TITLE: GCN CIRCULAR
NUMBER: 36680
SUBJECT: GRB 240615A: FLWO-1.2m optical upper limits
DATE: 24/06/17 02:24:03 GMT
FROM: Harsh Kumar at Center for Astrophysics | Harvard & Smithsonian <harshkosli13(a)gmail.com>
H. Kumar (CFA) D. Hiramatsu (CFA), and E. Berger (CFA) report on behalf of the FLWO team:
We observed GRB 240615A detected by Fermi GBM (GCN #36671)and Swift/BAT-GUANO (GCN #36672), with the FLWO 1.2m (48”) robotic telescope. We obtained multiple 300-sec exposures in the g, r, and i filters and did not detect any new source in our stacked images within 4 arcmin of BAT position: RA (J2000) = 21:44:33.91, Dec(J2000) = 38:35:41.3. We obtained the following upper limits:
---------------------------------------------------------------------------------
JD (mid) | T-T0(hrs) | Exposure (sec) | Filter | Lim_mag (5-sigma)
---------------------------------------------------------------------------------
2460477.78778 | 13.04 | 900 (stacked) | r | > 21.92
2460477.79915 | 13.32 | 900 (stacked) | g | > 21.33
2460477.81047 | 13.59 | 900 (stacked) | i | > 21.47
---------------------------------------------------------------------------------
The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
We thank the FLWO staff for their support.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36680.
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TITLE: GCN CIRCULAR
NUMBER: 36677
SUBJECT: Konus-Wind detection of GRB 240615A (short/hard)
DATE: 24/06/16 16:36:40 GMT
FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru>
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short GRB 240615A (The Fermi GBM team, GCN 36671;
Swift/BAT-GUANO arcminute localization: DeLaunay et al., GCN 36672).
triggered Konus-Wind (KW) at T0=64306.225 s UT (17:51:46.225).
The burst light curve shows a single pulse,
which starts at ~T0-0.02 s and has a duration of ~0.1 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240615_T64306/
As observed by Konus-Wind, the burst had the total fluence
of 1.85(-0.49,+0.65)x10^-6 erg/cm^2 and a 16-ms peak energy flux,
measured from T0, of 3.21(-0.89,+1.15)x10^-5 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst (measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.55(-0.27,+0.37) and Ep = 878(-281,+441) keV (chi2 = 24.4/28 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.15 (chi2 = 24.5/27 dof).
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.
View this GCN Circular online at https://gcn.nasa.gov/circulars/36677.
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TITLE: GCN CIRCULAR
NUMBER: 36676
SUBJECT: GRB 240615A: GOTO optical upper limits
DATE: 24/06/16 08:59:28 GMT
FROM: Amit Kumar at University of Warwick, UK <amitkundu515(a)gmail.com>
A. Kumar; B. P. Gompertz; G. Ramsay; S. Belkin; R. Starling; D. K. Galloway; K. Ackley; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. O'Neill; D. Steeghs; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Palle and D. Pollacco report on behalf of the GOTO collaboration:
We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to the Fermi GBM detected GRB 240615A (Fermi GBM Team, GCN 36671). Targeted observations also covered the Swift/BAT-GUANO updated localisation (DeLaunay, et al., GCN 36672) with GOTO-N on 2024-06-16 from UT 01:39:52 to 03:56:07 (from ~7.80 to 10.07 hours after trigger, respectively) distributed over four epochs. Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).
Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks.
No significant optical counterpart is detected within the Swift/BAT-GUANO localisation region to a 5-sigma limiting L-band magnitude range of 19.8-20.4 (AB) across 4 epochs of observations.
Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
View this GCN Circular online at https://gcn.nasa.gov/circulars/36676.
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TITLE: GCN CIRCULAR
NUMBER: 36673
SUBJECT: GRB 240615A: Swift ToO observations
DATE: 24/06/16 04:54:26 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 Swift/BAT-GUANO GRB 240615A.
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021696
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 Swift/BAT-GUANO 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/36673.
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TITLE: GCN CIRCULAR
NUMBER: 36672
SUBJECT: GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
DATE: 24/06/16 01:36:09 GMT
FROM: Aaron Tohuvavohu at University of Toronto <aaron.tohu(a)gmail.com>
James DeLaunay (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea
(PSU), Samuele Ronchini (PSU), Gayathri Raman (PSU), Tyler Parsotan (GSFC) report:
Swift/BAT did not localize GRB 240615A onboard (T0: 2024-06-15T17:51:45 UTC, Fermi GCN 36671).
The Fermi/GBM 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 burst is detected in BAT with a duration of < 0.1 seconds.
The burst occurred during a Swift slew.
A confident location is found for the burst with SNR of 12.
The BAT position is
RA, Dec = 326.1413, +38.5948 deg which is
RA(J2000) = 21h 44m 33.91s
Dec(J2000) = +38d 35’ 41.3″
with an estimated uncertainty of 4 arcmin.
This position is consistent with the Ferm/GBM localization (GCN 33023).
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/36672.
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