Goldstone Radar Observations Planning: 2018 PK21


Background


2018 PK21 was discovered by Pan-STARRS 1 on 2018 August 11.  
This diminutive asteroid has an absolute magnitude of 25.9, suggesting a diameter of 
roughly 20 meters, and a rotation period of about 0.6 hours (N. Moskovitz and M. Devogele, pers. comm.).
Spectroscopy obtained by Moskovitz and Devogele suggests that this asteroid is either a Q- or T-type,
and their photometry hints at possible non-principal axis rotation.

This asteroid is a possible target for NASA's NEA Scout cubesat mission that may launch in 2021.
NEA Scout is a tiny spacecraft propelled by a solar sail.  

This asteroid will approach within 0.031 au on 2020 December 8 and we 
are expecting weak SNRs at Goldstone that may be on the edge of detection due to the distance
and small diameter.  Our principal objective is to obtain a CW detection and a Doppler
correction to the ephemeris, which has significant uncertainties.

The SNRs at Arecibo will be much stronger and sufficient for CW observations and ranging, but due
to a cable failure in August, we do not know if Arecibo will be able to observe this asteroid.

Observations at Goldstone are scheduled on a number of dates between 2020 Dec 2 - 12.

Additional photometry would be very helpful to improve constraints on the spin state, but obtaining
it will be challenging because 2018 PK21 will brighten to only about 21st magnitude in late November and
early December.  

Optical astrometry would also be valuable to reduce the uncertainties, which could be very
helpful for mission navigation.

The 2020 Earth flyby is the closest by this asteroid until 2059 when it will approach within 0.023 au.


Orbital and Physical Characteristics  
Name                     2018 PK21
Asteroid number          Not numbered
Discoverer               Pan-STARRS 1
Discovery date           2018 Aug 11
orbit type               Aten
Close approach dist.     0.0313 au 
Close approach dist.     12.2 lunar distances     
Close approach date      2020 Dec  8

semimajor axis           0.988 au                 
eccentricity             0.080
inclination              1.2 deg                 
Orbital period           0.982 years              
perihelion distance      0.908 au                 
aphelion distance        1.067 au                 
MOID                     0.0066 au

absolute magnitude (H)   25.9
diameter                ~20 meters 
optical albedo           unknown                  
rotation period          0.6 h    Devogele and Moskovitz, pers. comm.
lightcurve amplitude     ?
pole direction           possibly tumbling
spectral class           Q or T (?)
PHA?                     No

Last update: 2020 October 22

Discovery M.P.E.C.

2018 PK21
https://www.minorplanetcenter.net/mpec/K18/K18PA4.html


SNR Calculations

Goldstone SNRs
SNRs assume Ptx = 450 kW and D = 20 meters, P = 0.6 h, radar albedo = 0.2, Tsys = 17 K.

wk DOY start date    window       RA, dec   dist    runs   SNR/day  SNR/run
48 328 2020 Nov 23  06:38-19:28   142, +44  0.040     579      4       <1
48 329 2020 Nov 24  06:47-19:35   145, +44  0.039     593      4       <1
48 330 2020 Nov 25  06:57-19:42   148, +43  0.038     606      4       <1
48 331 2020 Nov 26  07:07-19:49   151, +43  0.037     618      5       <1
48 332 2020 Nov 27  07:18-19:56   154, +42  0.036     630      5       <1
48 333 2020 Nov 28  07:29-20:03   158, +41  0.035     640      6       <1
48 334 2020 Nov 29  07:41-20:09   161, +40  0.034     649      6       <1
49 335 2020 Nov 30  07:54-20:15   164, +39  0.034     657      7       <1
49 336 2020 Dec 01  08:07-20:21   168, +38  0.033     662      7       <1
49 337 2020 Dec 02  08:20-20:27   171, +37  0.033     666      8       <1  Scheduled
49 338 2020 Dec 03  08:34-20:32   174, +35  0.032     667      8       <1  Scheduled
49 339 2020 Dec 04  08:48-20:37   178, +34  0.032     666      8       <1
49 340 2020 Dec 05  09:02-20:41   181, +32  0.032     663      9       <1  Scheduled
49 341 2020 Dec 06  09:15-20:45   184, +30  0.031     657      9       <1  
50 342 2020 Dec 07  09:29-20:48   187, +28  0.031     650      9       <1  Scheduled
50 343 2020 Dec 08  09:42-20:51   190, +26  0.031     639      9       <1  Scheduled
50 344 2020 Dec 09  09:55-20:53   193, +24  0.031     627      9       <1  Scheduled
50 345 2020 Dec 10  10:08-20:55   196, +22  0.032     613      8       <1  Scheduled
50 346 2020 Dec 11  10:20-20:56   199, +20  0.032     597      8       <1  Scheduled
50 347 2020 Dec 12  10:32-20:56   201, +18  0.032     580      8       <1  Scheduled
50 348 2020 Dec 13  10:44-20:57   204, +16  0.033     562      7       <1
51 349 2020 Dec 14  10:55-20:57   206, +14  0.033     542      7       <1
51 350 2020 Dec 15  11:05-20:56   208, +12  0.034     522      6       <1
51 351 2020 Dec 16  11:15-20:55   210, +10  0.035     502      6       <1
51 352 2020 Dec 17  11:25-20:54   212,  +8  0.035     482      5       <1
51 353 2020 Dec 18  11:34-20:53   214,  +6  0.036     462      5       <1
51 354 2020 Dec 19  11:43-20:51   216,  +4  0.037     442      4       <1
51 355 2020 Dec 20  11:51-20:49   218,  +3  0.038     422      4       <1

