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GMRT Spitzer FLS

The 610-MHz GMRT survey of the Spitzer First Look Survey field

This survey is the first in a series of surveys of the deep Spitzer legacy fields, taken at 610 MHz with the Giant Metrewave Radio Telescope (GMRT). Full details of the observations, data reduction, mosaic and source catalogue can be found in Garn T., Green D. A., Hales S. E. G., Riley J. M., Alexander P. (2007, MNRAS, 376, 1251) (or arXiv:astro-ph/0701534).


Observations of the Spitzer extragalactic First Look Survey field taken at 610 MHz with the Giant Metre-wave Radio Telescope are presented. Seven individual pointings were observed, covering a total area of 4 square degrees with a resolution of 5.8″ × 4.7″, PA 60°. The r.m.s. noise at the centre of the pointings is between 27 and 30 μJy before correction for the GMRT primary beam. The techniques used for data reduction and production of a mosaicked image of the region are described, and the final mosaic, along with a catalogue of 3944 sources detected above ~5 σ are presented. The survey complements existing radio and infrared data available for this region.

The mosaicked image and source catalogue are available through links in the table below.

05-May-2008 new catalogue released A new release of the source catalogue and matching ReadMe file are now available below, incorporating a minor revision to the source positions. A rounding error in the right ascension and declination positions listed for some sources has now been corrected (05-May-2008). The source IAU designations remain unchanged, having been based on the correctly computed positions throughout. The main purpose in correcting the positions was to eliminate sporadic mismatches betweeen IAU designation and listed position in the original release. In other respects the effect on the positions is negligible.

FITS ImageASCII catalogueCDS-style ReadMe for catalogue
GMRT_FLS_dr1.fits GMRT_FLS_dr1.1.dat ReadMe

Two modifications were made to the UV data before image processing – both using custom-made AIPS tasks. The tasks, along with full descriptions, are available via the links below:

  • UVFLP reorders the uv channels so that the upper and lower sidebands can be combined together, increasing the uv coverage for the image.
  • UVFXT corrects the time-stamps on GMRT data for an error in the online software at the GMRT (now fixed).

Last modified 21 April 2010

Dave Green (