TITLE: GCN CIRCULAR
NUMBER: 40142
SUBJECT: GRB 250412A: AstroSat CZTI detection
DATE: 25/04/14 06:02:43 GMT
FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar(a)iitb.ac.in>
M. Tembhurnikar (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 long-duration GRB 250412A which was also detected by Fermi GBM (Trigger Num. 766173972).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-04-12 18:06:07.50 UTC. The measured peak count rate associated with the burst is 109 (+29, -26) counts/s above the background in the combined data of three quadrants (out of four), with a total of 411 (+108, -138) counts. The local mean background count rate was 204 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 6.9 (+2.1, -2.9) s.
The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-04-12 18:06:08 UTC. The measured peak count rate associated with the burst is 219 (+64, -53) counts/s above the background in the combined data of all quadrants, with a total of 768 (+244, -251) counts. The local mean background count rate was 1231 (+6, -7) counts/s. We cannot reliably estimate the T90 for this GRB in the veto detector data.
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
View this GCN Circular online at https://gcn.nasa.gov/circulars/40142.
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TITLE: GCN CIRCULAR
NUMBER: 40141
SUBJECT: EP250404a: Nanshan 0.43m Telescope optical observatios
DATE: 25/04/13 13:41:02 GMT
FROM: Abdusamatjan Iskandar at XAO,CAS <abudu(a)xao.ac.cn>
S. Yaqup, J.Z. Liu, A. Iskandar, Y. Zhang, A. Esamdin, C.H. Bai, T.H. Zhong (XAO) report on behalf of optical group of the XAO:
We observed the field of the EP250404a (Einstein Probe mission, Trigger ID 01709133918) with the 0.43m telescope at Nanshan Station of Xinjiang Astronomical Observatory (XAO). The observations were started at 2025-04-04T14:54:21(UTC), and obtained a series of gri band images.
The optical afterglow (Jiang et al., GCN 40052; Perez-Garcia et al., GCN 40053; Du et al., GCN 40058;
Zhu et al., GCN 40061; Konno et al., GCN 40063; Odeh et al, GCN 40064; He et al., GCN 40069;
Perez-Fournon et al., GCN 40071; Jelinek et al., GCN 40072; Rakotondrainibe et al, GCN 40073;
Taguchi et al., GCN 40074; Ruocco et al., GCN 40076; Martin-Carrillo et al., GCN 40080; Pavoni et al.,
GCN 40083; Li et al., GCN 40084; Yin et al., GCN 40085; Pankov et al., GCN 40086; Chu Chen et al.,
GCN 40088 and Chen et al., GCN 40089) was clearly detected at position R.A. = 125.0606 deg, DEC = 35.5282 deg J2000.
The preliminary photometric magnitudes are below:
Observation Start-Time T-T0(hr) Exposure Filter Mag. Err.