We expect to have both klystrons and full power in time for these observations.
Note that SNRs above assume a radar albedo = 0.2.


2018 PK21 ARECIBO SNRs
 start date    window        RA, dec   dist   runs      SNR/day   SNR/run
2020 Dec 02  10:32-11:34    171, +37  0.033    57         16         2
2020 Dec 03  10:28-11:57    174, +35  0.032    83         24         3
2020 Dec 04  10:27-12:17    177, +34  0.032   105         33         4
2020 Dec 05  10:28-12:34    181, +32  0.032   121         40         4
2020 Dec 06  10:31-12:49    184, +30  0.031   133         44         4
2020 Dec 07  10:34-13:03    187, +28  0.031   143         48         4
2020 Dec 08  10:38-13:14    190, +26  0.031   150         49         4
2020 Dec 09  10:43-13:25    193, +24  0.031   156         50         4
2020 Dec 10  10:48-13:34    196, +22  0.032   159         50         4
2020 Dec 11  10:54-13:41    198, +20  0.032   160         48         4
2020 Dec 12  11:01-13:47    201, +18  0.032   146         45         4
2020 Dec 13  11:08-13:52    203, +16  0.033   153         43         4
2020 Dec 14  11:15-13:56    206, +14  0.033   145         40         4
2020 Dec 15  11:23-13:58    208, +12  0.034   140         36         3
2020 Dec 16  11:31-13:59    210, +10  0.034   130         32         3
2020 Dec 17  11:40-13:59    212,  +8  0.035   118         28         3
2020 Dec 18  11:49-13:57    214,  +6  0.036   106         24         3
2020 Dec 19  11:59-13:54    216,  +5  0.037    95         20         2
2020 Dec 20  12:10-13:49    218,  +3  0.038    80         15         2
2020 Dec 21  12:23-13:42    219,  +1  0.039    60         10         2

Arecibo SNRs assume Ptx = 800 kW, Gain = 7 K/Jy, radar albedo = 0.2, and P = 0.6 h.

Arecibo is currently offline due to failure of an auxiliary cable in August, 2020, 
and as of late October, 2020, it seems unlikely that Arecibo will be available.


Track Assignments


DOY  BOA   BOT   EOT   EOA
337  1040  1210  1315  1345  GSSR AST 2018 PK21
338  0945  1115  1330  1400  GSSR AST 2018 PK21
340  1215  1345  1645  1715  GSSR AST 2018 PK21
342  0850  1020  1310  1340  GSSR AST 2018 PK21
343  0920  1050  1255  1325  GSSR AST 2018 PK21
344  0920  1050  1415  1445  GSSR AST 2018 PK21
345  0925  1055  1530  1600  GSSR AST 2018 PK21
346  0840  1010  1615  1645  GSSR AST 2018 PK21
347  0905  1035  1255  1325  GSSR AST 2018 PK21

