{
  "bibcode": "2024GCN.37146....1P",
  "body": "N. Pankov (HSE, IKI), V. Kim (FAI), M. Krugov (FAI), S. Belkin (IKI, HSE),\nA. Pozanenko (IKI) report on\nbehalf of GRB-IKI-FuN:\n\nWe observed the field of EP240801a (Zhou et al, GCN 36997) with AZT-20\ntelescope of Assy-Turgen observatory. The observation were conducted on\nepochs\n2024-08-04 17:16, 2024-08-07 19:03, and 2024-08-08 19:36 (UT, starting\ntime).\nThe optical source (Fu et al, GCN 36998; Li et al, GCN 36999; Zheng et al,\nGCN 37000; Aryan et al, GCN 37002; An et al, GCN 37004; Pérez-Fournon et\nal,\nGCN 37007; Malesani et al, GCN 37008; Zhu et al, GCN 37010;\nMoskvitin & Spiridonova, GCN 37012; Quirola-Vásquez et al, GCN 37013;\nMoretti et al, GCN 37014; Turpin et al, GCN 37015; Pankov et al, GCN 37016;\nMoskvitin & Spiridonova, GCN 37017; Ruocco et al, GCN 37024; Pankov et al,\nGCN\n37040; Moskvitin et al, GCN 37049) is detected only on the first epoch.\nPreliminary photometry is the following:\n\nDate       UT start  t-T0     Exp.    Filter   OT     Err.     UL\n                  (mid, days)  (s)                          (3sigma)\n2024-08-04 17:16:21 3.373472  95*60   r'       23.29  0.14    23.6\n2024-08-07 19:03:15 6.437292  65*60   r'       n/d    n/d     23.9\n2024-08-08 19:36:10 7.458070  59*60   r'       n/d    n/d     24.0\n\nThe magnitudes were calibrated using nearby stars from SDSS-DR12 catalog\nand are not corrected for the expected Galactic extinction A(r) = 0.252 mag\n(S&F 2011) towards the EP240801a source.\n\nThe light curve in the r and R filters (AB mags) can be fitted with a\nsmoothed broken power law (Beuermann et al, 1999) with parameters:\nalpha_1 = 1.1, alpha_2 = 0.33, t_break = 1.5 days with fixed smoothing\nparameter omega = 1.0. We also note, that there\nis a point-like source in the LS DR10 at the position of EP240801a. The\nsource magnitudes are g = 25.14, r = 24.40, and the photometric redshift of\n0.995 +- 0.352, which is marginally consistent with the redshift of 1.673\nobtained with GTC spectroscopy (Quirola-Vásquez et al, GCN 37013).\n",
  "subject": "EP240801a: Assy-Turgen optical observations",
  "eventId": "EP240801a",
  "circularId": 37146,
  "submittedHow": "email-legacy",
  "createdOn": 1723444528460,
  "submitter": "Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>"
}