which suggests
a shape with relatively low elongation.  
Nothing else is known about the asteroid's physical properties.

2019 UM12 will approach within 0.0033 au (1.28 lunar distances) on November 8.  
At Goldstone we will attempt to detect radar echoes on Nov. 8 using the 34 meter DSS-13 antenna as a transmitter
and the 34 meter DSS-28 Goldstone Apple Valley Radio Telescope (GAVRT) as a receiver.

This will be the first attempt to observe a near-Earth asteroid with radar using GAVRT as 
a receiver.  We expect rather modest signal-to-noise ratios sufficient for CW echoes but
they probably will not be strong enough for delay-Doppler imaging.

2019 UM12 will be be a strong radar target at Arecibo and observations are scheduled there on November 10.

Radar observations at Goldstone's DSS-14 antenna are not possible because its X-band klystrons are not operational.

Thank you to everyone who has provided optical astrometry for this asteroid!


Orbital and Physical Characteristics  
Name                     2019 UM12
Asteroid number          Not numbered             
Discoverer               Mt. Lemmon Survey
Discovery date           2019 October 29
orbit type               Apollo
Close approach dist.     0.0033 au
Close approach dist.     1.28 lunar distances     
Close approach date      2019 Nov 8

semimajor axis           2.167 au                 
eccentricity             0.609
inclination              7.8 deg                 
Orbital period           3.190 years              
perihelion distance      0.847 au
MOID                     0.0023 au

absolute magnitude (H)   24.7
diameter                 35 m +- a factor of two
optical albedo           unknown                 
rotation period          0.34 h    
lightcurve amplitude     0.3 mag
pole direction           unknown                 
spectral class           unknown                 

Last update: 2019 November 7

Discovery M.P.E.C.

2019 UM12

https://www.minorplanetcenter.net/mpec/K19/K19US1.html


SNR Calculations


2019 UM12 GOLDSTONE SNRS

               H        P (h)  D (m) 
2019 UM12     24.7	0.5	35	   
                                                                    DSS-14            7190 MHz
                                                                  <-MONOSTATIC -->   DSS13-GAVRT
wk DOY Date (UT)       window (UT)  RA,DEC      Dist.      Runs    SNR/day SNR/run    SNR/RTT    
44 309 2019 NOV 05     02:25-10:30   23.3, -5   0.0260      560       14        1
44 310 2019 NOV 06     02:10-10:20   20.7, -4   0.0183      804       58        2
44 311 2019 NOV 07     01:40-10:05   14.5,  0   0.0108     1407      490       13
44 312 2019 NOV 08     00:15-09:00  347.1, 17   0.0043     3657    19000      320        2      Soln 2 rise/set
44 312 2019 NOV 08     18:35-03:15  253.5, 29   0.0033     4742    57000      820 *      4      1844-0313    Scheduled
44 313 2019 NOV 09     14:40-00:50  224.9, 18   0.0077     2395     2100       43
45 314 2019 NOV 10     14:05-00:10  218.2, 15   0.0149     1219      150        4
45 315 2019 NOV 11     13:50-23:50  215.4, 13   0.0225      800       28        1

DSS-13 horizons assume elevations = 20 deg.  
DSS13-GAVRT SNRs assume Ptx = 80 kW, Tsys at GAVRT = 44 K, and equal gains at both antennas.
                                                                       
Goldstone DSS-14 SNRs assume Ptx = 450 kW.  
DSS-14 is not currently operational as a radar due to klystron problems.

The round-trip time varies by a factor of 1.4 during the Nov. 8-9 viewing period,
corresponding to a signal-to-noise reduction of nearly a factor of four, so we scheduled time
at the beginning of the observing window when the SNRs are strongest.


The SNRs above do not use the 0.34 h rotation period estimated by J. Chatelain and T. Lister.
All else being equal, that period corresponds to SNRs about 20% lower than shown above.


2019 UM12 ARECIBO SNRS

 start date    window        RA, dec   dist   runs   SNR/day  SNR/run
2019 Nov 08  00:31-02:35      3,  +8  0.006    684    13000     540
2019 Nov 08  19:48-21:04    287, +34  0.003   1083   113000    4100
2019 Nov 09  15:19-17:54    231, +21  0.008    621     4900     210
2019 Nov 10  14:29-17:10    220, +16  0.015    327      380      22   Scheduled
2019 Nov 11  14:12-16:50    216, +14  0.023    217       75       5
2019 Nov 12  14:02-16:38    215, +13  0.031    156       23       2
2019 Nov 13  13:55-16:29    214, +12  0.038    122        9       1

Arecibo SNRs assume Ptx = 350 kW, Gain = 7 K/Jy, Tsys = 25 K, D = 35 m, and P = 0.5 h.
Prior to Nov. 8, this asteroid will be too far south for Arecibo to track.

