TITLE:   GCN CIRCULAR
NUMBER:  24686
SUBJECT: GRB 190530A: NOT photometry and spectroscopy
DATE:    19/05/30 22:52:43 GMT
FROM:    Kasper Elm Heintz at Univ. of Iceland and DAWN/NBI  <keh14@hi.is>

K. E. Heintz (Univ. of Iceland), J. P. U. Fynbo (DAWN/NBI), A. de Ugarte Postigo (HETH/IAC and DARK/NBI), D. B. Malesani (DTU Space), J. Selsing (DAWN/NBI), B. Milvang-Jensen (DAWN/NBI) and S. Moran (NOT and Univ. of Turku), report on behalf of a larger collaboration:

We observed the optical counterpart (Lipunov et al., GCN 24680) of the bright Fermi-LAT GRB 190530A (Longo et al., GCN 24679), with the 2.5-m Nordic Optical Telescope (NOT) equipped with ALFOSC, starting at 21:21:12 UT on 30 May 2019. We obtained 30 s images in each of the g, r, i, and z-filters and measure magnitudes of: m(g) = 17.72 +/- 0.03, m(r) = 17.53 +/- 0.02, m(i) = 17.41 +/- 0.02, and m(z) = 17.37 +/- 0.03 AB mag at 11.2 hr post-burst. The calibration was performed using local Pan-STARRS stars in the GRB field. This apparent magnitudes are not corrected for foreground extinction.

We subsequently obtained spectroscopy for a total of 2x600 s, using grism #4 and covering the wavelength range 3650-9450 AA. The spectrum shows a blue, power-law continuum from 3900 AA to 9000 AA. We do not detect any significant absorption or emission lines in our low-resolution spectrum, but based on the detected continuum we infer an upper limit on the redshift of z < 2.2. We encourage the community to obtain spectra of this GRB with bluer wavelength coverage.