[vsnet-grb-info 10381] GRB 101225A: revised analysis of narrow band imaging

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11819
SUBJECT: GRB 101225A: revised analysis of narrow band imaging
DATE:    11/03/22 19:16:23 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3 at star.le.ac.uk>

N. R. Tanvir (U. Leicester) and A. J. Levan (U. Warwick) report:

We have re-reduced and re-analysed more thoroughly the imaging reported
in GCN 11642. While it remains the case that the optical transient is
detected in the H-alpha narrow-band filter, and at best marginally present
in the r-band, the significance of the excess H-alpha detection is reduced. 
Within the associated errors the revised photometry is broadly consistent
with the red colour of the transient at this time (the narrow-band filter being
somewhat redward of the central wavelength of the r-band filter), and hence,
the data do not require significant line emission. This argument for a z~0
origin is therefore weakened.