TITLE: GCN CIRCULAR
NUMBER: 34576
SUBJECT: GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
DATE: 23/08/27 18:35:09 GMT
FROM: Vishwajeet Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in>
V. Swain, A Salgundi, R. Kumar, R. Sharma, H. Kumar, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed ZTF23abaanxz/AT2023qxj discovered by ZTF (M. L. Li et al., GCN 34574) in localization region of the Fermi GRB230827.256 (trigger No 714809315), with the 0.7m GROWTH-India Telescope (GIT). The observations started at 15:04:47 UT on 2023-08-27, roughly 8.9 hours after the Fermi GBM trigger. We obtained a 300s exposure in the r' filter. We clearly detected the candidate at the position reported by M. L. Li et al., GCN 34574. The photometric results are follow as:
------------------------------------------------------------------------------------
jd (mid) | Filter | Total Exposure (s) | Magnitude (AB) |
-------------------------------------------------------------------------------------
2460184.13030952 | r' | 300 | 19.3 +/- 0.1 |
-----------------------------------------------------------------------------------
We confirm that the object is still fading, thereby confirming it as an afterglow. The magnitude is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34574
SUBJECT: AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
DATE: 23/08/27 17:43:38 GMT
FROM: jlv93(a)cornell.edu
Maggie L. Li, Jada L. Vail, Anna Y. Q. Ho (Cornell University), Michael Coughlin (University of Minnesota), Daniel Perley (LJMU), Anirudh Salgundi, Vishwajeet Swain, Gaurav Waratkar (IITB)
We report the discovery of a fast-evolving red transient by the Zwicky Transient Facility (ZTF). The transient is coincident with Fermi GRB 230827256 (trigger 714809315).
AT 2023qxj (ZTF23abaanxz) was discovered at the position (J2000) of:
RA = 19:58:33.55 (299.6397739 deg)
Dec = +54:27:48.02 (54.4633396 deg)
on 2023-08-27 07:10:10.94 UT by ZTF at r = 17.11 +/- 0.04 mag (MJD=60183.26872). ZTF obtained a non-detection 1 day prior (MJD=60182.26553) at r > 20.18 mag, indicating a fast rise rate of >3 mag/day in r. ZTF also obtained detections later that night at r = 18.88 +/- 0.08 mag (MJD=60183.33919) and g = 19.27 +/- 0.16 mag (MJD=60183.40719), implying that the transient was red and fading quickly.
The Galactic latitude of AT 2023qxj is 12.8 degrees, and the Galactic reddening toward the direction of AT 2023qxj is: E_(g-r) = 0.227 from Schlafly & Finkbeiner (2011).
The fast rise, fast decay, red color, and lack of archival optical counterpart of AT 2023qxj make it a strong candidate afterglow. We identify the coincident GRB 230827256 discovered by Fermi at the position (J2000) of:
RA = 19:57:16.8
Dec = +56:28:12
with an error radius of 2.17 deg. The time of the GRB trigger was 2023-08-27 06:08:31 UT (MJD=60183.25591), 18.45 minutes prior to the first ZTF detection of AT 2023qxj.
ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34573
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
DATE: 23/08/27 14:57:12 GMT
FROM: Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini(a)iol.it>
S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:
We observed the field of Swift J1727.8-1613 (GRB 230824A)
(Page et al., GCN 34537; Odeh et al., GCN 34543; Dutton et al., GCN 34556; Odeh et al., GCN 34561; Quadri et al., GCN 34562; Lopresti, GCN 34566; Pavoni & Moretti, GCN 34570) with the remote controlled 0.53m Ritchey-Chretien telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88) in 2 epochs, starting on Aug 24.78994 (5 hours after trigger) and Aug. 26.79422 2023 (53 hours after trigger) with multiple exposures in V, Rc and Ic band.
The OT was detected at the following position:
RA (J2000.0) 17h 27m 43.32s +/-0.2
Dec. (J2000.0) -16° 12' 18.60" +/-0.2
Photometry was obtained using nearby PanSTARRS stars as follows:
==============================
Obs. midtime UT Filter Mag. Err.
==============================
2460181.2962325 V 13.45 0.002
2460181.3049015 V 13.48 0.002
2460181.3127082 V 13.50 0.002
2460181.3205208 V 13.50 0.002
2460181.3305952 V 13.47 0.002
2460183.3018576 V 12.54 0.003
2460183.3062470 V 12.52 0.003
2460183.3143382 V 12.48 0.004
2460183.3208796 V 12.50 0.004
-----------------------------------------------
2460181.2973320 R 13.39 0.001
2460181.3053240 R 13.42 0.001
2460181.3131307 R 13.42 0.001
2460181.3213754 R 13.44 0.001
2460181.3315657 R 13.39 0.001
2460183.2976407 R 12.43 0.002
2460183.3047650 R 12.43 0.002
2460183.3089728 R 12.41 0.002
2460183.3200694 R 12.44 0.002
-----------------------------------------------
2460181.2940451 I 13.29 0.002
2460181.3031443 I 13.28 0.002
2460181.3109548 I 13.26 0.002
2460181.3187615 I 13.22 0.002
2460181.3265489 I 13.26 0.001
2460181.3336487 I 13.26 0.001
2460183.2980439 I 12.28 0.003
2460183.3052912 I 12.26 0.003
2460183.3164382 I 12.27 0.003
2460183.3204745 I 12.26 0.003
-----------------------------------------------
Magnitudes were converted using Lupton 2005 equations and are not corrected for galactic dust extinction.
Further observations are planned.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34572
SUBJECT: GRB 230826A: GRBAlpha detection
DATE: 23/08/27 14:13:41 GMT
FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz>
M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), yyT. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration.