Observations at Arecibo are scheduled on November 10.



Track Assignments


DOY BOA  BOT  EOT  EOA
321 1715 1845 2245 2315 DSS-13 GSSR  2019 UM12
321 1715 1845 2245 2315 DSS-28 GSSR  2019 UM12

Goldstone tracks:
     UT       UT          PST               Duration Round-trip    
DOY  Date     TX Window   TX Window         hh:mm    time (sec)  
321  Nov  8   1845-2245   1045-1445 Nov 8    4:00    3.3 - 3.6   

Due to the rapidly increasing distance during the Goldstone track, the SNRs will decrease by 
about 30% per round-trip time.

Elevations will exceed 80 degrees during the last 30 minutes of the track.



Uncertainties

2019 UM12
JPL/Horizons solution 9, # obs: 64 (14 days)
2019 Nov 7
This includes astrometry reported during the day (PST) on Nov. 7 from J95 and K91.
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38247  -6.30215 0.02939897498659      0.373      142.12      516.53       0.019497
 2019-Nov-06 00:00 *m   22.44337  -5.06576 0.02164038992304      0.461      141.12      512.88       0.014354
 2019-Nov-07 00:00 *m   18.40370  -2.41724 0.01396039197777      0.638      138.51      503.40       0.009270
 2019-Nov-08 00:00 *m    5.08360   6.39933 0.00661029311126      1.982      123.33      448.24       0.004425
 2019-Nov-09 00:00 *m  266.93722  32.42901 0.00383221077687     14.762       74.36      270.24       0.002578
 2019-Nov-10 00:00 *m  225.43583  18.79810 0.01039041729116      5.905      134.88      490.20       0.006868
 2019-Nov-11 00:00 *   218.34512  14.92997 0.01798565645335      4.692      140.17      509.43       0.011886
 2019-Nov-12 00:00 *   215.56836  13.29017 0.02572064628661      4.338      141.64      514.80       0.017005
 2019-Nov-13 00:00 *   214.10136  12.37876 0.03350641104108      4.178      142.37      517.43       0.022162

Solution 9 uncertainties at 30 minute intervals during the track:
 2019-Nov-08 18:45 *   299.07131  32.65000 0.00327968022154     15.954       20.74       75.39       0.002217
 2019-Nov-08 19:15 *   295.71853  33.03732 0.00329557494786     16.094       25.63       93.14       0.002229
 2019-Nov-08 19:45 *   292.36846  33.32954 0.00331960808681     16.168       31.04      112.80       0.002246
 2019-Nov-08 20:15 *   289.04493  33.52602 0.00335174937334     16.179       36.63      133.13       0.002269
 2019-Nov-08 20:45 *   285.77116  33.62852 0.00339190313292     16.130       42.23      153.47       0.002296
 2019-Nov-08 21:15 *   282.56884  33.64108 0.00343991038196     16.026       47.73      173.46       0.002328
 2019-Nov-08 21:45 *   279.45730  33.56964 0.00349555316670     15.875       53.06      192.86       0.002364
 2019-Nov-08 22:15 *   276.45286  33.42171 0.00355856073123     15.681       58.20      211.54       0.002405
 2019-Nov-08 22:45 *   273.56848  33.20583 0.00362861701070     15.452       63.12      229.40       0.002450

- - - - - - - - - - 

JPL/Horizons solution 7,  # obs: 57 (14 days)
2019 Nov 7
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38247  -6.30215 0.02939897497930      0.621      245.28      891.46       0.033850
 2019-Nov-06 00:00 *m   22.44337  -5.06576 0.02164038991543      0.752      243.53      885.11       0.024977
 2019-Nov-07 00:00 *m   18.40370  -2.41724 0.01396039196956      1.020      239.05      868.80       0.016209
 2019-Nov-08 00:00 *m    5.08360   6.39933 0.00661029310214      7.172      213.67      776.58       0.007851
 2019-Nov-09 00:00 *m  266.93722  32.42901 0.00383221077592     46.121      123.27      448.02       0.004396
 2019-Nov-10 00:00 *m  225.43583  18.79810 0.01039041729643     13.890      232.08      843.50       0.011704
 2019-Nov-11 00:00 *   218.34512  14.92997 0.01798565645968      9.613      241.73      878.56       0.020347
 2019-Nov-12 00:00 *   215.56836  13.29017 0.02572064629335      8.398      244.38      888.19       0.029177
 2019-Nov-13 00:00 *   214.10136  12.37876 0.03350641104805      7.867      245.67      892.87       0.038073

