{
  "createdOn": 1687220155024,
  "bibcode": "2023GCN.34030....1A",
  "submitter": "Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>",
  "circularId": 34030,
  "subject": "ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations",
  "body": "T. Adami (ENS/Saclay, LAM/Pytheas/AMU), C. Adami (LAM/Pytheas/AMU),\nD. Turpin, E. Le Floc'h (CEA Paris-Saclay), J. T. Palmerio, \nS. D. Vergani (GEPI, Obs. de Paris), B. Schneider (MIT),\nS. Basa (LAM), D. Götz (CEA Paris-Saclay), report on behalf of a \nlarger collaboration:\n\nWe observed the field of ZTF23aaoohpy/AT2023lcr (Swain et al., GCN 34022, \nGompertz et al., GCN34023, Kumar et al., GCN34025)using the T193cm \nand T120cm telescopes at Observatoire de Haute-Provence (France) \nrespectively equipped with the MISTRAL spectro-imager and the T120 CCD camera. \nA total of 8 exposures were obtained in the imaging mode of MISTRAL in \nthe r-band filter (1x360s +7x600s). Observations were made \nfrom 2023-06-19 21:13:47.60 UT to 2023-06-19T22:37:40.86 UT \n(mid time ~1.85d after the T_GOTO = 2023-06-18 01:27:41 \n(Gompertz et al., GCN34023)). \nA total of 16 exposures were also obtained with the T120 CCD camera \nin the R-band filter (1x300s +8x450s, mid time ~ T_GOTO+1.83d) \nand V-band (7x600s, mid time ~ T_GOTO+1.88d). \n\nIn the coadded images, we measured the following magnitudes:\n----------------------------------------------------------------------\nJD (mid) | Telescope |  Filter | Exposure (s) | Magnitude (AB) |\n----------------------------------------------------------------------\n2460115.3875 | OHP-T120 | R | 3900 | 20.70 +/- 0.12 | \n2460115.413706 | OHP-T193/MISTRAL | r' | 4560 | 20.84 +/- 0.04 | \n2460115.440972 | OHP-T120 | V | 4200 | 20.85 +/- 0.07 | \n----------------------------------------------------------------------\nThe photometric calibration was performed using nearby stars \nfrom the PS1 catalog and the magnitudes are not corrected for \nGalactic extinction.\n\nOur measurements confirm that the source is fading at a mag rate ~ 0.9 mag/day\ncompared to the last r magnitude reported by ZTF (Swain et al., GCN 34022).\nThe red color of this transient g-r ~ 0.3 and its confirmed fast-fading evolution\nare consistent with a Gamma-ray Burst afterglow emission.\n\nWe strongly encourage spectroscopic follow-up of this source in order to identify \nits astrophysical origin.\n\nAdditional I-band follow-up observation will be performed at OHP this night. \n\nWe acknowledge the excellent support from Observatoire de Haute-Provence, \nin particular Yoann Degot Longhi for the MISTRAL observations, Gavin Coleman\nthe observer using the T193/SOPHIE instrument who allowed us to perform \nthese ToO observations as well as Pascal Gallais, Antoine Claret and \nMatthias Tornay for the T120 observations.",
  "eventId": "ZTF23aaoohpy"
}