TITLE: GCN CIRCULAR
NUMBER: 35820
SUBJECT: GRB 240225B: Liverpool Telescope optical afterglow observations
DATE: 24/02/27 16:49:48 GMT
FROM: Jacob Wise at Liverpool John Moores University <J.L.Wise(a)2022.ljmu.ac.uk>
J. Wise, A. Bochenek, D. A. Perley (LJMU) report:
We report observations the optical afterglow GOTO24tz/AT2024dgu (Gompertz et al, GCN 35805; D'Ai et al, GCN 35810; Xu, D., GCN 35812; Malesani et al, GCN 35819) associated with GRB 240225B (Nakajima et al, GCN 35796; Joshi et al, GCN 35798; Kawakubo et al, GCN 35811) using the IO:O optical camera on the 2-meter Liverpool Telescope. Observations commenced at 2024-02-27 00:20:06.433 UTC, approximately 28.1 hours after the burst. 2x75s exposures were taken using the SDSS g, r, i, and z filters, with Pan-STARRS foreground stars used for calibration. Conditions were generally favourable throughout.
The transient was well detected in all 4 filters, with magnitudes listed in the following table. Times since burst for each filter were calculated using the strongest peak found with the AstroSat CsI anticoincidence (Veto) detector as reference (Joshi et al, GCN 35798).
MJD Time since burst (hours) Filter Mag. (AB)
60367.01396 28.135 g 19.97 ± 0.12
60367.01624 28.189 r 19.51 ± 0.15
60367.01848 28.243 i 19.44 ± 0.10
60367.02073 28.297 z 19.28 ± 0.14
Magnitudes are not corrected for foreground extinction.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35820.
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TITLE: GCN CIRCULAR
NUMBER: 35819
SUBJECT: GRB 240225B: NOT optical observations
DATE: 24/02/27 12:24:03 GMT
FROM: Daniele B. Malesani at IMAPP / Radboud University <d.malesani(a)astro.ru.nl>
D. B. Malesani (DAWN/NBI and Radboud Univ.), B. P. Gompertz (Birmingham), Z.-P. Zhu, D. Xu (NAOC), L. Izzo (INAF/OACN and DARK/NBI), on behalf of a larger collaboration, and R. Forsberg (Lund), S. Bijavara Seshashayana (Malmo univ.), report:
We observed the optical afterglow (Gompertz et al., GCN 35805; D'Ai et al., GCN 35810) of GRB 240225B (Nakajima et al., GCN 35796; Joshi et al., GCN 35798; Kawakubo et al., GCN 35811). We used the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started on 2024 Feb 26.934 UT (1.09 days after the MAXI trigger time).
In a single 300-s exposure in the r band, we measure r = 19.53 +- 0.03 (AB), calibrated against nearby Pan-STARRS stars.
This confirms the decay of the GOTO candidate noted by Liu et al. (GCN 35812). Assuming an unbroken power law decay (F propto t^-alpha) between their observation and ours, the inferred decay slope is alpha = 1.8 +- 0.3, suggesting a faster decay then indicated in Liu et al. (GCN 35812).
View this GCN Circular online at https://gcn.nasa.gov/circulars/35819.
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TITLE: GCN CIRCULAR
NUMBER: 35818
SUBJECT: GRB 240218A: CMO SAI NIR upper limit
DATE: 24/02/27 12:04:54 GMT
FROM: Alexei Pozanenko at IKI, Moscow <apozanen(a)iki.rssi.ru>
A. Volnova (IKI), A. Pozanenko (IKI), B. Safonov (SAI MSU), A. Tatarnikov (SAI MSU), N. Pankov (HSE, IKI), S. Belkin (IKI, HSE) report on behalf of IKI-GRB-FuN:
We observed the field of GRB 240218A (Page et al., GCN 35742; Veres et al., GCN 35755; Svinkin et al., GCN 35758) with the Astronomical Near-Infrared Camera-spectrograph (ANC) of the 2.5-meter telescope (SAI-2.5) of the Caucasian Mountain Observatory (CMO SAI) on Feb.23, 2024 starting on 22:16:46 UT, taking 47 frames of 1-minute exposure in the H-band under moderate conditions with seeing of 1.4". We do not detect the NIR counterpart (D'Avanzo et al., GCN 35747; Saccardi et al., 35756; Schroeder et al., GCN 35794; Rossi et al., GCN 35762; de Wet et al., GCN 35765) within the enhanced XRT error box (Evans et al., GCN 35748).
