Physical Data Objects (sbpy.data.Phys
)ΒΆ
Phys
is designed to contain and query physical properties for
small bodies; functions to query these properties are
available. from_sbdb
queries the JPL Small-body
Database Browser (SBDB) for physical
properties and stores the data in a Phys
object, offering
the same functionality as all the other data
functions,
including the use of units
.
As an example, the following code will query the properties for a small number of asteroids:
>>> from sbpy.data import Phys
>>> phys = Phys.from_sbdb(['Ceres', '12893', '3552'])
>>> phys['targetname', 'H', 'diameter']
<QTable length=3>
targetname H diameter
mag km
str26 float64 float64
-------------------------- ------- --------
1 Ceres (A801 AA) 3.56 939.4
12893 Mommert (1998 QS55) 13.98 5.214
3552 Don Quixote (1983 SA) 12.96 19.0
Please note that the SBDB database is not complete with respect to physical properties and should be considered as a sparse dataset.
Phys
also contains a function to query molecular data that
might be useful for various calculations such as production rate calculations.
from_jplspec
queries the JPL Molecular Spectroscopy Catalog molecular properties, and stores the
data in a Phys
object, offering the same functionality as all the
other data
functions, including the use of units
. The results
from from_jplspec
include the following data:
Transition frequencyTemperatureIntegrated line intensity at 300 KPartition function at 300 KPartition function at designated temperatureUpper state degeneracyUpper level energy in JoulesLower level energy in JoulesDegrees of freedom
>>> from sbpy.data.phys import Phys
>>> import astropy.units as u
>>> temp_estimate = 47. * u.K
>>> transition_freq = (230.53799 * u.GHz).to('MHz')
>>> mol_tag = '^CO$'
>>> mol_data = Phys.from_jplspec(temp_estimate, transition_freq, mol_tag)
>>> mol_data
<QTable length=1>
Transition frequency Temperature ... Degrees of freedom Molecule Identifier
MHz K ...
float64 float64 ... int64 int64
-------------------- ----------- ... ------------------ -------------------
230538.0 47.0 ... 2 28001