[vsnet-grb-info 14382] GRB 140105A: continued iPTF observations and rejection of optical candidates

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15696
SUBJECT: GRB 140105A: continued iPTF observations and rejection of optical candidates
DATE:    14/01/07 06:03:23 GMT
FROM:    Leo Singer at CIT/PTF  <lsinger at caltech.edu>

L. P. Singer (Caltech), M. M. Kasliwal (Carnegie Observatories/Princeton),
S. B. Cenko (NASA/GSFC), E. Bellm (Caltech), and Y. Cao (Caltech) report
on behalf of the intermediate Palomar Transient Factory (iPTF)
collaboration:

We have continued to observe four optical transients (Singer et al.,
GCN 15686) in the Fermi GBM error circle for GRB 140105A (Xiong &
Connaughton, GCN 15688) with the Palomar 48-inch Oschin telescope
(P48), the robotic Palomar 60-inch (P60), and the Palomar 200-inch
(P200) equipped with the Double Beam Spectrograph (DBSP).

At 33 hours after the burst, with the P48 we obtain the following
host-subtracted magnitudes in the Mould R filter:
 iPTF14x,  R = 20.0
 iPTF14ac, R = 20.3
 iPTF14ae, R = 20.5

With the P60, at 34 hours after the burst, we obtain the following
magnitude in the SDSS system:
 iPTF14ai, r = 20.4

We obtained spectra of all four with the P200. iPTF14x resembles a
Type II supernova. Our spectra for iPTF14ac, iPTF14ae, and iPTF14ai
show a mostly featureless continuum.

The lack of significant optical fading in any of the four candidates
strongly argues against association with the GRB.