GRB 250322A
GCN Circular 39835
Subject
GRB 250322A: Swift detection of a short burst
Date
2025-03-22T16:26:08Z (2 months ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
R. Gupta (NASA GSFC), R. Brivio (INAF-OAB), M. Ferro (INAF-OAB),
J. A. Kennea (PSU), H. A. Krimm (NSF), M. J. Moss (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), M. H. Siegel (PSU)
and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 16:06:12 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250322A (trigger=1297832). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 106.734, +7.199 which is
RA(J2000) = 07h 06m 56s
Dec(J2000) = +07d 11' 56"
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 1 sec. The peak count rate
was ~10,000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 16:07:25.4 UT, 73 seconds
after the BAT trigger. Using promptly downlinked data we find an
uncatalogued X-ray source with an enhanced position: RA, Dec 106.76025,
7.19285 which is equivalent to:
RA(J2000) = 07h 07m 02.46s
Dec(J2000) = +07d 11' 34.2"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
position may be improved as more data are received; the latest position
is available at https://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.70
x 10^21 cm^-2 (Willingale et al. 2013).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 76 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.154.
Burst Advocate for this burst is R. Gupta (rahulbhu.c157 AT gmail.com).
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 39838
Subject
GRB 250322A: MASTER optical observation
Date
2025-03-22T18:47:54Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, G.Antipov,D.Vlasenko,K.Zhirkov, P.Balanutsa, N.Tyurina, Ya.Kechin,
A.Chasovnikov, V.Topolev, V.Senik, K.Labzina (Lomonosov MSU),
D.Buckley (SAAO),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A.Sosnovskij (Crao RAS),
O.Gress, N.Budnev, O.Ershova (ISU),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)
located in South African Astronomical Observatory was pointed to the SWIFT (GCN 39835, Gupta et al.)
GRB250322A (trigger No 1297832,07h 06m 56.00s , +07d 11m 56.0s, R=0.05) errorbox
4876 sec after notice time (5017 sec after trigger time) at 2025-03-22 17:29:49 UT,with upper limit up to 18.5 mag.
Observations started at twilight.
The observations began at zenith distance = 39 deg. The sun altitude is -9.8 deg.
The galactic latitude b = 7 deg., longitude l = 209 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2820337
We obtain the following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
5032 | MASTER-SAAO | C | 30 | 16.7 |
5077 | MASTER-SAAO | C | 120 | 17.4 | Coadd
5082 | MASTER-SAAO | C | 30 | 16.8 |
5146 | MASTER-SAAO | C | 60 | 16.9 |
5226 | MASTER-SAAO | C | 60 | 17.0 |
5320 | MASTER-SAAO | C | 90 | 17.0 |
5415 | MASTER-SAAO | C | 60 | 17.4 |
5494 | MASTER-SAAO | C | 60 | 17.4 |
5559 | MASTER-SAAO | C | 30 | 17.4 |
5604 | MASTER-SAAO | C | 120 | 18.2 | Coadd
5608 | MASTER-SAAO | C | 30 | 17.5 |
5672 | MASTER-SAAO | C | 60 | 17.6 |
5752 | MASTER-SAAO | C | 60 | 17.7 |
5812 | MASTER-SAAO | C | 180 | 18.3 | Coadd
5831 | MASTER-SAAO | C | 60 | 17.8 |
5910 | MASTER-SAAO | C | 60 | 17.8 |
6020 | MASTER-SAAO | C | 120 | 17.6 |
6129 | MASTER-SAAO | C | 60 | 17.8 |
6209 | MASTER-SAAO | C | 60 | 17.9 |
6289 | MASTER-SAAO | C | 60 | 17.9 |
6398 | MASTER-SAAO | C | 120 | 17.8 |
6537 | MASTER-SAAO | C | 120 | 17.8 |
6677 | MASTER-SAAO | C | 120 | 17.9 |
6816 | MASTER-SAAO | C | 120 | 17.9 |
6961 | MASTER-SAAO | C | 120 | 17.7 |
7036 | MASTER-SAAO | C | 270 | 18.1 | Coadd
7100 | MASTER-SAAO | C | 120 | 17.6 |
7194 | MASTER-SAAO | C | 30 | 17.8 |
7243 | MASTER-SAAO | C | 30 | 17.9 |
7273 | MASTER-SAAO | C | 90 | 18.5 | Coadd
7292 | MASTER-SAAO | C | 30 | 17.8 |
7342 | MASTER-SAAO | C | 30 | 17.8 |
7391 | MASTER-SAAO | C | 30 | 17.9 |
7421 | MASTER-SAAO | C | 90 | 18.4 | Coadd
