findNearestVLBISources
Return to directory of Todd's CASA extensions
Reads a VLBI catalog from
astrogeo.org and finds all sources within specified radius
of the specified target. Downloads the file first, if necessary.
Usage:
au.findNearestVLBISources(radecString, radius=3, catalog='rfc_2014b_cat.txt',
server='http://asa.alma.cl/sourcecat/xmlrpc', phasecalFluxLimit=0.15,
checksourceFluxLimit=0.05, ageLimit=30)
Inputs:
- radecString: various acceptable formats, including '17:20:05.3 -03:20:15' (see help radec2rad for a complete description)
- radius: search radius (in degrees)
- server: this is only needed to instantiate the calDatabaseQuery object that holds the catalog parsing logic
- phasecalFluxLimit: minimum flux required (in Janskys)
- checksourceFluxLimit: minimum flux required (in Janskys)
- ageLimit: maximum age (in days) to consider flux measurement current
Returns:
- a dictionary, keyed by source name, with values equal to the separation (in degrees)
Examples:
1. Example without flux densities
CASA <4>: au.findNearestVLBISources('12:30:00 -19:50:00', 2)
number of VLBI sources 9101
Found 3 sources within 2 degrees
Out[4]:
{'J1226-1904': 1.1038003580273426,
'J1232-1836': 1.3887205245946872,
'J1238-1959': 1.9819660154049168}
2. Example with flux density at 230 GHz
CASA <5>: au.findNearestVLBISources('12:30:00 -19:50:00', 3, 230)
number of VLBI sources 9101
Found 3 sources within 3 degrees
Querying ALMA catalog for flux densities.
The highest flux density object is J1238-1959 with 90.6+-18.3 mJy at 2.0 deg.
Out[5]:
{'J1226-1904': {'ageDifference': 0,
'fluxDensity': 0.009157436914833325,
'fluxDensityUncertainty': 0.0010773455193921558,
'meanAge': 292,
'separationDegrees': 1.1038003580273426,
'spectralIndex': -0.7,
'spectralIndexUncertainty': 0.2},
'J1232-1836': None,
'J1238-1959': {'ageDifference': 0.0,
'fluxDensity': 0.090572419131667262,
'fluxDensityUncertainty': 0.018278865452864206,
'meanAge': 307.0,
'separationDegrees': 1.9819660154049168,
'spectralIndex': -0.13444847788140779,
'spectralIndexUncertainty': 0.039941467673884526}}
--
ToddHunter - 2015-07-24