Goldstone Radar Observations Planning: 2020 SW


Background


2020 SW was discovered on September 18, 2020 by the Mt. Lemmon Survey in Arizona.

This asteroid will approach within 0.00019 au (0.7 Earth-Moon distances) at 11:12 UT 
(04:12 am PDT) on 2020 Sep. 24.
The approach distance is only about 3.4 Earth radii above the surface.  
With an absolute magnitude of 28.9, this object is roughly 5-10 meters in diameter.  
Nothing else is known about its physical properties.

In principle, radar SNRs Goldstone would be very strong on Sep. 24 if we could observe
the asteroid on that date.  The time we were able to schedule on short notice is on Sep. 25
when the distance will be about 0.005 au (roughly 2 lunar distances) and the SNRs will be 
much weaker.  Due to the short round-trip light travel time, the observations will be bistatic
with transmission at DSS-14 and reception at DSS-13.  

Due to the unusual close approach distance, an official NASA statement was released
about this object at:
https://www.jpl.nasa.gov/news/news.php?feature=7752


Orbital and Physical Characteristics  
Name                     2020 SW
Asteroid number          not numbered
Discoverer               Mt. Lemmon Survey
Discovery date           2020 Sep 18
orbit type               Apollo
Close approach distance  0.00019 au  (0.7 lunar distances)
Close approach date      2020 Sep 24

semimajor axis           1.0149 au
eccentricity             0.190
inclination              4.2 deg                 
Orbital period           1.02 years              
perihelion distance      0.822 au
aphelion distance        1.208 au                 
MOID                     0.00051 au

absolute magnitude (H)   28.9
diameter                ~6 meters       
optical albedo           unknown              
rotation period          unknown
lightcurve amplitude     unknown
pole direction           unknown                  
spectral class           unknown
PHA?                     No

Last update: 2020 September 24

Discovery M.P.E.C.


2020 SW
https://www.minorplanetcenter.net/mpec/K20/K20S83.html



SNR Calculations

Goldstone SNRs
SNRs assume Ptx = 250 kW, D = 6 m, P = 0.5 h, radar albedo = 0.1, Tsys = 17 K.

Monostatic at DSS-14 with 1/2 power                                                  DSS13
DOY      start date       window        RA, dec   dist   runs      SNR/day   SNR/run SNR/RTT
264     2020 Sep 20     02:17-13:00    357, +22  0.014   1409         10         0
265     2020 Sep 21     02:15-12:56    358, +22  0.010   1845         29         1
266     2020 Sep 22     02:14-12:52    358, +22  0.007   2675        130         3
267     2020 Sep 23     02:17-12:49    359, +20  0.004   4880       1500        23      6
268     2020 Sep 24     03:00-10:19     14,  +4  0.001  20000    2600000     19000   4700      
268-269 2020 Sep 24-25  16:38-00:45    194,  -5  0.001  10540      80000       850    210      
269-270 2020 Sep 25-26  16:22-01:08    199,  +1  0.005   3356        640        12      3      DOY 269 1625-1810 UTC
270-271 2020 Sep 26-27  16:17-01:10    200,  +2  0.008   2005         78         2
271-272 2020 Sep 27-28  16:13-01:08    200,  +3  0.011   1430         20         1
272-273 2020 Sep 28-29  16:09-01:06    200,  +3  0.015   1112          7         0

Goldstone has only one klystron and full power is not expected until Dec. 2020 or Jan. 2021.



2020 SW ARECIBO SNRs
 start date    window        RA, dec   dist    runs      SNR/day   SNR/run

...Not computed yet...Arecibo is not operational due to a cable failure in August, 2020...


Track Assignments


DOY  BOA   BOT   EOT   EOA
269  1455  1625  1810  1840  DSS-14   GSSR AST 2020 SW  Transmit
269  1455              1840  DSS-13   DSSR AST 2020 SW  Receive only

Goldstone tracks:
     UT       UT          PDT               Duration Round-trip     
DOY  Date     TX Window   TX Window         hh:mm    time (sec)   SNR/run
269  Sep 25   1625-1810   0925-1110 Sep 25   1:35         5          3


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

...Not scheduled...



Uncertainties

2020 SW
JPL/Horizons solution 5, #obs: 191 (6 days)
2020 Sep 24
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2020-Sep-20 00:00 *m  357.40825  22.25211 0.01486050031517      0.352       15.61       56.74       0.002464
 2020-Sep-21 00:00 *m  357.64441  22.04443 0.01157567953460      0.341       15.54       56.47       0.001899
 2020-Sep-22 00:00 *m  358.07700  21.64665 0.00829090637240      0.342       15.43       56.09       0.001337
 2020-Sep-23 00:00 *m  359.09006  20.69524 0.00499857284069      0.396       15.22       55.31       0.000782
 2020-Sep-24 00:00 *m    3.98338  15.87444 0.00167559372219      0.733       14.17       51.49       0.000250
 2020-Sep-25 00:00 *m  195.27653  -2.84183 0.00187363826032     60.981       15.00       54.52       0.000266
 2020-Sep-26 00:00 *m  198.96441   1.36181 0.00519312391589     59.976       16.02       58.23       0.000801
 2020-Sep-27 00:00 *m  199.76221   2.29291 0.00848436620899     59.856       16.26       59.11       0.001358
 2020-Sep-28 00:00 *m  200.09834   2.70368 0.01176893946514     59.786       16.41       59.63       0.001922
 2020-Sep-29 00:00 *   200.27310   2.93354 0.01505447580618     59.713       16.53       60.06       0.002492

