Goldstone Radar Observations Planning: 2019 GC6


Background


2019 GC6 was discovered on 2019 April 9 by the Catalina Sky Survey near Tucson, Arizona.
This asteroid has an absolute magnitude of 26.6 that suggests a diameter
within a factor of two of 15 meters.  Nothing else is known about its physical properties.

2019 GC6 will approach within 0.00146 au (0.57 lunar distances) on April 18 and it will
be a strong radar target.  The flyby will be the closest currently known through the end of 2019.
The close approach will occur at a declination of -60 deg when the asteroid will be too far
south for Goldstone to track, but at that time the asteroid will be visible at Deep Space Network 
antennas near Canberra, Australia.
NASA's Planetary Defense Coordination Office has requested follow-up observations for asteroids larger than 
10 meters in diameter that approach within one lunar distance; this is major reason
why we will observe 2019 GC6.
We plan to observe 2019 GC6 using DSS-13 to transmit and the Very Long Baseline Array
and the Australian Telescope Compact Array to receive.  

The SNRs may be strong enough for radar imaging at 1.875 m and 3.75 m resolutions if we receive at Green Bank.
This object will also be a strong radar target at Arecibo starting on April 20, but the asteroid is so small
that Arecibo may not be able to resove it in time delay. 

Radar observations at Goldstone's DSS-14 antenna are not possible because its X-band klystrons are not operational.
We have one track scheduled at Goldstone's DSS-13 antenna on April 18 (DOY 108). 
Tracks are not currently scheduled at Arecibo. 
Radar observations are also scheduled in Australia using DSS-35 and DSS-43 to transmit and the ATCA to receive.

Shortly after its discovery 2019 GC6 was on NASA's risk page of potential impactors with a cumulative
impact probability of 10^-4 over the next 100 years.  New astrometry reported on April 11 improved the
orbit substantially and this object is no longer on the risk page.  

However, the orbital uncertainties with JPL/Horizons solution 6 are
substantial and the motion cannot be computed reliably for more than about 30 years.

2019 GC6 is on the NHATS list of potential mission targets.

Orbital and Physical Characteristics  
Name                     2019 GC6
Asteroid number          Not numbered             
Discoverer               Catalina Sky Survey
Discovery date           2019 April  9
orbit type               Apollo
Close approach dist.     0.00146 au
Close approach dist.     0.57 lunar distances     
Close approach date      2019 Apr 18

semimajor axis           1.106 au                 
eccentricity             0.178
inclination              0.095 deg                 
Orbital period           1.106 years              
perihelion distance      0.910 au                 
aphelion distance        1.303 au
MOID                     0.00156 au

absolute magnitude (H)   26.6                
diameter                 15 m +- a factor of two
optical albedo           unknown                 
rotation period          unknown
lightcurve amplitude     unknown
pole direction           unknown                 
spectral class           unknown                 
                         NHATS

Past and Future Close Approaches: (JPL/Horizons solution 6)

          Date (TDB)      Body   CA Dist  MinDist  MaxDist   Vrel  TCA3Sg  Nsigs  P_i/p
  A.D. 1963 Aug 19.94204  Earth  .057055  .001579 4.633626   3.874 6.33E6 18937. .000000
  A.D. 1983 Apr 16.61192  Earth  .009736  .001497  .076590   5.616 12378. 74333. .000000
  A.D. 1998 Sep 11.22079  Earth  .034492  .024450  .043969   6.313 1121.2 16725. .000000
  A.D. 2005 Aug 08.45059  Earth  .080319  .074809  .086636   3.927 9958.0 41886. .000000
  A.D. 2012 Jun 08.12419  Earth  .099889  .098550  .101279   4.403 6233.4 3.33E5 .000000
  A.D. 2019 Apr 17.55774  Moon   .001854  .001853  .001854   5.860   0.64 63448. .000000
  A.D. 2019 Apr 18.27843  Earth  .001465  .001463  .001466   5.625   0.29 2464.8 .000000
  A.D. 2034 Sep 11.91625  Earth  .042748  .031502  .053762   6.456 1288.9 53734. .000000
  A.D. 2041 Jul 23.16787  Earth  .097633  .094079  .101523   4.246 12558. 1.15E5 .000000
  A.D. 2048 May 09.45209  Earth  .069427  .051177  .100361   3.819 25115. 1.68E5 .000000

Last update: 2019 April 16

Discovery M.P.E.C.

