2014 BR57 Goldstone Radar Observations Planning


Goldstone Radar Images of 2014 BR57


Sequence of images with a resolution of 3.75 meters x 0.06 Hz.  Time delay (range) 
increases down and Doppler frequency increases to the right, so the rotation is 
counterclockwise.  Each image is a weighted sum of 15 individual transmit-receive cycles.
The images were obtained during an interval of 4.2 hours
on February 18 when the asteroid was 0.018 AU (7 lunar dsitances) from Earth.

The images indicate that 2014 BR57 is a rounded object and suggest that it's roughly 
80 meters in diameter.  Radar-bright spots appear in two locations and persist over a
range of rotation phases.  The spots appear in frames 5, 6, 7 at the trailing edge of
the echo and in frames 11, 12, and 13 near the two o'clock position.
The spots are more conspicuous in the movie (a link is provided below).
The images suggest that the rotation period is a few hours.

Radar astrometry obtained on Feb. 18 permits reliable orbit estimation for 
261 years and has prevented this object from being lost.  The encounter in 2014 was
the closest for the forseeable future.

Although there have been problems recently with one of the klystrons, we were
fortunate with these observations that both klystrons were operational and that
we were able to transmit 440 kW.

An animation showing 2014 BR57 rotating is available here.


Background


2014 BR57 was discovered by the Mt. Lemmon Survey (Arizona) on January 28, 2014.
It has an absolute magnitude of 23.9 suggesting a diameter within a factor of two
of 60 meters, but nothing else is known about its physical properties.
2014 BR57 will approach within 0.011 AU (4.3 lunar distances) on February 20.

We have time scheduled on Feb. 18 to observe this asteroid.  

Due to the klystron problem, we will be running at 200 kW.  The SNRs probably won't
be strong but we are cautiously optimistic that we'll still get a detection.

Arecibo is offline due to damage experienced
during an earthquake on January 13, so Goldstone provides our only chance to
observe this asteroid with radar.

Orbital and Physical Characteristics  
 orbit type               Apollo
 semimajor axis           1.357 AU
 eccentricity             0.398
 inclination              3.8 deg
 perihelion distance      0.817 AU
 aphelion distance        1.896 AU
 absolute magnitude (H)   23.9
 diameter                 60 m (+/- a factor of two)
 rotation period          unknown
 pole direction           unknown
 lightcurve amplitude     unknown
 spectral class           unknown

Last update: 2014 February 19

Discovery MPEC

M.P.E.C. 2014-B80                                Issued 2014 Jan. 30, 20:13 UT

     The Minor Planet Electronic Circulars contain information on unusual
         minor planets and routine data on comets.  They are published
   on behalf of Commission 20 of the International Astronomical Union by the
          Minor Planet Center, Smithsonian Astrophysical Observatory,
                          Cambridge, MA 02138, U.S.A.

             Prepared using the Tamkin Foundation Computer Network

                              MPC@CFA.HARVARD.EDU
            URL http://www.minorplanetcenter.net/    ISSN 1523-6714

                                   2014 BR57

Observations:
     K14B57R* C2014 01 28.37791 09 51 28.06 +28 38 58.4          20.3 VqEB080G96
     K14B57R  C2014 01 28.38733 09 51 28.15 +28 39 06.4          21.1 VqEB080G96
     K14B57R  C2014 01 28.39200 09 51 28.21 +28 39 10.2          21.0 VqEB080G96
     K14B57R  C2014 01 28.45897 09 51 28.75 +28 40 04.8          20.9 VqEB080G96
     K14B57R  C2014 01 28.46349 09 51 28.74 +28 40 08.6          20.5 VqEB080G96
     K14B57R  C2014 01 28.46804 09 51 28.83 +28 40 12.0          20.9 VqEB080G96
     K14B57R  C2014 01 28.47257 09 51 28.86 +28 40 15.2          19.5 VqEB080G96
     K14B57R KC2014 01 30.26509 09 52 25.09 +29 08 03.7          20.3 RoEB080291
     K14B57R KC2014 01 30.26950 09 52 25.10 +29 08 08.4          20.7 RoEB080291
     K14B57R KC2014 01 30.27390 09 52 25.14 +29 08 13.2          20.5 RoEB080291
     K14B57R  C2014 01 30.44949 09 52 25.88 +29 11 08.5          20.7 RoEB080926
     K14B57R  C2014 01 30.46503 09 52 25.99 +29 11 22.8          21.1 RoEB080926
     K14B57R  C2014 01 30.47934 09 52 26.11 +29 11 35.6          21.0 RoEB080926

Observer details:
291 LPL/Spacewatch II.  Observer R. A. Mastaler.  1.8-m f/2.7 reflector + CCD.
926 Tenagra II Observatory.  Observers M. Schwartz, P. R. Holvorcem.  0.41-m
    f/3.75 astrograph + CCD, 0.81-m f/7 Ritchey-Chretien + CCD.
G96 Mt. Lemmon Survey.  Observer A. R. Gibbs.  Measurers E. J. Christensen,
    A. R. Gibbs, A. D. Grauer, R. E. Hill, J. A. Johnson, R. A. Kowalski,
    S. M. Larson, F. C. Shelly.  1.5-m reflector + CCD.

