TITLE:   GCN CIRCULAR
NUMBER:  25671
SUBJECT: GRB 180620A: SEDM Observations
DATE:    19/09/05 22:46:33 GMT
FROM:    Virginia Cunningham at U of MD  <vcunning@astro.umd.edu>

V. Cunningham (U of Maryland), J. D. Neill (Caltech), S. B. Cenko

(NASA GSFC), and R. Walters (Caltech) report on behalf of the

SEDM team:


We observed the optical counterpart to GRB 180620A (Evans, et al.,

GCN 22798)  with the Spectral Energy Distribution Machine (SEDM)

on the 60 inch telescope at Palomar Observatory. The SEDM is a

low resolution (R ~ 100) integral field unit spectrometer with a multi-

band (ugri) rainbow camera imager (see Blagorodnova et al. 2018,

PASP, 130, 035003, and Rigault et al. 2019, A&A, 627, A115).


The SEDM began observing the optical counterpart at 9:37:37 UTC

(63 minutes after the burst trigger time). We performed 2 x 1200 s

exposures over the wavelength range 3800-9200 A. The continuum

emission is well-fit by a power law spectrum with index alpha = 1.4

(f_nu ~ nu^-alpha). We do not confidently identify any obvious

emission or absorption features in the spectrum.