GRB 230116C

E. Sonbas (Adiyaman Univ.), R. A. J. Eyles-Ferris (U Leicester),
C. Gronwall (PSU), J.D. Gropp (PSU), A. Y. Lien (U Tampa),
K. L. Page (U Leicester), D. M. Palmer (LANL),
A. Tohuvavohu (U Toronto) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 15:33:21 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230116C (trigger=1149250).  Due to an observing constraint,
Swift could not slew to the burst. 
The BAT on-board calculated location is 
RA, Dec 223.463, -16.871 which is 
   RA(J2000) = 14h 53m 51s
   Dec(J2000) = -16d 52' 16"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Although this is an image trigger, the
BAT lightcurve seems to show a complex structure starting around T-50
until a pre-planned slew away from the burst location at T+30, with
a peak of ~300 counts/s (15-350 keV) near the time of the trigger. 

Due to a Moon observing constraint, Swift cannot slew to the BAT
position until 09:10 UT on 2023 January 18. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU)(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230116C (trigger #1149250)
(Sonbas et al., GCN Circ. 33173
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 ).  The BAT ground-calculated position is
RA, Dec = 223.467, -16.883 deg which is
   RA(J2000)  =  14h 53m 52.0s
   Dec(J2000) = -16d 52' 57.5"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 65%.

The BAT light curve showed a complex structure with a duration of about 400 sec.
T90 (15-350 keV) is 316.77 +- 52.50 sec (estimated error including systematics).

The time-averaged spectrum from T-35.86 to T+346.68 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.72 +- 0.14.  The fluence in the 15-150 keV band is 6.1 +- 0.5 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+247.71 sec in the 15-150 keV band
is 0.8 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1149250/BA/

J. D. Gropp (PSU), S. Dichiara (PSU), A.P. Beardmore (U. Leicester),
J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAB), J.A. Kennea (PSU) and A. Y. Lien
(U Tampa) report on behalf of the Swift-XRT team:

We have analysed 9.4 ks of Photon Counting (PC) mode XRT data for the
Swift-BAT-detected burst GRB 230116C (Lien et al. GCN Circ. 33193
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 ),
collected between T0+159.6 ks and T0+537.9 ks. 

Six uncatalogued X-ray sources have been detected consistent with being
within 296 arcsec of the Swift-BAT position, 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):  223.47316  =  14:53:53.56
  Dec (J2000.0): -16.91649  =  -16:54:59.4
  Error: 2.7 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0102 +/- 0.0013 ct s^-1   
  Distance: 167 arcsec from Swift-BAT position.
  Flux: (3.43 [+0.44, -0.43])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000.0):  223.4729  =  14:53:53.49
  Dec (J2000.0): -16.8864  =  -16:53:11.2
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (2.80 [+1.09, -0.88])e-3 ct s^-1	 
  Distance: 65 arcsec from Swift-BAT position.

Source 3:
  RA (J2000.0):  223.4516  =  14:53:48.38
  Dec (J2000.0): -16.9158  =  -16:54:56.8
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (3.15 [+0.84, -0.69])e-3 ct s^-1	 
  Distance: 165 arcsec from Swift-BAT position.
  Flux: (1.45 [+0.39, -0.32])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 8:
  RA (J2000.0):  223.4602  =  14:53:50.44
  Dec (J2000.0): -16.8420  =  -16:50:31.2
  Error: 6.3 arcsec (radius, 90% conf.)
  Count-rate: (1.79 [+0.90, -0.70])e-3 ct s^-1	 
  Distance: 104 arcsec from Swift-BAT position.

Source 9:
  RA (J2000.0):  223.4090  =  14:53:38.16
  Dec (J2000.0): -16.9156  =  -16:54:56.0
  Error: 8.1 arcsec (radius, 90% conf.)
  Count-rate: (8.7 [+5.4, -4.3])e-4 ct s^-1   
  Distance: 245 arcsec from Swift-BAT position.

Source 15:
  RA (J2000.0):  223.4391  =  14:53:45.37
  Dec (J2000.0): -16.8309  =  -16:49:51.2
  Error: 8.7 arcsec (radius, 90% conf.)
  Count-rate: (5.7 [+4.3, -3.4])e-4 ct s^-1   
  Distance: 166 arcsec from Swift-BAT position.

Eleven uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/01149250.

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