GRB 241030B
GCN Circular 38158
R. Jayaraman (MIT), M.M. Fausnaugh (TTU), and G.R. Ricker (MIT) report:
The Transiting Exoplanet Survey Satellite (TESS; Ricker et al. JATIS 1 2015) observed GRB 241030B (Klingler et al., GCN 37981; Fermi GBM Team, GCN 37980) during its scheduled sky survey. TESS observed this region continuously from 3.72 days before the trigger to 2.71 days after the trigger, at a cadence of 200 seconds. The GRB occurred during TESS observational Sector 85, and the localization fell within Camera 1, CCD 4.
We performed forced difference-imaging photometry at the location of the confirmed X-ray afterglow (Evans et al., GCN 37992) using the full-frame images from the publicly available TICA data archived at MAST (https://archive.stsci.edu/hlsp/tica). Our data reduction routine is described in Fausnaugh et al. 2023 (ApJ 956(2):108).
We detect an optical transient at the location of the GRB in the 3 exposures during and after the time of trigger from Klingler et al. The trigger occurred 115 seconds before the end of a concurrent 200-second TESS exposure. The optical transient has a magnitude of 16.40 ± 0.14 in the TESS band in this image. The magnitude falls to 16.50 ± 0.15 in the next exposure, and then 17.08 ± 0.25 mag in the third exposure. These values are in line with the upper limits of 16.2 (r) at T0+1 min, and 17.4 at T0+15 min from Klotz et al., GCN 37989.
This circular includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by the NASA Explorer Program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
GCN Circular 38029
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 5.6 ks of XRT data for GRB 241030B, from 168 s to 51.2
ks after the BAT trigger. The data are entirely in Photon Counting
(PC) mode.
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.17 (+/-0.07).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+0.31, -0.28). The
best-fitting absorption column is 2.9 (+1.3, -0.9) x 10^21 cm^-2,
consistent with the Galactic value of 2.0 x 10^21 cm^-2 (Willingale et
al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux
conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.5 x
10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.9 (+1.3, -0.9) x 10^21 cm^-2
Galactic foreground: 2.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index: 2.00 (+0.31, -0.28)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01263840.
This circular is an official product of the Swift-XRT team.
GCN Circular 38024
This was a duplicate submission of GCN 38023.
GCN Circular 38023
Zh. Abdullayev (NU), Zh. Maksut (NU), T. Komesh (NU), B. Grossan (UCB, NU), D. Berdikhan (NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 241030B observing in Sloan g' and r' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations at 20:15:59 UT on 2024-10-30, 1.7 h after the BAT trigger. Observations were made in partly cloudy conditions. No source consistent with the XRT (P.A. Evans 2024, GCN Circ. 37983) was detected. We report the following results:
start time t-t0(s) end time UL g' UL r' exposure_time (s)
--------------------------------------------------------------
20:15:59 6100 20:16:59 19.2 19.0 60
start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL g' and UL r' give the 5 sigma upper limit sensitivity in magnitudes, for images co-added to the given exposure time. The results in in the table corresponds to co-adds of an initial short exposure image sequence of 0.5 s (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active). Calibration was done with the 3 bright Pan-STARRS catalog stars on our images.
----------------------------------
NU = Nazarbayev University, Astana, Kazakhstan
UCB = University of California, Berkeley, USA
FAI = Fesenkov Astrophysical Institute, Kazakhstan
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN Circular 38020
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy, part of UAI/SSV-GRB section), M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy) and B. De Simone (Universita' degli Studi Di Salerno) report:
We performed follow-up observations of the field of GRB 241030B with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).
Observations were started at 2024-10-30 21:55:28 UT, 3.33 hours after burst (Fermi-GBM team, GCN 37980; Swift trigger 1263840, GCN 37981 Klingler et al.; SVOM/ECLAIRs, GCN 37984 Zhao et al.) stacking 140x40s Rc-band CCD images.
In our preliminary analysis, we have not found any optical transient candidate within the error-box (2.4 arcmin.) of the Neil Gehrels Swift Observatory enhanced position (RA 03h 23m 10.19s, Dec. +34d 26m 49.2s - J2000) down to the following 3-sigma optical upper limits:
MJD Exp. Filter UL (3-sigma)
60614.4476 140x40s Rc > 20.91
Magnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. No correction for galactic dust extinction was applied.
Our observations are consistent with other fading detection and upper limits already reported (Fu et al., GCN 37985; Odeh et al., GCN 37986; Moskvitin et al., GCN 37987; Klotz et al., GCN 37989