{
  "format": "text/plain",
  "submittedHow": "web",
  "subject": "GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.",
  "bibcode": "2025GCN.40095....1C",
  "createdOn": 1743961464954,
  "eventId": "GRB 250404A",
  "submitter": "Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy <giovannicalapai@tiscali.it>",
  "circularId": 40095,
  "body": "Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy \nMember of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. \n\nReport:\n\nWe observed the field of GRB 250404A detected by Fermi Gamma-ray Burst Monitor (GBM team, GCN 40050) with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. \n  \nThe observations were started at 2025-04-04 22:45 UT (approximately 8.42 hours after burst) stacking a set of unfiltered CCD image. The observations were made with modest visibility conditions: passing clouds and Moon (illumin. 48%, dist. 19°)\n\nThe OT was detected at the following position (+/- 0.3 arcsec):\n\nRA    (J2000.0)  08h 20m 14.59s   \nDecl. (J2000.0) +35° 31' 41.5\" \n\nPhotometry was obtained using nearby PanSTARRS stars as follows: \n\nObservation    Mid-Time    T-T0 (hr)      Exposure        Filter      Mag.      Err.\n2025-04-04   23:27:00 UT    9.12           82x60s          CR        20.16     +/-0.2\n\nMagnitude was calibrated with the nearby PanSTARRS stars converted using Lupton (2005) equations. \nNo correction for galactic dust extinction was applied.\n\nOur observations are consistent with other already reported Jiang et al. (GCN 40052), Perez-Garcia et al. (GCN 40053), Du et al. (GCN 40058), Zhu et al. (GCN 40061), Konno et al. (GCN 40063), Odeh et al. (GCN 40064), Lipunov et al. (GCN 40066), Min-He et al. (GCN 40069), Lipunov et al. (GCN 40070), Perez-Fournon et al. (GCN 40071), Jelinek et al. (GCN 40072), Rakotondrainibe et al. (GCN 40073), Taguchi et al. (GCN 40074), Brivio et al. (GCN 40075), Ruocco (GCN 40076), Martin-Carrillo et al. (GCN 40080), Pavoni et al. (GCN 40083), Li et al. (GCN 40084), Yin et al. (GCN 40085), Pankov et al. (GCN 40086), Chen et al. (GCN 40088), Chen et al. (GCN 40089), Pankov et al. (GCN 40090), Leonini et al. (GCN 40093).\n\nThe message may be cited."
}