GCN Circular 21543
Subject
LIGO/Virgo G298048: Galaxy-Targeted Optical Followup With Las Cumbres Observatory
Event
Date
2017-08-18T04:54:23Z (8 years ago)
From
Iair Arcavi at LCOGT <iarcavi@lcogt.net>
I. Arcavi, D. A. Howell, C. McCully, G. Hosseinzadeh, S. Vasylyev (UCSB/Las
Cumbres Obs), M. Zalzman, D. Poznanski (TAU), L.P. Singer (NASA/GSFC), S.
Valenti (UC Davis), T. Piran (HUJI), D. Kasen, J. Barnes (UC Berkeley) and
W-f. Fong (UA) report on optical followup observations of the LIGO-Virgo
G298048 trigger using the Las Cumbres Observatory (LCO) worldwide telescope
network.
We target galaxies from the GLADE catalog and prioritize them by their
position in the LIGO/Virgo localization region, their mass (estimated from
their absolute B-band magnitude), and inversely by their distance.
Between 2017-08-17 17:04 and 18:42 UT we observed the following galaxies
using the two LCO 1-meter telescopes at the South African Astronomical
Observatory in the following filters with a 300s exposure per filter:
GLADE ID RA Dec Dist [Mpc] Galaxy B-mag Filters Observed
2037 199.749649 -47.908653 40.926 11.8 g,r,i
564852 214.019012 -48.127373 54.444 11.69 g,r
621160 194.532623 -46.264214 29.3765 10.93 g,r,i
732352 204.16272 -33.965916 49.125 11.24 g,r,i
737707 213.977814 -48.114883 59.917 12.06 g,r,i
815140 193.363815 -48.749153 49.556 11.98 g,r,i
1306036 198.491943 -49.478775 45.278 11.47 g,r,i
1850978 194.305 -46.37728 46.9894 12.12 g,r,i
All r-band images were visually inspected for new sources compared to
archival DSS images. No obvious ones were found.
The above galaxies were chosen to also lie close to the FERMI localization
region. Following the revised LIGO/Virgo localization from Singer et al.
(LVC GCN 21513), we observed the following galaxies using the two LCO
1-meter telescopes at the Cerro Tololo Inter-American Observatory in Chile
in the following filters with a 300s exposure per filter:
GLADE ID RA Dec Dist [Mpc] Galaxy B-mag Filters Observed
341075 197.018005 -23.796844 34.097 12.87 w
564852 214.019012 -48.127373 54.444 11.69 g,r,i
602087 196.774902 -23.67704 33.42 13.18 w
645472 196.907242 -23.57892 41.75 14.21 w
667146* 197.448776 -23.383831 33.806 12.87 w
770765 196.89064 -24.008606 43.944 12.68 w
773496 196.735474 -23.91707 33.653 13.07 w
777014 196.270554 -22.383947 30.479 13.98 w
1366038 197.691406 -23.865728 33.42 12.64 w
1478047 197.466 -24.23937 38.548 13.6 w
1486718 196.937 -22.85784 26.792 12.88 w
1486724 197.329 -24.38456 33.42 13.85 w
1850989 197.465 -24.24 42.2669 12.78 w
* GLADE 667146 is also NGC 4993 where we detect SSS17a / DLT17ck, the
possible optical counterpart reported by Coulter et al. (LVC GCN 21529),
Allam et al. (LVC GCN 21530), Yang et al. (LVC GCN 21531) and Melandri et
al. (LVC GCN 21532). See Arcavi et al. (LCV GCN 21538).
The w-band is wide filter covering the g+r+i-bands.
Analysis of all images obtained is ongoing.
The following GLADE galaxies have been submitted for observations starting
at 2017-08-18 08:32 UT using the two LCO 1-meter telescopes at the Siding
Spring Observatory in Australia with 300s w-band exposures:
GLADE ID RA Dec Dist [Mpc] Galaxy B-mag
7 192.519547 -14.73349 53.528 13.21
626 193.998657 -19.26899 41.944 13.27
3644 192.248566 -14.399235 49.583 12.55
420937 198.880432 -23.982388 35.3367 12.31675
557076 194.366257 -19.691298 44.75 12.68
635635 196.600052 -24.164007 33.431 13.78
645300 196.580811 -22.98033 39.361 15.71
646603 193.219254 -15.413292 56.139 13.09
684330 193.363464 -17.005495 54.417 12.76
708169 196.666443 -22.455793 42.222 15.15
795473 199.096786 -26.561554 44.319 13.95
977319 194.252274 -17.320408 54.444 13.97
1486596 193.107 -15.51722 50.431 14.25
1486614 193.706 -16.0522 46.375 14.95
1486713 196.719 -22.84175 33.958 14.67
A spectrum of SSS17a / DLT17ck has also been submitted to start at
2017-08-18 08:32 UT using the LCO 2-meter telescope at Siding Spring, as
well as g,r,i 300s imaging with one of the LCO 1-meter telescopes there.