[vsnet-grb-info 23464] GRB 190829A: NOT optical afterglow detection and spectroscopy

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25563
SUBJECT: GRB 190829A: NOT optical afterglow detection and spectroscopy
DATE:    19/08/30 03:42:22 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley at ljmu.ac.uk>

K. E. Heintz (Univ. of Iceland), J. P. U. Fynbo (DAWN/NBI), P. Jakobsson 
(Univ. of Iceland), D. Xu (NAOC), D. A. Perley (LJMU), D. B. Malesani 
(DTU space), and J. Viuho (NOT), report on behalf of a larger 
collaboration:

We observed the Swift-detected GRB 190829A (Dichiara et al., GCN 25552) 
with the Nordic Optical Telescope (NOT) equipped with AlFOSC. We 
obtained 3x300s r-band images at a mid-time of 02:03:52 UT on August 30 
(i.e. 6.1 hr post-burst). We clearly detect the optical counterpart 
reported by Xu et al. (GCN 25555), superimposed on the SDSS galaxy 
J025810.28-085719.2 at z=0.08 as noted previously.  We measure a 
preliminary magnitude of r(AB) = 18.9 +/- 0.1 for this source, 
calibrated against photometry of nearby field stars from the Pan-STARRS 
catalog.

Following the imaging sequence, we obtained a series of spectra with an 
integration time of 4x600s using grism 4 (covering 320-960 nm), 
beginning at 02:27:42 UT. The spectrum shows a featureless red 
continuum, with no clear absorption lines to identify the redshift. 
Since the continuum is detected at all observed wavelengths we can place 
a limit on the redshift of z < 1.8.









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