GRB 191210A

V. D'Elia (SSDC), A. Tohuvavohu (U Toronto), A. D'Ai (INAF-IASFPA), A.
Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B.
Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of
the Swift-XRT team:

Swift-XRT has performed follow-up observations of the possible
HAWC-detected burst GRB 191210A
(https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon) in a
series of observations tiled on the sky. The total exposure time is 8.1
ks, distributed over 20 tiles; the maximum exposure at a single sky
location was 948 s. The data were collected between T0+7.0 ks and
T0+30.1 ks, and are entirely in Photon Counting (PC) mode. 

Four uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 1:
  RA (J2000.0):  210.3973  =  14:01:35.35
  Dec (J2000.0): -0.7503  =  -00:45:01.1
  Error: 10.2 arcsec (radius, 90% conf.)
  Count-rate: (3.8 [+6.0, -2.9])e-3 ct s^-1   
  Distance: 3115 arcsec from HAWC position.

Source 2:
  RA (J2000.0):  210.1243  =  14:00:29.84
  Dec (J2000.0): -1.3003  =  -01:18:01.1
  Error: 10.5 arcsec (radius, 90% conf.)
  Count-rate: 0.019 [+0.017, -0.011] ct s^-1   
  Distance: 2561 arcsec from HAWC position.

Source 4:
  RA (J2000.0):  211.3249  =  14:05:17.98
  Dec (J2000.0): -1.9738  =  -01:58:25.8
  Error: 6.0 arcsec (radius, 90% conf.)
  Count-rate: 0.0139 [+0.0102, -0.0069] ct s^-1   
  Distance: 2502 arcsec from HAWC position.

Source 5:
  RA (J2000.0):  210.6745  =  14:02:41.89
  Dec (J2000.0): -1.9321  =  -01:55:55.6
  Error: 8.4 arcsec (radius, 90% conf.)
  Count-rate: 0.0110 [+0.0081, -0.0054] ct s^-1   
  Distance: 1572 arcsec from HAWC position.

A catalogued source was also detected.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00087.

This circular is an official product of the Swift-XRT team.

Alexis Coleiro (APC/Univ de Paris) and Damien Dornic (CPPM/CNRS) on behalf of the ANTARES Collaboration. 
Using data from the ANTARES detector, we have performed a follow-up analysis of the recently reported HAWC alert (https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon <https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon>). 

No up-going muon neutrino candidate events were detected within 3 degrees from the event coordinates over a time window of +/-1h during which the potential source remained visible in the up-going field of view of ANTARES. A search over an extended time window of +/-1 day has also yielded no detection (50.5% visibility). 

This leads to a preliminary 90% confidence level upper limit on the muon-neutrino radiant fluence from a point source of about 17 GeV.cm^-2 over the energy range 3 TeV - 3 PeV (the range corresponding to 5-95% of the detectable flux) for an E^-2 power-law spectrum, and about 69 GeV.cm^-2 (600 GeV - 3 TeV) for an E^-2.5 spectrum, computed for the time of the alert. 

ANTARES is the largest undersea neutrino detector (Mediterranean Sea) and it is primarily sensitive to astrophysical neutrinos in the TeV-PeV energy range. At 10 TeV, the median angular resolution for muon neutrinos is about 0.5 degrees. In the range 1-100 TeV ANTARES has a competitive sensitivity to this position in the sky.

N. Omodei (Stanford U.), S. Cutini (INFN Perugia), and F.Longo (University and INFN, Trieste) 

report on behalf of the Fermi-LAT Collaboration:

Fermi-LAT has performed follow-up observations of the possible HAWC-detected burst GRB 191210A: https://gcn.gsfc.nasa.gov/notices_amon_hawc/9066_1171.amon

At the time of the HAWC trigger (T0), the location of the candidate transient was outside the LAT field of view, at an inclination angle of 145 degrees.

The region of Interest entered in LAT field of view at about T0+2.5 ks and exited again at 4.5 ks.

During this time window we performed a search for a transient counterpart, and no significant new sources are found. 

The flux upper bounds in the 100 MeV - 10 GeV (90% CL), assuming a E^-2 power law spectrum, are:

Energy flux < 8.76e-10 [erg/cm2/s]
Photon flux < 1.18e-06 [ph./cm2/s]

We also searched for late time emission (until T0+100 ks seconds) and no significant excess is found. 

The Fermi-LAT point of contact for this event is:
Nicola Omodei (nicola.omodei@stanford.edu).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.