7440 | MASTER-SAAO | C | 30 | 17.8 |
7490 | MASTER-SAAO | C | 30 | 17.8 |
7539 | MASTER-SAAO | C | 30 | 17.8 |
7569 | MASTER-SAAO | C | 90 | 18.5 | Coadd
7588 | MASTER-SAAO | C | 30 | 17.8 |
7637 | MASTER-SAAO | C | 30 | 17.9 |
7687 | MASTER-SAAO | C | 30 | 17.7 |
7736 | MASTER-SAAO | C | 30 | 17.8 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 39841
Subject
GRB 250322A: Enhanced Swift-XRT position
Date
2025-03-22T21:33:49Z (2 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1707 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 250322A, 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 = 106.76048, +7.19313 which is equivalent
to:
RA (J2000): 07h 07m 2.52s
Dec (J2000): +07d 11' 35.3"
with an uncertainty of 2.6 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 39842
Subject
GRB 250322A: NOT optical upper limits
Date
2025-03-22T23:10:07Z (2 months ago)
From
Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo@ucd.ie>
Via
Web form
A. Martin-Carrillo (UCD), B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud Univ.), L. Izzo (INAF/OACn and DARK/NBI), D. Xu (NAOC), A. A. Djupvik (NOT), and A. Kadela (NOT and NBI), report on behalf of a larger collaboration:
We observed the field of the GRB 250322A (Gupta et al., GCN 39835) using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 5 exposures of 300 s each in the SDSS-r and SDSS-z band, starting at 20:45:22 UT on 2025-03-22 (4.65 hr after the trigger).
Preliminary analysis shows that no new source is detected within the Swift/XRT enhanced error box (Goad et al., GCN 39841), down to the 5-sigma AB limiting magnitudes r > 24.3 and z > 22.6, calibrated with nearby Pan-STARRS stars and without Galactic extinction correction.
We note that the XRT location includes an extended object (J2000 coordinates RA = 07:07:02.60, Dec = +07:11:33.8) also visible in the Pan-STARRS images, which is a host galaxy candidate for the GRB. Photometry of this source reveals a magnitude consistent with that reported in the Pan-STARRS catalogue, indicating no bright additional component on top of it.
GCN Circular 39844
Subject
GRB 250322A: VLT near-infrared observations
Date
2025-03-23T02:40:38Z (2 months ago)
From
Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>
Via
Web form
Rosa Becerra (U Rome), Yu-Han Yang (U Rome), Eleonora Troja (U Rome) report on behalf of the ERC BHianca team:
We observed the field of GRB 250322A (Gupta et al., GCN 39835) with the HAWKI imager on the ESO VLT UT4 (Yepun). Observations began at T+7.4 hr with a total exposure of 360 sec in the J filter, and were carried out at an average airmass of about 1.2 and seeing of 0.56’’.
We do not detect any new source at the enhanced Swift-XRT position (Goad et al. GCN 39841) down to the following 5-sigma limit J>23.0 mag (Vega) calibrated using nearby stars in the 2MASS Catalogue.
We detect the host galaxy candidate reported by Martin-Carrillo et al. 2025 (GCN 39842) in our image. We estimate a preliminary magnitude of J=18.9±0.2 mag (Vega).
Further observations are planned to investigate potential variations in the brightness.
We thank the staff at the VLT, especially Thomas Rivinius, for the rapid execution of these observations.
GCN Circular 39845
Subject
GRB 250322A: VLT optical observations
Date
2025-03-23T02:42:36Z (2 months ago)
Edited On
2025-03-23T12:40:12Z (2 months ago)
From
Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra@roma2.infn.it>
Via
Web form
Rosa Becerra (U Rome), Yu-Han Yang (U Rome), Eleonora Troja (U Rome) report on behalf of the ERC BHianca team:
We observed the field of GRB 250322A (Gupta et al., GCN 39835, Goad et al. GCN 39841) with the FORS2 imager on the ESO VLT UT1 (Antu). Observations began at T+8.1 hours after the trigger and were carried out in the R filter with a total exposure of 1200 seconds, at an average seeing of 0.5" and airmass about 1.2.