2019 GC6
https://www.minorplanetcenter.net/mpec/K19/K19GE6.html


SNR Calculations


2019 GC6 GOLDSTONE SNRS

                                                        MONOSTATIC DSS14   DSS13-GBT
DOY  start date    window       RA, dec   dist   runs   SNR/day   SNR/run   SNR/RTT          
103  2019 Apr 13  03:38-10:50   193, -12  0.015    845      34         1
104  2019 Apr 14  03:37-10:38   192, -14  0.012   1026      80         3
105  2019 Apr 15  03:39-10:19   191, -16  0.009   1296     240         7                       DSS-13 Transmissions
106  2019 Apr 16  03:47-09:43   189, -20  0.006   1708    1000        26       2               VLBA rx    ATCA rx
107  2019 Apr 17  04:37-07:36   184, -31  0.004   1629    6800       170      14  CANCELLED 
108  2019 Apr 18  18:20-22:42    29, -25  0.002   3884   50000       850      68  Scheduled    1920-1940  2020-2250
109  2019 Apr 19  15:18-23:25    19,  -4  0.005   3017    3600        71       6           
110  2019 Apr 20  14:37-23:30    17,  +3  0.008   2039     580        14       1
111  2019 Apr 21  14:18-23:29    16,  +6  0.011   1522     160         4
112  2019 Apr 22  14:06-23:27    15,  +7  0.014   1210      61         2
113  2019 Apr 23  13:57-23:25    15,  +8  0.017   1003      28         1

DSS-13 horizons assume Ptx = 20 deg.  However, we can start transmitting at 14 deg on Apr 17 and 13.6 deg on Apr. 18,
so the view periods are longer than shown above.
                                                                       
Goldstone DSS-14 SNRs assume Ptx = 450 kW.  DSS-14 is not currently operational as a radar due to klystron problems.

Reception is scheduled at the Very Long Baseline Array and at the Australian Telescope Compact Array.

Not scheuled at Green Bank.


2019 GC6 ARECIBO SNRS

 start date    window       RA, dec   dist   runs   SNR/day   SNR/run
2019 Apr 20  14:57-16:29    17,  +2  0.008    399    1700        99
2019 Apr 21  14:33-16:34    16,  +5  0.011    366     590        34
2019 Apr 22  14:20-16:33    15,  +7  0.014    308     230        14
2019 Apr 23  14:11-16:30    15,  +8  0.017    262     100         7
2019 Apr 24  14:04-16:27    14,  +9  0.020    226      53         4
2019 Apr 25  13:58-16:23    14, +10  0.023    199      30         2
2019 Apr 26  13:52-16:20    14, +10  0.026    177      18         1

Arecibo SNRs assume Ptx = 400 kW, Gain = 8 K/Jy, and Tsys = 25 K.


Track Assignments


DOY BOA  BOT  EOT  EOA
107 0255 0425 0745 0815 DSS-13 GSSR  2019 GC6   CANCELLED 
108      0935 1025      DSS-43 GSSR  2019 GC6   Receive at the ATCA
108 1640 1810 2250 2320 DSS-13 GSSR  2019 GC6   Receive at the VLBA and ATCA


Goldstone tracks:
     UT       UT          PDT                  Duration Round-trip    
DOY  Date     TX Window   TX Window            hh:mm    time (sec)  VLBA       ATCA receive from DSS-13
108  Apr 18   1735-2250   1035-1550 Apr 18      5:15    2.0 - 2.5   1920-1940  2020-2250  

We have an unsually long precal time for this track. 

We will uplink to the VLBA from 19:20-19:40.
We will uplink to the ATCA from 20:20-22:50.
We will NOT uplink to Green Bank. 

ATCA horizons = 12 degrees

DSS-13 Transmit powers due to airspace coordination:
Apr 17 0335-0435  40 kW   CANCELLED
       0435-0735  60 kW   CANCELLED
       0735-0745  40 kW   CANCELLED
Apr 18 1735-1820  40 kW   no receive antenna scheduled
       1820-1935  60 kW   VLBA
       1935-2125  80 kW   VLBA, ATCA
       2125-2240  60 kW   ATCA
       2240-2250  40 kW   ATCA
DSS-13 transmissions can begin at elevations below 15 degrees on both days but not at full power.



