GRB 250327A
GCN Circular 39876
Subject
GRB 250327A: Fermi GBM Final Real-time Localization
Date
2025-03-27T07:40:37Z (2 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 07:30:06 UT on 27 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250327A (trigger 764753411.32631 / 250327313).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 246.1, Dec = 62.3 (J2000 degrees, equivalent to J2000 16h 24m, 62d 17'), with a statistical uncertainty of 3.6 degrees.
The angle from the Fermi LAT boresight is 47.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_skymap_all_bn250327313.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_healpix_all_bn250327313.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/quicklook/glg_lc_medres34_bn250327313.gif
GCN Circular 39877
Subject
GRB 250327A: Swift detection of a burst
Date
2025-03-27T08:11:09Z (2 months ago)
From
Jamie Kennea at Penn State <jak51@psu.edu>
Via
email
T. M. Parsotan (GSFC), J. J. DeLaunay (PSU), R. Gupta (NASA GSFC),
J. A. Kennea (PSU) and K. L. Page (U Leicester) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 07:30:04 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250327A (trigger=1299088). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 248.197, +61.595 which is
RA(J2000) = 16h 32m 47s
Dec(J2000) = +61d 35' 43"
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 40 sec. The peak count rate
was ~1648 counts/sec (15-350 keV), at ~3 sec after the trigger.
Due to an observing constraint, Swift did not get data immediately. We will
report on XRT data in a later GCN.
Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT 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/)
GCN Circular 39878
Subject
GRB 250327A: COLIBRÍ optical upper limit
Date
2025-03-27T11:59:15Z (2 months ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
Jean-Grégoire Ducoin (CPPM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Rosa L. Becerra (U Roma), Stéphane Basa (LAM), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Jean-Luc Atteia (IRAP), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM) and Ny Avo Rakotondrainibe (LAM) report:
We observed the field of the Swift/BAT GRB 250327A (Parsotan et al., GCN 39877) also detected by Fermi/GBM (Fermi GBM Team, GCN 39876) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We obtained 23 minutes of exposure in the i filter from 2025-03-27 07:50 to 08:34 UTC (20.5 to 64.1 minutes after the trigger).
Within the Swift/BAT localization, we do not detect any credible uncatalogued source to a 5-sigma limiting magnitude of:
i > 22.9 mag (AB)
We also performed an image subtraction using HOTPANTS and the PanSTARRS i-band image as a reference, which did not reveal any credible residuals.
The data were coadded with the COLIBRI pipeline and analysed in STDWeb/STDPipe (Karpov 2021). The photometric calibration was performed using nearby stars from the Pan-STARRS DR1 catalog and the magnitude is not corrected for Galactic extinction.
Further observations are ongoing.
We acknowledge the excellent support from the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.
GCN Circular 39879
Subject
GRB 250327A: DDOTI Optical Observations
Date
2025-03-27T13:00:18Z (2 months ago)
From
Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>
Via
Web form
Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Sahil Atri (U Roma), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), and Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report:
We observed the field of the Swift/BAT GRB 250327A (Parsotan et al., GCN 39877) also detected by Fermi/GBM (Fermi GBM Team, GCN 39876) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on the Sierra of San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-03-27 UTC.
DDOTI observed the Swift/BAT error region (Parsotan et al., GCN 39877) from 08:13 UTC to 10:43 UTC (from T+0.7 h to T+3.2 h after the trigger) with a total exposure of 1.4 hours.
Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues and after performed image subtraction against PanSTARRS PS1 DR2, we detect no evident uncatalogued sources within the observed field to a 5-sigma limiting AB magnitude of
w > 21.82
This non-detection is consistent with the reported by Ducoin et al. (GCN 39877).
We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.
GCN Circular 39880
Subject
Swift GRB 250327A: Global MASTER-Net observations report
Date
2025-03-27T13:57:44Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Tunka robotic telescope (Global 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 250327A ( T. M. Parsotan et al., GCN 39877) errorbox 22478 sec after notice time and 22599 sec after trigger time at 2025-03-27 13:46:44 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 56 deg. The sun altitude is -20.9 deg.