2025-04-04 14:54:21 0.583 060s g 16.914 0.106
2025-04-04 14:55:56 0.604 060s r 16.067 0.076
2025-04-04 14:57:12 0.626 060s i 15.610 0.080
2025-04-04 14:58:29 0.648 060s g 17.090 0.108
2025-04-04 14:59:48 0.669 060s r 16.294 0.072
2025-04-04 15:01:05 0.690 060s i 15.940 0.105
2025-04-04 15:02:22 0.712 060s g 17.484 0.108
2025-04-04 15:03:41 0.734 060s r 16.398 0.071
2025-04-04 15:04:58 0.755 060s i 15.965 0.099
2025-04-04 15:11:08 0.858 120s i 16.388 0.067
2025-04-04 15:13:25 0.897 120s g 17.690 0.106
2025-04-04 15:15:44 0.934 120s r 17.066 0.077
2025-04-04 15:18:01 0.972 120s i 16.496 0.074
2025-04-04 15:20:19 1.011 120s g 17.735 0.096
2025-04-04 15:22:38 1.049 120s r 17.030 0.059
2025-04-04 15:24:54 1.087 120s i 16.736 0.061
2025-04-04 15:27:12 1.126 120s g 18.184 0.105
2025-04-04 15:29:31 1.164 120s r 17.407 0.070
2025-04-04 15:31:48 1.202 120s i 17.033 0.067
2025-04-04 15:34:27 1.247 200s g 18.252 0.090
2025-04-04 15:52:56 1.554 200s r 17.719 0.085
2025-04-04 15:56:33 1.615 200s i 17.332 0.088
2025-04-05 16:00:10 1.676 200s g 18.508 0.116
2025-04-05 16:03:50 1.736 200s r 18.121 0.087
2025-04-05 16:07:27 1.796 200s i 17.742 0.101
2025-04-05 16:11:04 1.857 200s g 18.335 0.093
2025-04-05 16:14:43 1.917 200s r 17.924 0.070
2025-04-05 16:18:19 1.978 200s i 17.569 0.090
2025-04-05 16:25:36 2.099 200s r 18.261 0.081
2025-04-05 16:36:30 2.280 200s r 18.681 0.117
2025-04-05 16:40:06 2.341 200s i 18.319 0.136
2025-04-05 16:43:45 2.402 200s g 18.815 0.129
2025-04-05 16:47:42 2.467 300s g 18.713 0.123
2025-04-05 16:52:59 2.555 300s r 18.799 0.132
2025-04-05 16:58:16 2.643 300s i 17.798 0.094
2025-04-05 17:03:34 2.732 300s g 19.368 0.188
2025-04-05 17:08:52 2.820 300s r 18.608 0.111
The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40141.
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TITLE: GCN CIRCULAR
NUMBER: 40138
SUBJECT: GRB 250411A: DDOTI Optical Observations
DATE: 25/04/12 15:05:03 GMT
FROM: sahil.atri(a)students.uniroma2.eu
Sahil Atri (U Roma), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Eleonora Troja (U Roma), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM) and Margarita Pereyra (UNAM) report:
We observed the field of the GRB 250411A detected by Fermi/GBM (Fermi GBM Team, GCN 40136) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-04-12 UTC from 07:13 UTC to 12:05 UTC (from T+12.9 h to T+17.8 h after the trigger) and obtained a total exposure of 1.94 hours.
Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect no evident uncatalogued sources within the observed field to a 10-sigma limiting AB magnitude of:
w > 18.93-19.65
This value is not corrected for the Galactic extinction.
We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40138.
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TITLE: GCN CIRCULAR
NUMBER: 40137
SUBJECT: Fermi GRB 250411A: Global MASTER-Net observations report
DATE: 25/04/11 20:31:21 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250411A ( Fermi GBM team, GCN 40136) errorbox 7115 sec after notice time and 7149 sec after trigger time at 2025-04-11 20:16:18 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 75 deg. The sun altitude is -49.3 deg.
The galactic latitude b = 24 deg., longitude l = 1 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2840071
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
7179 | 2025-04-11 20:16:18 | MASTER-SAAO | (16h 18m 59.95s , -13d 56m 46.1s) | C | 60 | 17.6 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40137.
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TITLE: GCN CIRCULAR
NUMBER: 40135
SUBJECT: GRB 250407A: Continued KAIT/Nickel optical observations
DATE: 25/04/11 07:26:26 GMT
FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu>
Asia deGraw, Gracelynn Jost, WeiKang Zheng and Alexei V. Filippenko
(UC Berkeley) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, continued the observation of GRB 250407A optical
afterglow (Zheng et al., GCN 40116; Ducoin et. al, GCN 40117;
Pérez-Fournon et. al, GCN 40125; Pankov et al., GCN 40133) at
03:35 UT, Apr. 09, namely ~1.55 days after burst. A set of clear
(roughly R) filter images were obtained. Compared to our earlier
observations (Zheng et al., GCN 40116), the reported afterglow had
faded to ~20.8 +/- 0.3 mag (Vega) measured in our coadd image.
