{
  "eventId": "GRB 230812B",
  "submittedHow": "web",
  "body": "D. Turpin (CEA), M. Serrau (KNC), S. Leonini (KNC), M. Freeberg (KNC), \nF. D. Romanov (KNC), S. Karpov (FZU), S. Antier (OCA/Artemis) report \non behalf of the GRANDMA/Kilonova-Catcher collaboration:\n\nThe Kilonova-Catcher telescope network responded to the alert of \nGRB 230812B (Fermi GBM detection: Roberts et al., GCN 34391;\nFermi LAT detection: Scotton et al., GCN 34392). \n\nThe KNC observations were taken by M. Serrau at the Chante-Perdrix \nObservatory (France), S. Leonini at the Montarrenti Observatory (Italy),\nM. Freeberg at the Hidden Valley Observatory (USA) and F.~D. Romanov at the\niTelescope.Net in Sierra Remote Observatory (USA).\nThe afterglow is first detected in 50x30s R-band coadded images at\nabout 1 day (midtime of the exposure) after the Fermi/GBM trigger time.\n\nBelow, we report a subset of our photometric measurements.\n---------------------------------------------------------------------------------\nT-T0 (midtime,day)  |Exposure| Filter | Mag +/- err |Mag.Lim. (5sig AB) |Observer\n---------------------------------------------------------------------------------\n1.024 | 50 x 30s | Rc | 20.35 +/- 0.16 | -- | Leonini\n1.164 | 15 x 180s | V | 20.74 +/- 0.08 | -- | Serrau\n1.182 | 30 x 180s | Rc | 20.87 +/- 0.15 | -- | Serrau\n1.425 | 6 x 300s | Ic | -- | 18.6 | Romanov\n2.334 | 12 x 300s | r | -- | 20.6 | Freeberg\n2.397 | 12 x 300s | i | -- | 19.3 | Freeberg\n2.624 | 30 x 180s | Rc | 21.29 +/- 0.11 | -- | Serrau\n4.080 | 40 x 180s | V | 22.20 +/- 0.21 | -- | Serrau\n\nOur detections are consistent with the fading behavior previously reported\nby GRANDMA Mao et al., GCN 34404; Pyshna et al., GCN 34425. We note that\nthe underlying host galaxy may contribute to our late photometric \nmeasurements. The reported magnitudes are not corrected for the galactic\ndust extinction in the line of sight of the burst. \n\nThe GRANDMA/Kilonova-Cacther images have been calibrated using field\nstars from the PanSTARRS-DR1 catalog using the STDpipe pipeline\n(Karpov 2022) and the ps1/r to Rc mag conversion from (Pancino et al. 2022).\n\nGRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr)\ndevoted to the observation of transients in the context of multi-messenger\nastrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is\nthe citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).",
  "createdOn": 1692623722689,
  "bibcode": "2023GCN.34508....1T",
  "circularId": 34508,
  "subject": "GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits",
  "submitter": "Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>"
}