{
  "bibcode": "2017GCN.20862....1P",
  "body": "A. Pozanenko (IKI), A. Volnova (IKI), E. Mazaeva (IKI), E. Klunko \n(ISTP), A. Kusakin (AFIF), I. Reva (AFIF),  V. Rumyantsev (CrAO), R. \nInasaridze (AbAO), T. Movsisyan (BAO), A. Sergeev (IRA NASU) on behalf \nof IKI-GW follow-up collaboration:\n\n\nWe report results of photometric observations and possible \nclassifications of the bright SN PS17yt, PS orphan sources PS17lk, \nPS17nv, PS17qk, PS17pv, PS17rc and MASTER J090737.22+611200.5 in the \nfield of the LIGO G270580 localizations (LIGO Scientific Collaboration \nGCN 20486). Observations were conducted using telescopes/observatories \nAZT-33IK/Mondy, Zeiss-1000/TSHAO, ZTSh2.6/CrAO, AS-32/AbAO, ZTA2.6/BAO \nand Zeiss-1000/Koshka.\n\n===============\n\nPS17lk RA   09 29 58.27 Dec +15 11 58.5\n\nWe observed the source PS17lk (Huber et al., GCN 20518) taking 6 \nobservational sets in different epochs between Jan 25 and Feb 18. All \nobservations were performed with filter R. We clearly detected the \nsource in all but one epochs. The photometry is based on nearby SDSS stars.\n\nObservations\ndate Filter MJD mid Mag(Vega) err\n2017-01-25 R 57778.72969 20.92 0.16\n2017-01-29 R 57782.74483 >22.5 (3 sigma uplim)\n2017-01-30 R 57783.70939 21.10 0.11\n2017-01-31 R 57784.69874 21.22 0.12\n2017-02-07 R 57791.93095 21.60 0.40\n2017-02-18 R 57802.73167 21.89 0.24\n\nThe source is not detected in any SDSS frames up to the limit of r~23.1, \ni~22.8. Also there is no any source  in the SDSS stacked ugriz frame. We \nshould note, that PS17lk is located near the ecliptic plane (ecliptic \ncoordinates lambda = 139.955198 deg, beta = 0.391980 deg). Upper limit \non possible proper motion of the source during 25 days of observations \nis 0.6 arcsec.\n\n===============\n\nPS17nv   09 57 41.01  +17 49 33.4\n\nWe observed the localization of the source PS17nv (Huber et al., GCN \n20518) taking 3 observational sets in different nights between Jan 25 \nand Jan 31. All observations were performed with filter R. We did not \ndetect any source no one night. The photometry is based on nearby SDSS \nstars.\n\nObservations\ndate Filter MJD mid         3 sigma uplim\n2017-01-25 R 57778.74557 >22.2\n2017-01-27 R 57780.82339 >22.2\n2017-01-31 R 57784.03700 >23.4\n\nThe source is not detected in any SDSS frames up to the limit of r~23.0, \ni~22.4. Also there is no any source in the SDSS stacked ugriz frame. The \nsource is not detected neither before the discovery (SDSS frames), nor a \nfew days after (our observational epochs). The PS17nv is located near \nthe ecliptic plane (ecliptic coordinates lambda = 145.362711 deg, beta = \n5.060578 deg) and might be an uncataloged asteroid.\n\n===============\n\nPS17pv   09 25 07.35  +50 12 28.9\n\nWe observed the source PS17pv (Huber et al., GCN 20518) taking 3 \nobservational sets in different epochs between Jan 25 and Jan 30. All \nobservations were performed with filter R. We detected the source only \non Jan 30. The photometry is based on nearby SDSS stars.\n\nObservations\ndate Filter MJD mid Mag(Vega) err\n2017-01-25 R 57778.82847 >20.5\n2017-01-28 R 57781.86958 >22.4\n2017-01-30 R 57783.80134 20.74 0.11\n\nThe source is not detected in any SDSS frames up to the limit of r~23.1, \ni~22.5. Also there is no any source in the SDSS stacked ugriz frame.\n\n===============\n\nPS17qk   09 29 12.15  +25 49 06.4\n\nWe observed the source PS17qk (Huber et al., GCN 20518) taking 8 \nobservational sets in different epochs between Jan 25 and Feb 18. We \nperformed observations with filter R and in one case in filter B. We \nclearly detected the source in all our observations. The photometry is \nbased on nearby USNO-B1.0 stars.