Solution 7 uncertainties at 30 minute intervals during the track:
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-08 18:45 *   299.07131  32.65000 0.00327968021639     53.168       52.81      191.95       0.003858
 2019-Nov-08 19:15 *   295.71853  33.03732 0.00329557494311     53.381       56.24      204.39       0.003869
 2019-Nov-08 19:45 *   292.36846  33.32954 0.00331960808247     53.364       61.30      222.79       0.003889
 2019-Nov-08 20:15 *   289.04493  33.52602 0.00335174936941     53.124       67.53      245.42       0.003918
 2019-Nov-08 20:45 *   285.77116  33.62852 0.00339190312941     52.674       74.52      270.83       0.003956
 2019-Nov-08 21:15 *   282.56884  33.64108 0.00343991037887     52.033       81.96      297.87       0.004003
 2019-Nov-08 21:45 *   279.45730  33.56964 0.00349555316402     51.223       89.61      325.70       0.004058
 2019-Nov-08 22:15 *   276.45286  33.42171 0.00355856072896     50.267       97.33      353.72       0.004120
 2019-Nov-08 22:45 *   273.56848  33.20583 0.00362861700883     49.190      104.97      381.50       0.004191

- - - - - - - - - - 

JPL/Horizons solution 6, # obs: 44 (13 days)
2019 Nov 6
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38249  -6.30218 0.02939388409884      0.776      379.91     1380.77       0.051205
 2019-Nov-06 00:00 *m   22.44340  -5.06580 0.02163664118405      1.280      377.20     1370.90       0.037484
 2019-Nov-07 00:00 *m   18.40375  -2.41731 0.01395796948578      4.558      369.92     1344.46       0.023955
 2019-Nov-08 00:00 *m    5.08370   6.39918 0.00660913238795     32.961      324.19     1178.24       0.011208
 2019-Nov-09 00:00 *m  266.93660  32.42881 0.00383152399364    145.339      271.50      986.76       0.007380
 2019-Nov-10 00:00 *m  225.43544  18.79785 0.01038861979289     28.011      363.57     1321.39       0.019397
 2019-Nov-11 00:00 *   218.34479  14.92976 0.01798255100870     14.761      375.44     1364.51       0.032812
 2019-Nov-12 00:00 *   215.56806  13.28998 0.02571620513724     11.846      378.98     1377.39       0.046489
 2019-Nov-13 00:00 *   214.10107  12.37858 0.03350062421079     10.900      380.79     1383.98       0.060268
Solution 6 pointing uncertainties are small enough to support the Arecibo observations on Nov. 10.

Solution 6 uncertainties at 30 minute intervals during the track:
 2019-Nov-08 18:45 *   299.07102  32.64986 0.00327908559299    186.187      208.83      758.98       0.005890
 2019-Nov-08 19:15 *   295.71821  33.03719 0.00329497711320    185.562      217.36      789.97       0.005969
 2019-Nov-08 19:45 *   292.36811  33.32941 0.00331900576452    184.014      225.36      819.06       0.006064
 2019-Nov-08 20:15 *   289.04454  33.52589 0.00335114131116    181.593      232.74      845.87       0.006174
 2019-Nov-08 20:45 *   285.77073  33.62839 0.00339128811410    178.376      239.46      870.32       0.006299
 2019-Nov-08 21:15 *   282.56838  33.64094 0.00343928723046    174.459      245.56      892.49       0.006437
 2019-Nov-08 21:45 *   279.45680  33.56950 0.00349492075123    169.949      251.11      912.63       0.006587
 2019-Nov-08 22:15 *   276.45232  33.42156 0.00355791796832    164.960      256.18      931.06       0.006748
 2019-Nov-08 22:45 *   273.56792  33.20566 0.00362796286672    159.607      260.87      948.11       0.006919

The 1-sigma pointing uncertainty is about 62 arcseconds when the Nov. 8 track starts, so we still need additional
astrometry.  
1-sigma Doppler uncertainties at C-band are small enough that we can use our standard CW bandwidth of 5 kHz.

