[task #15911] Query NED extinction calculator

[Mohammad Akhlaghi]

URL:
  <https://savannah.gnu.org/task/?15911>

                 Summary: Query NED extinction calculator
                 Project: GNU Astronomy Utilities
            Submitted by: makhlaghi
            Submitted on: Sat 06 Mar 2021 04:33:00 PM UTC
         Should Start On: Sat 06 Mar 2021 12:00:00 AM UTC
   Should be Finished on: Sat 06 Mar 2021 12:00:00 AM UTC
                Category: Query
                Priority: 5 - Normal
              Item Group: New feature
                  Status: Postponed
                 Privacy: Public
        Percent Complete: 0%
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
                  Effort: 0.00

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Details:

After contacting the NED helpdesk, I got the following reply (in P.S.) for
automatically extracting the extinction tables for a certain coordinate.

We can easily automate this command in Gnuastro's Query program. What is a
little complicated is that Gnuastro doesn't yet recognize the VOTable format
<https://ivoa.net/documents/VOTable/20191021/index.html> (a format based on
XML).

But the good thing is that XML is a plain-text format, so we can use things
like AWK and SED to extract the necessary columns rows for now (until reading
of VOTables is supported within Gnuastro).

P.S.

You can call the following URL using curl (or wget, Python, whatever) to
retrieve Galactic extinction estimates at a given input location on the sky.
Since you are not converting the coordinate system type or equinox, in_csys
and out_csys are set to the same value (Equatorial), and in_equinox and
out_equinox are also set the same (J2000.0).

This example has input in decimal degree units ("d" after the digits):

https://ned.ipac.caltech.edu/cgi-bin/calc?in_csys=Equatorial&out_csys=Equatorial&in_equinox=J2000.0&out_equinox=J2000.0&obs_epoch=2000.0&lon=58.268000d&lat=35.591944d&of=xml_main&ext=1

The output is in VOTable (XML) format, which includes metadata describing the
fields (columns), and you can extract the Galactic extinction values in
bandpasses of interest such as this one:


<TR><TD>Landolt V</TD><TD>0.54</TD><TD>
0.562</TD><TD>2011ApJ...737..103S</TD></TR>


Here is an example with equatorial coordinates input in sexigesimal format:

https://ned.ipac.caltech.edu/cgi-bin/calc?in_csys=Equatorial&out_csys=Equatorial&in_equinox=J2000.0&out_equinox=J2000.0&obs_epoch=2000.0&lon=13h42m16.36s&lat=-34d18m14.4s&of=xml_main&ext=1

Where in the VOTable you will find entries such as this: 


<TR><TD>Landolt V</TD><TD>0.54</TD><TD> 0.140</TD
<TD>2011ApJ...737..103S</TD></TR>


Please note our general Guidelines for Automated Queries
<https://ned.ipac.caltech.edu/Documents/Guides/Interface/QueryAuto>, to limit
the rate of your programmed queries so they do not inadvertently make NED
unusable for others.

We hope you find this helpful.
Thanks for using NED.

Joe, for the NED Team

@@@@@@@@@@@@@@@@@@
Dr. Joseph M. Mazzarella
NASA/IPAC Extragalactic Database (NED), Science Lead
MS 100-22, IPAC, Caltech
Pasadena, CA 91125




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