TITLE: GCN CIRCULAR
NUMBER: 36631
SUBJECT: GRB 240606B: Swift-XRT afterglow detection
DATE: 24/06/07 03:12:47 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini
(INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), D.N.
Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), A.P. Beardmore (U.
Leicester) and P.A. Evans (U. Leicester) reports on behalf of the
Swift-XRT team:
Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 240606B, collecting 4.0 ks of Photon
Counting (PC) mode data between T0+22.9 ks and T0+35.1 ks.
Four uncatalogued X-ray sources are detected consistent with being
within 493 arcsec of the BAT-GUANO position, of which one ("Source 1")
is fading with 2.1 sigma significance and is undetected by eRosita to
deeper upper limits. It is likely the afterglow.
Using 3507 s of PC mode data and 3 UVOT images, we find an enhanced XRT
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 40.29507, -60.61201 which is
equivalent to:
RA (J2000): 02h 41m 10.82s
Dec(J2000): -60d 36' 43.2"
with an uncertainty of 2.4 arcsec (radius, 90% confidence). This
position is 53 arcsec from the BAT-GUANO position.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.2 (+0.9, -1.0).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+0.4, -0.3). The
best-fitting absorption column is 6 (+11, -4) x 10^20 cm^-2,
consistent with the Galactic value of 2.4 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 4.1 x 10^-11 (4.5 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 6 (+11, -4) x 10^20 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.7 (+0.4, -0.3)
If the light curve continues to decay with a power-law decay index of
1.2, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.2 x
10^-13 (5.7 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/00021695.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021695.
This circular is an official product of the Swift-XRT team.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36631.
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TITLE: GCN CIRCULAR
NUMBER: 36630
SUBJECT: Swift GRB240606.15: Global MASTER-Net observations report
DATE: 24/06/07 02:14:24 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) was pointed to the Swift GRB240606.15 (trigger No 1235109,00h 48m 30.00s , -19d 44m 49.2s, R=0.05) errorbox 80973 sec after notice time and 81005 sec after trigger time at 2024-06-07 02:03:52 UT, with upper limit up to 17.8 mag. The observations began at zenith distance = 58 deg. The sun altitude is -43.7 deg.
The galactic latitude b = -82 deg., longitude l = 122 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2483894
We obtain a following upper limits.
Tmid-T0 | Site |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________
81096 | MASTER-SAAO | C | 180 | 17.8 |
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/36630.
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TITLE: GCN CIRCULAR
NUMBER: 36629
SUBJECT: GRB 240606B: Swift ToO observations
DATE: 24/06/06 19:54:54 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
P. A. Evans (U. Leicester) reports on behalf of the Swift team:
Swift has initiated a ToO observation of the GECAM GRB 240606B.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021695
Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the GECAM event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a
GCN Circular after manual consideration.
Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
This circular is an official product of the Swift-XRT team.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36629.
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TITLE: GCN CIRCULAR
NUMBER: 36628
SUBJECT: GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
DATE: 24/06/06 17:48:32 GMT
FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com>
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:
Swift/BAT did not localize GRB 240606B onboard (T0: 2024-06-06T13:33:06.5 UTC, GECAM trigger 392).
The GECAM notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).
Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.
The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 4.096 s analysis time bin starting at T0 - 2.048 s with a sqrt(TS) of 28.9.
An arcminute localization is found with DeltaLLHOut of 29.3 and a DeltaLLHPeak of 17.9.
See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.
The BAT position is
RA, Dec = 40.234, -60.637 deg which is
RA(J2000) = 02h 40m 56.16s
Dec(J2000) = -60d 38′ 13.2″
with an estimated uncertainty of 4 arcmin radius.
XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.
GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.
A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/
View this GCN Circular online at https://gcn.nasa.gov/circulars/36628.
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TITLE: GCN CIRCULAR
NUMBER: 36627
SUBJECT: Konus-Wind detection of GRB 240603A
DATE: 24/06/06 12:47:29 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 240603A
(GECAM-B detection: Wang & Xiong, GCN 36602;
Fermi-GBM detection: The Fermi GBM team, GCN 36608;
IPN triangulation: Kozyrev et al., GCN 36618)
triggered Konus-Wind at T0=8857.191 s UT (02:27:37.191).
The burst light curve shows a single pulse,
which starts at ~T0-0.3 s and has a total duration of ~1.1 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240603_T08857/
As observed by Konus-Wind, the burst
had a fluence of 3.81(-0.02,+0.84)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.504 s,
of 8.34(-2.03,+2.74)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
Since a significant fraction of the burst counts
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 T0-0.260 s to T0+0.784 s)
by a power law with exponential cutoff (CPL) model,
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = -1.08(-0.68,+1.42) and Ep = 592(-82,+92) 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/36627.
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TITLE: GCN CIRCULAR
NUMBER: 36626
SUBJECT: Swift Trigger 1235109: a possible GRB 240606A
DATE: 24/06/06 04:07:34 GMT
FROM: Mike Siegel at PSU/Swift MOC <siegel(a)swift.psu.edu>
A. D'Ai (INAF-IASFPA), R. Gupta (NASA/GSFC), A. Y. Lien (U Tampa) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 03:33:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a possible GRB 240606A (trigger=1235109).
Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 12.125, -19.747 which is
RA(J2000) = 00h 48m 30s
Dec(J2000) = -19d 44' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve does not show any
obvious structure.
The XRT began observing the field at 03:35:56.7 UT, 129.8 seconds after
the BAT trigger. No source was detected in 1.7 ks of promptly
downlinked data. We are waiting for the full dataset to detect and
localise the XRT counterpart.
UVOT data are unavailable at this time.
Due to the marginal significance of the BAT image (6.54 sigma),
and the lack of an observed counterpart in the XRT data,
this trigger may be due to a noise fluctuation. Further ground
data are required to determine the nature of this trigger.
Burst Advocate for this burst is A. D'Ai (antonino.dai AT inaf.it).
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/36626.
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TITLE: GCN CIRCULAR
NUMBER: 36624
SUBJECT: IPN triangulation of GRB 240531A (short)
DATE: 24/06/05 19:51:13 GMT
FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru>
D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko,
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, and A. Tohuvavohu
on behalf of the Swift-BAT team,
and
G. Waratkar (IITB), J.Joshi (IUCAA), A. Vibhute (IUCAA),
V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA),
A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL)
on behalf of the Astrosat-CZTI team, report:
The short-duration GRB 240531A
(Astrosat-CZTI detection: Wang et al., GCN 36586)
was detected by Astrosat (CZTI), Konus-Wind (KW), in the waiting mode,
and Swift (BAT) at about 68052 s UT (18:54:12).
The burst occurred during Swift slewing interval
(when normal BAT triggering is disabled).
We have triangulated it to a BAT-Konus annulus centered at
RA(2000)=91.405 deg (06h 05m 37s) Dec(2000)=+25.128 deg (+25d 07' 40"),
whose radius is 84.474 +/- 16.042 deg (3 sigma).
The annulus combined with Swift and Astrosat Earth occultation information, and the KW ecliptic latitude response, gives 3848 sq. deg (3 sigma) localization region.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB240531_T68052/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of probability density.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36624.
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