The pointing uncertainties are still uncomfortably large for Goldstone so additional astrometry
obtained up to about 12:00 UT on Sep. 24 would be helpful.

- - - - - - - - - - 

JPL/Horizons solution 4, # obs: 76 (5 days)
2020 September 23

 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2020-Sep-21 00:00 *m  357.64442  22.04441 0.01157566596598      0.473       61.25      222.61       0.008195
 2020-Sep-22 00:00 *m  358.07703  21.64661 0.00829101191681      0.645       60.79      220.94       0.006018
 2020-Sep-23 00:00 *m  359.09008  20.69518 0.00499879817494      1.289       59.83      217.43       0.003910
 2020-Sep-24 00:00 *m    3.98242  15.87524 0.00167594407169     20.640       54.87      199.41       0.002069
 2020-Sep-25 00:00 *m  195.27316  -2.84513 0.00187317762678    291.574       59.86      217.54       0.001413 
 2020-Sep-26 00:00 *m  198.96258   1.36035 0.00519255212274    269.427       63.70      231.52       0.002852 *
 2020-Sep-27 00:00 *m  199.76059   2.29169 0.00848367815331    266.716       64.59      234.76       0.004904
 2020-Sep-28 00:00 *m  200.09678   2.70256 0.01176813336539    265.619       65.13      236.73       0.007073
 2020-Sep-29 00:00 *   200.27159   2.93247 0.01505355070675    264.892       65.61      238.44       0.009289

- - - - - - - - - - 

JPL/Horizons solution 3, # obs: 57 (4 days)
2020 Sep 22
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2020-Sep-21 00:00 *m  357.64443  22.04441 0.01157563230713      0.902      146.41      532.11       0.010110
 2020-Sep-22 00:00 *m  358.07703  21.64662 0.00829099192288      0.982      146.04      530.77       0.006723
 2020-Sep-23 00:00 *m  359.09008  20.69521 0.00499879173270     10.131      145.81      529.94       0.006692
 2020-Sep-24 00:00 *m    3.98239  15.87539 0.00167595077759    198.536      145.94      530.41       0.010102
 2020-Sep-25 00:00 *m  195.27381  -2.84481 0.00187315932187    323.303      130.80      475.37       0.014094
 2020-Sep-26 00:00 *m  198.96325   1.36064 0.00519252098415    371.163      146.24      531.49       0.018648 *
 2020-Sep-27 00:00 *m  199.76127   2.29198 0.00848363348115    383.335      149.82      544.53       0.023622
 2020-Sep-28 00:00 *m  200.09747   2.70285 0.01176807490332    387.513      151.62      551.07       0.028768
 2020-Sep-29 00:00 *   200.27227   2.93275 0.01505347826156    389.321      152.97      555.95       0.034017