\n\nObservations\ndate Filter MJD mid Mag(Vega) err\n2017-01-25 R 57778.77275 21.01 0.12\n2017-01-29 R 57782.78859 20.61 0.11\n2017-01-30 R 57783.74301 20.46 0.06\n2017-01-31 R 57784.73083 20.36 0.05\n2017-01-31 R 57784.84479 20.50 0.03\n2017-01-31 B 57784.85668 20.87 0.04\n2017-02-01 R 57785.77138 20.17 0.05\n2017-02-18 R 57802.75716 20.55 0.07\n2017-03-06 CR 57818.86623 20.53 0.09\n\nThere is no data for this region in the SDSS latest release. We did not \nfind any source at the position in the archival DSS2 B and R plates up \nto B~21.0, R~20.5. B-R magnitude for the source is ~0.4 mag at the epoch \nJan 31 (MJD = 57784.8). The source is unlikely a Supernova.\n\n===============\n\nPS17rc  09 32 19.16 +47 03 38.3\n\nWe observed the source PS17rc (Huber et al., GCN 20518) taking 5 \nobservational sets in different epochs between Jan 25 and Feb 1. We \nperformed observations with filter R and in one case in filter B. We \nclearly detected the source in all epochs. The photometry is based on \nnearby SDSS stars.\n\nObservations\ndate Filter MJD mid Mag(Vega) err\n2017-01-25 R 57778.81470 20.96 0.15\n2017-01-30 R 57783.77229 21.04 0.10\n2017-01-31 R 57784.76358 21.13 0.11\n2017-01-31 R 57784.88885 21.28 0.05\n2017-01-31 B 57784.87345 23.57 0.24\n2017-02-01 R 57785.80742 21.28 0.09\n\nThe source is not detected in any SDSS  frames as well as in stacked \nugriz. In our observations the source is red: B-R color is ~2.3 mag at \nthe epoch of 2017-01-3 (MJD = 57784.9). It might be a SN well after \nmaximum and not related to the LIGO G270580.\n\n===============\n\nWe observed the bright SN PS17yt (Chambers et al., GCN 20512; Huber et \nal., GCN 20518) between Jan. 24 and Mar. 08 in BVR filters. We clearly \ndetected the source in all epochs. The preliminary light curve of the SN \nmay be found at http://grb.rssi.ru/PS17yt/PS17yt_lc_v7.png\n\nThe photometry is based on nearby SDSS stars.\n\nThe observed maximum of the SN in B-filter is approximately at the epoch \nMJD = 57788 (B=18.09 +/-0.05 at MJD=57789.74,  not corrected for Galaxy \nextinction).\n\nRiess et al. (1999, AJ 118, 2668) found that for low-redshift SNs Ia the \naverage rise time is t_r = 19.98 +/- 0.15 days in the rest frame for \nB-band light curve. Taking into account the low redshift of the SN \nPS17yt z = 0.067 (Chambers et al., GCN 20512; Malesani GCN 20527), we \nmay conclude that the time of the SN explosion could be at MJD = 57767 - \n57768, i.e. Jan. 14-15, and most probably not related to the LIGO G270580.\n\n===============\n\nMASTER OT J090737.22+611200.5   09 07 37.22 +61 12 00.5\n\nWe observed the source MASTER OT J090737.22+611200.5 (Lipunov et al.. \nLVC 20488) taking 3 observational sets in different epochs between Jan \n21 and 23. We performed observations with filter R. We clearly detected \nthe source in all epochs. The photometry is based on nearby SDSS stars.\n\nObservations\ndate  Filter MJD mid     Mag(Vega) err\n2017-01-21 R 57774.62327 19.07 0.01\n2017-01-22 R 57775.64491 19.10 0.02\n2017-01-23 R 57776.63227 19.18 0.03\n\nThe source is coincident with the SDSS QSO J090737.15+611200.7 (r = \n19.75 +/- 0.02) with the redshift z = 3.751227.",
  "circularId": 20862,
  "createdOn": 1489454937000,
  "email": "grbgw.iki@gmail.com",
  "subject": "LIGO/Virgo G270580: optical observations and classification of PS and MASTER sources",
  "submitter": "Alexei Pozanenko at IKI,Moscow  <grbgw.iki@gmail.com>",
  "eventId": "LIGO/Virgo G270580"
}