TITLE:   GCN CIRCULAR
NUMBER:  20409
SUBJECT: LIGO/Virgo G268556/GW170104: 10.4m GTC spectroscopic observations of iPTF17fs
DATE:    17/01/09 18:49:59 GMT
FROM:    Alberto J. Castro-Tirado at IAA-CSIC  <ajct@iaa.es>

A. J. Castro-Tirado, B.-B. Zhang, J. C. Tello, Y. Hu (IAA-CSIC, Granada), M. D. Caballero-Garcia (ASU-CAS), V. V. Sokolov, V. V. Vlasjuk, A. F. Valeev (SAO-RAS), E. Pian (SNS-Pisa), S. Jeong (SKKU), S. R. Oates (Warwick) and P. Pessev (GRANTECAN), on behalf of a larger collaboration, report:

We observed the transient iPTF17fs (Singer et al., LVC GCN 20401) with the 10.4m GTC telescope located at La Palma (Canary Islands, Spain) equipped with the OSIRIS spectrograph. The observations were carried out starting on Jan 9, 5:30 UT. The iPTF16fs spectra covering the range 3700-10000 A shows that this transient is a type Ia SN about 1 week before maximum at a redshift z~0.068.

We acknowledge excellent support from the GTC staff.