The galactic latitude b = 40 deg., longitude l = 92 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2825096
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
22690 | MASTER-Tunka | C | 180 | 19.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 39881
Subject
Fermi GRB 250327A: Global MASTER-Net observations report
Date
2025-03-27T14:01:03Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko,
A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin,
V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Tunka robotic telescope (Global 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) started inspect of the Fermi GRB 250327A ( Fermi GBM team, GCN 39876) errorbox 22555 sec after notice time and 22597 sec after trigger time at 2025-03-27 13:46:44 UT, with upper limit up to 19.1 mag. The observations began at zenith distance = 56 deg. The sun altitude is -20.9 deg.
The galactic latitude b = 41 deg., longitude l = 93 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2825101
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
22688 | 2025-03-27 13:46:44 | MASTER-Tunka | (16h 33m 04.03s , +61d 29m 19.4s) | C | 180 | 19.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 39882
Subject
GRB 250327A: Fermi GBM observation
Date
2025-03-27T14:52:00Z (2 months ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
Via
email
A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:
"At 07:30:06.33 UT on 27 March 2025, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 250327A (trigger 764753411 / 250327313), which was
also detected by the Swift/BAT (Parsotan et al. 2025, GCN 39877). The Fermi
GBM Final Real-time Localization (GCN 39876) is consistent with the Swift position.
The angle from the Fermi LAT boresight at the GBM trigger time is 47 degrees.
The GBM light curve shows a structured emission episode
with a duration (T90) of about 160 s (50-300 keV).
The time-averaged spectrum from T0-1.024s to T0+90.114s is
best fit by a Band function with Epeak = 480 +/- 50 keV,
alpha = -1.08 +/- 0.03, and beta = -2.14 +/- 0.15.
The event fluence (10-1000 keV) in this time interval is
(2.97 +/- 0.07)E-05 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+0.704 s in the 10-1000 keV band
is 5.08 +/- 0.23 ph/s/cm^2.
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 39884
Subject
GRB 250327A: SVOM/VT optical candidate
Date
2025-03-27T16:42:22Z (2 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
L.P. Xin (NAOC), J. T. Palmerio (CEA), L. Zhang (IHEP), Y.D. Hu (GXU), X.L. Chen (YNU), Y. L. Qiu, H.L. Li., C. Wu, Z.H. Yao, Y.N. Ma, X.H. Han, H.B. Cai, J.Y. Wei (NAOC), B. Cordier (CEA), report on behalf of the SVOM/VT team:
SVOM performed a Target of Opportunity observation of GRB 250327A (Fermi GBM team, GCN 39876; Parsotan et al., GCN 39877). SVOM/VT began observing the field at 2025-03-27T11:25:40.50 UT, ~3.9 hours after the Swift/BAT trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
An uncatalogued candidate is detected inside the Swift/BAT error circle at ra=248.18018, dec=61.63347 (J2000), corresponding to:
RA (J2000) = 16:32:43.2
Dec (J2000) = +61:38:00.5
with an uncertainty of 1.0 arcsec.
This source is not present in the archival Legacy Survey.
The source is detected in the VT_R stacked image with exposure time of 47x60 seconds with VT_R = 22.8 +/- 0.3 mag (AB).
The 3 sigma upper limit in the VT_B is 23.4 mag (AB).
We thank D.B. Malesani for helpful discussion.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
GCN Circular 39885
Subject
GRB 250327A: J-band observations with WINTER
Date
2025-03-27T19:40:58Z (2 months ago)
From
Geoffrey Mo at MIT <gmo@mit.edu>
Via
Web form
Geoffrey Mo (MIT), Benjamin Schneider (LAM), Tomas Ahumada (Caltech), Danielle Frostig (CfA), Viraj Karambelkar (Caltech), Robert Stein (UMD), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:
We observed the field of GRB 250327A (Fermi GBM Team, GCN 39876; Parsotan et al., GCN 39877, Kienlin et al., GCN 39882) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024).
Observations were triggered automatically and began at 2025-03-27T07:41:48 UTC (12 min after the GRB), consisting of 5 x 120 s exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar
(https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565).
We do not detect a source at the SVOM/VT counterpart location (Xin et al., GCN 39884), and also do not detect any new sources in the Swift/BAT localization after visual comparison to archival PanSTARRS-1 (Chambers et al. 2016) y-band imaging. This is consistent with other observations (Ducoin et al., GCN 39878; Becerra et al., GCN 39879; Lipunov et al., GCN 39880; Lipunov et al., GCN 39881). We obtain the following 5-sigma upper limit: J ~ 18.3 mag (AB).
WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.
GCN Circular 39892
Subject
GRB 250327A: Swift-XRT refined Analysis
Date
2025-03-28T00:07:39Z (2 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC &
INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB) and P.A.