Additional R band images with 600sx5 exposure were obtained with the
1-m Nickel telescopes located at Lick observatory, starting at ~1.55
days after burst. We measure the brightness of R ~ 21.0 +/- 0.2 mag
(Vega), similar to the R band magnitude reported by Pankov et al.
(GCN 40133) at a slightly later epoch (1.98 days), suggesting that
this might be the host galaxy of GRB 250407A as suggested by Ducoin
et. al, GCN 40117).
View this GCN Circular online at https://gcn.nasa.gov/circulars/40135.
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TITLE: GCN CIRCULAR
NUMBER: 40134
SUBJECT: GRB 250314A: e-MERLIN observations
DATE: 25/04/10 20:17:58 GMT
FROM: Aishwarya L Thakur at INAF-IAPS, Rome <aishth(a)outlook.com>
A.L. Thakur [1], G. Bruni [1], L. Piro [1] and G. Gianfagna [1] report:
We observed the z=7.3 GRB 250314A (SVOM GCN 39719, VLT/X-shooter GCN 39732, GTC/OSIRIS+ GCN 39743), with the e-MERLIN radio telescope under project RR19004 (PI: Thakur) at 5 GHz starting from Mar 31 (~17 days post-GRB) for three runs of ~12 hours each.
1331+3030 was used for flux scale calibration, and 1332-0509 for complex gain. The beam size was 122x34 milli-arcsec. Data were reduced with the e-MERLIN pipeline and imaged with CASA. The image RMS was 18 uJy/beam.
We do not find statistically significant emission at a level above 5-sigma at the position of the NOT counterpart (GCN 39727) or in the broader 2x2 arcsec field. We thus set a 5-sigma upper limit of 90 uJy at 5 GHz.
Further e-MERLIN observations are planned.
We thank the e-MERLIN director for promptly approving these DDT observations and acknowledge Justin Bray's excellent support in scheduling and executing them. e-MERLIN is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC, part of UK Research and Innovation.
—------------------------
[1] INAF-IAPS
View this GCN Circular online at https://gcn.nasa.gov/circulars/40134.
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TITLE: GCN CIRCULAR
NUMBER: 40133
SUBJECT: GRB 250407A: Mondy and AbAO Optical Observations
DATE: 25/04/10 09:17:26 GMT
FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com>
N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze (AbAO) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 250407A detected by Fermi (the Fermi GBM team, GCN 40104; Preis & Greiner, GCN 40105; Mukherjee & Meegan, GCN 40114), SRG (Molkov et. al, GCN 40110), Swift (Evans, GCN 40111; Dichiara et. al, GCN 40113), EP (Zheng et. al, GCN 40119), Konus-Wind (Frederiks et. al, GCN 40121) with the 1.5-meter AZT-33IK telescope of the Sayan Solar Observatory (Mondy), and the 0.7-meter AS-32 telescope of the Abastumani Astrophysical Observatory (AbAO). The R-band observations began on 2025-04-08 at 18:01:15 UT, i.e. ~1.12 days since trigger at AbAO. The optical counterpart (Zheng & Fillipenko, GCN 40116; Ducoin et. al, GCN 40117; Pérez-Fournon et. al, GCN 40125) is marginally detected in the stacked image taken with AZT-33IK. The preliminary photometry is as follows:
Date UTstart Exptime t-T0 Filter OT Err UL Telescope
(s) (mid, days) (3sigma)
2025-04-08 18:01:15 89*60 1.12319 R n/d n/d 17.5 AS-32
2025-04-09 14:42:55 34*120 1.97818 R 21.0 0.3 21.2 AZT-33IK
Ref. stars
USNO-B1.0
RA Dec R2mag
110.81407 36.79950 15.86
110.78017 36.81867 14.55
The photometry is based on nearby USNO-B1.0 stars (R2 magnitudes) and has not been corrected for the Galactic extinction.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40133.
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