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TGSS Data Release 5
We announce the fifth data release of the TIFR GMRT Sky Survey (TGSS) - the all sky radio continuum survey at 150 MHz using the Giant Metrewave Radio Telescope (GMRT) on 30 November 2012. This data release, which includes the fields from DR4 (the last release), covers about 1 steradian of the southern sky as shown in the adjoining figure. DR5 consists of a total of 558 fields out of which 67 are new fields. In this data release, all the images have been regenerated using the more powerful analysis pipeline which we introduced in our last release. As informed in the last couple of releases, the analysis pipeline has undergone some major improvements and the results are demonstrated by the higher quality images. In this release, all the images are made with the modified pipeline and hence are uniform. Analysis with the modified pipeline has resulted in better sensitivity to extended structure and this new version has been adopted as replacement for the analysis pipeline used until DR3.
Please note that in DR5, all the images released till DR4 which used the old pipeline have been reimaged with the modified pipeline and the catalogues have also been replaced.
TGSS DR5 images are now available for download. All the images have been generated by the automated data analysis pipeline running in the AIPS++ environment. The images have an angular resolution of about 24" x 15" at a position angle 30d and typical rms noise is less than 9 mJy/beam.
Click here for plots showing the number of sources and rms noise in the inner and outer parts of the primary beam for the 558 images being released as part of TGSS Data Release 5.
Download TGSS data products
TGSS Image Server (plots contours and grey scale,slow: jpeg, FITS)
TGSS Image Server (plots grey scale, quicklook: jpeg, FITS)
FITS files (4.5dx4.5d)
Important notes on TGSS DR5 - must read before using TGSS data products!1. The images and catalogues have been corrected for the sky temperature variation using extrapolated values from the Haslam et al. (1982, A&AS, 47, 1) 408 MHz all sky map. A temperature spectral index of -2.55 has been used for the extrapolation.
2. We estimate the maximum error on the flux density scale to be of the order of 25%. This will be improved with better modeling of systematics in later data releases. Larger systematic errors may be present for fields close to the Galactic plane.
3. Images of neighbouring pointings (where available) have been mosaiced to give a 4.5dx4.5d field. The regions of the beam where the adjoining fields are not yet available for mosaicing show higher rms noise. While we have quoted the worst rms noise (7-9 mJy/beam) based on which the completion (40 mJy) of the catalogue is estimated, we find that regions away from the Galactic plane or strong radio sources, typically show an rms noise of 4-7 mJy/beam.
4. Sidelobes of some strong sources might have been listed as a source in the catalogues. A flag indicating the same will be included in the final release.
5. A listing of sources is generated for each of the mosaiced field which is a square field of size 4.5d x 4.5d. Since the catalogues for each field is independently generated they contain common sources from the overlapping ergions. Additionally while using the catalogue browser, note that only those sources available in the relevant field will be listed. Hence the source list might not be complete when searching around a position close to the edge of the field.
6. Position errors are of the order of 4".
7. Source catalogue containing unique entries will be made with the final data release.
8. If you use TGSS data products in your research work, please include the following statement
(till the publication on the survey which is in preparation is available for citation):
"This research work has used the TIFR GMRT Sky Survey (http://tgss.ncra.tifr.res.in) data products".
Suggestions and comments to tgss AT ncra.tifr.res.in
Sky covered in TGSS DR5:Aitoff projection of Equatorial coordinates showing the TGSS images which are being released in TGSS Data release 5. TGSS, when complete, will cover the entire sky north of -55d.