Planet

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This page documents the planet function of Python module analysisUtils.

This function returns the apparent position and angular size of any Solar System body for the specified date from the specified observatory. By default, it contacts the JPL Horizons telnet server to get apparent angular size, position and rate (in the J2000 reference frame) of any Solar System body. If the date and time is not specified, today's date is assumed at 0:00 UT. If the time is not specified, 0:00 UT is assumed. If the observatory is not specified, ALMA is assumed. In case an internet connection is not available, there is an option to instead query the casa ephemerides (useJPL=False). However, the reported values will be less accurate due to the need to interpolate from a coarser grid. Also, using the casa ephemerides presently requires the observatory to be ALMA.

Usage

au.planet(solarSystemBody="", date="", observatory='ALMA', verbose=False, help=False, beam="",useJPL=True, standard='Butler-JPL-Horizons 2010')

 body: string name of Solar system body
 date: one possible format of the date string is: '2011-10-31 11:59:59'
   or simply '2011-10-31' for 0:00 UT. A list of allowed formats for date
   is at:   http://ssd.jpl.nasa.gov/?horizons_doc#time
 useJPL: if False, first try the casa ephemerides.  Note that the casa tables
   are quantized to one day, and can be in error by many arcminutes. If the
   casa tables fail for any reason, it will automatically revert to using
   JPL's server.  It may require a few seconds to reach the JPL server.
 observatory: Observatories can be specifed by JPL ID string, or by the
   following names:

'VLA'	(which will be converted to = '-5')
'ALMA'	(which will be converted to = '-7')
'GBT'	(which will be converted to = '-9')
'MAUNAKEA'	(which will be converted to = '-80')
'OVRO'	(which will be converted to = '-81')

 beam:  If a beam size is included (in arcsec), the expected FWHM will be
   computed using scipy.signal.convolve() of a Gaussian with a uniform disk.

The return values are apparent values as seen from the specified observatory: The dictionary returned is:

 data['directionRadians']
 data['angularDiameter'] (in arc seconds)
 data['rateRadiansPerSecond'] (only present if useJPL=True)
 data['rangeRateKms'] (only present if useJPL=True)
 data['rangeAU'] (only present if useJPL=True)

Examples

CASA <7>: au.planet('Titan','2012-04-01','EVLA')
Using observatory: VLA = -5
Assuming 0 hours UT
MJD= 56018.00000, MJDseconds = 4839955200.0
LST day = 62742,  LST = 5.4757 hours (at longitude=-107.618334)
Julian day = 2456018.500000, MJD = 56018.000000, MJD seconds = 4839955200.000000
Confirmed Observatory name =  VLA
Confirmed Target ID = 606 = Titan
J2000 Position: 13:44:49.19, -007:52:27.645, rate: -11.9723, 3.3884 arcsec/hr
Angular diameter = 0.811703 arcsec
  Out[7]:
{'angularDiameter': 0.81170299999999995,
 'directionRadians': [3.5989557494879238, -0.13743326065058692],
 'rangeRateKms': -12.3860165,
 'rateRadiansPerSecond': [-1.6123152317632495e-08, 4.5631673694531841e-09]
}

CASA <10>: au.planet('Moon','2012-04-01 12:55')
Contacting JPL Horizons for Moon
MJD= 56018.53819, MJDseconds = 4840001700.0
LST day = 62742,  LST = 21.0853 hours (at longitude=-67.754929)
Julian day = 2456019.038194, MJD = 56018.538194, MJD seconds = 4840001700.000000
Confirmed Observatory name =  ALMA
Confirmed Target ID = 301 = Moon
Range rate = -0.156855 km/sec
J2000 Position: 08:14:33.97, +015:40:16.537, rate: 2648.9190, -473.5570 arcsec/hr
Angular diameter = 1831.355000 arcsec
  Out[10]:
{'angularDiameter': 1831.355,
 'directionRadians': [2.1579522305263157, 0.27351509191740353],
 'rangeRateKms': -0.15685499999999999,
 'rateRadiansPerSecond': [3.5673115870860856e-06, -6.3774142329219044e-07]}


CASA <7>: au.planet('Juno',useJPL=False)
No date/time specified, assuming today=2012-03-27 at UT 0:00
Using casa's ephemerides for Juno. Note these can be in error by a
few arcminutes.  Set useJPL=True for highest accuracy.
2012-03-27 15:10:05     WARN    FluxCalc_SS_JPL_Butler::compute_constant_temperature   
 Juno has a large crater and temperature changes that CASA does not fully account for.
J2000 Position: 16:30:24.74, -007:40:44.976
Angular diameter = 0.117258 arcsec
  Out[7]:
{'angularDiameter': 0.1172575956882015,
 'directionRadians': [-1.9616964976335904, -0.13402662578744778]}