High Energy Network (HEN)

There are news from the gravitational wave observatories: The planned pause in the O4 observation run is almost over, and the O3b part of the run is scheduled to resume on April 10th, 0800 Pacific time. Low latency alerts are already active already now. So it's time again to be prepared for the vent everybody is waiting for: an alert about the next Binary Neutron Star (BNS) merger event with sky localization that would allow amateurs and professionals alike to hunt down any optical counterpart!

Details can be found at https://observing.docs.ligo.org/plan/

The KiloNova Catcher (KNC) project has requested a Target Of Opportunity observation for the southern hemispehere (Gravitational Wave detectors are currently offline so this is not related to a "kilonova" trigger from LIGO/VIRGO (the main "business" of KNC), but could still be very interesting)

An interesting X-ray flare was observed by the newly launched Einstein Probe https://www.mpe.mpg.de/7867826/EinsteinProbe and floowed up by observations of by Neil Gehrels/SWIFT which conformed a source. Deep (say, 18 mag and fainter) observations in the optical are requested.

The question is about AAVSO 0313+41, well known Perseus A, or NGC 1275, or QSO B0316+413, or... In spite of noted AAVSO number, the object is not presented in VSX, unlike of such QSOs as BL Lac, MRK 421 or QSO B0954+658.

What is the reason? Large diffuse galaxy light obstructs photometry of active nucleus? Low variability? Or something other?

Soon after the Zwicky Transient Facility (ZTF) had recorded the optical transient ZTF20abrbeie, it became clear that this one didn't quite match any of the more frequent types of an extra-galactic transient like a supernova, Gamma Ray Burst afterglow or a common type of AGN outburst. The light curve and spectroscopy hinted that this one was very energetic, and probably of some rarer type.

I'd like to start a series of semi-regular (say ca once every 2 weeks) series of news for the HEN forum subscribers here...if this catches on we could also maybe have semi-regular zoom meetings later, like other observing sections have now.

This week, I'd like to draw attention to a project that allows you to contribute to the science of Gamma Ray Burst from the comfort of an armchair:

https://www.zooniverse.org/projects/amylien/burst-chaser/about/research

A Happy New Year to all followers of the High Energy Network Obs Section!

I hope that 2024 will see some exciting new HE astrohysics events that we can follow up together

Responding to an Astro-COLIBRI alert, I imaged the unclassified optical transient AT 2023yoa in M31 using a Rc filter.  My general question about optical transients - are there any archives interested in saving an optical transient image?  I signed up for Kilonova Catcher / GRANDMA but noticed they are selective on what events they wish to archive observer images.  Are these optical transients of scientific interest?  I understand that afterglows from gravity waves, gamma ray bursts, and bright supernovas are of interest, but GWs and GRBs are difficult to capture because of the large field

There is a possible optical counterpart (a supernova of type Ibn) that seems consistent with a neutrino event.

https://www.wis-tns.org/object/2023uqf

Unfortunately the SN is quite dim  (ca 20 mag in V and R ) and fading already, so amateur observations will be difficult except for those with really huge scopes....but it might be interesting to follow events.

Here is the link to the search for related GCN circulars: https://gcn.nasa.gov/circulars?query=+IC231004A&limit=100

On the evening of October 14 (JWST starts at 20:00 UT ), we'll have a coordinated campaign with all the telescopes above on V404 Cygni, which is a quiescent black hole X-ray binary.  It's about 16.6 in R in quiescence, and it's relatively red due to foreground extinction.  It would be great to have some folks in Europe get some additional photometry.  Hipercam on the Gran Telescopio Canarias will already be observing, but it would be good to have a backup in case of bad weather (which seems likely given forecasts for La Palma).  

There was just now an alert about a BNS merger

https://gracedb.ligo.org/superevents/S230918aq/view/

but it's not a Gold plated one: There is a significant probability that this was just a false alarm, the sky localization is not great and partly in a part of the sky that is not easy to observe at the moment, and the distance could be rather far away.

Stay tuned!!

HB