GRB 230430A
GCN Circular 33713
Subject
GRB 230430A: Fermi GBM Final Real-time Localization
Date
2023-04-30T07:57:58Z (2 years ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
The Fermi GBM team reports the detection of a likely SHORT GRB
At 07:47:18 UT on 30 Apr 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230430A (trigger 704533643.80535 / 230430325).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 184.2, Dec = 40.8 (J2000 degrees, equivalent to J2000 12h 16m, 40d 47'), with a statistical uncertainty of 2.5 degrees.
The angle from the Fermi LAT boresight is 22.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_skymap_all_bn230430325.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_healpix_all_bn230430325.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230430325/quicklook/glg_lc_medres34_bn230430325.gif
GCN Circular 33714
Subject
GRB 230430A: AstroSat CZTI detection
Date
2023-05-01T07:00:58Z (2 years ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a short GRB 230430A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33713).
The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-04-30 07:47:18.95 UTC. The measured peak count rate associated with the burst is 4406 (+1160, -973) counts/s above the background in the combined data of all quadrants, with a total of 405 (+71, -61) counts. The local mean background count rate was 423 (+13, -39) counts/s. Using cumulative rates, we measure a T90 of 0.28 (+0.04, -0.02) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 33715
Subject
GRB 230430A: Fermi GBM observation
Date
2023-05-02T07:00:05Z (2 years ago)
From
Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>
J.Mangan (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of the Fermi-GBM Team:
"At 07:47:18.81 UT on 30 April 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230430A (trigger 704533643 / 230430325), which was also detected by AstroSat CZTI (P K. Navaneeth et al. 2023, GCN 33714). The Fermi GBM Final Real-time Localization is reported in GCN 33713.
The angle from the Fermi LAT boresight at the GBM trigger time is 22 degrees.
The GBM light curve consists of a single emission
with a duration (T90) of about 0.32 s (50-300 keV).
The time-averaged spectrum from T0-0.19 s to T0+0.45 s is best fit by
a power law function with an exponential
high-energy cutoff. The power law index is -0.6 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 528.4 +/- 58.1 keV. A Band function fits the spectrum equally well with Epeak= 363.8 +/- 57.2 keV, alpha = -0.4 +/- 0.1 and beta = -2.2 +/- 0.3.
The event fluence (10-1000 keV) in this time interval is
(1.7 +/- 0.1)E-6 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+-0.13 s in the 10-1000 keV band
is 25.9 +/- 1.5 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/"
GCN Circular 33718
Subject
IPN triangulation of GRB 230430A (short)
Date
2023-05-02T15:49:34Z (2 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@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. Ridnaia, A. Lysenko,
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,
E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB 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 230430A
(Fermi-GBM detection: the Fermi GBM team, GCN Circ. 33713;
Mangan et al., GCN Circ. 33715;
AstroSat-CZTI detection: Navaneeth et al., GCN Circ. 33714)
was detected by Fermi (GBM trigger 704533643),
Konus-Wind, INTEGRAL (SPI-ACS), AstroSat (CZTI),
and Mars-Odyssey (HEND), at about 28039 s UT (07:47:19).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
191.335 (12h 45m 20s) +33.912 (+33d 54' 42")
Corners:
191.333 (12h 45m 20s) +34.000 (+34d 00' 02")
191.427 (12h 45m 42s) +34.079 (+34d 04' 45")
191.338 (12h 45m 21s) +33.823 (+33d 49' 22")
191.244 (12h 44m 58s) +33.743 (+33d 44' 36")
---------------------------------------------
The error box area is 51 sq. arcmin, and its maximum
dimension is 22 arcmin (the minimum one is 3.2 arcmin).
The Sun distance was 125 deg.
This box may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (GCN 33713).