Preliminary photometry of the stacked image is following
Date UT start t-T0 Filter Exp. OT UL(3sigma)
(mid, days) (s)
2024-02-23 22:16:46 5.86743 H 47*59 n/d 20.8
The photometry is based on nearby 2MASS stars:
2MASS_ID RA Dec H errH
10471145+0118146 10:47:11.45808 +01:18:14.6268 15.422 0.098
10471594+0117439 10:47:15.94200 +01:17:43.9836 14.562 0.062
10471583+0116464 10:47:15.83136 +01:16:46.4844 14.243 0.045
View this GCN Circular online at https://gcn.nasa.gov/circulars/35818.
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TITLE: GCN CIRCULAR
NUMBER: 35817
SUBJECT: Fermi GRB 240226A: Global MASTER-Net observations report
DATE: 24/02/27 11:30:55 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile
(Observatorio Astronomico Felix Aguilar OAFA),
R. Rebolo, M. Serra
(The Instituto de Astrofisica de Canarias),
D. Buckley
(South African Astronomical Observatory),
O.A. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),
A. Tlatov, D. Dormidontov
(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich
(Blagoveschensk Educational State University)
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 240226A ( Fermi GBM team, GCN 35804) errorbox 16246 sec after notice time and 16283 sec after trigger time at 2024-02-27 00:04:30 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 79 deg. The sun altitude is -45.7 deg.
The galactic latitude b = -23 deg., longitude l = 355 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2386845
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
16314 | 2024-02-27 00:04:30 | MASTER-SAAO | (19h 06m 29.14s , -46d 29m 24.3s) | C | 60 | 16.3 |
16314 | 2024-02-27 00:04:30 | MASTER-SAAO | (18h 59m 24.88s , -46d 17m 34.7s) | C | 60 | 16.5 |
16393 | 2024-02-27 00:05:50 | MASTER-SAAO | (18h 56m 09.53s , -42d 41m 16.4s) | C | 60 | 16.0 |
16393 | 2024-02-27 00:05:50 | MASTER-SAAO | (18h 49m 32.02s , -42d 29m 23.5s) | C | 60 | 16.4 |
16473 | 2024-02-27 00:07:10 | MASTER-SAAO | (18h 49m 52.02s , -44d 33m 18.5s) | C | 60 | 16.5 |
16473 | 2024-02-27 00:07:10 | MASTER-SAAO | (18h 43m 01.98s , -44d 21m 24.2s) | C | 60 | 16.8 |
16633 | 2024-02-27 00:09:50 | MASTER-SAAO | (19h 04m 23.32s , -44d 22m 12.6s) | C | 60 | 16.7 |
16713 | 2024-02-27 00:11:09 | MASTER-SAAO | (19h 02m 49.54s , -48d 22m 23.9s) | C | 60 | 16.4 |
16713 | 2024-02-27 00:11:09 | MASTER-SAAO | (18h 55m 29.79s , -48d 10m 32.0s) | C | 60 | 16.8 |
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/35817.
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TITLE: GCN CIRCULAR
NUMBER: 35816
SUBJECT: Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
DATE: 24/02/27 06:29:34 GMT
FROM: Simone Dichiara at Pennsylvania State University <sbd5667(a)psu.edu>
S. Dichiara (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
Swift-BAT triggers 1217733, 1217734 and 1217736 are also related to the ongoing star tracker loss-of-lock event, and they are not of astrophysical interest.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35816.
