GRB 230205A
GCN Circular 34640
Subject
GRB 230205A: LBT spectroscopy of two host galaxy candidates
Date
2023-09-08T08:40:01Z (2 years ago)
From
Elisabetta Maiorano at INAF <elisabetta.maiorano@inaf.it>
Via
Web form
E. Maiorano (INAF-OAS), V. D'Elia (SSDC & INAF-OAR), D. B. Malesani (Radboud Univ. and DAWN/NBI), A. Rossi, E. Palazzi (INAF-OAS), P. D’Avanzo (INAF-OAB), A. Melandri ( INAF-OAR), M. De Pasquale (Messina Univ.) on behalf of CIBO collaboration.
We report the results of the spectroscopic observations of two host galaxy candidates for the short GRB 230205A (Ambrosi et al., GCN 33271), first identified by Tomasella et al. (GCN 33302) and Urata et al. (GCN 33307) in deep Subaru archival imaging.
The optical spectra of the two candidate host galaxies were obtained with the Multi-Object Double Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope (Mt. Graham, AZ, USA) on 2023-03-04, 27 days after the burst trigger. The spectra cover the wavelength range 3200-10000 AA, with a total of exposure time of 1.5 hours.
We detect a faint and red continuum with few emission lines for the brightest galaxy that we tentatively identify as H-alpha, and H-beta at a common redshift of z=0.429 (consistent with the photometric redshift of z = 0.484 ± 0.090 provided by SDSS, see Tomasella et al., GCN 33302). The spectral trace of the fainter galaxy is too weak to allow a reliable identification of any emission line, thus not permitting its redshift estimate.
Multiband photometry was also collected between June and July (4-5 months after the GRB trigger) in the r, z and H bands, with both galaxies detected in all filters. These images also show an additional fainter host galaxy candidate at coordinates 13:28:16.56 +46:43:34.7, underlining the complexity of the field.
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly D. Thompson, E. Marini, and D. Paris, in obtaining these observations.
GCN Circular 33372
Subject
GRB 230205A: VLA radio afterglow confirmation
Date
2023-02-23T21:04:20Z (3 years ago)
From
Genevieve Schroeder at Northwestern University <genevieveschroeder2023@u.northwestern.edu>
G. Schroeder, (Northwestern), T. Laskar (Utah) report:
"We re-observed the position of the possibly short GRB 230205A (Ambrosi et
al., GCN 33271; Sakamoto et al., GCN 33280) with the Karl G. Jansky Very
Large Array (VLA) under program 23A-296 (PI: Schroeder) beginning on 2023
February 22.52 UT (17.08 days post-burst) at a mean frequency of 6 GHz.
The radio source detected in the previous VLA observation at 2.81 days
(Schroeder et al. GCN 33309) has brightened significantly at 6 GHz,
confirming this source as the radio afterglow of GRB 230205A. We report an
updated radio position of:
RA(J2000) = 13:28:16.837
Dec(J2000) = +46:43:33.13
With an uncertainty of ~0.1" in each coordinate.
Further observations are planned. We thank the VLA staff for quickly
approving and executing these observations."
GCN Circular 33334
Subject
GRB 230205A: Lowell Discovery Telescope Observations
Date
2023-02-17T00:43:14Z (3 years ago)
From
Brendan O'Connor at UMD <oconnorb@umd.edu>
B. O'Connor (UMD, GWU), E. Hammerstein (UMD), S.B. Cenko (UMD,
NASA-GSFC), E. Troja (UTV, ASU), S.Dichiara (PSU),
J. Durbak (UMD, NASA-GSFC), A. Kutyrev (UMD, NASA-GSFC),
S. Veilleux (UMD), I. Andreoni (UMD, NASA-GSFC), and
G. Srinivasaragavan (UMD):
We observed the field of GRB 230205A (Ambrosi et al. GCN 33271;
Sakamoto et al. GCN 33280) using the Large Monolithic Imager (LMI)
on the 4.3m Lowell Discovery Telescope (LDT) at Happy Jack, AZ.
We began observations on February 13, 2023 at 12:54:52 UT in
r-band and i-band for 600 s each. The target was at airmass
1.1 with seeing ~2".
We do not detect any source within the XRT enhanced position
(Goad et al. GCN 33275) to depth r>23.8 AB mag. The host
galaxy candidate (Tomasella et al. GCN 33302), hereafter S1,
is clearly detected in both filters. We likewise detect
the source (S2) reported by Urata et al. (GCN 33307).
