TITLE:   GCN CIRCULAR
NUMBER:  6217
SUBJECT: GRB 070318: Gemini + Magellan spectra
DATE:    07/03/19 07:39:56 GMT
FROM:    Hsiao-Wen Chen at U Chicago  <hchen@oddjob.uchicago.edu>

H.-W. Chen (U Chicago), J. X. Prochaska (UCO/Lick Observatory), S. 
Herbert-Fort (Steward Observatory), D. Christlein (Universidad de 
Chile/Yale), and S. Cortes (Steward Observatory) report on behalf of a 
larger collaboration:

"We obtained 2x1800 sec long-slit spectra of the optical transient of
GRB070318 (Cummings et al., GCN 6210), using GMOS and an the R400 grating
on the Gemini south telescope.  The observations started at March 19.001 
UT, ~ 16.5 hours after the initial Swift trigger.  The spectra covered a
wavelength range from 5930 Ang through 8750 Ang.  We also obtained 2700 
sec long-slit spectra, using IMACS and the 300 l/mm grism on the Magellan 
Baade telescope.  The observations started at March 19.011 UT, and the 
spectra cover a wavelength range from 4200 Ang through 6500 Ang.  We 
identify MgII 2796,2803, MgI 2852, FeII 2600, and TiII 3384 lines at 
z=0.840 +/- 0.002, but no other apparent MgII absorption doublet.  We 
therefore confirm the redshift reported by Jaunsen et al. (GCN 6216) as 
the location of the afterglow.

Further analysis is underway."