We do not detect any new source at the enhanced Swift-XRT position (Goad et al. GCN 39841) down to the following 5-sigma limit R>25.8 AB mag calibrated with nearby Pan-STARRS stars and without Galactic extinction correction.
In our images, we detect the host galaxy candidate reported by Martin-Carrillo et al. (GCN 39842) with no significant variation in brightness.
We thank the staff at the VLT for the rapid execution of these observations.
GCN Circular 39846
Subject
GRB 250322A: Gemini-South optical observations
Date
2025-03-23T03:06:38Z (2 months ago)
From
Charles Kilpatrick at Northwestern U <ckilpatrick@northwestern.edu>
Via
Web form
C. D. Kilpatrick and W. Fong (Northwestern) report on behalf of a larger collaboration:
We observed the location of the short-duration GRB 250322A (Gupta et al., GCN 39835) with the Gemini Multi-Object Spectrograph (GMOS) mounted on Gemini-South under Program GS-2025A-Q-112 (PI: Fong). We obtained 10x120-sec imaging each in the r- and i-bands starting at 2025-03-23 00:06:31 UT (8.0 hrs post-burst), at a median airmass of 1.3 and seeing of 0.6-0.9’’.
Within or proximate to the enhanced XRT localization (Goad et al., GCN 39841), we do not detect any additional sources relative to Pan-STARRS1, to 3-sigma limits of r > 24.2 AB mag and i > 24.4 AB mag (calibrated to Pan-STARRS), consistent with the non-detections reported (Martin-Carrillo et al., GCN 39842; Becerra et al. GCN 39845).
Regarding the galaxy within the XRT position, first pointed out by Martin-Carrillo et al. (GCN 39842), we measure magnitudes of r = 21.7 +/- 0.1 AB mag and i = 21.1 +/- 0.1 AB mag. We note that these are ~0.3-0.6 mag brighter than the catalogued Pan-STARRS values (Flewelling et al., 2020, ApJS, 251, 7). We caution that these differences are not significant enough to claim presence of an afterglow and could instead be due to a combination of filter differences or aperture differences for the catalog values.
Further observations are planned to monitor the variability of the source. We thank Jennifer Andrews, Veronica Firpo, Daniel May, and Aleksandar Cipota for the rapid scheduling and execution of these observations.
GCN Circular 39847
Subject
GRB250322A: STEP/T80S optical limits
Date
2025-03-23T04:56:42Z (2 months ago)
From
André Santos at Centro Brasileiro de Pesquisas Físicas (CBPF) <andsouzasanttos@gmail.com>
Via
Web form
A. Santos (CBPF), C. R. Bom (CBPF), C. D. Kilpatrick (Northwestern), L. Santana-Silva (CBPF), P. Darc (CBPF), Gabriel Teixeira (CBPF), C. Mendes de Oliveira (IAG-USP) report on behalf of the STEP collaboration:
We conducted optical follow up with the T80S 0.8-m robotic telescope (Santos et al., 2024, MNRAS, 529, 59) of the short gamma-ray burst GRB250322A discovered by the Swift-BAT and XRT instruments (GCN [39835](https://gcn.nasa.gov/circulars/39835), [39841](https://gcn.nasa.gov/circulars/39841)). The T80S observations started on Mar 23 00:08:38 UT (~8 hours after the trigger). We obtained images totaling 1800s (6x300s) in g-band with the T80S camera centered at the position of the latest XRT position (GCN [39841](https://gcn.nasa.gov/circulars/39841)) at R.A.=07:07:02.52 and Decl.=+07:11:35.3 (J2000).
After subtracting a Pan-STARRS template image from the T80S frames using photpipe (Rest et al., 2005), we do not detect any transient source in our difference image within the XRT error circle and derive a 3-sigma limiting magnitude of g > 22.48 mag.
