GCN Circular 34030
Subject
ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations
Event
Date
2023-06-20T00:15:55Z (2 years ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
T. Adami (ENS/Saclay, LAM/Pytheas/AMU), C. Adami (LAM/Pytheas/AMU),
D. Turpin, E. Le Floc'h (CEA Paris-Saclay), J. T. Palmerio,
S. D. Vergani (GEPI, Obs. de Paris), B. Schneider (MIT),
S. Basa (LAM), D. Götz (CEA Paris-Saclay), report on behalf of a
larger collaboration:
We observed the field of ZTF23aaoohpy/AT2023lcr (Swain et al., GCN 34022,
Gompertz et al., GCN34023, Kumar et al., GCN34025)using the T193cm
and T120cm telescopes at Observatoire de Haute-Provence (France)
respectively equipped with the MISTRAL spectro-imager and the T120 CCD camera.
A total of 8 exposures were obtained in the imaging mode of MISTRAL in
the r-band filter (1x360s +7x600s). Observations were made
from 2023-06-19 21:13:47.60 UT to 2023-06-19T22:37:40.86 UT
(mid time ~1.85d after the T_GOTO = 2023-06-18 01:27:41
(Gompertz et al., GCN34023)).
A total of 16 exposures were also obtained with the T120 CCD camera
in the R-band filter (1x300s +8x450s, mid time ~ T_GOTO+1.83d)
and V-band (7x600s, mid time ~ T_GOTO+1.88d).
In the coadded images, we measured the following magnitudes:
----------------------------------------------------------------------
JD (mid) | Telescope | Filter | Exposure (s) | Magnitude (AB) |
----------------------------------------------------------------------
2460115.3875 | OHP-T120 | R | 3900 | 20.70 +/- 0.12 |
2460115.413706 | OHP-T193/MISTRAL | r' | 4560 | 20.84 +/- 0.04 |
2460115.440972 | OHP-T120 | V | 4200 | 20.85 +/- 0.07 |
----------------------------------------------------------------------
The photometric calibration was performed using nearby stars
from the PS1 catalog and the magnitudes are not corrected for
Galactic extinction.
Our measurements confirm that the source is fading at a mag rate ~ 0.9 mag/day
compared to the last r magnitude reported by ZTF (Swain et al., GCN 34022).
The red color of this transient g-r ~ 0.3 and its confirmed fast-fading evolution
are consistent with a Gamma-ray Burst afterglow emission.
We strongly encourage spectroscopic follow-up of this source in order to identify
its astrophysical origin.
Additional I-band follow-up observation will be performed at OHP this night.
We acknowledge the excellent support from Observatoire de Haute-Provence,
in particular Yoann Degot Longhi for the MISTRAL observations, Gavin Coleman
the observer using the T193/SOPHIE instrument who allowed us to perform
these ToO observations as well as Pascal Gallais, Antoine Claret and
Matthias Tornay for the T120 observations.