[vsnet-grb-info 22150] LIGO/Virgo S190426c: Tentative Red Transient Candidate from Las Cumbres Observatory

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24249
SUBJECT: LIGO/Virgo S190426c: Tentative Red Transient Candidate from Las Cumbres Observatory
DATE:    19/04/26 21:16:24 GMT
FROM:    Iair Arcavi at LCOGT  <arcavi at gmail.com>

Iair Arcavi (Tel Aviv University), Curtis McCully (LCO), Daichi Hiramatsu
(LCO/UCSB), D. Andrew Howell (LCO/UCSB), Jamison Burke (LCO/UCSB), Craig
Pellegrino (LCO/UCSB) on behalf of the Las Cumbres GW Follow-up
Collaboration

We detect a possible transient at RA Dec 217.28296 -38.190458,

which we tentatively name “Nemo”, on the outskirts of the galaxy 2MASX
J14290828-3811214 (redshift 0.07478 / distance 338 Mpc; Jones et al. 2009,
“The 6dF Galaxy Survey Data Release 3,” via NED).


We measure a preliminary aperture magnitude of 19.74 +- 0.12 in the i-band
(but host contamination is likely) in a 300s image taken on 2019-04-26
18:19:33 UT at a Las Cumbres SAAO 1m telescope. This corresponds to an
absolute magnitude of -17.9 at this distance. These values are corrected
for MW extinction (E(B-V) = 0.0874; Schlafly, E.F. & Finkbeiner, D.P.
 2011, ApJ 737, 103).

“Nemo” is not visible in g-band images taken at the same time (2019-04-26
18:13:52 UT) using a Las Cumbres SAAO 1m. The source does not appear in DSS
red or blue images, though they are not as deep as our discovery image. The
transient is also not visible in images taken from the Las Cumbres
Observatory 2m Faulkes telescope in the i band at 16:27:54, the r band at
16:33:39 , and the g band at 16:39:24 (all on 2019-04-26; all times UT) but
these images are also shallower than the discovery image. Therefore the
transient nature of “Nemo” is not yet confirmed.