We measure the following magnitudes for S1 and S2:
S1: r ~ 22.0 +/- 0.1 AB mag
S1: i ~ 21.20 +/- 0.05 AB mag
S2: r ~ 23.7 +/- 0.3 AB mag
S2: i ~ 22.7 +/- 0.2 AB mag
The magnitudes of S1 are consistent with the earlier report
of Tomasella et al. (GCN 33302) and the SDSS catalog. For S2,
we derive a slightly fainter i-band magnitude compared to
Urata et al. (GCN 33307). However, as their images were obtained
prior to the explosion, this is not an indication of fading.
Thus, both these sources are candidate host galaxies to
GRB 230205A (Schroeder et al. GCN 33309).
Magnitudes are calibrated against the SDSS catalog and are not
corrected for Galactic extinction.
We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.
GCN Circular 33309
Subject
GRB 230205A: 6 GHz VLA observations
Date
2023-02-09T22:07:28Z (3 years ago)
From
Genevieve Schroeder at Northwestern University <genevieveschroeder2023@u.northwestern.edu>
G. Schroeder, J. C. Rastinejad, W. Fong, C. D. Kilpatrick, A. E. Nugent
(Northwestern), E. Berger (Harvard), T. Laskar (Utah) report:
"We observed the position of the possibly short GRB 230205A (Ambrosi et al,
GCN 33271; Sakamoto et al., GCN 33280) with the Karl G. Jansky Very Large
Array (VLA) under program 23A-296 (PI: Schroeder) beginning on 2023
February 8.25 UT (2.81 days post-burst) at a mean frequency of 6 GHz.
We detect a radio source with a flux of ~40 microJy at the position:
RA(J2000) = 13:28:16.838
Dec(J2000) = +46:43:32.87
with an uncertainty of ~0.5" in each coordinate. This position is on the
outskirts of the XRT position (Goad et al. GCN 33275), on the NW edge. The
radio source position is consistent with the position of the optical source
reported by Urata et al. GCN 33307, although with a slight offset of
~0.85". If we assume this optical source is the host galaxy of GRB 230205A
and the radio source is afterglow, we find a probability of chance
coincidence of Pcc ~ 0.003 (Bloom et al. 2002). Alternatively, the detected
radio emission could originate from the host. In contrast, the radio source
is offset by ~3.6" from the center of the cataloged optical source (SDSS
J132816.81+464329.8) mentioned by Tomasella et al. GCN 33302. If we instead
assume that SDSS J132816.81+464329.8 is the host galaxy of GRB 230205A, we
find Pcc ~ 0.02.
Further observations are planned to determine the variability of the radio
source. We thank the VLA staff for quickly approving and executing these
observations."
GCN Circular 33307
Subject
GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
Date
2023-02-09T16:31:10Z (3 years ago)
From
Kuiyun Huang at CYCU <kuiyun@gmail.com>
Y. Urata, K.Y. Huang on behalf of a larger collaboration
We processed pre-imaging data for the field of the possible short GRB
230205A (Ambrosi et al., GCN Circ. 33271; Sakamoto et al., GCN Circ. 33280)
obtained by SUBRU Hyper-Suprime-Cam with i-band filter on June 6, 2019.
No clear source is identified within the enhanced XRT position (Goad et
al., GCN Circ. 33275).
The host galaxy candidate suggested by Tomasella et al. (GCN Circ. 33302)
is clearly detected.
In addition to this source, there is a source with i = 22.1 +/- 0.1
at the NW edge of the XRT error circle at RA = 13:28:16.92 Dec =
+46:43:32.73.
The image is available at the following link.
https://lh3.googleusercontent.com/VfQ2VhB3PtkCkwrfTVEKX0M0ARJ4bMKJk5g8vnVejx2Onx5CO5HamxaU6h34PDI1m0_MYmf3s-QSkacCSJYbEIMLV57-NkLBpnrVQCxVrMatuUvc4uf0euvRk9m65tiY7A=w1280
GCN Circular 33302
Subject
GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
Date
2023-02-08T14:42:11Z (3 years ago)
From
Paolo D'Avanzo at INAF-OAB <pda.davanzo@gmail.com>
L. Tomasella (INAF-OAPd), P. D���Avanzo, (INAF-OAB), E. Cappellaro (INAF-OAPd) on behalf of a larger collaboration report:
We observed the field of the possibly short GRB 230205A (Ambrosi et al, GCN Circ. 33271