Evans report on behalf of the Swift-XRT team:
We have analysed 8.0 ks of XRT data for GRB 250327A, from 12.1 ks to
47.5 ks after the BAT trigger. The data are entirely in Photon
Counting (PC) mode. The refined XRT position is RA, Dec = 248.1950,
+61.6164 which is equivalent to:
RA (J2000): 16 32 46.80
Dec(J2000): +61 36 58.9
with an uncertainty of 3.6 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=0.92 (+0.22, -0.21).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.38 (+0.32, -0.29). The
best-fitting absorption column is 3.0 (+1.1, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 2.6 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 3.1 x 10^-11 (5.7 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 3.0 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 2.6 x 10^20 cm^-2
Excess significance: 4.6 sigma
Photon index: 2.38 (+0.32, -0.29)
If the light curve continues to decay with a power-law decay index of
0.92, the count rate at T+24 hours will be 0.016 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.1 x
10^-13 (9.3 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/01299088.
This circular is an official product of the Swift-XRT team.
GCN Circular 39899
Subject
GRB 250327A: SVOM/VT upper limits on the XRT position
Date
2025-03-28T06:44:48Z (2 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
H.L. Li(NAOC), L. Zhang (IHEP), Y.D. Hu (GXU), X.L. Chen (YNU), Y. L. Qiu, L.P. Xin, C. Wu, Z.H. Yao, Y. Xu, P.P. Zhang, J. Wang, Y.N. Ma, X.H. Han, H.B. Cai, W. J. Xie, J.Y. Wei (NAOC), J. T. Palmerio (CEA)report on behalf of the SVOM/VT team:
SVOM performed a Target of Opportunity observation of GRB 250327A (Fermi GBM team, GCN 39876; Parsotan et al., GCN 39877). SVOM/VT began observing the field at 2025-03-27T11:25:40.50 UT, ~3.9 hours after the Swift/BAT trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With the full X-band data, no any source was detected in the stacked images within the errorbox of Swift/XRT (Burrows et al. GCNC39892).
The 3 sigma limits in AB magnitude were derived as follows:
---------------------------------------------------------
(t-T0)_mid(hr) exptime(ks) Band upperlim (3sigma)
5.9 7.32 VT_R 23.8
5.9 7.38 VT_B 23.8
Deeper or redder observations are encouraged to investigate the nature of the burst.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC),CAS.
GCN Circular 39987
Subject
GRB 250327A Swift-BAT refined analysis
Date
2025-03-31T21:38:12Z (2 months ago)
From
Mike Moss at NASA GSFC <mikejmoss3@gmail.com>
Via
Web form
S. D. Barthelmy (GSFC), R. Gupta (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (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+843 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 250327A (trigger #1299088)
(Parsotan, et al., GCN Circ. 39877). The BAT ground-calculated position is
RA, Dec = 248.209, 61.610 deg which is
RA(J2000) = 16h 32m 50.1s
Dec(J2000) = +61d 36' 35.4"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 10%.
The mask-weighted light curve shows a single main pulse lasting ~60 sec composed
of several shorter pulses. The remainder of the burst emission is included in a
dim tail. The T90 (15-350 keV) is 91.008 +- 12.21 sec (estimated error including
systematics).
The time-averaged spectrum from T+1.67 to T+109.928 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.28 +- 0.12. The fluence in the 15-150 keV band is 7.6 +- 0.5 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+24.49 sec in the 15-150 keV band
is 2.1 +- 0.7 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/1299088
GCN Circular 40008
Subject
GRB 250327A: Swift/UVOT Upper Limits
Date
2025-04-02T13:08:08Z (2 months ago)
From
Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>
Via
Web form
M. H. Siegel (PSU) and T. M. Parsotan (GSFC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250327A 13.8 ks after the BAT trigger (Parsotan et al., GCN Circ. 39877). No optical afterglow consistent with the XRT position (Burrows et al., GCN Circ. 39892) GCN Circ. 39977) 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
B 25500 43748 1714 >20.88
UVM2 47869 48769 885 >20.28
U 14704 42891 1711 >20.58
V 21282 21402 117 >18.30
UVW1 13797 49176 1885 >20.62
UVW2 20376 21275 885 >20.31
WHITE 26413 27065 633 >20.81
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.053 in the direction of the burst
(Schlegel et al. 1998).