TITLE:   GCN CIRCULAR
NUMBER:  24901
SUBJECT: GRB 190627A: Optical imaging and spectroscopy from Calar Alto
DATE:    19/06/28 18:44:11 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), L. Izzo, M. Blazek, C. C. Thoene (all HETH/IAA-CSIC), A. 
Guijarro, and S. Pedraz (both CAHA) report:

We observed the afterglow of the short-soft GRB 190627A (Sonbas et al. 
GCN 24888, Siegel et al. GCN 24889, Evans et al. GCN 24890, Pozanenko et 
al. GCN 24892, Leonini et al. GCN 24893, Morris et al. GCN 24894, 
Lipunov et al. GCN 24895, Mao et al. GCN 24896, Barthelmy et al. GCN 
24899) with CAFOS at the 2.2 m telescope of the Calar Alto Observatory, 
in Almeria (Spain). We obtained imaging in g', r', i' and z' bands, as 
well as a low resolution spectrum. Observations were obtained in 
inclement weather conditions (2".5 seeing and low transparency because 
of Calima).

The imaging consisted of 5 x 60 s exposures each in the z' and i' bands, 
and 1 x 300 s each in r' and g' band. The optical counterpart is well 
detected in each of the individual images. At a mean epoch 21:54:42 UT 
(10.603 hr after the burst,) the object had a magnitude of r'(AB) = 
18.33 +/- 0.04 mag as compared to field stars from the PanSTARRS 
catalog.

The spectrum was obtained at a mean time of 11.675 hrs after trigger and 
consisted of an exposure of 3 x 1800 s. We used the B-200 grism that 
covers the range between 3500 and 8800 AA with a resolving power of R ~ 
400. The spectrum shows a clear continuum across the complete range, 
with an average signal-to-noise ratio per dispersion element of 5.5. 
However, we are not able to match any of the marginal absorption 
features with a particular redshift. We have made the reduced spectrum 
publicly available through GRBSpec [1].

Further observations are planned.

[1] http://GRBSpec.iaa.es