- - - - - - - - - - 

JPL/Horizons solution 5, # obs: 30 (12 days)
2019 Nov 5
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38249  -6.30220 0.02938776652317      1.019      475.70     1728.91       0.064470
 2019-Nov-06 00:00 *m   22.44340  -5.06582 0.02163209773038      2.429      472.30     1716.56       0.047343
 2019-Nov-07 00:00 *m   18.40372  -2.41732 0.01395498287194      9.606      463.24     1683.63       0.030509
 2019-Nov-08 00:00 *m    5.08333   6.39937 0.00660763885800     66.183      407.87     1482.39       0.014788
 2019-Nov-09 00:00 *m  266.93362  32.42831 0.00383079576918    280.546      384.18     1396.27       0.009351
 2019-Nov-10 00:00 *m  225.43471  18.79745 0.01038665377251     52.380      454.77     1652.83       0.024431
 2019-Nov-11 00:00 *   218.34432  14.92948 0.01797905733295     25.104      469.95     1708.00       0.041106
 2019-Nov-12 00:00 *   215.56766  13.28974 0.02571114726738     18.247      474.47     1724.43       0.058170
 2019-Nov-13 00:00 *   214.10070  12.37835 0.03349398964417     15.742      476.77     1732.78       0.075388

- - - - - - - - - - 

JPL/Horizons solution 4, # obs: 25 (11 days)
2019 Nov 4
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38256  -6.30225 0.02939290981191      2.838      710.24     2581.34       0.099461
 2019-Nov-06 00:00 *m   22.44360  -5.06596 0.02163624074103      7.038      705.34     2563.53       0.073964
 2019-Nov-07 00:00 *m   18.40439  -2.41778 0.01395812840538     23.109      693.03     2518.80       0.048946
 2019-Nov-08 00:00 *m    5.08738   6.39672 0.00660974117631    138.570      630.37     2291.03       0.025454
 2019-Nov-09 00:00 *m  266.95531  32.43145 0.00383067427203    544.427      570.86     2074.77       0.013103
 2019-Nov-10 00:00 *m  225.43780  18.79904 0.01038673359626     99.562      671.14     2439.22       0.034442
 2019-Nov-11 00:00 *   218.34563  14.93024 0.01798004714167     46.787      699.66     2542.88       0.058925
 2019-Nov-12 00:00 *   215.56850  13.29024 0.02571310981532     32.893      707.46     2571.23       0.084227
 2019-Nov-13 00:00 *   214.10133  12.37874 0.03349694153149     27.469      711.21     2584.87       0.109837

- - - - - - - - - - 

JPL/Horizons solution 3, # obs: 21 (8 days)
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.38218  -6.30220 0.02940088932961     14.182      800.18     2908.21       0.109204
 2019-Nov-06 00:00 *m   22.44275  -5.06574 0.02164112231534     34.288      793.95     2885.59       0.083311
 2019-Nov-07 00:00 *m   18.40199  -2.41681 0.01395997246630    104.840      775.69     2819.22       0.060339
 2019-Nov-08 00:00 *m    5.07492   6.40327 0.00660895217334    581.381      694.97     2525.85       0.042322
 2019-Nov-09 00:00 *m  266.89780  32.42049 0.00383399781404   2104.973     2034.07     7392.73       0.027561
 2019-Nov-10 00:00 *m  225.43131  18.79451 0.01039438465134    342.783      792.91     2881.79       0.061764
 2019-Nov-11 00:00 *   218.34366  14.92833 0.01799090153102    135.766      796.06     2893.23       0.086676
 2019-Nov-12 00:00 *   215.56769  13.28915 0.02572711181752     78.845      800.72     2910.17       0.113188
 2019-Nov-13 00:00 *   214.10100  12.37803 0.03351408793355     55.445      803.78     2921.30       0.140730

- - - - - - - - - - 

JPL/Horizons solution 1
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Nov-05 00:00 *m   24.37841  -6.30040 0.02937659695475    168.747     5853.84    21275.50       0.875233
 2019-Nov-06 00:00 *m   22.43418  -5.06125 0.02161259569506    389.913     5809.80    21115.46       0.701667
 2019-Nov-07 00:00 *m   18.37730  -2.40259 0.01392755745389   1150.106     5686.88    20668.71       0.554247
 2019-Nov-08 00:00 *m    4.94305   6.48327 0.00657578403196   6216.758     5689.27    20677.38       0.430076
 2019-Nov-09 00:00 *m  266.27549  32.31838 0.00385582066945  21498.905    19919.94    72398.08       0.255886
 2019-Nov-10 00:00 *m  225.35442  18.75022 0.01043807008969   3454.238     5818.23    21146.08       0.535930
 2019-Nov-11 00:00 *   218.31598  14.90930 0.01804060116462   1354.382     5817.81    21144.55       0.697852
 2019-Nov-12 00:00 *   215.55291  13.27782 0.02578170062320    776.092     5854.12    21276.54       0.875672
 2019-Nov-13 00:00 *   214.09154  12.37006 0.03357333756721    536.321     5877.50    21361.50       1.065842


Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: 2019 UM12 JPL/Horizons solution 1 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-O-T /r T-O-M/Illu% 2019-Nov-01 00:00 27.20505 -7.92617 0.06073360436775 19.84 156.2003 /T 112.8/ 18.1 2019-Nov-02 00:00 26.78905 -7.71848 0.05285228537806 19.54 155.5637 /T 99.9/ 26.9 2019-Nov-03 00:00 26.23875 -7.41749 0.04499802951249 19.20 154.8918 /T 87.1/ 36.3 2019-Nov-04 00:00 25.47014 -6.96751 0.03716979106664 18.80 154.1693 /T 74.5/ 45.9 2019-Nov-05 00:00 24.31054 -6.25389 0.02936957717351 18.30 153.3520 /T 61.8/ 55.6 2019-Nov-06 00:00 22.34165 -4.99722 0.02160787132739 17.65 152.2907 /T 48.6/ 64.8 2019-Nov-07 00:00 18.23376 -2.30191 0.01392704520446 16.75 150.2982 /T 33.7/ 73.5 2019-Nov-08 00:00 4.64833 6.68573 0.00658773260785 15.36 141.4424 /T 15.7/ 81.3 2019-Nov-09 00:00 266.53017 32.37344 0.00389567862629 17.22 63.8690 /T 100.5/ 88.1 2019-Nov-10 00:00 225.53977 18.85278 0.01045905454252 22. 35.8507 /T 146.0/ 93.5 2019-Nov-11 00:00 218.42644 14.97680 0.01805581136709 24. 33.0648 /L 156.3/ 97.4 2019-Nov-12 00:00 215.63088 13.32714 0.02579412775028 25. 32.7977 /L 154.4/ 99.5

Setups



If we adopt the rotation period of 0.34 hours and assume D = 35 meters, then 
we could see a bandwidth of about 10 Hz. 
We want to start with a relatively coarse frequency resolution of 2 Hz in order 
to see an echo quickly.  

The CW setup below should provide enough bandwidth even if the echo has a Doppler correction
of several hundred Hz.  

We are planning to transmit 7190 MHz fixed and take out the Dopplers on the downlink at GAVRT.


CW setup:
---------------------------------------------------------------------------
TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hopping
Bandwidth:               5000 Hz 
TXoffset                 +500 Hz
FFT                      2500 for 2.0 Hz resolution 

Ranging setups:
---------------------------------------------------------------------------
10-usec
baud             10 usec
code            127
PRP            1270 usec
ncoh              1 
bandwidth       787 Hz   
FFT             128
resolution       6.15 Hz
TXoffset       +100 Hz  (echo in column 80)
---------------------------------------------------------------------------
11-usec 
baud             11 usec
code            127
PRP            1397 usec
ncoh              1 
bandwidth       716 Hz   
FFT             128
resolution      5.6 Hz
TXoffset     +100 Hz  (echo in column 82) 
-------------------------------------------------------------------------
1-usec 
baud              1 usec
code            255
ncoh             16
bandwidth       245 Hz   
FFT             128
resolution        1.9 Hz
TXoffset        +50 Hz  (echo in column 116)
---------------------------------------------------------------------

Instructions

NOTE: Data should be moved to the appropriate subdirectories in aardvark:/export/data0/2019um12/raw/

POINTING:

  OSOD and predicts will be on aardvark:

/export/data3/osod/ops/2019um12/PRDX.OUT.13f-28-28.s9     Transmit fixed 7190 MHz at DSS-13.  Take out Dopplers at DSS-28.
/export/data3/osod/ops/2019um12/PRDX.OUT.13v-28-28.s9     Variable transmit frequency at DSS-13. Receive constant frequency at DSS-28.  
/export/data3/osod/ops/2019um12/PUNCH.OUT.13f-28-28.s9
/export/data3/osod/ops/2019um12/PUNCH.OUT.13v-28-28.s9
/export/data3/osod/ops/2019um12/EPH.OUT.s9


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

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/2019UM12_planning.html

Asteroid Radar Astronomy
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