Goldstone tracks:
     UT       UT          PST                Duration Round-trip     
DOY  Date     TX Window   TX Window          hh:mm    time (sec)   
337  Dec 02   1210-1315   0410-0515 Dec 02    1:05      33       too short; we may cancel. el >75 deg in last 5 minutes.
338  Dec 03   1115-1330   0315-0530 Dec 03    2:15      32       el > 75 deg in last 10 minutes
339  Dec 04   ...not scheduled...
340  Dec 05   1345-1645   0545-0845 Dec 04    3:00      32       el > 75 deg from 1340-1603. Will cause problems.
341  Dec 06   ...not scheduled...
342  Dec 07   1020-1310   0220-0510 Dec 07    2:50      31       el < 75 deg 
343  Dec 08   1050-1255   0250-0455 Dec 08    2:05      31       el < 75 deg 
344  Dec 09   1050-1415   0250-0615 Dec 09    3:25      31       el < 75 deg 
345  Dec 10   1055-1530   0255-0730 Dec 10    4:35      32       el > 75 deg during last 30 minutes
346  Dec 11   1020-1615   0220-0815 Dec 11    5:55      32       el < 75 deg
347  Dec 12   1035-1255   0325-0455 Dec 12    1:30      32       el < 75 deg


Arecibo tracks:
UT                      UT          PST                Round-trip  
Date                    TX Window   TX Window          time (sec)  

...Due to a cable failure in August, 2020, it seems unlikely that Arecibo observations will be possible...



Uncertainties

2018 PK21
JPL/Horizons solution 26, # obs: 100 (2018-2019) 
2020 Sep 17
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2020-Nov-28 00:00 *m  155.64101  41.52372 0.03564848306726      9.056        4.41       16.04       0.006911
 2020-Nov-29 00:00 *m  158.93450  40.68684 0.03487244618223      9.248        4.27       15.51       0.006776
 2020-Nov-30 00:00 *   162.26897  39.71924 0.03416238807558      9.423        4.12       14.96       0.006650
 2020-Dec-01 00:00 *   165.62710  38.61701 0.03352220678751      9.578        3.96       14.39       0.006534
 2020-Dec-02 00:00 *   168.99066  37.37860 0.03295578792428      9.710        3.79       13.79       0.006427
 2020-Dec-03 00:00 *   172.34124  36.00518 0.03246691677822      9.814        3.62       13.14       0.006331
 2020-Dec-04 00:00 *   175.66086  34.50093 0.03205917884214      9.886        3.43       12.46       0.006246
 2020-Dec-05 00:00 *   178.93259  32.87309 0.03173585303343      9.924        3.23       11.73       0.006172
 2020-Dec-06 00:00 *   182.14108  31.13196 0.03149980388719      9.927        3.01       10.95       0.006110
 2020-Dec-07 00:00 *   185.27295  29.29057 0.03135338059900      9.892        2.79       10.14       0.006060
 2020-Dec-08 00:00 *   188.31702  27.36433 0.03129833165887      9.821        2.56        9.30       0.006022
 2020-Dec-09 00:00 *   191.26444  25.37037 0.03133574350644      9.714        2.33        8.47       0.005997
 2020-Dec-10 00:00 *   194.10864  23.32694 0.03146600986449      9.574        2.11        7.68       0.005985
 2020-Dec-11 00:00 *   196.84518  21.25260 0.03168883514365      9.405        1.93        7.00       0.005985
 2020-Dec-12 00:00 *   199.47163  19.16557 0.03200327086644      9.212        1.79        6.49       0.005998
 2020-Dec-13 00:00 *   201.98726  17.08304 0.03240777938856      8.998        1.72        6.24       0.006024
 2020-Dec-14 00:00 *m  204.39284  15.02068 0.03290031573838      8.768        1.73        6.31       0.006062
 2020-Dec-15 00:00 *m  206.69041  12.99229 0.03347841760773      8.527        1.84        6.69       0.006113


