5.4.1 Available databases ¶

The current list of databases supported by Query are listed at the end of this section. To get the list of available datasets within each database, you can use the --information option. for example, with the command below you can get a list of the roughly 100 datasets that are available within the ESA Gaia server with their description:

$ astquery gaia --information

However, other databases like VizieR host many more datasets (tens of thousands!). Therefore it is very inconvenient to get the full information every time you want to find your dataset of interest (the full metadata file VizieR is more than 20Mb). In such cases, you can limit the downloaded and displayed information with the --limitinfo option. For example, with the first command below, you can get all datasets relating to the MUSE (an instrument on the Very Large Telescope), and those that include Roland Bacon (Principle Investigator of MUSE) as an author (Bacon, R.). Recall that -i is the short format of --information.

$ astquery vizier -i --limitinfo=MUSE
$ astquery vizier -i --limitinfo="Bacon R."

Once you find the recognized name of your desired dataset, you can see the column information of that dataset with adding the dataset name. For example, with the command below you can see the column metadata in the J/A+A/608/A2/udf10 dataset (one of the datasets in the search above) using this command:

$ astquery vizier --dataset=J/A+A/608/A2/udf10 -i

For very popular datasets of a database, Query provides an easier-to-remember short name that you can feed to --dataset. This short name will map to the officially recognized name of the dataset on the server. In this mode, Query will also set positional columns accordingly. For example, most VizieR datasets have an RAJ2000 column (the RA and the epoch of 2000) so it is the default RA column name for coordinate search (using --center or --overlapwith). However, some datasets do not have this column (for example, SDSS DR12). So when you use the short name and Query knows about this dataset, it will internally set the coordinate columns that SDSS DR12 has: RA_ICRS and DEC_ICRS. Recall that you can always change the coordinate columns with --ccol.

For example, in the VizieR and Gaia databases, the recognized name for data release 3 data is respectively I/355/gaiadr3 and gaiadr3.gaia_source. These technical names are hard to remember. Therefore Query provides gaiadr3 (for VizieR) and dr3 (for ESA’s Gaia database) shortcuts which you can give to --dataset instead. They will be internally mapped to the fully recognized name by Query. In the list below that describes the available databases, the available short names, that are recognized for each, are also listed.

$ astquery astron -i

The list of databases recognized by Query (and their names in Query) is described below. Since Query is a new member of the Gnuastro family (first available in Gnuastro 0.14), this list will hopefully grow significantly in the next releases. If you have any particular datasets in mind, please let us know by sending an email to bug-gnuastro@gnu.org. If the dataset supports IVOA’s TAP (Table Access Protocol), it should be very easy to add.

astron ¶

The ASTRON Virtual Observatory service (https://vo.astron.nl) is a database focused on radio astronomy data and images, primarily those collected by ASTRON itself. A query to astron is submitted to https://vo.astron.nl/__system__/tap/run/tap/sync.

Here is the list of short names for dataset(s) in ASTRON’s VO service:

• tgssadr --> tgssadr.main

gaia ¶

The Gaia project (https://www.cosmos.esa.int/web/gaia) database which is a large collection of star positions on the celestial sphere, as well as peculiar velocities, parallaxes and magnitudes in some bands among many others. Besides scientific studies (like studying resolved stellar populations in the Galaxy and its halo), Gaia is also invaluable for raw data calibrations, like astrometry. A query to gaia is submitted to https://gea.esac.esa.int/tap-server/tap/sync.

Here is the list of short names for popular datasets within Gaia:

• dr3 --> gaiadr3.gaia_source
• edr3 --> gaiaedr3.gaia_source
• dr2 --> gaiadr2.gaia_source
• dr1 --> gaiadr1.gaia_source
• tycho2 --> public.tycho2
• hipparcos --> public.hipparcos

ned ¶

The NASA/IPAC Extragalactic Database (NED, http://ned.ipac.caltech.edu) is a fusion database, integrating the information about extra-galactic sources from many large sky surveys into a single catalog. It covers the full spectrum, from Gamma rays to radio frequencies and is updated when new data arrives. A TAP query to ned is submitted to https://ned.ipac.caltech.edu/tap/sync.

