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[task #15911] Query NED extinction calculator
From: |
Mohammad Akhlaghi |
Subject: |
[task #15911] Query NED extinction calculator |
Date: |
Sat, 6 Mar 2021 11:33:02 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:86.0) Gecko/20100101 Firefox/86.0 |
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
_______________________________________________________
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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- [task #15911] Query NED extinction calculator,
Mohammad Akhlaghi <=