GCN Circular 39849
Subject
GRB 250322A: AstroSat CZTI detection of a short burst
Date
2025-03-23T08:02:08Z (2 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
M. Tembhurnikar(IUCAA), J. Joshi (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short-duration GRB 250322A which was also detected by Swift/BAT (Gupta et.al., GCN Circ. 39835).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-03-22 16:06:12.85 UTC. The measured peak count rate, as measured with 10 ms binning, associated with the burst is 1322 (+851, -197) counts/s above the background in the combined data of all quadrants, with a total of 113 (+37, -25) counts. The local mean background count rate was 426 (+24, -61) counts/s. Using cumulative rates, we measure a T90 of 0.18 (+0.04, -0.03) s.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 39852
Subject
GRB 250322A: Gemini-North redshift of candidate host galaxy
Date
2025-03-23T13:40:27Z (2 months ago)
From
Wen-fai Fong at Northwestern University <wfong@northwestern.edu>
Via
Web form
W. Fong (Northwestern), A. J. Levan (Radboud), J.C. Rastinejad (Northwestern), N. R. Tanvir (Leicester), C. D. Kilpatrick (Northwestern) report on behalf of a larger collaboration:
We observed the putative host galaxy within the XRT localization (Goad et al., GCN 39841) of the short-duration GRB 250322A (Gupta et al., GCN 39835; Tembhurnikar et al., GCN 39849) using the Gemini Multi-Object Spectrograph (GMOS-N) mounted on Gemini-North telescope in Hawaii. We obtained 4x900-sec exposures using the R400 grating, spanning approximately 5000A to 9500A, starting at 2025-03-23 05:33:34 UT (approx 13.5 hr post-burst), under Program GN-2025A-Q-114 (PI: Fong).
The continuum is well-detected along with several prominent emission lines. In particular, we identify emission lines of H-alpha, NII, OIII (5007), H-beta and H-gamma, corresponding to a common redshift of z=0.42.
We thank Jennifer Andrews, Adam Smith, and Hyewon Suh for the rapid scheduling and execution of these observations.
GCN Circular 39855
Subject
GRB 250322A: Swift-XRT refined Analysis
Date
2025-03-23T16:54:19Z (2 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
M. Perri (SSDC & INAF-OAR), J.A. Kennea (PSU), D.N. Burrows (PSU), M.
A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB) and
P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 3.7 ks of XRT data for GRB 250322A, from 58 s to 22.2
ks after the BAT trigger. The data comprise 7 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=2.28 (+0.18, -0.17).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.09 (+0.49, -0.26). The
best-fitting absorption column is consistent with the Galactic value
of 2.7 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.6 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.7 (+/-2.3) x 10^21 cm^-2
Galactic foreground: 2.7 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.09 (+0.49, -0.26)
If the light curve continues to decay with a power-law decay index of
2.28, the count rate at T+24 hours will be 2.2 x 10^-7 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.9 x
10^-18 (1.2 x 10^-17) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01297832.
This circular is an official product of the Swift-XRT team.
GCN Circular 39859
Subject
GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
Date
2025-03-24T11:41:00Z (2 months ago)
From
Yu-Han Yang at University of Rome Tor Vergata <yyang@roma2.infn.it>
Via
Web form
Yu-Han Yang (U Rome), Eleonora Troja (U Rome), Rosa Becerra (U Rome), Massine El Kabir (U Rome) report on behalf of the ERC BHianca team:
We observed the bright galaxy within the localization of GRB 250322A (Gupta et al., GCN 39835, Goad et al. GCN 39841, Martin-Carillo et al. GCN 39842) with the X-Shooter spectrograph on the ESO VLT UT3 (Melipal). Observations began at T+32.2 hours and obtained a total of 2x600s spectra at an average airmass of about 1.2 and seeing of 0.6”.
We detect a bright continuum in the VIS and NIR arms and identify multiple emission lines, including H_alpha, H_beta, NII, OII, SII, at a common redshift of 0.4215±0.0005, consistent with measurement by Fong et al. (GCN 39852). We estimated that the chance coincidence between the bright galaxy and the XRT localization is <2% (Bloom et al. 2002), supporting it as a likely host galaxy of the GRB.
We thank the staff at the VLT, for the rapid execution of these observations.
GCN Circular 39861
Subject
GRB 250322A: Swift/UVOT Upper Limits
Date
2025-03-24T12:52:39Z (2 months ago)
From
Sam Shilling at Lancaster University <shilling.sam@gmail.com>
Via
Web form
S. P. R. Shilling (Lancaster U.) and R. Gupta (NASA/GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250322A
77 s after the BAT trigger (Gupta et al., GCN Circ. 39835).