2018 PK21 Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-brt S-O-T /r T-O-M/MN_Illu% 2020-Oct-20 00:00 87.17332 37.04656 0.09215439323581 22.876 n.a. 118.4734 /L 158.6/ 14.5491 2020-Oct-21 00:00 88.06586 37.33338 0.09035598424178 22.828 n.a. 118.6846 /L 166.3/ 23.6162 2020-Oct-22 00:00 88.97457 37.62136 0.08857023509938 22.780 n.a. 118.8849 /L 163.6/ 33.7294 2020-Oct-23 00:00 89.90089 37.91047 0.08679744841166 22.731 n.a. 119.0731 /L 154.1/ 44.2665 2020-Oct-24 00:00 90.84634 38.20067 0.08503786313748 22.682 n.a. 119.2482 /L 143.2/ 54.7096 2020-Oct-25 00:00 91.81253 38.49191 0.08329167651824 22.632 n.a. 119.4090 /L 132.1/ 64.6479 2020-Oct-26 00:00 92.80113 38.78409 0.08155906204532 22.583 n.a. 119.5544 /L 121.0/ 73.7607 2020-Oct-27 00:00 93.81392 39.07709 0.07984018316741 22.533 n.a. 119.6832 /L 110.1/ 81.7939 2020-Oct-28 00:00 94.85276 39.37077 0.07813520368201 22.483 n.a. 119.7940 /L 99.3/ 88.5417 2020-Oct-29 00:00 95.91964 39.66492 0.07644429610389 22.433 n.a. 119.8856 /L 88.7/ 93.8349 2020-Oct-30 00:00 97.01663 39.95929 0.07476764915268 22.382 n.a. 119.9566 /L 78.1/ 97.5371 2020-Oct-31 00:00 98.14595 40.25358 0.07310547514494 22.332 n.a. 120.0055 /L 67.6/ 99.5456 2020-Nov-01 00:00 99.30995 40.54743 0.07145801768848 22.282 n.a. 120.0308 /L 57.3/ 99.7960 2020-Nov-02 00:00 100.51108 40.84039 0.06982555975907 22.231 n.a. 120.0309 /L 47.1/ 98.2660 2020-Nov-03 00:00 101.75196 41.13192 0.06820843205280 22.181 n.a. 120.0042 /L 37.2/ 94.9786 2020-Nov-04 00:00 103.03536 41.42139 0.06660702147826 22.130 n.a. 119.9489 /L 28.0/ 90.0027 2020-Nov-05 00:00 104.36421 41.70806 0.06502177976883 22.080 n.a. 119.8632 /L 20.4/ 83.4521 2020-Nov-06 00:00 105.74159 41.99102 0.06345323239875 22.030 n.a. 119.7451 /L 17.2/ 75.4866 2020-Nov-07 00:00 107.17076 42.26922 0.06190198818387 21.980 n.a. 119.5926 /L 20.7/ 66.3166 2020-Nov-08 00:00 108.65516 42.54142 0.06036875002261 21.930 n.a. 119.4035 /L 28.8/ 56.2137 2020-Nov-09 00:00 110.19839 42.80617 0.05885432705385 21.881 n.a. 119.1755 /L 39.0/ 45.5284 2020-Nov-10 00:00 111.80423 43.06177 0.05735964794505 21.832 n.a. 118.9061 /L 50.2/ 34.7085 2020-Nov-11 00:00 113.47665 43.30623 0.05588577399963 21.784 n.a. 118.5928 /L 62.1/ 24.3122 2020-Nov-12 00:00 115.21978 43.53722 0.05443390941447 21.736 n.a. 118.2327 /L 74.6/ 14.9954 2020-Nov-13 00:00 117.03794 43.75203 0.05300540490851 21.690 n.a. 117.8229 /L 87.3/ 7.4590 2020-Nov-14 00:00 118.93559 43.94753 0.05160175121070 21.644 n.a. 117.3601 /L 100.2/ 2.3479 2020-Nov-15 00:00 120.91736 44.12010 0.05022456167555 21.599 n.a. 116.8408 /L 113.0/ 0.1220 2020-Nov-16 00:00 122.98790 44.26561 0.04887554832609 21.556 n.a. 116.2612 /L 125.3/ 0.9479 2020-Nov-17 00:00 125.15181 44.37935 0.04755650022846 21.515 n.a. 115.6172 /L 136.9/ 4.6639 2020-Nov-18 00:00 127.41344 44.45601 0.04626927364574 21.475 n.a. 114.9044 /L 147.0/ 10.8345 2020-Nov-19 00:00 129.77668 44.48965 0.04501579885430 21.438 n.a. 114.1183 /L 154.6/ 18.8668 2020-Nov-20 00:00 132.24468 44.47366 0.04379810184964 21.403 n.a. 113.2543 /L 157.9/ 28.1324 