Re: Comet NEOWISE (C/2020 F3)


Chanan Greenberg
 

This is a sample of the data I get from JPL
There is RA ICRF / Apparent RA and dRA*COS D  - I know there is an interface to newer versions that converts all this automatically via an interface. But i do not have that. Can someone help me figure out the custom RA and DA rate or at least how to calculate them?

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JPL/HORIZONS                 NEOWISE (C/2020 F3)           2020-Jul-19 17:55:59
Rec #:90004465 (+COV) Soln.date: 2020-Jul-18_14:19:12     # obs: 372 (113 days)
 
IAU76/J2000 helio. ecliptic osc. elements (au, days, deg., period=Julian yrs):
 
  EPOCH=  2459064.5 ! 2020-Aug-03.0000000 (TDB)    RMSW= n.a.
   EC= .9991691234351144   QR= .2946512233784272   TP= 2459034.1790709617
   OM= 61.00939569131192   W= 37.27847625028863    IN= 128.9374034572737
   A= 354.6269516206773    MA= .004474958062287851 ADIST= 708.9592520179763
   PER= 6678.2984358648    N= .000147586           ANGMOM= .013202626
   DAN= .32816             DDN= 2.87401            L= 35.4432405
   B= 28.1073672           MOID= .36253801         TP= 2020-Jul-03.6790709617
 
Comet physical (GM= km^3/s^2; RAD= km):
   GM= n.a.                RAD= n.a.
   M1=  10.7     M2=  14.9     k1=  17.75  k2=  5.      PHCOF=  .030
 
COMET comments 
1: soln ref.= JPL#14, data arc: 2020-03-27 to 2020-07-18
2: k1=17.75, k2=5., phase coef.=0.03;
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Ephemeris / WWW_USER Sun Jul 19 17:55:59 2020 Pasadena, USA      / Horizons
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Target body name: NEOWISE (C/2020 F3)             {source: JPL#14}
Center body name: Earth (399)                     {source: DE431}
Center-site name: (user defined site below)
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Start time      : A.D. 2020-Jul-19 00:00:00.0000 UT
Stop  time      : A.D. 2020-Aug-19 00:00:00.0000 UT
Step-size       : 1 minutes
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Target pole/equ : No model available
Target radii    : (unavailable)                                           
Center geodetic : 238.110000,37.3378000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
Center cylindric: 238.110000,5077.34335,3847.2668 {E-lon(deg),Dxy(km),Dz(km)}
Center pole/equ : High-precision EOP model        {East-longitude positive}
Center radii    : 6378.1 x 6378.1 x 6356.8 km     {Equator, meridian, pole}
Target primary  : Sun
Vis. interferer : MOON (R_eq= 1737.400) km        {source: DE431}
Rel. light bend : Sun, EARTH                      {source: DE431}
Rel. lght bnd GM: 1.3271E+11, 3.9860E+05 km^3/s^2                         
Small-body perts: Yes                             {source: SB431-N16}
Atmos refraction: NO (AIRLESS)
RA format       : HMS
Time format     : CAL 
RTS-only print  : NO       
EOP file        : eop.200717.p201008                                           
EOP coverage    : DATA-BASED 1962-JAN-20 TO 2020-JUL-17. PREDICTS-> 2020-OCT-07
Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s 
Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO )
Table cut-offs 2: Solar elongation (  0.0,180.0=NO ),Local Hour Angle( 0.0=NO )
Table cut-offs 3: RA/DEC angular rate (     0.0=NO )                           
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Initial IAU76/J2000 heliocentric ecliptic osculating elements (au, days, deg.):
  EPOCH=  2459064.5 ! 2020-Aug-03.0000000 (TDB)    RMSW= n.a.         
   EC= .9991691234351144   QR= .2946512233784272   TP= 2459034.1790709617
   OM= 61.00939569131192   W= 37.27847625028863    IN= 128.9374034572737       
  Equivalent ICRF heliocentric equatorial cartesian coordinates (au, au/d):
   X=-8.321621038925854E-02  Y=-8.646020467729936E-01  Z= 3.618176019624061E-02
  VX=-1.306354356457230E-02 VY=-2.045458056181457E-02 VZ=-9.533388646221023E-03
Comet physical (GM= km^3/s^2; RAD= km):                               
   GM= n.a.                RAD= n.a.                                           
   M1=  10.7     M2=  14.9     k1=  17.75  k2=  5.      PHCOF=  .030           
************************************************************************************************************************************
 Date__(UT)__HR:MN     R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt L_Ap_Sid_Time            delta      deldot
************************************************************************************************************************************
$$SOE
 2020-Jul-19 00:00 *m  09 01 50.18 +48 07 02.9 09 03 11.57 +48 02 20.9 543.8484  -35.6628 11 41 25.4736 0.71619678171961 -20.7392241
 2020-Jul-19 00:01 *m  09 01 51.08 +48 07 02.3 09 03 12.48 +48 02 20.3 543.8628  -35.7024 11 42 25.6378 0.71618846394532 -20.7348636
 2020-Jul-19 00:02 *m  09 01 51.99 +48 07 01.7 09 03 13.38 +48 02 19.7 543.8771  -35.7421 11 43 25.8021 0.71618014791953 -20.7305061

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