How Can I Use NAVO Services Directly?

Most NAVO services are accessed simply by formatting a simple URL and parsing the results. The results are normally a VOTable which is an XML file format, which is most conveniently read with an appropriate parser but is usually human readable. The URLs comprise a base URL which varies from center to center, and a query payload which varies according to the protocol. The base URLs are given in the table below. In some cases the base URL is characterized by the table or mission that is to be queried.

For cone searches the query payload comprises the three keywords RA, DEC and SR giving the ICRS right ascension, ICRS declination and search radius, all in decimal degrees. E.g., to query the xmmmaster HEASARC table using a cone search near 3c273 we substitute the table name for XXXXX in the base query below and use the RA and Dec of 3c273 and then pick a search radius appropriate for our needs. For XMM a radius of 0.5 degrees might be sensible. So we end with the URL:
https://heasarc.gsfc.nasa.gov/xamin/vo/cone?table=xmmmaster&RA=187.25&DEC=2.05&SR=0.5 .

Another example - Retrieve basic data for Arp 220:
http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=arp+220&of=xml_main&RA=0&DEC=0&SR=0.5 .

Simple image queries have a payload of POS and SIZE where POS is a string with the RA and Dec separated by a comma and SIZE is the size of the region in which images are requested in decimal degrees. The result of this query is table describing images in the region. You can look at and parse the table to find the images you want. One of the columns will be a URL where the image described in that row can be downloaded.
http://irsa.ipac.caltech.edu/ibe/sia/twomass/allsky/allsky?POS=20,40&SIZE=0.5 .

To do a general SQL-like query in a table access service you can just add /sync?REQUEST=doQuery&LANG=ADQL&QUERY=xxx where xxx is the URI-encoded query string where most non-alphanumeric characters are replaced by hex escapes. You can get a dump of the entire database schema (tables and columns available) by appending /tables to the base.
https://heasarc.gsfc.nasa.gov/xamin/vo/tap/sync?REQUEST=doQuery&LANG=ADQL&QUERY=select+*+from+xmmmaster .

Simple spectral queries have a payload of POS and SIZE where POS is a string with the RA and Dec separated by a comma and SIZE is the size of the region in which spectra are requested in decimal degrees.
http://archive.stsci.edu/ssap/search2.php?id=FUSE&pos=151.0,69.0&size=2.0 .

These interfaces support additional constraints and query modes which are discussed in the detailed protocol specifications available at the IVOA website but this can get you started.

Table Access VO Services at NAVO Archives
Service P N Limits Base URL
MAST/STScICone12 archive.stsci.edu/XXX/search.php?
MAST/KeplerCone3 archive.stsci.edu/kepler/XXX/search.php?
MAST HST instrumentsCone9 archive.stsci.edu/hst.php?sci_data_set_name=X*&
??Cone2 archive.stsci.edu/spec_class/search[2].php?
MAST GALEXCone1 galex.stsci.edu/gxWS/ConeSearch/gxConeSearch.aspx?
HEASARC TablesCone7331,2https://heasarc.gsfc.nasa.gov/xamin/vo/cone?table=XXXX&
HEASARC TablesTAP11,2,3heasarc.gsfc.nasa.gov/xamin/vo/tap
IRSA 2MASSCone2 irsa.ipac.caltech.edu/cgi-bin/Oasis/CatSearch/npa-catsearch?cat=fp_XXX&
IRSA TablesCone3855,6,9irsa.ipac.caltech.edu/SCS?table=XXXX&
NEDCone1 ned.ipac.caltech.edu/cgi-bin/NEDobjsearch?search_type=Near+Position+Search&of=xml_main&
ADSCone17,8adsabs.harvard.edu/cgi-bin/abs_connect?data_type=VOTABLE&
CXC ChandraCone2 cda.harvard.edu/XXX/coneSearch?
CXC ChandraTAP1 cda.harvard.edu/cxctap
Total 1153

Limits:

