This was originally classified as GRB 181123A,
but was later found to be a flare from Swift_J1858.6-0814 [23nov18]
////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23431
SUBJECT: GRB 181123A: Swift detection of a burst
DATE:    18/11/23 04:30:51 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Y. Lien (GSFC/UMBC), P. D'Avanzo (INAF-OAB), D. M. Palmer (LANL)
and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 04:19:22 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181123A (trigger=873178).  Swift could not slew to the
burst due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 284.651, -8.237 which is 
   RA(J2000) = 18h 58m 36s
   Dec(J2000) = -08d 14' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for an image trigger, there is
no obvious variation in the immediately-available BAT lightcurve. 

Due to an observing constraint, Swift will not be able to slew
to the burst until February 19. There will therefore be no XRT or
UVOT data on this burst. 

Burst Advocate for this burst is A. Y. Lien (amy.y.lien AT nasa.gov). 
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/too.html.)

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23442
SUBJECT: GRB 181123A, Swift-BAT refined analysis
DATE:    18/11/23 21:28:55 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (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 181123A (trigger #873178)
(Lien et al., GCN Circ. 23431).  The BAT ground-calculated position is
RA, Dec = 284.753, -8.208 deg which is
  RA(J2000)  =  18h 58m 36.2s
  Dec(J2000) = -08d 14' 14.3"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows some weak emission that starts at ~ T-60 s
and ends at ~T+190 s. T90 (15-350 keV) is 220.9 +- 55.9 sec (estimated error
including systematics).

The time-averaged spectrum from T-61.3 to T+187.4 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.88 +- 0.31.  The fluence in the 15-150 keV band is 9.9 +- 1.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-36.46 sec in the 15-150 keV band
is 0.3 +- 0.2 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/873178/BA/
////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23445
SUBJECT: Swift trigger 873178: GRB 181123A is Swift J1858.6-0814
DATE:    18/11/24 19:47:35 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

J. Greiner (MPE Garching), A. Y. Lien (GSFC/UMBC), and S. D. Barthelmy (GSFC)
report on behalf of the Swift team:

The location of Swift trigger 873178, which was previously identified as GRB 181123A
(Lien et al., GCN Circ. 23431 and 23442), is only 0.3 arcmin away from the XRT location
of the recently discovered transient, Swift J1858.6-0814 (Kennea et al. ATEL 12160;
Krimm et al., ATEL 12151). Therefore, we believe that the Swift trigger 873178 is
a flare from Swift J1858.6-0814, instead of a new GRB.

This flare is also seen in the BAT transient monitor (Krimm et al. 2013;
https://swift.gsfc.nasa.gov/results/transients/weak/SWIFTJ1858.6-0814/).
////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23446
SUBJECT: Swift J1858.6-0814/GRB 181123A: Swift/BAT location correction to GCN 23442
DATE:    18/11/24 19:49:50 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC) reports on behalf of the Swift/BAT team:

In GCN Circ. 23442, the transient location was correct in sexadecimal units, 
but incorrect in the degree units. The correct degrees should be

RA: 284.6507   Dec: -8.2373 deg

We thank Jochen Greiner for noticing the error and we apologize for any confusion 
caused by this mistake.