GRB 251014D

D. M. Palmer (LANL), S. D. Barthelmy (GSFC), 
R. Gupta (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII)
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), T. Parsotan (GSFC),
D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU)
(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 251014D (trigger #1404126)
(Klingler, et al., GCN Circ. 42274
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 ).  The BAT ground-calculated position is
RA, Dec = 323.933, -41.873 deg which is 
   RA(J2000)  =  21h 35m 43.9s 
   Dec(J2000) = -41d 52' 23.0" 
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 49%.
 
The mask-weighted BAT light curve shows a main emission followed by weaker 
emission. T90 (15-350 keV) is 286.98 +- 70.09 sec (estimated error including 
systematics).
 
The time-averaged spectrum from T+0.39 to T+310.10 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.74 +- 0.38.  The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+5.18 sec in the 15-150 keV band
is 0.5 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 
 
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1404126

A.A. Breeveld (UCL-MSSL) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 251014D 160 s after the BAT trigger (Klingler et al., GCN Circ. 42274
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 ).
No optical afterglow consistent with the XRT position (Page et al., GCN Circ. 42284
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 )is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:

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

white_FC           160          310          147         >20.7
white              160         4287          344         >20.9
v                 4498         4697          197         >19.2
b                 3882         5439          317         >19.9
u                  318         5312          204         >19.8
w1                4907         5107          197         >19.7
m2                4702         4902          197         >19.6
w2                4293         4493          197         >19.4

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.020 in the direction of the burst (Schlegel et al. 1998).

S. Guziy, I. Perez-Garcia, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki), M. Jelinek (ASU-CAS), A. Kumar (ARIES) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:

Following the detection of GRB 251014D by Swift/BAT (Klingler et al., GCNC 42272), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) responded to this event starting on Oct 14, 23:03 UT (~ 1.1 h after trigger) with 120s clear-filter images. No new source is detected within the Swift/XRT X-ray afterglow error box (Page et al., GCNC 42284) up to magnitude 18.3 using Gaia DR3 Gmag magnitude as reference. Further images were gathered, resulting on an upper limit of 21.0 (a coadd of 1200s on the aggregate, 1.6 post burst, at 23:30 UT).

We thank the staff at Boyden Observatory for their excellent support.

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), S. Campana
(INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), S. Dichiara
(PSU), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of GRB 251014D. We
searched for X-ray sources in  2.9 ks of Photon Counting (PC) mode
data. The total exposure at the position of the afterglow (see below)
is 5.0 ks, obtained between T0+159.4 s and T0+22.3 ks.

An uncatalogued X-ray source is detected within the estimated 3-sigma
Swift-BAT error region (296 arcsec) and is fading with >3-sigma
significance, and is therefore likely the GRB afterglow. Using 1351 s
of PC mode data and 3 UVOT images, we find an enhanced XRT position
(using the XRT-UVOT alignment and matching UVOT field sources to the
USNO-B1 catalogue): 
RA, Dec = 323.92080, -41.85533 which is equivalent to:

RA (J2000): 21h 35m 40.99s
Dec(J2000): -41d 51' 19.2"

with an uncertainty of 3.4 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.71 (+0.12, -0.11).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	 of 1.64 (+/-0.06). The
best-fitting absorption column is  9.7 (+1.9, -1.8) x 10^20 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.1 x 10^-11 (4.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     9.7 (+1.9, -1.8) x 10^20 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 6.8 sigma
Photon index:	     1.64 (+/-0.06)


The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/01404126.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/01404126.

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

N. J. Klingler (GSFC/UMBC/CRESSTII), S. Dichiara (PSU),
R. Gupta (NASA GSFC), N. P. M. Kuin (UCL-MSSL), A. Mei (INAF-OAB),
C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 21:54:40.55 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 251014D (trigger=1404126).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 323.918, -41.839 which is 
   RA(J2000) = 21h 35m 40s
   Dec(J2000) = -41d 50' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). The BAT light curve is not available because of a 
telemetry gap; however, the rate significance of 8.71 indicates that the 
event is likely real.

The XRT began observing the field at 21:57:16.2 UT, 155.7 seconds
after the BAT trigger. No source was detected in the 2.5-s promptly
available image. We are waiting for the full dataset to detect and
localise the XRT counterpart.

The UVOT source list for the first white image shows no detection of a
new source. Typical upper limits are 17th magnitude. Further details
will become available when the full data are downloaded.

Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.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/)