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TITLE: GCN CIRCULAR
NUMBER: 35815
SUBJECT: Swift-BAT triggers 1217729-1217732 are not astrophysical
DATE: 24/02/27 05:36:15 GMT
FROM: Simone Dichiara at Pennsylvania State University <sbd5667(a)psu.edu>
S. Dichiara (PSU) reports on behalf of the Neil Gehrels Swift Observatory Team:
Swift triggers 1217729, 1217731 and 1217732 were caused by a star track loss-of-lock event, and are not interesting astrophysical events.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35815.
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TITLE: GCN CIRCULAR
NUMBER: 35813
SUBJECT: Fermi Gamma-ray Burst Monitor trigger 730618809/240226236 is not a GRB
DATE: 24/02/27 00:17:45 GMT
FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com>
L. Scotton (UAH) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:
"The Fermi Gamma-ray Burst Monitor (GBM) trigger 730618809/240226236 at 05:40:04.58 UT
on 26 February 2024 was initially classified as a GRB, and named GRB 240226B (GCN 35809).
This trigger is in fact not due to a GRB, but to a solar flare."
View this GCN Circular online at https://gcn.nasa.gov/circulars/35813.
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TITLE: GCN CIRCULAR
NUMBER: 35812
SUBJECT: GRB 240225B: Nanshan/HMT optical afterglow detection
DATE: 24/02/26 23:18:55 GMT
FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn>
X. Liu,, J. An, S.Y. Fu, S.Q. Jiang, Z.P. Zhu, T.H. Lu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:
We observed the field of GRB 240225B detected by MAXI (Nakajima et al., GCN 35796) and AstroSat (Joshi et al., GCN 35798) using the HMT-0.5m telescope with big FOV (~1 deg^2) located at Nanshan, Xinjiang, China. Photometry was carried out twice in the same night without any filter..
A slowly decaying uncatalogued optical transient is detected at coordinates
R.A. = 08:33:26.80 (J2000)
Dec. = +27:04:32.77 (J2000)
with an uncertainty of radius ~ 0.3 arcsec, with r ~ 18.9 +/- 0.1 mag (AB) at a median time of 18.90 hr post-burst, calibrated with the nearby PanSTAR field. This OT is positionally at the border of the error circle of Swift/XRT "Source 1" (D'Ai et al., GCN 35810), and is also consistent with and thus confirming the GOTO candidate (Gompertz et al., GCN 35805).
We thus think the OT is the optical afterglow of GRB 240225B.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35812.
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TITLE: GCN CIRCULAR
NUMBER: 35811
SUBJECT: GRB 240225B: CALET Gamma-Ray Burst Monitor detection
DATE: 24/02/26 22:35:56 GMT
FROM: Yuta Kawakubo at Louisiana State University <kawakubo1(a)lsu.edu>
Y. Kawakubo (LSU), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 240225B (MAXI/GSC detection: Nakajima et al.,
GCN Circ. 35796; AstroSat CZTI detection: Joshi et al., 35798)
was detected in the ground analysis of the CALET Gamma-ray
Burst Monitor (CGBM) data around 20:12:08.50 on 25 February
2024 (referenced to the AstroSat detection: GCN Circ. 35798)
(http://cgbm.calet.jp/cgbm_trigger/flight/1392926875/index.html).
The main episode that AstroSat CZTI detected was seen by all CGBM
detectors. Also, a hint of emission that MAXI/GSC detected was seen
in the HXM data around T+230 s.
The burst light curve of the main episode shows a multi-peaked
structure that starts at T-7.6 sec, and ends at T+31.1 sec. The T90
and T50 durations measured by the SGM data are 33.0 +/- 0.9 sec
and 17.1 +/- 1.3 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1392926875/index.html
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35811.
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