Orbital elements:
2014 BR57                                                Earth MOID = 0.0115 AU
Epoch 2013 Nov. 4.0 TT = JDT 2456600.5                  MPC
M 262.25657              (2000.0)            P               Q
n   0.62268309     Peri.  236.99938     -0.78259773     +0.62217413
a   1.3581821      Node   341.44810     -0.54690236     -0.70323540
e   0.3989325      Incl.    3.78081     -0.29738629     -0.34403390
P   1.58           H   23.8           G   0.15           U   9
Residuals in seconds of arc
140128 G96  0.7-  0.2+    140128 G96  0.4+  0.0     140130 926  0.0   0.1-
140128 G96  0.3-  0.2+    140128 G96  0.1+  0.4-    140130 926  0.1-  0.1+
140128 G96  0.2+  0.0     140130 291  0.2+  0.0     140130 926  0.2-  0.0
140128 G96  0.5+  0.1-    140130 291  0.1-  0.0
140128 G96  0.2-  0.1+    140130 291  0.0   0.0

Ephemeris:
2014 BR57                a,e,i = 1.36, 0.40, 4                   q = 0.8164
Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase     V
2013 12 31    09 31 10.2 +25 15 22   0.3912  1.3112   141.1    28.1    23.6
...
2014 01 15    09 43 49.9 +26 25 04   0.2574  1.2179   152.6    21.8    22.3
...
2014 01 23    09 48 44.2 +27 32 55   0.1942  1.1668   158.2    18.3    21.5
...
2014 01 29    09 51 46.4 +28 48 13   0.1502  1.1283   161.3    16.2    20.8
2014 01 30    09 52 15.1 +29 03 51   0.1431  1.1219   161.7    16.0    20.7
2014 01 31    09 52 43.9 +29 20 38   0.1361  1.1154   162.0    15.9    20.6
...
2014 02 06    09 56 01.8 +31 37 35   0.09539 1.0771   161.9    16.6    19.7
...
2014 02 14    10 07 47.3 +39 38 50   0.04408 1.0270   153.2    25.7    18.3
...
2014 03 01    21 36 28.1 -14 09 17   0.05424 0.9395    18.3   160.6    28.5

A. U. Tomatic                (C) Copyright 2014 MPC           M.P.E.C. 2014-B80

SNR Calculation

2014 BR57
D = 60 meters
P = 0.5 h       (an educated guess)
OC albedo = 0.1 (a relatively conservative lower bound)

w DOY  start date      window         RA, dec   dist   runs      SNR/day   SNR/run
8  48  2014 Feb 17     01:45-15:40   159, +52  0.024   1040         27         1
8  49  2014 Feb 18     01:31-17:23   166, +61  0.018   1488         81         2  Scheduled
8  50  2014 Feb 19-20  01:03-02:10   198, +74  0.014   2870        300         6  Visible continuously for more than 24 hours
8  51  2014 Feb 20-21  07:07-00:44   297, +59  0.011   2391        590        13
8  52  2014 Feb 21-22  12:21-00:07   312, +31  0.013   1580        270         7
8  53  2014 Feb 22     13:39-23:40   317, +13  0.017   1032         84         3
8  54  2014 Feb 23     14:19-23:19   320,  +3  0.023    715         27         1

Goldstone SNRs assume Ptx = 200 kW 



Arecibo SNRs

...Arecibo is still offline...


Track Assignments


Goldstone tracks:
049 0005 0135 0715 0745  DSS-14  GSSR   AST 2014 BR57  


        UT         UT            PST                       Duration   Round-trip   SNR/  
DOY     Date       TX Window     TX Window                   hh:mm    time (sec)   Run 
---     ----       ---------     ---------                 ---------  ---------    ----
049     Feb 18     0100-0715     1700-2315 Feb 17             6:15     18           2    Assumes Ptx = 200 kW


Arecibo tracks:

...none...



Uncertainties

From Jon Giorgini, 2014 Feb 17:

New optical measurements have been reported for 2014 BR57.

Based on 51 observations (Jan 28-Feb 15),2014 BR57 orbit
solution #14 was estimated. OSOD and nominal predicts have
been updated on aardvark.

Formal 3-sigma X-band uncertainties for 2014 BR57:

 Date__(UT)__HR:MN  POS_3sigma   DOP_X_3sig  RT_delay_3sig
 2014-Feb-18 00:00       6.051      1531.87       0.061122
 2014-Feb-18 01:00       6.415      1524.84       0.060487
 2014-Feb-18 02:00       6.787      1517.57       0.059854
 2014-Feb-18 03:00       7.160      1510.05       0.059224
 2014-Feb-18 04:00       7.526      1502.27       0.058597
 2014-Feb-18 05:00       7.881      1494.22       0.057974
 2014-Feb-18 06:00       8.218      1485.90       0.057354
 2014-Feb-18 07:00       8.537      1477.31       0.056738
 2014-Feb-18 08:00       8.834      1468.42       0.056125

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

From Jon Giorgini, 2014 Feb 14:

Based on 44 optical maeasurements (Jan 28-Feb 13),
2014 BR57 orbit solution #10 was estimated. OSOD with 
nominal predicts was established on aardvark.

