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<ri:Resource created="2026-05-29T00:00:00" status="active" updated="2026-05-29T00:00:00" version="1.2" xmlns:ri="http://www.ivoa.net/xml/RegistryInterface/v1.0" xmlns:sia11="http://www.ivoa.net/xml/SIA/v1.1" xmlns:stc="http://www.ivoa.net/xml/STC/stc-v1.30.xsd" xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0" xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.ivoa.net/xml/SIA/v1.1 http://vo.ari.uni-heidelberg.de/docs/schemata/SIA.xsd http://www.ivoa.net/xml/STC/stc-v1.30.xsd http://vo.ari.uni-heidelberg.de/docs/schemata/stc-v1.30.xsd http://www.ivoa.net/xml/VOResource/v1.0 http://vo.ari.uni-heidelberg.de/docs/schemata/VOResource.xsd http://www.ivoa.net/xml/VODataService/v1.1 http://vo.ari.uni-heidelberg.de/docs/schemata/VODataService.xsd http://www.w3.org/1999/xlink http://vo.ari.uni-heidelberg.de/docs/schemata/xlink.xsd" xsi:type="vs:CatalogService">
   <title>GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release</title>
   <shortName>TGSS</shortName>
   <identifier>ivo://nasa.heasarc/skyview/tgss</identifier>
   <curation>
      <publisher ivo-id="ivo://nasa.heasarc/ASD">NASA/GSFC HEASARC</publisher>
      <creator>
         <name>TGS ADR Team</name>
      </creator>
      <contributor>Skyview Project</contributor>
      <date role="created">2026-05-29</date>
      <contact>
         <name>SkyView Help</name>
         <email>Skyview at skyview.gsfc.nasa.gov</email>     
      </contact>
   </curation>
   <content>
      <subject>surveys</subject>
      <description>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).
&lt;p&gt;
&lt;i&gt;SkyView&lt;/i&gt; uses Lanczos resampling and Sqrt image scaling by default for this
survey.  Provenance:  TGS ADR Team. This is a service of NASA HEASARC.
      </description>

      <referenceURL>
         https://skyview.gsfc.nasa.gov
      </referenceURL>
      <type>Archive</type>
      <contentLevel>Research</contentLevel>


      <relationship>
         <relationshipType>service-for</relationshipType>
            <relatedResource ivo-id="ivo://nasa.heasarc">
               HEASARC
            </relatedResource>
         </relationship>
   </content>
   <capability standardID="ivo://ivoa.net/std/SIA" xsi:type="sia11:SimpleImageAccess">
      <interface role="std" xsi:type="vs:ParamHTTP">

         <accessURL use="base">
         https://skyview.gsfc.nasa.gov/cgi-bin/vo/sia.pl?survey=tgss&amp;
      </accessURL>

         <queryType>GET</queryType>

         <resultType>text/xml+votable</resultType>
         <param>
            <name>POS</name>
            <description>
            Search Position in the form "ra,dec" where ra and dec are given in decimal degrees
            in the ICRS coordinate system.
         </description>   
            <unit>degrees</unit>
            <dataType>real</dataType>
         </param>
       
         <param>
            <name>SIZE</name>
            <description>
            Size of search region in the RA and Dec. directions.   
         </description>
            <unit>degrees</unit>
            <dataType>real</dataType>
         </param>

         <param>
            <name>FORMAT</name>
            <description>
            Requested format of images.
         </description>
            <dataType>string</dataType>
         </param>

         <param>
            <name>CFRAME</name>
            <description>
            Coordinate frame: ICRS, FK5, FK4, GAL, ECL
         </description>
            <dataType>string</dataType>
         </param>

         <param>
            <name>EQUINOX</name>
            <description>
            Equinox used in FK4 or FK5 frames.

      </description>
            <dataType>real</dataType>
         </param>
      </interface>
   
      <imageServiceType>Cutout</imageServiceType>
      
      
      <maxQueryRegionSize>
         <long>360.0</long>
         <lat>180.0</lat>
      </maxQueryRegionSize>
      
      <maxImageExtent>
         <long>360.0</long>
         <lat>180.0</lat>
      </maxImageExtent>

      <maxImageSize>5000</maxImageSize>

       <maxFileSize>10000000</maxFileSize>
       <maxRecords>500</maxRecords>  
       <testQuery>
         <pos>
	           <long>0</long>
	           <lat>0</lat>
	        </pos>
         <size>
	           <long>1</long>
	           <lat>1</lat>
	        </size>
      </testQuery>
      
   </capability>
   <capability>
      <interface xsi:type="vr:WebBrowser">
         <accessURL use="base">
                https://skyview.gsfc.nasa.gov/cgi-bin/query.pl
              </accessURL>
      </interface>
   </capability>
   <coverage>
      <stc:STCResourceProfile>

         <stc:AstroCoordSystem xlink:type="simple" xlink:href="ivo://STClib/CoordSys#UTC-ICRS-TOPO" id="_sia_tgss_UTC-ICRS-TOPO1de838123d1112f9a8da9fcb5fd65986"/>

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      </stc:STCResourceProfile>

      <waveband>Radio</waveband>
   </coverage>
</ri:Resource>