From msdemlei at ari.uni-heidelberg.de  Wed Aug 13 15:46:33 2025
From: msdemlei at ari.uni-heidelberg.de (Markus Demleitner)
Date: Wed, 13 Aug 2025 15:46:33 +0200
Subject: More on VOEvent registration
Message-ID: <20250813134633.zcid5izkwndzog5m@victor>

Dear VOEventers,

News on VOEvent registration!  (Reference:
http://mail.ivoa.net/pipermail/voevent/2025-June/003329.html).

Thanks to the kind people at GCN, we now have a bunch of
VOEvent-over-Kafka streams registered.  The new examples can be found
in the registry:
http://dc.zah.uni-heidelberg.de/wirr/q/ui/fixed?field0=ivoid&operator0=%3D&operand0=ivo%3A%2F%2Forg.gavo.dc%2Fstd%2Fgcn

(WIRR doesn't show VOEvent URLs yet and hence makes these things look
as if they only had Browser interfaces, but they are there; see below).

I would be particularly grateful if people could review some of these
records, for instance

http://dc.g-vo.org/I/ivo%3A//org.gavo.dc/std/gcn-fermi/fermi-grb

Do they contain enough information to let you senibly find them?  And
then connect to one of the streams?

A question I have pondered for a while is: is one capability per
physical stream the right granularity?  This *would* let us attach
individual descriptions per stream.  Right now, we instead have a
terse, human-readable description of the various streams in the
resource description.  Is that enough for now?

Alternatives would be a full resource record per stream -- or going
for even less per-stream metadata by having multiple interfaces per
capability.

With these new streams, by the way, doing VOEvent discovery by
waveband becomes fun.  You can try on http://reg.g-vo.org/tap (other
searchable registries should work as well):

  SELECT res_title, access_url, res_description
  FROM rr.resource
  NATURAL JOIN rr.capability
  NATURAL JOIN rr.interface
  NATURAL JOIN rr.stc_spectral
  WHERE
    standard_id='ivo://ivoa.net/std/voevent'
    AND 1=ivo_interval_overlaps(spectral_start, spectral_end,
      gavo_specconv(2, 'keV', 'J'), gavo_specconv(10, 'keV', 'J'))

to find streams with messengers between 2 and 10 keV;

Also try

      gavo_specconv(10, 'm', 'J'), gavo_specconv(10, 'mm', 'J'))

for streams in the radio band between 10 meters and 10 mms of
wavelength.

Also, if you have unregistered, live VOEvent streams and want to be
discoverable like that, too, do let me know.

Thanks,

        Markus