The first full release of a survey of the 150 MHz radio sky observed with
the Giant Metrewave Radio Telescope between April 2010 and March 2012 as
part of the TGSS project.
Aimed at producing a reliable compact source survey, the automated data reduction
pipeline efficiently processed more than 2000 hours of observations with minimal
human interaction. Through application of innovative techniques such as image-based
flagging, direction-dependent calibration of ionospheric phase errors, correcting
for systematic offsets in antenna pointing, and improving the primary beam model,
good quality images were created for over 95 percent of the 5336 pointings.
This data release covers 36,900 square degrees (or 3.6 pi steradians) of the
sky between -53 deg and +90 deg DEC, which is 90 percent of the total sky.
The majority of pointing images have a background RMS noise below 5 mJy/beam
with an approximate resolution of 25" x 25" (or 25" x 25" / cos (DEC - 19 deg)
for pointings south of 19 deg DEC).
The associated catalog has 640 thousand radio sources derived from an initial,
high reliability source extraction at the 7 sigma level.
The measured overall astrometric accuracy is better than 2" in RA and DEC,
while the flux density accuracy is estimated at ~10 percent.
Data is stored as 5336 mosaic images (5 deg x 5 deg).
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<i>SkyView</i> uses Lanczos resampling and Sqrt image scaling by default for this
survey. Provenance: TGS ADR Team. This is a service of NASA HEASARC.