////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  23342
SUBJECT: GRB 181016A: Swift detection of a burst
DATE:    18/10/16 01:07:47 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

P. D'Avanzo (INAF-OAB), H. A. Krimm (NSF/USRA), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (PSU) and A. Tohuvavohu (PSU) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 00:55:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181016A (trigger=867252).  Due to an observing constraint,
Swift could not slew to the burst. 
The BAT on-board calculated location is 
RA, Dec 231.268, -35.279 which is 
   RA(J2000) = 15h 25m 04s
   Dec(J2000) = -35d 16' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 40 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 09:03 UT on 2019 January 03. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is P. D'Avanzo (paolo.davanzo AT brera.inaf.it). 
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:  23343
SUBJECT: GRB 181016A: Swift-BAT refined analysis
DATE:    18/10/16 14:44:39 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI), 
P. D'Avanzo (INAF-OAB),  H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181016A (trigger #867252)
(D'Avanzo, et al., GCN Circ. 23342).  The BAT ground-calculated position is
RA, Dec = 231.273, -35.307 deg which is 
  RA(J2000)  =  15h 25m 05.6s 
  Dec(J2000) = -35d 18' 23.6" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The mask-weighted light curve shows a single peak starting at ~T-20 sec, peaking
at T+0 sec, and declining to background around T+90 sec.
T90 (15-350 keV) is 111.6 +- 26.3 sec (estimated error including systematics).

The time-averaged spectrum from T-18.00 to T+110.14 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.51 +- 0.20.  The fluence in the 15-150 keV band is 1.9 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.39 sec in the 15-150 keV band
is 0.7 +- 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/867252/BA/