No optical afterglow consistent with the enhanced XRT position
(Goad et al., GCN Circ. 39841) 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 77 226 147 >20.5
u_FC 291 541 246 >19.8
white 77 1711 411 >20.9
v 620 1760 136 >18.9
b 546 1686 117 >19.7
u 291 1661 343 >20.0
w1 669 1807 134 >19.2
m2 644 1785 136 >19.0
w2 596 1736 136 >19.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.153 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 39863
Subject
GRB 250322A: further NOT optical observations
Date
2025-03-24T16:33:39Z (2 months ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
B. Schneider (LAM), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. M. Kadela (NOT and NBI) report on behalf of a larger collaboration:
We secured a second observation of the field of GRB 250322A (Gupta et al., GCN 39835; Tembhurnikar et al., GCN 39849) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. Our observation consisted of 7x360 s in the r-band, with mean time 2025 Mar 23.88 UT (29.7 hr after the GRB). Unfortunately, the delivered seeing is worse than in our first epoch (Martin-Carrillo et al., GCN 39842), taken 4.65 hr after the GRB (1.5 vs 1.0").
The galaxy noted by Martin-Carrillo et al. (GCN 39842), Becerra et al. (GCN 39844, 39845), Kilpatrick & Fong (GCN 39846), and Fong et al. (GCN 39852) is detected in our second epoch. Image subtraction was carried out using Hotpants. No residuals are detected in the difference image, corresponding to a limiting magnitude of r > 23.2 (AB).
For the galaxy, we measure (in our first epoch) r = 22.04 +/- 0.12 (AB), calibrated against nearby Pan-STARRS point-like objects. Considering a 2.5”-radius XRT error circle (Goad et al., GCN 39841; Perri et al., 39855), we estimate a chance association probability of 2%, which provides moderate evidence for a physical association with the GRB.
GCN Circular 39867
Subject
GRB 250322A: Swift-BAT refined analysis
Date
2025-03-25T14:56:16Z (2 months ago)
From
Rahul Gupta at NASA GSFC <rahulbhu.c157@gmail.com>
Via
Web form
D. Sadaula (GSFC/UMBC), 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),
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 250322A (trigger #1297832)
(Gupta, et al., GCN Circ. 39835). The BAT ground-calculated position is
RA, Dec = 106.775, 7.197 deg which is
RA(J2000) = 07h 07m 06.1s
Dec(J2000) = +07d 11' 47.8"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted BAT light curve shows multi-peak emission.
T90 (15-350 keV) is 0.62 +- 0.05 sec (estimated error including systematics).
The time-averaged spectrum from T+0.00 to T+0.67 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
0.65 +- 0.19. The fluence in the 15-150 keV band is 1.5 +- 0.2 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.16 sec in the 15-150 keV band
is 1.4 +- 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/1297832
GCN Circular 39868
Subject
GRB 250322A: third epoch of NOT optical observations
Date
2025-03-25T17:11:56Z (2 months ago)
From
Benjamin Schneider at MIT <bschn@mit.edu>
Via
Web form
D. B. Malesani (DAWN/NBI and Radboud), B. Schneider (LAM), A. Martin-Carrillo (UCD), A. M. Kadela (NOT and NBI) report on behalf of a larger collaboration:
We secured a third observation of the field of GRB 250322A (Gupta et al., GCN 39835; Tembhurnikar et al., GCN 39849) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC imager. Our observation consisted of 5x600 s in the r-band, with mean time 2025 Mar 24.86 UT (2.19 days after the GRB). This observation reaches a depth comparable to our first epoch (Martin-Carrillo et al., GCN 39842), taken at 4.65 hr after the GRB, unlike our second epoch (Schneider et al., GCN 39863), which suffered from worse seeing.
Image subtraction of our third epoch from the first was carried out using HOTPANTS. No residuals are detected in the difference image, down to a limiting magnitude r > 23.8 AB (calibrated against Pan-STARRS). This limit is consistent with, but strengthens, our earlier determination r > 23.2 (Schneider et al., GCN 39863).
GCN Circular 39873
Subject
Konus-Wind detection of GRB 250322A (short)
Date
2025-03-26T12:50:11Z (2 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 short-duration GRB 250322A
(Swift-BAT detection: Gupta et al., GCN 39835; Sadaula et al., GCN 39867;
AstroSat-CZTI detection: Tembhurnikar et al., GCN 39849)
triggered Konus-Wind at T0=57974.215 s UT (16:06:14.215).
The burst light curve shows a multipeaked structure,
which starts at T0-0.102 s and has a total duration of ~0.18 s.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250322_T57974/
As observed by Konus-Wind, the burst
had a fluence of 1.02(-0.13,+0.14)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.086 s,
of 1.05(-0.24,+0.25)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
Since the brightest peak of the burst light curve
was detected before the trigger, the spectral analysis
was performed using the KW 3-channel light curve data.