Uncertainties

2019 GC6
JPL/Horizons solution 6, # obs: 85 (16 days)
2019 Apr 16
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Apr-14 00:00 *m  192.65757 -13.00688 0.01336074998153      0.440       52.72      191.62       0.008353
 2019-Apr-15 00:00 *m  191.85880 -14.85350 0.01030053452307      0.636       52.14      189.51       0.006451
 2019-Apr-16 00:00 *m  190.37432 -18.24643 0.00725898600750      1.098       51.03      185.48       0.004580
 2019-Apr-17 00:00 *m  186.54708 -26.39220 0.00427331746820      3.601       47.74      173.52       0.002782
 2019-Apr-18 00:00 *   154.44217 -60.14870 0.00171947401606     39.769       30.51      110.88       0.001300 *
 2019-Apr-19 00:00 *    25.47331 -18.96826 0.00269458917743     62.829       37.55      136.47       0.001558
 2019-Apr-20 00:00 *    18.37132  -1.76942 0.00556745552565     51.765       49.17      178.70       0.003208
 2019-Apr-21 00:00 *    16.26898   3.57421 0.00859461616563     49.390       51.48      187.09       0.005043
 2019-Apr-22 00:00 *    15.27131   6.12931 0.01165617281670     48.502       52.41      190.48       0.006929

JPL/Horizons solution 4, # obs: 73 (14 days)
2019 Apr 15
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Apr-14 00:00 *m  192.65757 -13.00687 0.01336087538495      0.618       58.55      212.78       0.009656
 2019-Apr-15 00:00 *m  191.85880 -14.85347 0.01030066417728      1.377       57.90      210.43       0.007569
 2019-Apr-16 00:00 *m  190.37436 -18.24633 0.00725911978099      4.015       56.70      206.08       0.005534
 2019-Apr-17 00:00 *m  186.54728 -26.39178 0.00427345317392     16.699       53.46      194.31       0.003614 
 2019-Apr-18 00:00 *   154.44801 -60.14600 0.00171956434194    147.654       65.26      237.19       0.001831 *
 2019-Apr-19 00:00 *    25.47423 -18.97028 0.00269447514768    112.116       41.47      150.72       0.001819
 2019-Apr-20 00:00 *    18.37159  -1.77007 0.00556731437086     66.818       54.19      196.93       0.003514
 2019-Apr-21 00:00 *    16.26914   3.57385 0.00859446630559     59.264       57.02      207.24       0.005469
 2019-Apr-22 00:00 *    15.27142   6.12905 0.01165601690516     56.767       58.12      211.24       0.007520

JPL/Horizons solution 3, # obs: 56 (13 days),
2019 April 14
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Apr-14 00:00 *m  192.65754 -13.00686 0.01336225606525      1.236       75.71      275.16       0.012696
 2019-Apr-15 00:00 *m  191.85876 -14.85345 0.01030173783051      2.825       74.87      272.12       0.010021
 2019-Apr-16 00:00 *m  190.37429 -18.24628 0.00725989106599      7.765       73.34      266.54       0.007426
 2019-Apr-17 00:00 *m  186.54720 -26.39158 0.00427393288923     30.126       69.35      252.06       0.005002
 2019-Apr-18 00:00 *   154.45033 -60.14436 0.00171979316846    249.600      104.17      378.61       0.002598
 2019-Apr-19 00:00 *    25.47583 -18.97310 0.00269469679185    168.639       54.98      199.82       0.002574
 2019-Apr-20 00:00 *    18.37265  -1.77231 0.00556779698049     91.281       69.90      254.06       0.004661
 2019-Apr-21 00:00 *    16.27010   3.57175 0.00859524433984     78.763       73.68      267.77       0.007110
 2019-Apr-22 00:00 *    15.27235   6.12700 0.01165709894988     74.742       75.13      273.06       0.009720

