The ability of NED to support automated access involving large data volumes
or high query rates is limited. Such support is provided on an as-available,
best-effort basis. Please keep in mind that the limited computing and network
bandwidth resources are shared by thousands of users, and too many
simultaneous queries can make the services unresponsive for everyone.
Our goal is to provide fair use and responsive access to
NED resources for the entire astronomical community and
the general public. To help us with this,
please conform to the following guidelines when running
programs or scripts that automate access to NED:
- Please contact the
NED Helpdesk
before starting any set of queries that might extend
over more than 6 hours.
- Do not query NED more frequently than 1 per second.
- Do not run multiple concurrent automated queries.
- Use XML(VOTable output format) whenever possible
(HTML and other formats may change at any time).
- On queries that support optional image retrieval set
img_stamp=NO
- On queries that support detailed information lists, set
list_limit=0
- If you need multiple XML VOTable outputs, consider using
of=xml_all
- Do NOT automate image retrieval -- please contact
the
NED Helpdesk
if this is essential to you.
- For further information about automating queries to NED, see
"NED for a New Era" (Mazzarella et al. 2007, ASPC, 376, 153).
- Specific sample query URLs, which can be accessed via utilities such as
wget and curl or from programs written in Perl, Python, or Java,
can be found in the book chapter
"NED VO Services" (Mazzarella et al. 2008).
Thank you for your cooperation.
Contact the
NED helpdesk.
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