GCN Circular 17228
Subject
GRB 141221A: Keck spectroscopy
Date
2014-12-25T13:26:00Z (9 years ago)
From
Daniel Perley at Caltech <dperley@astro.caltech.edu>
D. A. Perley, Y. Cao (Caltech), and S. B. Cenko (GSFC) report:
We observed the optical afterglow of GRB 141221A (Sonbas et al., GCN
17206) with the DEIMOS spectrograph on the Keck II telescope between
12:48 and 13:10 UT on 2014-12-21. Two 900-second exposures were
acquired at high airmass.
We detect significant continuum flux across the entire spectral range
between 4490-9660 Angstroms. Inspection of the 1D spectrum shows two
apparent absorption features at 6854 and 6873 Angstroms which we
tentatively associate with the Mg II doublet at z=1.452.
Lower-significance probable absorption lines are also seen at the
wavelengths of the Fe II 2599, 2585, 2383, 2374, and 2344 lines at
similar redshift, lending additional credence to this association.
However, due to a failure of the blue arc calibration lamps, we note
that our wavelength solution is preliminary and this result should be
considered tentative.