GRB 211223C

P. A. Evans (U Leicester), S. D. Barthelmy (GSFC),
N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), B. Sbarufatti (PSU) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 14:29:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211223C (trigger=1090656).  Swift did not slew to the burst
due to a pointing constraint.  The BAT on-board calculated location is 
RA, Dec 227.164, -26.873 which is 
   RA(J2000) = 15h 08m 39s
   Dec(J2000) = -26d 52' 20"
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 20 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 23:31 UT on 2021 December 29. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is P. A. Evans (pae9 AT leicester.ac.uk). 
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/)

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

B.L.Carrasco, J.R.Valdes,V.Chavushyan, C.J.Martinez, V.M.Patino Alvarez,
M.L.H.Rodriguez (INAOE, OAGH)

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) was pointed to the Swift GRB 211223C ( P. A. Evans et al., GCN 31288
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 ) errorbox  54750 sec after notice time and 54769 sec after trigger time at 2021-12-24 05:42:16 UT, with upper limit up to  16.4 mag. The observations began at zenith distance = 82 deg. The sun  altitude  is -27.6 deg. 

The galactic latitude b = 26 deg., longitude l = 338 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1824979

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   54860 |          MASTER-IAC |   C |   180 | 16.4 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.

Y.-D. Hu, T.-R. Sun, A. J. Castro-Tirado, E. Fernandez-Garcia, M. D. Caballero-Garcia, R. Sanchez-Ramirez, M. A. Castro Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:

Following the detection of GRB 211223C by Swift (Evans et al. GCNC 31288), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically responded to this burst starting on Dec. 23 at 21:58:25 UT (~7.5 hours after trigger). No new source is detected within the BAT error region in the co-added image (60 x 20 s, clear filter) down to 20.1 mag.

We thank the staff at the Lijiang observatory for their excellent support.

H. A. Krimm (NSF), S. D. Barthelmy (GSFC), S. Laha (GSFC/UMBC), A. Y. Lien
(U Tampa), 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 211223C (trigger #1090656)
(Evans, et al., GCN Circ. 31288
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 ).  The BAT ground-calculated position is
RA, Dec = 227.165, -26.878 deg which is

   RA(J2000)  =  15h 08m 39.7s

   Dec(J2000) = -26d 52' 41.0"

with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The
partial coding was 32%.



The BAT light curve showed a complex structure with a duration of about 20
sec. T90 (15-350 keV) is 15.00 +- 5.00 sec (estimated error including
systematics).



The time-averaged spectrum from T-13.01 to T+8.99 sec is best fit by a
simple power-law model.  The power law index of the time-averaged spectrum
is 1.15 +- 0.09.  The fluence in the 15-150 keV band is 2.4 +- 0.1 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T-0.01 sec in the 15-150
keV band is 3.1 +- 0.4 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/1090656/BA/