GRB 250207A
GCN Circular 39463
Subject
GRB 250207a: ATCA Radio Upper Limits
Date
2025-02-25T01:32:43Z (7 months ago)
From
agul8829@uni.sydney.edu.au
Via
Web form
A. Gulati (USyd), G. E. Anderson (Curtin), S. Chastain (UNM), A. J. van der Horst (GWU), J. K. Leung (UofT/HUJI), and L. Rhodes (TSI/McGill) on behalf of the ATCA PanRadio GRB collaboration
We observed Swift and Fermi-detected GRB 250207A (Ferro et al., GCN 39182; Fermi GBM Collaboration, GCN 39181) as part of The Australia Telescope Compact Array (ATCA) "PanRadio GRB" Large Project C3542 (PI: G. Anderson) at 5.5 and 9 GHz on 2025-02-12, 2025-02-14 and 2025-02-21.
No radio sources were detected near the Swift/XRT enhanced position (Osborne et al., GCN 39217 )in any of the observation epochs. The 3-sigma upper limits for the 9 GHz observations are 174, 96, and 60 uJy respectively.
We thank the CSIRO Space and Astronomy staff for supporting these observations.
We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.
GCN Circular 39291
Subject
GRB 250207A: Fermi GBM Observation
Date
2025-02-11T21:31:46Z (8 months ago)
From
oindabimukherjee@gmail.com
Via
Web form
O. Mukherjee (USRA), R. Hamburg (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 01:16:03.15 UT on 07 February 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250207A (trigger 760583768/250207053).
which was also detected by Swift BAT (Ferro et al. 2025, GCN 39182), COLIBRÍ/DDRAGO (Angulo et al. 2025, GCN 39186),
Swift/UVOT (Kuin et al. 2025, GCN 39199), and Konus-Wind (Ridnaia. et al. 2025, GCN 39284)
The Fermi GBM Final Real-time Localization (GCN 39181) is consistent with the Swift BAT position.
The angle from the Fermi LAT boresight is 46 degrees.
The GBM light curve consistes of a single emission episode with multiple peaks with a duration (T90)
of about 20 s (50-300 keV). The time-averaged spectrum
from T0-3.1 to T0+25.6 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.10 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 290 +/- 30 keV.
The event fluence (10-1000 keV) in this time interval is
(1.04 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+12 s in the 10-1000 keV band is 4.7 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 240 +/- 30 keV, alpha = -1.03 +/- 0.08 and beta = -2.3 +/- 0.3.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN Circular 39284
Subject
Konus-Wind detection of GRB 250207A
Date
2025-02-11T13:50:11Z (8 months ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 250207A
(Fermi-GBM detection: Fermi GBM team, GCN 39181;
Swift-BAT detection: Ferro et al., GCN 39182; Moss et al., GCN 39245)
was detected by Konus-Wind (KW) in the waiting mode.
A Bayesian block analysis of the KW waiting mode data
reveals a >27 sigma count rate increase in the interval
from T0-7.699 s to T0+15.853 s where T0 = T0(BAT) = 01:16:07.33 UT.
The KW light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB250207A/
Modeling a time-integrated spectrum of the burst
(from T0-7.699 s to T0+15.853 s)
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep):
yields alpha = -1.26 (-0.12, + 0.14) and Ep = 329(-64,+91) keV.
The total burst fluence is 1.04(-0.11,+0.13)x10^-5 erg/cm^2,
and the 2.944 s peak energy flux, measured from T0+4.077 s,
is 7.05(-0.98,+1.08)x10^-7 erg/cm^2.
(both in the 20 keV - 10 MeV energy range).
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
GCN Circular 39274
Subject
GRB 250207A: Skynet optical afterglow observations
Date
2025-02-11T01:35:36Z (8 months ago)
From
dschlekat@unc.edu
Via
Web form
Donovan Schlekat, Dylan Dutton, Daniel Reichart, Joshua Haislip, and Vladimir Kouprianov report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.
We observed the field of GRB 250207A detected by Fermi (The Fermi GBM Team, GCN 39181) and Swift (Ferro et al., GCN 39182; Osborne et al., GCN 39217; Melandri et al., GCN 39221; Moss et al., GCN 39245) with two of Skynet's PROMPT telescopes located at the Cerro Tololo Inter-American Observatory. The observation began at 01:20:03 UT on February 7 2025, roughly 4 minutes after the Swift-BAT trigger and lasted for around 14 minutes until the field was no longer observable. Observations were performed in the B, V, R, and I bands. Exposure lengths were calculated using our automated exposure length scaling model.
We detect the optical afterglow (Ferro et al., GCN 39182; Angulo et al., GCN 39186; Kuin & Ferro, GCN 39199; Brivio et al., GCN 39202; Jelinek et al., GCN 39209; Ferro et al., 39212; Ror et al., 39250) in the V, R, and I bands. The photometry of the initial detection for each band is reported below.
