TITLE: GCN CIRCULAR
NUMBER: 40637
SUBJECT: GRB 250602A: GECAM detection
DATE: 25/06/06 04:33:43 GMT
FROM: zhengchao_astro(a)foxmail.com
Chao Zheng, Chen-Wei Wang, Yan-Qiu Zhang, Shao-Lin Xiong, Yue Huang (IHEP) report on behalf of GECAM team:
GECAM-A detected burst GRB 250602A at 2025-06-02T03:04:31.310 UTC (denoted as T0), which was also detected by Fermi/GBM (Fermi GBM team, GCN #40602).
According to the GECAM-A light curves in about 70-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of about 8.68 s.
The GECAM-A light curve can be found here:
https://www.bursthub.cn//admin/static/gecamgrb250602A.png
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
View this GCN Circular online at https://gcn.nasa.gov/circulars/40637.
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TITLE: GCN CIRCULAR
NUMBER: 40635
SUBJECT: The EP-WXT trigger 01709177873 is likely a flaring star
DATE: 25/06/06 02:53:28 GMT
FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn>
T. Y. Lian, R. D. Liang (NAOC), H. L. Peng (NNU), T. C. Zheng (PMO), W. Yuan (NAOC) on behalf of the Einstein Probe (EP) team:
The EP-WXT trigger 01709177873 at the time of 2025-06-05T18:51:47, is likely a stellar flare associated with RX J1553.0+4457. The estimated flux of the flare is around 1.2e-10 erg/s/cm^2 in 0.5-10.0 keV, corresponding to an X-ray luminosity of around 2e31 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
View this GCN Circular online at https://gcn.nasa.gov/circulars/40635.
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TITLE: GCN CIRCULAR
NUMBER: 40634
SUBJECT: GRB 250605A: LT optical observations
DATE: 25/06/05 22:51:33 GMT
FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk>
B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham), A. Martin-Carrillo (UCD), G. Corcoran (UCD) and D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration:
We initiated follow-up observations of GRB 250605A (Gupta et al., GCN 40633) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 20:48:52.89 UT, ~2 hours after the Swift/BAT trigger, and consisted of 10x60 s exposures in the SDSS i filter. Observations were taken close to twilight, at high airmass, and the target was 28 deg from the moon at 77% illumination.
Within the Swift/XRT error box, we detect a possible optical counterpart, not present in archival imaging, with an AB magnitude of i ~ 21.1 at RA = 11:07:49.7, Dec = -19:47:15.4. However, this detection is only significant at the 2-sigma level and further, deeper observations are required to confirm its reality. Formally, we measure a 3-sigma upper limit of i > 20.6 within the XRT localisation region.
We also note the presence of a faint source visible in the Legacy Survey archival imaging with an AB magnitude of i = 23.54. The source position is consistent with the possible optical counterpart, and may be the host galaxy of GRB 250605A.
Magnitudes are calibrated against nearby Pan-STARRS stars and not corrected for galactic extinction.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40634.
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TITLE: GCN CIRCULAR
NUMBER: 40633
SUBJECT: GRB 250605A: Swift detection of a burst
DATE: 25/06/05 19:08:03 GMT
FROM: K.L. Page at U Leicester <klp5(a)leicester.ac.uk>
R. Gupta (NASA GSFC), J. J. DeLaunay (PSU), S. Dichiara (PSU),
C. Gronwall (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
H. A. Krimm (NSF), M. J. Moss (GSFC), K. L. Page (U Leicester),
T. M. Parsotan (GSFC), M. H. Siegel (PSU) and M. A. Williams (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:
At 18:52:31.27 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250605A (trigger=1321323). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 166.977, -19.795 which is
RA(J2000) = 11h 07m 54s
Dec(J2000) = -19d 47' 42"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a complex light curve
with one strong pulse between T0-2 sec to T0+10 sec and a second dimmer but
broad pulse between T0+40 sec to T0+100 sec. The peak count rate was 4,000
counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 18:54:09.2 UT, 98.0 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 166.9571, -19.7882 which is equivalent to:
RA(J2000) = 11h 07m 49.70s
Dec(J2000) = -19d 47' 17.5"
with an uncertainty of 5.5 arcseconds (radius, 90% containment). This
location is 71 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy.
UVOT took a finding chart exposure of 144 seconds with the White filter
starting 106 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 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
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
0.039.
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/)
View this GCN Circular online at https://gcn.nasa.gov/circulars/40633.