  1. No limits on size of query
  2. 100,000 row limit on results
  3. Result limit can be overridden
  4. Services not indexed in registry
  5. 0.75 degree radius limit on query
  6. 50,000 row limit on results
  7. Echoes input position in results
  8. 200 row limit on results
  9. 25 currently in registry
Data Access VO Services at NAVO Archives
Service P N Limits Base URL
MAST GOODSSIA1 3,4http://archive.stsci.edu/eidol.php?
MAST Image ServicesSIA36 3,4http://archive.stsci.edu/siap/search.php?id=XXX&
MAST Spectra ServicesSSA11 3,4http://archive.stsci.edu/ssap/search2.php?id=XXX&
MAST GALEX SpectraSSA1 3,4http://galex.stsci.edu/gxWS/SSAP/gxSSAP.aspx?
MAST ScrapbookSIA1 3,4http://archive.stsci.edu/siap/search.php?representative=y&
MAST EPOSIA2 3,4http://archive.stsci.edu/stpr/vo_search.php?
MAST DSSSIA4 http://chart.stsci.edu/gscvo/DSSX.jsp?
MAST GALEXSIA1 http://galex.stsci.edu/gxWS/SIAP/gxSIAP.aspx?
MAST PRSIA1 http://hubblesite.org/cgi-bin/sia/hst_pr_sia.pl?
MAST Hubble Legacy ArchiveSIA1 http://hla.stsci.edu/cgi-bin/hlaSIAP.cgi?imagetype=best&inst=ACS,ACSGrism,WFC3,WFPC2,NICMOS,NICGRISM,COS,STIS,FOS,GHRS&proprietary=false&
IRSA AtlasSIA59 1http://irsa.ipac.caltech.edu/cgi-bin/Atlas/nph-atlas?mission=XXX&hdr_location=YYY&SIAP_ACTIVE=1&collection_desc=ZZZ&
IRSA AllWISESIA1 http://irsa.ipac.caltech.edu/ibe/sia/wise/allwise/p3am_cdd
IRSA WISE AllSkySIA5 http://irsa.ipac.caltech.edu/ibe/sia/wise/allsky/XXXX?
http://irsa.ipac.caltech.edu/ibe/sia/wise/cryo_3band/XXXX?
http://irsa.ipac.caltech.edu/ibe/sia/wise/postcryo/2band_p1bm_frm?
IRSA WISE PrelimSIA3 http://irsa.ipac.caltech.edu/ibe/sia/wise/prelim/XXX
http://irsa.ipac.caltech.edu/ibe/sia/wise/prelim_postcryo/2band_p1bm_frm/xxxx
IRSA Merged WISESIA2 http://irsa.ipac.caltech.edu/ibe/sia/wise/merge/XXXX
IRSA 2MASSSIA5 http//sha.ipac.caltech.edu/ibe/sia/twomass/XXX/XXXX
IRSA SpitzerSIA2 http://sha.ipac.caltech.edu/applications/Spitzer/VO/VOServices?SERVICE=SIAP&DATASET=ivo://irsa.ipac/spitzer.levelX&;
HEASARC SkyView GeneralSIA1 1https://skyview.gsfc.nasa.gov/cgi-bin/vo/sia.pl?
HEASARC SkyView SurveySIA48 2https://skyview.gsfc.nasa.gov/cgi-bin/vo/sia.pl?survey=XXX&
HEASARC SIASIA https://heasarc.gsfc.nasa.gov/xamin/vo/sia?table=XXX&
NED SIASIA1 http://irsa.ipac.caltech.edu/cgi-bin/Atlas/nph-nedsiap?mission=NED&hdr_location=\NEDDataPath\&SIAP_ACTIVE=1&collection_desc=NASA/IPAC+Extragalactic+Database+Image+Data+Atlas+(NED)&&
NED SED ServiceSSA1 http://vo.ned.ipac.caltech.edu/services/querySED?REQUEST=queryData&
CXC ChandraSIA1 http://cda.harvard.edu/cxcsiap/queryImages?
CXC Chandra Grating imagesSIA1 http://tgcat.mit.edu/tgSia.php?
Total Count 162

Limits:

  1. Variable limit on query size but typically of order 10 degrees.
  2. By default results returned depend on ratio of query size and intrinsic pixel resolution of survey datasets.
  3. Default limit of 2,000 rows returned.
  4. Default can be overridden.