Formal 3-sigma X-band uncertainties for (s10):

 Date__(UT)__HR:MN  POS_3sigma   DOP_X_3sig  RT_delay_3sig
 2014-Feb-18 01:00      35.795      3168.41       0.130534
 2014-Feb-18 02:00      37.442      3154.96       0.129219
 2014-Feb-18 03:00      39.097      3140.93       0.127910
 2014-Feb-18 04:00      40.737      3126.30       0.126607
 2014-Feb-18 05:00      42.342      3111.08       0.125310
 2014-Feb-18 06:00      43.896      3095.29       0.124019
 2014-Feb-18 07:00      45.391      3078.92       0.122735
 2014-Feb-18 08:00      46.824      3062.03       0.121458

Will be updated Monday or sooner if more data is reported.

===================================================================

Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination:

 Date__(UT)__HR:MN     R.A._(a-appar)_DEC.            delta  APmag    S-O-T /r  T-O-M/Illu%
 2014-Feb-14 00:00     152.16497  39.56855 0.04400640969560  18.37 153.2282 /L   31.5/ 98.9
 2014-Feb-15 00:00     153.18388  41.93981 0.03787696842908  18.11 150.5483 /L   33.9/ 99.8
 2014-Feb-16 00:00     154.71754  45.17646 0.03185847581595  17.83 146.9474 /L   40.6/ 98.9
 2014-Feb-17 00:00     157.28526  49.82407 0.02601348472379  17.52 141.8375 /L   50.3/ 96.2
 2014-Feb-18 00:00     162.43341  56.89253 0.02047696717722  17.21 134.0443 /L   62.2/ 91.6
 2014-Feb-19 00:00     177.30093  67.89939 0.01556859965321  16.97 121.1443 /L   76.0/ 85.3
 2014-Feb-20 00:00     249.74862  75.57929 0.01207101138938  17.11  99.0743 /L   90.4/ 77.4
 2014-Feb-21 00:00     302.52413  51.91563 0.01136838652227  18.40  68.2891 /L   97.3/ 68.2
 2014-Feb-22 00:00     313.63855  26.48887 0.01389459615210    21.  42.3395 /L   89.9/ 57.9
 2014-Feb-23 00:00     317.95137  10.79814 0.01836791190535    24.  27.5290 /L   76.2/ 47.0
 2014-Feb-24 00:00     320.22733   1.64619 0.02371847341311    26.  20.2123 /L   61.4/ 35.9
 2014-Feb-25 00:00     321.63823  -4.04906 0.02948124444768    28.  17.0985 /L   46.5/ 25.3


Setups



We don't know anything about the spin state,  but if it's similar
to other tiny asteroids, it could have a rapid rotation period in the realm of
only ten minutes.  If so, then the bandwidth could be roughly 10 Hz. 

CW setup:
---------------------------------------------------------------------------
TX polarization           RCP
RCV polarization          LCP & RCP
Frequency hops:           no hops (+0.5 kHz offset)                  
Bandwidth:                4000 Hz 
Sampling interval:        2500 x 0.1 usec 
PFS FFT:                  4000 for 1.0 Hz res 

Ranging setups:
---------------------------------------------------------------------------
10-usec
baud             10 usec
code            127
PRP            1270 usec
FFT             128   
ncoh              1 
bandwidth       787 Hz   
resolution      6.15 Hz
TXOFF          +100Hz  (echo in bin 64+16=80)
---------------------------------------------------------------------------
11-usec 
baud             11 usec
code            127
PRP            1397 usec
FFT             128  
ncoh              1 
bandwidth       716 Hz   
resolution      5.6 Hz
TXOFF          +100 Hz  (echo in bin 64+18=82) 
-------------------------------------------------------------------------
1-usec 
baud            1 usec
code            127
FFT             512
ncoh             128
bandwidth        61.3 Hz   
resolution       0.12 Hz
TXOFF           +8 Hz -> echo would be centered at 256 + 67=323
-------------------------------------------------------------------------------
0.25-usec ranging 
baud            0.25 usec
code            255
FFT             128
ncoh             16
bandwidth       980  Hz     
resolution       7.7 Hz
TXOFF          +80 Hz -> echo would be centered at 64 + 10 = 74
-------------------------------------------------------------------------------
0.125-usec ranging 
baud            0.125 usec
code            255
FFT             128
ncoh             32
bandwidth       980  Hz     
resolution       7.7 Hz
TXOFF          +80 Hz -> echo would be centered at 64 + 10 = 74


Instructions

POINTING:

  OSOD and predicts are aardvark:

Monostatic with the new waveform generator:
/export/data3/osod/ops/2014br57/PRDX.OUT.14v-14-14.s??
                              /PUNCH.OUT.14v-14-14.s??
                              /EPH.OUT.s??


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.s?? ...not available yet...

2014 BR57 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 183-610 | 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/2014BR57/2014BR57_planning.html

Asteroid Radar Astronomy
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