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TITLE: GCN CIRCULAR
NUMBER: 40632
SUBJECT: Swift GRB250605.79: Global MASTER-Net observations report
DATE: 25/06/05 18:56:40 GMT
FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru>
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO),
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) was pointed to the Swift GRB250605.79 (trigger No 1321323,11h 07m 54.48s , -19d 47m 42.0s, R=0.05) errorbox 16 sec after notice time and 37 sec after trigger time at 2025-06-05 18:53:08 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 31 deg. The sun altitude is -39.9 deg.
The galactic latitude b = 37 deg., longitude l = 273 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2893644
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
43 | MASTER-SAAO | C | 10 | 17.9 |
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/40632.
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TITLE: GCN CIRCULAR
NUMBER: 40631
SUBJECT: Konus-Wind detection of GRB 250601A
DATE: 25/06/05 15:52:19 GMT
FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru>
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 250601A
(Fermi GBM detection: Fermi GBM team, GCN 40596; Sharma et al., GCN 40621;
Swift/BAT-GUANO localization: DeLaunay et al., GCN 40600)
triggered Konus-Wind at T0=62975.326 s UT (17:29:35.326).
The burst light curve shows a multi-peaked pulse,
which starts at ~T0-0.5 s and has a total duration of ~0.8 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250601_T62975/
As observed by Konus-Wind, the burst
had a fluence of 2.02(-0.28,+0.31)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.004 s,
of 7.00(-2.01,+2.06)x10^-6 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 T0-0.492 s to T0+0.276 s)
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = 0.31(-0.37,+0.52) and Ep = 436(-62,+76) keV.
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40631.
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TITLE: GCN CIRCULAR
NUMBER: 40630
SUBJECT: IPN triangulation of GRB 250404B
DATE: 25/06/05 15:32:58 GMT
FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
E. Burns on behalf of the IPN,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu,
and J. DeLaunay on behalf of the Swift-BAT team,
G. Waratkar, J.Joshi, V. Bhalerao, D. Bhattacharya,
and S. Vadawale, on behalf of the Astrosat-CZTI team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 250404B
(AstroSat CZTI detection: Salunke et al., GCN Circ. 40078)
was detected by Konus-Wind, Swift (BAT), AstroSat (CZTI),
and Mars-Odyssey (HEND) at about 66970 s UT (18:36:10).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
273.629 (18h 14m 31s) -2.251 ( -2d 15' 03")
Corners:
273.108 (18h 12m 26s) -2.676 ( -2d 40' 35")
274.127 (18h 16m 31s) -1.659 ( -1d 39' 32")
274.151 (18h 16m 36s) -1.842 ( -1d 50' 30")
273.131 (18h 12m 31s) -2.866 ( -2d 51' 58")
---------------------------------------------
The error box area is 768 sq. arcmin, and its maximum
dimension is 1.6 deg (the minimum one is 9 arcmin).
The Sun distance was 100 deg.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250404_T66970/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40630.
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TITLE: GCN CIRCULAR
NUMBER: 40629
SUBJECT: IPN triangulation of GRB 250529A
DATE: 25/06/05 15:23:42 GMT
FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru>
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu,
and J. DeLaunay on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The long-duration GRB 250529A
(Fermi-GBM detection: Fermi GBM team, GCN 40567)
was detected by Fermi (GBM), Konus-Wind, Swift (BAT),
and Mars-Odyssey (HEND) at about 13576 s UT (03:46:16).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
18.193 (01h 12m 46s) +58.274 (+58d 16' 25")
Corners:
21.244 (01h 24m 58s) +56.039 (+56d 02' 19")
14.840 (00h 59m 22s) +60.456 (+60d 27' 22")
14.829 (00h 59m 19s) +60.366 (+60d 21' 57")
21.225 (01h 24m 54s) +55.944 (+55d 56' 37")
---------------------------------------------
The error box area is 1252 sq. arcmin, and its maximum
dimension is 5.6 deg (the minimum one is 4 arcmin).
The Sun distance was 48 deg.
This localization may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM (GCN 40567) localization.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250529_T13600/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40629.
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TITLE: GCN CIRCULAR
NUMBER: 40628
SUBJECT: The EP-WXT trigger 01709177837 is likely a flaring star
DATE: 25/06/05 09:41:18 GMT
FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn>
S. Q. Jiang (NAOC), T. C. Zheng (PMO), X. Y. Zhou (PRIC), H. W. Pan (NAOC) on behalf of the Einstein Probe (EP) team:
The EP-WXT trigger 01709177837 at the time of 2025-06-05T09:24:19, is likely a stellar flare associated with RV Crt. The estimated flux of the flare is around 8e-11 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 4e32 erg/s.
Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics).
View this GCN Circular online at https://gcn.nasa.gov/circulars/40628.
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