JPL/Horizons solution 2, # obs: 20 (8 days) 
2019 April 11
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Apr-14 00:00 *m  192.65752 -13.00676 0.01336220201630      7.206      107.90      392.16       0.021182
 2019-Apr-15 00:00 *m  191.85875 -14.85324 0.01030179918424     16.893      106.70      387.79       0.018168
 2019-Apr-16 00:00 *m  190.37434 -18.24577 0.00726006504387     45.062      104.42      379.52       0.015569
 2019-Apr-17 00:00 *m  186.54768 -26.38987 0.00427420637053    166.199       99.69      362.32       0.013425
 2019-Apr-18 00:00 *   154.46796 -60.13519 0.00171998772150   1280.557      472.39     1716.88       0.008065
 2019-Apr-19 00:00 *    25.47854 -18.97795 0.00269423717377    665.067      162.69      591.31       0.010411
 2019-Apr-20 00:00 *    18.37320  -1.77320 0.00556717011243    224.223      102.02      370.78       0.013475
 2019-Apr-21 00:00 *    16.27025   3.57162 0.00859449322464    148.129      105.44      383.23       0.015907
 2019-Apr-22 00:00 *    15.27234   6.12714 0.01165622796148    125.203      107.28      389.89       0.018728

JPL/Horizons solution 1 (6 days)
2019 Apr  9
 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta POS_3sigma  DOP_S_3sig  DOP_X_3sig  RT_delay_3sig
 2019-Apr-14 00:00 *m  192.65541 -13.00835 0.01339247060664     45.273      650.73     2365.03       0.078946
 2019-Apr-15 00:00 *m  191.85530 -14.85630 0.01032370205062     98.133      642.72     2335.95       0.062037
 2019-Apr-16 00:00 *m  190.36771 -18.25280 0.00727375207602    247.371      621.91     2260.32       0.050732
 2019-Apr-17 00:00 *m  186.52920 -26.41233 0.00428013630369    871.806      523.72     1903.44       0.047449
 2019-Apr-18 00:00 *   154.20311 -60.23387 0.00172196308609   6385.684     2208.12     8025.31       0.030359
 2019-Apr-19 00:00 *    25.48339 -18.96025 0.00270639488578   2831.649     1072.19     3896.81       0.065015
 2019-Apr-20 00:00 *    18.39286  -1.80724 0.00558747928465    745.175      666.83     2423.56       0.090997
 2019-Apr-21 00:00 *    16.29172   3.52828 0.00862304896763    495.491      654.10     2377.31       0.112772
 2019-Apr-22 00:00 *    15.29428   6.08064 0.01169315496801    472.391      657.07     2388.08       0.134931


Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: 2019 GC6 Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-O-T /r T-O-M/Illu% 2019-Apr-12 00:00 193.42025 -10.99103 0.01950075062214 18.68 172.9062 /T 94.9/ 41.3 2019-Apr-13 00:00 193.04622 -11.77289 0.01641819639958 18.36 171.5782 /T 81.2/ 52.4 2019-Apr-14 00:00 192.51116 -12.91454 0.01334649939142 17.97 169.9834 /T 67.4/ 63.7 2019-Apr-15 00:00 191.66555 -14.73496 0.01028643603081 17.49 167.8518 /T 53.8/ 74.4 2019-Apr-16 00:00 190.09212 -18.08167 0.00724488708231 16.84 164.3782 /T 41.2/ 83.9 2019-Apr-17 00:00 186.03103 -26.12490 0.00425889701060 15.95 156.2376 /T 34.5/ 91.5 2019-Apr-18 00:00 152.38278 -59.28737 0.00170645857810 15.07 117.3021 /T 67.1/ 96.8 2019-Apr-19 00:00 26.18216 -18.38223 0.00270078763603 22. 29.3826 /L 157.3/ 99.5 2019-Apr-20 00:00 18.71513 -1.51857 0.00557697773625 28. 15.5826 /L 159.7/ 99.4 2019-Apr-21 00:00 16.49567 3.73065 0.00860470816208 30. 14.2996 /L 145.8/ 96.8 2019-Apr-22 00:00 15.44061 6.24270 0.01166630410228 30. 14.9686 /L 132.0/ 91.9

Setups



The rotation period of this asteroid is unknown, but if D = 15 meters and P = 0.5 hours, then 
we could see a bandwidth of about 3 Hz. 


CW setup:
---------------------------------------------------------------------------
TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hopping
Bandwidth:               5000 Hz 
TXoffset                  +500 Hz
FFT                     10000 for 0.5 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/data0/2019gc6/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

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/2019GC6_planning.html

Asteroid Radar Astronomy
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