GRB 181202A

J. K. Cannizzo (NASA/UMBC), J.D. Gropp (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 06:36:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 181202A (trigger=874334).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 280.745, +27.951 which is 
   RA(J2000) = 18h 42m 59s
   Dec(J2000) = +27d 57' 03"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~1100 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 06:37:49.8 UT, 85.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 280.73563, 27.95894 which is equivalent
to:
   RA(J2000)  = 18h 42m 56.55s
   Dec(J2000) = +27d 57' 32.2"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 41 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.67
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting 86
seconds after the BAT trigger. There is a candidate afterglow in the rapidly
available 2.7'x2.7' sub-image at
  RA(J2000)  =	18:42:56.38 = 280.73490
  DEC(J2000) = +27:57:35.0  =  27.95973
with a 90%-confidence error radius of about 0.63 arc sec. This position is 3.4
arc sec. from the center of the XRT error circle. The estimated magnitude is
17.67 with a 1-sigma error of about  0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.14. 

Burst Advocate for this burst is J. K. Cannizzo (cannizzo AT milkyway.gsfc.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.)

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1454 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 181202A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 280.73491, +27.95964 which is equivalent
to:

RA (J2000): 18h 42m 56.38s
Dec (J2000): +27d 57' 34.7"

with an uncertainty of 1.8 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri
(INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti
(INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), J.P.
Osborne (U. Leicester) and J.K. Cannizzo report on behalf of the
Swift-XRT team:

We have analysed 7.0 ks of XRT data for GRB 181202A (Cannizzo et al.
GCN Circ. 23482
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 ), from 102 s to 29.4 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Evans et al. (GCN Circ. 23483
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.86 (+/-0.07).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.69 (+0.22, -0.17). The
best-fitting absorption column is  1.93 (+0.97, -0.26) x 10^21 cm^-2,
consistent with the Galactic value of 1.7 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum  is 4.2 x 10^-11 (5.1 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.93 (+0.97, -0.26) x 10^21 cm^-2
Galactic foreground: 1.7 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.69 (+0.22, -0.17)

If the light curve continues to decay with a power-law decay index of
0.86, the count rate at T+24 hours will be 3.4 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x
10^-13 (1.8 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00874334.

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

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. K. Cannizzo (NASA/UMBC), J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 181202A (trigger #874334)
(Cannizzo et al., GCN Circ. 23482
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 ).  The BAT ground-calculated position is
RA, Dec = 280.737, 27.976 deg which is
  RA(J2000)  =  18h 42m 56.9s
  Dec(J2000) = +27d 58' 33.4"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.

The mask-weighted light curve shows a double-peaked structure that starts
at ~T0 and ends at ~T+7 s. The two peaks occur at ~T+1 s and ~T+6 s, respectively.
T90 (15-350 keV) is 6.56 +- 0.61 sec (estimated error including systematics).

The time-averaged spectrum from T-0.26 to T+6.76 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.24.  The fluence in the 15-150 keV band is 2.5 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.69 sec in the 15-150 keV band
is 0.9 +- 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/874334/BA/

V. Lipunov, E. Gorbovskoy, V.Kornilov, D.Kuvshinov, N.Tyurina, P.Balanutsa,
A.Kuznetsov, V.V.Chazov, D. Vlasenko
Lomonosov Moscow State University,
Sternberg Astronomical Institute, Moscow State University

A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

K. Ivanov, O. Gres, N.M. Budnev, S. Yazev, O. Chuvalaev, V. Poleshchuk
Irkutsk State University

V. Yurkov, A. Gabovich, Yu. Sergienko
Blagoveschensk Educational State University, Blagoveschensk

R. Podesta, Carlos Lopez and F. Podesta
Observatorio Astronomico Felix Aguilar (OAFA)

Hugo Levato and Carlos Saffe
Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE)

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias

D. Buckley, S. Potter, A. Kniazev, M. Kotze
South African Astronomical Observatory



MASTER-Tunka robotic telescope (MASTER-Net: http://observ.pereplet.ru, 
Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in 
Russia (Applied Physics Institute, Irkutsk State University) was pointed 
to the  Swift GRB 181202A (Cannizzo et al., GCN  #23482
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 ) 13216 sec after 
trigger time at 2018-12-02 10:17:08. On best sum (1800s total
exposure)  set 
we haven`t found optical transient  within Swift error-box (ra=280.733 
dec=27.9592 r=0.05).

The 5-sigma upper limit has been about 19.0 mag


====================================================================


The galactic latitude b = 14 deg., longitude l = 58 deg.
The observations made on zenit distance = 42 deg.The moon (25 % bright 
part) below the horizon (The altitude of the Moon is -26 deg. ).
  Observations started at twilight.
The sun  altitude  is -10.6 deg.
The object can be observed till sunrise at 2018-12-02 00:56:06

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, 
Kislovodsk Solar Station of Pulkovo observatory) was pointed to the  SWIFT 
GRB181202.28 32902 sec after trigger time at 2018-12-02 15:46:09 UT, with 
upper limit up to  20.2 mag. No OT detected.

The observations began at zenit distance = 57 
deg. The sun  altitude  is -23.0 deg.


This message can be cited.

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC),
William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz
(UCSC), Jes��s Gonz��lez (UNAM), Carlos Rom��n-Z����iga (UNAM), Harvey
Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki
Toy (UMD) report:

We observed the field of GRB 181202A (Cannizzo et al., GCN 23482
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 ) with
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org)
on the 1.5m Harold Johnson Telescope at the Observatorio Astron��mico
Nacional on Sierra San Pedro M��rtir from 2018/12 3.09 to 2018/12 3.11
UTC (19.43 to 20.04 hours after the BAT trigger), obtaining a total of
0.09 hours exposure in the r and i bands and 0.12 hours exposure in the
Z, Y, J, and H bands in poor conditions.

For a source within the Swift-XRT error circle, in comparison with the
USNO-B1 and 2MASS catalogs, we obtain the following 3-sigma upper
limits:

 r	> 19.18
 i	> 19.17
 Z	> 16.52
 Y	> 16.30
 J	> 16.00
 H	> 16.31

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

However, we note that in our optimally-combined all-filter image, there
appears to be a very faint source present in the Swift-XRT error circle.
This suggests that there may be a source present at low significance in
at least some of our individual images.

We thank the staff of the Observatorio Astron��mico Nacional in San Pedro
M��rtir.

M. H. Siegel (PSU) and J. K. Cannizzo (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181202A
86 s after the BAT trigger (Cannizzo et al., GCN Circ. 23482
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 ).
A source consistent with the XRT position
(Evans et al. GCN Circ. 23483
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 )
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  18:42:56.38 = 280.73491 (deg.)
  Dec (J2000) = +27:57:35.0  =  27.95971 (deg.)
with an estimated uncertainty of 0.47 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

v                  623         1540          117        >18.7
b                  342          591          246         19.57 +/- 0.18
u (fc)              86          336          246         17.67 +/- 0.07
w1                 672         1441           97        >19.6
m2                 647         1560          112        >22.2
w2                 598         1516          117        >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).