Modelling the KW 3-channel time-integrated spectrum
(measured from T0-0.102 s to T0+0.078 s)
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = 0.22(-0.39,+0.52) and Ep = 472(-64,+85) keV.
Assuming the redshift z=0.42 (Fong et al., GCN 39852; Yang et al. GCN 39859)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is 4.9(-0.6,+0.7)x10^50 erg,
the peak luminosity L_iso is 7.1(-1.6,+1.7)x10^51 erg/s,
the rest-frame peak energy of the time-averaged spectrum
Ep,i,z is 670(-91,+121) keV.
With the obtained estimates, GRB 250322A is a clear outlier
in the 'Amati' relation derived for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021).
Meanwhile, in both Eiso-Ep,z and Liso-Ep,z planes, the GRB 250322A position
is consistent with short-hard (Type I) GRB population,
see http://www.ioffe.ru/LEA/GRBs/GRB250322_T57974/GRB250322A_rest_frame.pdf
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 39901
Subject
GRB 250322A: GRANDMA/TNOT optical upper limits
Date
2025-03-28T09:01:10Z (2 months ago)
From
duverne@apc.in2p3.fr
Via
Web form
E. Elhosseiny (NRIAG), N. Kochiashvili (AbAO), O. Pyshna (Caltech), Haichang Zhu (THU), A. Iskandar(XAO), Xiaofeng Wang (THU), Letian Wang (XAO) C. Andrade (UMN), S. Antier (OCA/IJCLAB), M. Coughlin (UMN), P-A. Duverne (APC), N. Guessoum (AUS), P. Hello (IJCLAB), S. Karpov (FZU), T. Pradier (Unistra/IPHC), D. Turpin (CEA-Saclay/Irfu) on behalf of the GRANDMA and Kilonova-Catcher collaborations:
The field of GRB 250322A (Gupta et al., GCN 39835, Goad et al. GCN 39841, Perri et al. GCN 39855, Sadaula et al. GCN 39867) has been imaged with the 80~cm Tsinghua-Nanshan Optical Telescope (TNOT) located at Nanshan Station of Xinjiang Astronomy observatory 1.1h post trigger with the r' filter for a total exposure of 100s.
We do not detect any new source at the enhanced Swift-XRT position (Goad et al. GCN 39841) down to r<21.2 AB mag (5-sigma) calibrated with nearby Pan-STARRS stars and without Galactic extinction correction.
All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2025 Acta Polytechnica, 65(1), 50-64).
We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023).
GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN Circular 40036
Subject
GRB 250322A: 10 GHz VLA radio upper limits
Date
2025-04-04T01:52:21Z (2 months ago)
From
Genevieve Schroeder at Cornell University <genevieveschroeder@u.northwestern.edu>
Via
Web form
G. Schroeder (Cornell), T. Laskar (Utah), W. Fong, J. Rastinejad (Northwestern) report:
We observed the position of the short GRB 250322A (Gupta et al., GCN 39835;
Tembhurnikar et al., GCN 39849; Ridnaia et al., GCN 39873) with the Karl G. Jansky Very Large Array (VLA) under program 25A-063 (PI Schroeder) beginning on 2025 March 25 at 22:07 UT (3.25 days post-burst) for 1 hour at a mean frequency of 10 GHz.
Based on preliminary analysis, we do not detect any radio emission at or near the position of the XRT afterglow (Perri et al., GCN 39855), to a 3 sigma limit of 20 microJy. We additionally do not detect the putative host galaxy in our image (Martin-Carrillo et al., GCN 39842; Becerra et al., GCN 39844; 39845l; Kilpatrick & Fong, GCN 39846; Fong et al., GCN 39852, Schneider et al., GCN 39863). Assuming a redshift of z = 0.42 (Fong et al., GCN 39852; Yang et al. GCN 39859), these observations imply a limit on the radio-inferred star formation rate of < 18 M_sol/year (following the formalism of Greiner et al. 2016). Using the putative host redshift, the lack of radio afterglow detection implies a radio luminosity of < 1.3e29 erg/Hz/s, which is a factor of >~4 lower than the median radio luminosity of radio-detected short GRBs at a similar epoch and rest frame time (Laskar et. al. 2022). Overall, this limit places GRB 250322A in the bottom 25% of radio-observed short GRBs with redshift determinations, in terms of radio luminosity.
We thank the VLA staff for quickly approving and executing these observations.