[AstroPy] Question re objects within radius of given co-ordinates

Jim Singh jimmyboysingh at gmail.com
Fri Apr 2 01:23:04 EDT 2021


Hi,
I am a beginner astropy user. What I'd like to be able to do is obtain the
names and RA and Dec of all objects above a certain Magnitude, within a
given angular FOV centered on a given named object. If I try this for
example...

from astropy.coordinates import SkyCoord
from astroquery.vo_conesearch import ConeSearch
c = SkyCoord.from_name('hadar')
print(c)
result = ConeSearch.query_region(c, '0.1 deg')
result.sort('Mag')
print(result)

...I get 2670 rows back. Assuming this is the right basic approach to begin
with, is there any way to constrain the search to just those rows with
'Mag'>8 for instance? Only a handful of records would qualify in this case.
My typical search radius would be a couple of degrees, so if the query were
to return everything like above, it would take forever to execute. Also,
how to get the name of each qualifying object? Would it entail a separate
lookup on the column 'objID'?

Thanks for your help!

Regards,
Jim
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