2020-Nov-21 00:00 134.81957 44.40082 0.04261833460476 21.371 n.a. 112.3077 /L 155.8/ 38.0548 2020-Nov-22 00:00 137.50219 44.26326 0.04147880675381 21.343 n.a. 111.2739 /L 150.0/ 48.1500 2020-Nov-23 00:00 140.29176 44.05255 0.04038201333823 21.318 n.a. 110.1485 /L 142.6/ 58.0290 2020-Nov-24 00:00 143.18562 43.75983 0.03933065553736 21.297 n.a. 108.9274 /L 134.5/ 67.3808 2020-Nov-25 00:00 146.17897 43.37595 0.03832765289090 21.282 n.a. 107.6067 /L 126.3/ 75.9488 2020-Nov-26 00:00 149.26470 42.89170 0.03737614619093 21.271 n.a. 106.1833 /L 118.0/ 83.5098 2020-Nov-27 00:00 152.43331 42.29811 0.03647949026054 21.267 n.a. 104.6549 /L 109.7/ 89.8600 2020-Nov-28 00:00 155.67291 41.58682 0.03564123560849 21.269 n.a. 103.0199 /L 101.5/ 94.8098 2020-Nov-29 00:00 158.96941 40.75050 0.03486509772990 21.279 n.a. 101.2785 /L 93.3/ 98.1857 2020-Nov-30 00:00 162.30683 39.78327 0.03415491279205 21.296 n.a. 99.4318 /L 85.1/ 99.8393 2020-Dec-01 00:00 165.66778 38.68121 0.03351457872645 21.322 n.a. 97.4830 /L 76.9/ 99.6593 2020-Dec-02 00:00 169.03398 37.44276 0.03294798143203 21.358 n.a. 95.4374 /L 68.8/ 97.5846 2020-Dec-03 00:00 172.38698 36.06909 0.03245890693268 21.403 n.a. 93.3021 /L 60.7/ 93.6156 2020-Dec-04 00:00 175.70874 34.56436 0.03205094190890 21.459 n.a. 91.0868 /L 52.6/ 87.8209 2020-Dec-05 00:00 178.98232 32.93584 0.03172736691288 21.527 n.a. 88.8034 /L 44.7/ 80.3429 2020-Dec-06 00:00 182.19234 31.19382 0.03149104852249 21.605 n.a. 86.4658 /L 37.1/ 71.4001 2020-Dec-07 00:00 185.32543 29.35135 0.03134433831376 21.695 n.a. 84.0900 /L 30.2/ 61.2929 2020-Dec-08 00:00 188.37040 27.42385 0.03128898739660 21.796 n.a. 81.6932 /L 24.8/ 50.4100 2020-Dec-09 00:00 191.31843 25.42849 0.03132608495074 21.909 n.a. 79.2936 /L 22.5/ 39.2368 2020-Dec-10 00:00 194.16294 23.38352 0.03145602743408 22.032 n.a. 76.9100 /L 24.6/ 28.3544 2020-Dec-11 00:00 196.89956 21.30754 0.03167852186448 22.165 n.a. 74.5606 /L 30.6/ 18.4194 2020-Dec-12 00:00 199.52585 19.21879 0.03199262214301 22.307 n.a. 72.2629 /L 39.0/ 10.1109 2020-Dec-13 00:00 202.04113 17.13447 0.03239679270566 22.456 n.a. 70.0327 /L 48.8/ 4.0429 2020-Dec-14 00:00 204.44619 15.07030 0.03288899033028 22.613 n.a. 67.8841 /L 59.3/ 0.6595 2020-Dec-15 00:00 206.74310 13.04007 0.03346675412932 22.774 n.a. 65.8289 /L 70.1/ 0.1504 2020-Dec-16 00:00 208.93495 11.05546 0.03412729592749 22.939 n.a. 63.8764 /L 81.0/ 2.4236 2020-Dec-17 00:00 211.02561 9.12599 0.03486758687589 23.106 n.a. 62.0335 /L 91.8/ 7.1476

Setups


Due the 0.6 h rotation period and a diameter of roughly 0.02 km, we are expecting a bandwidth
of roughly 3 Hz.  

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
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/data0/2018pk21/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

...not available yet... 

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

1999 AP10 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/2018PK21/2018pk21.2020.goldstone.planning.html

Asteroid Radar Astronomy
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