TITLE:   GCN CIRCULAR
NUMBER:  14342
SUBJECT: GRB 130327A: Gemini Observations
DATE:    13/03/27 21:20:55 GMT
FROM:    Antonino Cucchiara at UCSC/UCO Lick  <acucchia@ucolick.org>

A. Cucchiara (UCSC/UCO Lick Observatory) and S. B. Cenko 
(UC Berkeley) report on behalf of a large collaboration:

"On March 27.25 UT we observed the field of GRB 130327A 
(Ukwatta et al., GCN 14331) with the Gemini-North telescope
equipped with the GMOS camera.

We obtained a 4 minutes i' band image of the field:
the two sources identified by Butler et al. (GCN 14334)
are both detected.

The southern source (#1) is located at
RA: 06:08:09.12 (J2000)
Dec: +55:42:47.98 (J2000)

The northern source (#2) is located inside the XRT revised 
error circle (Osborne et al. GCN 14335) at:

RA: 06:08:09.25 (J2000)
Dec: +55:42:54.39  (J2000)

Using several nearby USNO-B1 stars we estimated i' = 19.81 
+- 0.02, (source #1), and i' = 21.75 +- 0.06 (source #2), 
which is 0.43 mag fainter than the RATIR observations. 

We also obtained a 2x900s spectra of these two sources under cloudy
conditions, covering the 6000-10000A wavelength range: source #1
presents several stellar features, while source #2 presents a noisy 
continuum, but no clear absorption features are identified.

If we assume that source #2 is indeed GRB 130327A afterglow, we can
place an upper limit on the GRB redshift of z < 3.9, based on the 
absence of a Lyman-break features. 
Our acquisition image can be found here:
https://www.dropbox.com/s/ygvcdykmpow6gq5/sources.jpeg

We thank the Gemini staff for performing this observations,
in particular Andre'-Nicolas Chene' "