VizieR help - FAQ - Tutorial

Instead of having to retype a list of positions (or more generally a list of constraints) for each catalogue to query, consider the possibility of saving your list in a file on your computer: you will then just need to give the name of this file to have your queries executed.

Click on the target (in Page3):

The input file accepted are:

1  Use a simple file

As a practical example, assuming that you have in a file named mylist which contains your favorite targets.
19 58 21.7 +35 12 06
Cyg X-1
and you want to find the Tycho sources close to these two positions. To do it, you have to click on "List Of Target" tab and put your file in the input box.

2  What can the input file contain ?

Besides the list of targets, one per line, you may add in your input file:

As an illustration, mylist could contain:

## This is my first test
# Just a comment... I love comments !

: Finding objects around 19 58 21.7 +35 12 06 
19 58 21.7 +35 12 06
: The same position in decimal degrees -- should give the same result!
: Or the target name -- should again give the same result...
Cyg X-1
: Still centered on Cyg X-1, but with a non-standard target radius
19 58 21.7 +35 12 06 , eq=B1950, rm=30

The definitions of the target parameters follows the ASU conventions for the -c parameter: specification of the target position equinox with the eq= option (galactic positions are possible with eq=G), and target radius or geometry with the rm= (circle with radius specified in arcminutes) or bm= (rectangular box with specified dimensions). Other possibilities are available, see the ASU document for details.

3  Having your input as first column in the output

Pushing the button labelled add your input as first column will add your input title or target as an additional column (named _1) in the results, typically for further processing of the VizieR results. This option is therefore especially usefull with formatted output like TSV or FITS.

Notice however that the width of this _1 additional column is currently limited to 24 bytes in the FITS output.

4  Combining an input file with other constraints

Even when a list of targets is submitted to VizieR, the input boxes may still contain qualifications: in the above example of searching Tycho stars around a few targets, writing in the Plx input the constraint   >=20   will restrict the search to stars closer than 50pc for all the targets in the file.

5  Using a TSV-file as Input file

In a Query from a File, it is possible in this new version to supply a file which was previously generated by a VizieR Query with the Tab-Separated-Values output layout choice. This allows to connect two catalogues, with the following operations:

  1. collect from your first catalogue the interesting objects – e.g. all IRAS objects with F12>30Jy. Choose the Tab-Separated-Values output layout, and save the result in a file on your computer, say myIRASobjects.tsv
  2. Choose your second catalogue – e.g. 2MASS – there push the LIST of Targets button, choose the appropriate maximal radius (e.g. 1 arcmin) and enter the name of your file (myIRASobjects.tsv) as input file near the bottom of the query form
  3. Pushing the Submit Query button should bring the result – all 2MASS objects closer than 1arcmin to each IRAS source selected in step 1.

6  Other possible searches from a file

Using an input file is not restricted to a search around targets — it is possible to choose a constraint on any column of a catalog. For instance, if the file mylist contains a list of interesting initials used for naming quasars like:

#### List of Qualifications for the Name column
: QSO which Name starts by Z
: QSO which Name starts by X
: QSO which Name starts by A

To execute this search, type mylist in the bottom input box of the Search Page on Vérons' compilation of QSOs, and specify that the input of the file mylist apply to the Name column by pushing the Sort button in front of the Name column. Further constraints can also be entered, as in the case of a list of targets: for instance a restriction to quasars with a redshift of at least 1 can be specified by typing >=1 in the z box.

Note that by pushing the _r button (located in the Search by Position section), the input file is then assume to contain a list of targets. In other words, the search from a File containing targets is a peculiar application of this more general Search from a file.

last update: 13 Feb 05:18