Tmid - T0 (s)| Telescope | Filter | Exposure (s) | Mag | Mag Error
------------------------------------------------------------------
747.0 | PROMPT-6 | V | 22 | 16.854 | 0.064
779.0 | PROMPT-5 | R | 16 | 16.593 | 0.097
805.0 | PROMPT-6 | I | 10 | 16.570 | 0.061
Our images have been calibrated using stars from the APASS catalog. Magnitudes were not corrected for dust extinction.
GCN Circular 39250
Subject
GRB 250207A: 1.3m DFOT Optical observations
Date
2025-02-09T14:25:06Z (8 months ago)
From
Amit Kumar Ror at ARIES <mitturor77894@gmail.com>
Via
email
Amit K. Ror, Anshika Gupta, Kiran, Shashi B. Pandey, Kuntal Mishra (ARIES)
report:
We observed the field of GRB 250207A detected by the Swift Burst Alert
Telescope (Swift team, Ferro et al. 2025; GCN 39182) with the 1.3m
Devasthal Fast Optical Telescope (DFOT), located at the Devasthal
Observatory of the Aryabhatta Research Institute of Observational Sciences
(ARIES), India. The observations were started on 2025-02-07 at 13:41:42 UT,
i.e., ~ 0.52 days after the Swift-BAT trigger. We have taken multiple
frames with an exposure time of 300 s in the R filter. We stacked the
images after the alignment. We detected an optical afterglow in our stacked
image within the error box of the enhanced Swift-XRT position by Osborne et
al. 2025 (GCN 39217). We obtain the following preliminary magnitude in the
stacked image:
Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude
=========================================================
2025-02-07 13:41:42 ~0.52 R 300s*4 21.12 +/- 0.15
Our detection is consistent with Angulo et al. 2025 (GCN 39186); Kuin et
al. 2025 (GCN 39199); Brivio et al. 2025 (GCN 39202); Jelinek et al. 2025
(GCN 39209) and Ferro et al. 2025 (GCN 39212).
The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalogue. This circular may be cited.
GCN Circular 39245
Subject
GRB 250207A: Swift-BAT refined analysis
Date
2025-02-09T00:53:00Z (8 months ago)
From
Rahul Gupta at NASA GSFC <rahul.gupta@nasa.gov>
Via
Web form
M. J. Moss (GSFC), S. D. Barthelmy (GSFC),
M. Ferro (INAF-OAB), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), 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 250207A (trigger #1287821)
(Ferro, et al., GCN Circ. 39182). The BAT ground-calculated position is
RA, Dec = 16.097, -12.165 deg which is
RA(J2000) = 01h 04m 23.4s
Dec(J2000) = -12d 09' 55.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 72%.
The masked weighted BAT light curve shows a prominent multi-peaked structure, with the most significant activity occurring within the first 50 seconds after the trigger. T90 (15-350 keV) is 52.54 +- 19.87 sec (estimated error including systematics).
The time-averaged spectrum from T-6.60 to T+100.22 sec is the best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.27 +- 0.08. The fluence in the 15-150 keV band is 3.7 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+7.01 sec in the 15-150 keV band is 2.6 +- 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/1287821
GCN Circular 39221
Subject
GRB 250207A: Swift-XRT refined Analysis
Date
2025-02-08T01:34:17Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), D.N. Burrows (PSU), M.
A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester), P. D'Avanzo (INAF-OAB) and P.A. Evans report on
behalf of the Swift-XRT team:
We have analysed 6.0 ks of XRT data for GRB 250207A, from 100 s to 73.6
ks after the BAT trigger. The data comprise 370 s in Windowed Timing
(WT) mode (the first 4 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The late-time light curve (from T0+4.2 ks) can be modelled with a
power-law decay with a decay index of alpha=1.22 (+0.13, -0.10).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.14 (+/-0.06). The
best-fitting absorption column is 6.7 (+/-1.2) x 10^20 cm^-2, in
excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.02 (+0.16, -0.15)
and a best-fitting absorption column of 5.5 (+3.5, -3.1) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.3 x 10^-11 (3.8 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.5 (+3.5, -3.1) x 10^20 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.02 (+0.16, -0.15)
If the light curve continues to decay with a power-law decay index of
1.22, the count rate at T+24 hours will be 0.010 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x
10^-13 (3.9 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/01287821.
This circular is an official product of the Swift-XRT team.
GCN Circular 39217
Subject
GRB 250207A: Enhanced Swift-XRT position
Date
2025-02-07T22:54:13Z (8 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1772 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 250207A, 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 = 16.08929, -12.16479 which is equivalent
to:
RA (J2000): 01h 04m 21.43s
Dec (J2000): -12d 09' 53.3"
with an uncertainty of 2.2 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.
GCN Circular 39212
Subject
GRB 250207A: REM IR afterglow detection
Date
2025-02-07T18:01:45Z (8 months ago)
From
Matteo Ferro at INAF-OAB <matteo.ferro@inaf.it>
Via
Web form
M. Ferro, R. Brivio, P. D’Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team:
We observed the field of GRB 250207A, detected by Fermi/GBM (Fermi GBM Team, GCN 39181