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230430_T28040/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 33720
Subject
Konus-Wind detection of GRB 230430A
Date
2023-05-03T14:19:49Z (2 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@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 230430A
(Fermi-GBM detection: Fermi GBM Team, GCN 33713;
Mangan & Meegan, GCN 33715;
AstroSat-CZTI detection: Navaneeth et al., GCN 33714;
IPN triangulation: Kozyrev et al., GCN 33718)
triggered Konus-Wind at T0=28040.858 s UT (07:47:20.858).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~0.3 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230430_T28040/
As observed by Konus-Wind, the burst
had a fluence of 2.24(-0.38,+0.44)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.008 s,
of 2.04(-0.63,+0.69)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+0.192 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.49(-0.25,+0.31)
and Ep = 704(-180,+254) keV (chi2 = 26/37 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 26/36 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 33723
Subject
GRB 230430A: A short GRB from a neutron star merger
Date
2023-05-04T08:30:05Z (2 years ago)
From
Remo Ruffini at ICRA <ruffini@icra.it>
R. Ruffini, Y. Aimuratov, L. Becerra, C.L. Bianco, C. Cherubini, S. Filippi, M. Karlica, Liang Li, R. Moradi, F. Rastegar Nia, J.A. Rueda, N. Sahakyan, Y. Wang, S.S. Xue, on behalf of the ICRANet team, report:
GRB 230430A appears to have strong similarities with GRB 090510 originating from merging binary neutron stars (Ruffini et al., 2016). Also in this case no supernova is expected. Attention should be given to the determination of the temporal slope of the late X-ray luminosity which for long GRBs coincide with the common value of the power-law index -1.48+/-0.32 of the afterglow, and for short GRBs appears to have a different power law, to be confirmed (see Fig. 5 in Ruffini et al., 2016). The GeV luminosity for long GRBs has a temporal power-law index -1.19+/-0.04 and for short GRBs it has a temporal power-law index -1.29+/-0.06 (Ruffini et al., 2021). Confirmation of the values of both slopes in GRB 230430A is highly recommended to differentiate short GRBs from long GRBs. We encourage monitoring for the possible appearance of a kilonova signal.
References:
Ruffini, R.; Muccino, M.; Aimuratov, Y.; et al.; ApJ, 831 (2016) 178.
Ruffini, R.; Moradi, R.; Rueda, J.A; et al.; MNRAS, 504 (2021) 5301.
GCN Circular 33783
Subject
GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
Date
2023-05-12T20:20:45Z (2 years ago)
From
Tomas Ahumada at U. of Maryland <tahumada@astro.umd.edu>
Tomas Ahumada (CIT), Shreya Anand (CIT), Viraj Karambelkar (CIT), Robert
Stein (CIT), Theophile du Laz (CIT), Michael Coughlin (UMN), Mansi Kasliwal
(CIT), Simeon Reusch (DESY), Jannis Necker (DESY) report on behalf of the
ZTF collaboration:
We observed the localization region of the short GRB 230430A (trigger
704533643) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi
satellite with the Palomar 48 inch telescope equipped with the 47 square
degree Zwicky Transient Facility (ZTF; Bellm et al., 2019; Graham et al.,
2019) camera. We obtained a series of g- and r-band images covering about
132.4 square degrees beginning at 2023-05-01T04:45:43.004 (~20 hours after
the burst trigger time) corresponding to ~93% of the probability enclosed
in the intersection between the GBM (GCN 33713) and the preliminary IPN
region. Our observations contain the final IPN region (GCN 33718).
Exposures reached a median depth of 21.5 mag in the g-band and 21.5 mag in
the r-band. No potential counterparts were found.
ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC,
USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan;
IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No
1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski
(Duev et al. 2019). GROWTH India telescope is located at the Indian
Astronomical Observatory (Hanle), operated by the Indian Institute of
Astrophysics (IIA). GROWTH-India project is supported by SERB and
administered by IUSSTF, under grant number IUSSTF/PIRE
Program/GROWTH/2015-16 and IUCAA.
<https://hackmd.io/JGjJMLLsSPW4EwSesjMTdA#>
--
Tomás Ahumada (he/him)
Ph.D. Candidate
Department of Astronomy
University of Maryland, College Park
NASA <tomas.f.ahumdamena@nasa.gov> Goddard Space Flight Center, Code 661
B.Sc. Astronomy, Pontificia Universidad Católica de Chile