• objdir --> NEDTAP.objdir: default TAP-based dataset in NED.
• extinction: A command-line interface to the NED Extinction Calculator. It only takes a central coordinate and returns a VOTable of the calculated extinction in many commonly used filters at that point. As a result, options like --width or --radius are not supported. However, Gnuastro does not yet support the VOTable format. Therefore, if you specify an --output file, it should have an .xml suffix and the downloaded file will not be checked.

  Until VOTable support is added to Gnuastro, you can use GREP, AWK and SED to convert the VOTable data into a FITS table with a command like below (assuming the queried VOTable is called ned-extinction.xml):

  grep '^<TR><TD>' ned-extinction.xml \
   | sed -e's|<TR><TD>||' \
         -e's|</TD></TR>||' \
         -e's|</TD><TD>|@|g' \
   | awk 'BEGIN{FS="@"; \
       print "# Column 1: FILTER [name,str15] Filter name"; \
       print "# Column 2: CENTRAL [um,f32] Central Wavelength"; \
       print "# Column 3: EXTINCTION [mag,f32] Galactic Ext."; \
       print "# Column 4: ADS_REF [ref,str50] ADS reference"} \
          {printf "%-15s %g %g %s\n", $1, $2, $3, $4}' \
   | asttable -oned-extinction.fits
  

  Once the table is in FITS, you can easily get the extinction for a certain filter (for example, the SDSS r filter) like the command below:

  asttable ned-extinction.fits --equal=FILTER,"SDSS r" \
           -cEXTINCTION
  

vizier ¶

Vizier (https://vizier.u-strasbg.fr) is arguably the largest catalog database in astronomy: containing more than 20500 catalogs as of mid January 2021. Almost all published catalogs in major projects, and even the tables in many papers are archived and accessible here. For example, VizieR also has a full copy of the Gaia database mentioned below, with some additional standardized columns (like RA and Dec in J2000).

The current implementation of --limitinfo only looks into the description of the datasets, but since VizieR is so large, there is still a lot of room for improvement. Until then, if --limitinfo is not sufficient, you can use VizieR’s own web-based search for your desired dataset: http://cdsarc.u-strasbg.fr/viz-bin/cat

Because VizieR curates such a diverse set of data from tens of thousands of projects and aims for interoperability between them, the column names in VizieR may not be identical to the column names in the surveys’ own databases (Gaia in the example above). A query to vizier is submitted to http://tapvizier.u-strasbg.fr/TAPVizieR/tap/sync.

Here is the list of short names for popular datasets within VizieR (sorted alphabetically by their short name). Please feel free to suggest other major catalogs (covering a wide area or commonly used in your field).. For details on each dataset with necessary citations, and links to web pages, look into their details with their ViziR names in https://vizier.u-strasbg.fr/viz-bin/VizieR.

• 2mass --> II/246/out (2MASS All-Sky Catalog)
• akarifis --> II/298/fis (AKARI/FIS All-Sky Survey)
• allwise --> II/328/allwise (AllWISE Data Release)
• apass9 --> II/336/apass9 (AAVSO Photometric All Sky Survey, DR9)
• catwise --> II/365/catwise (CatWISE 2020 catalog)
• des1 --> II/357/des_dr1 (Dark Energy Survey data release 1)
• gaiadr3 --> I/355/gaiadr3 (GAIA Data Release 3)
• gaiaedr3 --> I/350/gaiadr3 (GAIA Early Data Release 3)
• gaiadr2 --> I/345/gaia2 (GAIA Data Release 2)
• galex5 --> II/312/ais (All-sky Survey of GALEX DR5)
• nomad --> I/297/out (Naval Observatory Merged Astrometric Dataset)
• panstarrs1 --> II/349/ps1 (Pan-STARRS Data Release 1).
• ppmxl --> I/317/sample (Positions and proper motions on the ICRS)
• sdss12 --> V/147/sdss12 (SDSS Photometric Catalogue, Release 12)
• usnob1 --> I/284/out (Whole-Sky USNO-B1.0 Catalog)
• ucac5 --> I/340/ucac5 (5th U.S. Naval Obs. CCD Astrograph Catalog)
• unwise --> II/363/unwise (Band-merged unWISE Catalog)
• wise --> II/311/wise (WISE All-Sky data Release)