{
  "bibcode": "2019GCN.24459....1K",
  "body": "D. A. Kann (HETH/IAA-CSIC), C. Thoene (HETH/IAA-CSIC), C. Stachie \n(Artemis), X. Zhang (THU), Z. Vidadi (Shao), M. Blazek (HETH/IAA-CSIC), \nK. Bensch (HETH/IAA-CSIC), L. Izzo (HETH/IAA-CSIC), A. de Ugarte Postigo \n(HETH/IAA-CSIC, DARK/NBI), S. Antier (APC), S. Basa (LAM), M. Boer \n(Artemis), D. Corre (LAL), M. Coughlin (Caltech), D. Coward \n(OzGrav-UWA), J.G. Ducoin (LAL), B. Gendre (OzGrav-UWA), P. Hello (LAL), \nA. Klotz (IRAP), C. Lachaud (APC), N. Leroy (LAL), D. Turpin (NAOC), and \nX. Wang (THU)\n\nreport on behalf of the HETH group and GRANDMA collaboration:\n\nWe observed the location of the Swift UVOT transient (Breeveld et al., \nGCN #24296) discovered in the error region of the aLIGO/Virgo Binary \nNeutron Star merger event S190425z (Ligo Scientific Collaboration and\nVIRGO Collaboration, GCN #24168, #24228), with \nthe 2.2m CAHA telescope and CAFOS. We obtained 3 x 240 s each in U/B and \n6 x 120 s in V/Rc/Ic. The observations were performed on 2019-04-28 from \n02:11:50 to 03:52:47 UT.\n\nAt the position (Palmese et al., GCN #24312) of the likely counterpart \n(thought to be an M2 dwarf that had a powerful flare which UVOT \ndetected, Lipunov et al., GCN #24326; Bloom et al., GCN #24337), we \ndetect a source in Rc and Ic and derive the following upper limits and \nmagnitudes:\n\nU > 22.9 mag;\nB > 23.5 mag;\nV > 23.5 mag;\nRc = 22.51 +/- 0.15 mag (depth Rc > 23.8 mag);\nIc = 21.53 +/- 0.15 mag (depth Ic > 22.9 mag).\n\nMagnitudes are given in the AB system and were obtained vs. a comparison \nstar from PanSTARRS and the transformations of Lupton (2005).\n\nOur detections are in reasonable agreement with other reports (Palmese \net al., GCN #24312; Bloom et al., GCN #24337; Hu et al., GCN #24324) and \nindicate the source was quiescent during our observations.\n\nGRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger \nAddicts) is a network of robotic telescopes connected all over the world \nwith both photometry and spectrometry capabilities for Time-domain \nAstronomy (https://grandma.lal.in2p3.fr/).\n\nThis message may be cited.\n\n[GCN OPS NOTE(12jun19), The second reference in the first paragraph\nwas changed from \"Breeveld et al., #24296\" to\n\"Ligo Scientific Collaboration and VIRGO Collaboration, GCN #24168, #24228\".]",
  "circularId": 24459,
  "createdOn": 1557515775000,
  "email": "kann@iaa.es",
  "subject": "LIGO/Virgo S190425z: CAHA-GRANDMA Observation of the Swift UVOT Source",
  "submitter": "Alexander Kann at IAA-CSIC  <kann@iaa.es>",
  "eventId": "LIGO/Virgo S190425z"
}