GWsky is an interactive Python script to generate a sequence of pointings given a specific Field of View (FoV). The script aims to split the large GW sky localization into several independent areas.

It defines a sequence of FoVs from a fixed position over the sky, e.g., starting from the highest probability pixel. The results are displayed in Aladin Sky Atlas (http://aladin.u-strasbg.fr/) using the SAMPIntegratedClient class. The airmass and the integrated probability are provided in real time. Moreover, specifying the ID of a catalog, a query to the Vizier database is sent and the relative items are listed in each FoV.

The FoVs are evenly spaced assuming that the shortest angular distance between two points on the celestial sphere is measured along a great circle that passes through both of them:

                        cosθ=sinδ1sinδ2+cosδ1cosδ2cos(α1−α2), 

where (α1,δ1) and (α2,δ2) are the right ascensions and declinations of the two points on the sky.

The intercardinal and cardinal directions are allowed and the FoVs can be overlaid or separated from the default position following the user's selection.

Running it

from idle:  
          >>> import GWsky 
          >>> GWsky.main() 

from terminal: ./GWsky
if ./GWsky: Permission denied; type: chmod u+x GWsky

SUMMARY OF DEPENDENCIES

from astroquery.vizier import Vizier
import astropy.coordinates 
import astropy.units 
from astropy.vo.samp import SAMPIntegratedClient
import urlparse
import os.path
from astropy.io.votable import parse
import healpy
import numpy