The long-duration GRB 230826A (Fermi/GBM detection: GCN 34564; Swift/BAT detection: GCN 34565) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).
The detection was confirmed at the peak time 2023-08-26 19:32:45 UTC. The T90 duration measured by GRBAlpha is 18 s and the overall significance during T90 reaches 8.3 sigma.
The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230826A_GCN.pdf
All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34571
SUBJECT: GRB 230826A: Fermi GBM Observation
DATE: 23/08/27 11:36:56 GMT
FROM: rachel.hamburg(a)ijclab.in2p3.fr
O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:
"At 19:32:44.53 UT on 26 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230826A (trigger 714771169/230826814),
which was also detected by Swift-BAT (R.A.J. Eyles-Ferris et al. 2023, GCN 34565).
The Fermi GBM Final Real-time Localization (GCN 34564) is consistent with the Swift-BAT position.
The angle from the Fermi LAT boresight is 116 degrees.
The GBM light curve consists of a single FRED peak with a duration (T90)
of about 37 s (50-300 keV). The time-averaged spectrum
from T0-4.1 to T0+46.1 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.75 +/- 0.12 and the cutoff energy,
parameterized as Epeak, is 87 +/- 5 keV.
The event fluence (10-1000 keV) in this time interval is
(6.012 +/- 0.246)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.9 s in the 10-1000 keV band is 4.9 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html
For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34570
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
DATE: 23/08/27 10:40:23 GMT
FROM: leavittob(a)gmail.com
E. Pavoni and L. Moretti (Leavitt Observatory, Italy), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Università degli Studi Di Salerno)
report:
We observed the field of Swift J1727.8-1613 (GRB 230824A: Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543; U.Quadri et al., GCN 34562; C. Lopresti, GCN 34566) with the telescope of Leavitt Observatory, Italy. Member of:
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.
The observations began at 20:02 UT on 2023/08/24 (~6 hours after the Swift trigger), with our RC telescope D=250 mm F/D=8.
Weather conditions were good.
We took 25 images of 120 sec each. All images are Rc filtered, calibrated with master dark and master flat, stacked with ASTAP software and analyzed with AstroImageJ software.
We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8
The results of our photometry in Rc band are:
JD_UTC Source_Mag Source_Mag_Err
2460181.3385997 13,766 0,006
2460181.3457458 13,725 0,006
2460181.3528939 13,731 0,006
2460181.3603810 13,694 0,006
2460181.3689481 13,671 0,005
Magnitudes were estimated with PanSTARRS cat. and are not corrected for galactic dust extinction.
The message may be cited.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34569
SUBJECT: GRB 230826A: Enhanced Swift-XRT position
DATE: 23/08/27 07:40:11 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 1910 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 230826A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 83.06410, +66.12384 which is equivalent
to:
RA (J2000): 05h 32m 15.38s
Dec (J2000): +66d 07' 25.8"
with an uncertainty of 2.0 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34568
SUBJECT: GRB 230826A: Swift-XRT refined Analysis
DATE: 23/08/27 07:26:29 GMT
FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk>
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M.
Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows
(PSU) and P.A. Evans report on behalf of the Swift-XRT team:
We have analysed 8.3 ks of XRT data for GRB 230826A, from 65 s to 29.5
ks after the BAT trigger. The data comprise 56 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. The refined XRT position is RA,
Dec = 83.0642, +66.1244 which is equivalent to:
RA (J2000): 05 32 15.41
Dec(J2000): +66 07 27.9
with an uncertainty of 3.5 arcsec (radius, 90% confidence).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.44 (+0.25, -0.24). At T+213 s the decay
flattens to an alpha of -0.06 (+0.24, -0.26) before breaking again at
T+1264 s to a final decay with index alpha=1.39 (+0.22, -0.14).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.93 (+0.32, -0.29). The
best-fitting absorption column is 4.7 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.15 (+0.22, -0.21)
and a best-fitting absorption column of 4.4 (+1.1, -1.0) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 3.6 x 10^-11 (6.3 x 10^-11) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 4.4 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 4.8 sigma
Photon index: 2.15 (+0.22, -0.21)
If the light curve continues to decay with a power-law decay index of
1.39, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-13 (1.8 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/01187463.
This circular is an official product of the Swift-XRT team.
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…
TITLE: GCN CIRCULAR
NUMBER: 34567
SUBJECT: GRB 230826A: Mondy optical observations
DATE: 23/08/27 01:28:38 GMT
FROM: Alexei Pozanenko at IKI, Moscow <apozanen(a)iki.rssi.ru>
N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Pozanenko (IKI), S. Belkin (IKI) on behalf of GRB-IKI-FuN report.
We observed the field of GRB 230826A detected by Fermi GBM (Fermi GBM Team, GCN 34564) and Swift (Eyles-Ferris et al, 34565) with AZT-33IK telescope of Sayan observatory (Mondy). Observations started on 2023-08-26 220:06:00 (UT) (i.e. ~33 min since trigger). We obtained
series of images in R-filter. We do not detect evident candidate within XRT error circle (Swift-XRT Position: +05h 32m 14.20s +66d 07' 30.0" 5.3 arcsec, radius) in a stacked image. Preliminary photometry is following:
Date UT start t-T0 Filter Exp. OT Err. UL(3sigma)
(mid, days) (s)
2023-08-26 20:06:00 0.038345 R 44*60 n/d n/d 22.0
We note the presence of the object USNO-B1.0 1561-0095652 at 8.8 arces from the Swift-XRT Position. Measured brightness of the object is R = 18.1 +/- 0.01 what is brighter than USNO-B1.0 R2=18.22 magnitude.
All photometry is based on nearby USNO-B1.0 stars, R2 magnitudes
---
To unsubscribe, open this link in a web browser:
https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…