GRB 210708B

B. Sbarufatti (PSU), P. A. Evans (U Leicester), H. A. Krimm (NSF),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 13:23:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located possible GRB 210708B (trigger=1059494).  
The BAT on-board calculated location is 
RA, Dec 142.579, +14.471 which is 
   RA(J2000) = 09h 30m 19s
   Dec(J2000) = +14d 28' 16"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~1400 counts/sec (15-350 keV), at ~6 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 05:03 UT on 2021 September 30. There will thus be no XRT
or UVOT data for this trigger before this time. 

Due to a discrepancy between the on-board and ground analysis with
the limited data available, we cannot definitively determine
whether this is an astrophysical event.  Further analysis will
be done after the ground telemetry pass. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 AT psu.edu). 
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, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
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, O.Ershova 
(Irkutsk State University, API),

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

V. Yurkov, A. Gabovich, Yu. Sergienko 
(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 210708B ( B. Sbarufatti et al., GCN 30417
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 ) errorbox  27094 sec after notice time and 27800 sec after trigger time at 2021-07-08 21:06:45 UT, with upper limit up to  16.5 mag. Observations started at twilight.  The observations began at zenith distance = 79 deg. The sun  altitude  is -13.0 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 210708B errorbox  34540 sec after notice time and 35247 sec after trigger time at 2021-07-08 23:10:51 UT, with upper limit up to  17.2 mag. The observations began at zenith distance = 77 deg. The sun  altitude  is -17.6 deg. 

The galactic latitude b = 42 deg., longitude l = 218 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1655856

We obtain a following upper limits.  

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

   27891 |          MASTER-IAC |   C |   180 | 16.5 |        
   35337 |         MASTER-OAFA |   C |   180 | 17.2 |        
Filter C is a clear (unfiltred) band. 


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

M. Stamatikos (OSU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), B. Sbarufatti (PSU),
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 210708B (trigger #1059494)
(Sbarufatti, et al., GCN Circ. 30417
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 ).  The BAT ground-calculated position is
RA, Dec = 142.594, 14.523 deg which is 
   RA(J2000)  =  09h 30m 22.5s 
   Dec(J2000) = +14d 31' 22.6" 
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.

The mask-weighted light curve shows a broad peak with some sub-structure.
Emission begins around T-100 sec, peaks near the trigger time and decays
to background by T+200 sec.  The burst position was not in the field of view of
the BAT until about T-150 sec.  T90 (15-350 keV) is 298.43 +- 47.32 sec 
(estimated error including systematics).

The time-averaged spectrum from -99.8 to 263.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.62 +- 0.26.  The fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.84 sec in the 15-150 keV band
is 0.0 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

We note that in the original GCN circular, the event was described as a possible
burst.  Analysis of the full data set shows that the event is indeed a GRB.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1059494/BA/