GCN Circular 34061
Subject
LIGO/Virgo/KAGRA S230615az: LBT spectroscopic redshift of the host galaxy of GOTO23hn
Date
2023-06-22T14:28:29Z (2 years ago)
From
Andrea Rossi at INAF <andrea.rossi@inaf.it>
A. Rossi, E. Maiorano, E. Palazzi, F. Cusano (INAF-OAS Bologna), A. Melandri (INAF-OAR), P. D’Avanzo (INAF-OAB), V. D’Elia (SSDC and INAF-OAR), and L. Izzo (INAF-OAC, DARK/NBI) on behalf of the on behalf of GRAvitational Wave Inaf TeAm (GRAWITA) collaboration report:
We report the results of spectroscopic observations of GOTO23hn (Gompertz et al., GCN #33979; Strausbaugh et al., GCN 34020), one of the GOTO candidate counterparts of the LIGO/Virgo event S230615az.
The spectra were obtained with the Multi-Object Double Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope (Mt. Graham, AZ, USA) at the mid-time 04:33 UT on 2023-06-21, 5.7 days after the GW trigger, for a total on-source time of 1200 s, covering the wavelength range 3200-10000 AA.
The MODS slit of 1.2 arcsec and its inclination was adjusted to a parallactic angle of 4.8 degrees to cover the positions of the transient and its host, which is very elongated as visible also in Pan-STARRS and SDSS archival images. Preliminary analysis of the red part (>5800 AA) of the host spectrum shows several well detected emission lines which we interpret as H-alpha, [NII] 6548,6583AA, and [SII] 6716,6731AA, at a common redshift of z=0.0929, suggesting that this is a star-forming galaxy.
Analysis of the spectrum of the GOTO candidate is ongoing.
We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly D. Thompson, D. G. Huerta , and D. Paris, in obtaining these observations.