[vsnet-grb-info 2434] GRB 051111: Further spectroscopic analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4271
SUBJECT: GRB 051111: Further spectroscopic analysis 
DATE:    05/11/14 17:54:48 GMT
FROM:    Jason Prochaska at UCO/Lick Obs  <xavier at ucolick.org>

J.X. Prochaska (UCO/Lick) on behalf of GRAASP reports:

"We have further analyzed the Keck/HIRES spectrum of GRB 051111.
A total integration of 5400s was acquired covering 4200-8400Ang
with a SNR~20 per 1.3km/s pixel at 5500Ang.  The main component
is ~30km/s wide, contains 90% of the gas and is centered at
z=1.54948 +/- 0.00001.  The full line-profile, however, spans
~250km/s.

The gas in the GRB host is remarkable for several reasons:
(1) The SiII 1808 and ZnII 2026, 2062 transitions are saturated
implying log N(Zn) > 13.5 and log N(Si) > 15.9.  We believe these are
the largest Zn and Si column densities recorded outside the Local Group;
(2) The observed Zn/Fe ratio is [Zn/Fe] > 1.2 indicating significant
differential depletion;  (3) We detect the fine-structure SiII* 1816
transition and observe that the weak MgI 2026 transition is saturated.
(4) Perhaps more stunning, we detect nearly every FeII excited  
transition
in the Morton catalog redward of 2300Ang.  This includes several
transitions from the 977K excited level.  These suggest both a large
volume density and a warm gas.

We place a lower limit to N(HI) assuming a solar metallicity for
the gas: log N(HI) > 20.8.  The high metal column density and
significant differential depletion imply a rest-frame V-band
extinction A(V) > 0.5mag.  Adopting the Milky Way extinction curve,
this implies an observed R-band extinction A(R_obs) > 1.4mag.
The extinction is several times larger if one adopts the SMC or
Calzetti curves.

We also identify a very strong intervening MgII system at z=1.18975.

These data were kindly obtained by the Keck observing staff during
engineering and will be publically released.  For now, the raw data
are archived at www.graasp.org."

This GCN may be cited.