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-Sep-18 00:00 357.07075 22.50968 0.02143980531575 21.752 n.a. 155.6911 /L 153.1/ 0.6341 2020-Sep-19 00:00 357.15410 22.45886 0.01814458432870 21.372 n.a. 156.1537 /L 151.4/ 3.7535 2020-Sep-20 00:00 357.27675 22.36126 0.01485615369733 20.918 n.a. 156.6383 /T 143.7/ 9.6396 2020-Sep-21 00:00 357.47480 22.18366 0.01157175015264 20.354 n.a. 157.1820 /T 132.9/ 17.8002 2020-Sep-22 00:00 357.83973 21.84001 0.00828721695883 19.603 n.a. 157.8819 /T 121.1/ 27.5806 2020-Sep-23 00:00 358.69861 21.01517 0.00499459581750 18.461 n.a. 159.0894 /T 109.3/ 38.2828 2020-Sep-24 00:00 2.87571 16.83615 0.00166769499019 15.926 n.a. 163.6488 /L 98.9/ 49.2564 2020-Sep-25 00:00 196.10431 -2.06992 0.00189367021190 29. n.a. 13.9547 /T 88.2/ 59.9470 2020-Sep-26 00:00 199.25280 1.62436 0.00521588943845 30. n.a. 16.4311 /T 99.9/ 69.9070 2020-Sep-27 00:00 199.93910 2.45102 0.00850726839146 31. n.a. 16.4843 /T 112.3/ 78.7866 2020-Sep-28 00:00 200.22684 2.81676 0.01179157092611 32. n.a. 16.1056 /T 124.6/ 86.3174 2020-Sep-29 00:00 200.37450 3.02150 0.01507669097090 32. n.a. 15.5889 /T 136.7/ 92.2992 2020-Sep-30 00:00 200.45586 3.15003 0.01836712793430 33. n.a. 15.0233 /T 148.6/ 96.5911 After closest approach this object gets too close to the Sun for optical observations. Hourly intervals straddling the closest approach: 2020-Sep-23 18:00 0.81145 18.93711 0.00250655975470 16.883 n.a. 161.5234 /T 101.0/ 46.5197 2020-Sep-23 19:00 1.05644 18.69144 0.00236726610248 16.750 n.a. 161.7870 /T 100.6/ 46.9768 2020-Sep-23 20:00 1.33129 18.41463 0.00222779080548 16.608 n.a. 162.0791 /L 100.3/ 47.4335 2020-Sep-23 21:00 1.64187 18.10034 0.00208811658539 16.456 n.a. 162.4047 /L 99.9/ 47.8899 2020-Sep-23 22:00 1.99571 17.74034 0.00194822404674 16.293 n.a. 162.7697 /L 99.5/ 48.3458 2020-Sep-23 23:00 2.40262 17.32380 0.00180809151075 16.117 n.a. 163.1815 /L 99.2/ 48.8014 2020-Sep-24 00:00 2.87571 16.83615 0.00166769499020 15.926 n.a. 163.6488 /L 98.9/ 49.2564 2020-Sep-24 01:00 3.43279 16.25734 0.00152700850347 15.716 n.a. 164.1818 /L 98.6/ 49.7110 2020-Sep-24 02:00 4.09881 15.55899 0.00138600515622 15.484 n.a. 164.7919 /L 98.4/ 50.1650 2020-Sep-24 03:00 4.90982 14.69952 0.00124465994153 15.226 n.a. 165.4887 /L 98.3/ 50.6184 2020-Sep-24 04:00 5.92001 13.61556 0.00110295646171 14.936 n.a. 166.2728 /L 98.2/ 51.0712 2020-Sep-24 05:00 7.21495 12.20555 0.00096090298627 14.606 n.a. 167.1108 /L 98.3/ 51.5234 2020-Sep-24 06:00 8.93842 10.29635 0.00081857224145 14.229 n.a. 167.8599 /L 98.5/ 51.9749 2020-Sep-24 07:00 11.35295 7.56806 0.00067620737238 13.807 n.a. 168.0432 /L 99.1/ 52.4257 2020-Sep-24 08:00 14.99657 3.36491 0.00053453753494 13.359 n.a. 166.3389 /L 100.2/ 52.8757 2020-Sep-24 09:00 21.17878 -3.84758 0.00039588343446 12.923 n.a. 159.9381 /L 102.2/ 53.3249 2020-Sep-24 10:00 34.10459 -18.08502 0.00026894129089 12.580 n.a. 142.9672 /L 105.8/ 53.7733 2020-Sep-24 11:00 73.40429 -43.93495 0.00019036955506 13.035 n.a. 102.5410 /L 108.3/ 54.2209 2020-Sep-24 12:00 145.91409 -42.63111 0.00022862614230 16. n.a. 52.7429 /L 99.7/ 54.6675 2020-Sep-24 13:00 171.81059 -27.18460 0.00034409736054 20. n.a. 28.0937 /L 92.4/ 55.1133 2020-Sep-24 14:00 181.17977 -18.56319 0.00047995588117 24. n.a. 17.7873 /L 89.2/ 55.5581 2020-Sep-24 15:00 185.92692 -13.60520 0.00062089365290 27. n.a. 13.4225 /T 87.7/ 56.0019 2020-Sep-24 16:00 188.80511 -10.44240 0.00076312074432 29. n.a. 11.8258 /T 87.0/ 56.4447 2020-Sep-24 17:00 190.74357 -8.25892 0.00090550800846 29. n.a. 11.4992 /T 86.7/ 56.8865 2020-Sep-24 18:00 192.14166 -6.66257 0.00104768217887 29. n.a. 11.6960 /T 86.6/ 57.3272 2020-Sep-24 19:00 193.19969 -5.44468 0.00118952313609 29. n.a. 12.0780 /T 86.7/ 57.7667

Setups



The rotation period is unknown, but presumably this object will be a relatively rapid rotator,
so the bandwidth could be roughly 1 Hz.  

CW setup:
---------------------------------------------------------------------------
TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hopping
Bandwidth:               5000 Hz 
TXoffset                 +500 Hz
FFT                      5000 for 1.0 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              8
bandwidth       245 Hz   
FFT             128
resolution        3.8 Hz
TXoffset        +50 Hz  (echo in column 116)
---------------------------------------------------------------------

Instructions

NOTE: Data should be moved to the appropriate subdirectories in aardvark:/export/data0/2020sw/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

2020 SW 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/2020SW/2020SW.2020.goldstone.planning.html

Asteroid Radar Astronomy
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