[vsnet-grb-info 23863] LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25962
SUBJECT: LIGO/Virgo S190930t: SALT optical spectroscopy of Swift J221951-484240
DATE:    19/10/06 16:30:30 GMT
FROM:    Marina Orio at INAF-Padova and U of Wisconsin  <orio at astro.wisc.edu>

David Buckley (South African Astronomical Observatory), Subo Dong (Kavli Institute of Astronomy and Astrophysics of Peking University), Stefano Ciroi (Padova University), Mariusz Gromadzski (Warsaw University Observatory), Marina Orio (Istituto Nazionale di Astrofisica, Padova and University of Wisconsin), Jirong Mao (Yunnan Observatories, Chinese Academy of Sciences), Dong Xu (National Astronomical Observatory, Chinese Academy of Sciences) and Rajeev Manick (South African Astronomical Observatory and Southern African Large Telescope) report:

On 2019/10/04 at UT 22:39:21 we obtained a 1800 sec exposure SALT spectrum of the blue transient source, Swift J221951-484240, discovered by the Neil Gehrels Swift Observatory in the field of the gravitational wave event S190930t (GCN 25901, 25939). We used the Robert Stobie spectrograph with the PG 300 grating and a 1.5 arsec  slit, covering 3300-9800 Angstroms with a resolving power of 370.  The spectrum is characterized by a steeply rising blue continuum, consistent with the earlier report (GCN 25939). The spectrum is essentially featureless, except for a possible weak double-peaked emission line at 4250A, although its reality needs further confirmation.  Thus there is still no indication as to whether this transient is  Galactic or it is instead a hostless extragalactic object.