TITLE: GCN CIRCULAR NUMBER: 14590 SUBJECT: GRB 130427A: RHESSI observations DATE: 13/05/06 17:37:44 GMT FROM: Kevin Hurley at UCBerkeley/SSL David M. Smith (UC Santa Cruz), Andre Csillaghy (Fachhochschule Nordwestschweiz), Kevin Hurley (UC Berkeley), Hugh Hudson (UC Berkeley, U. Glasgow), Steven Boggs (UC Berkeley), and Andrew Inglis (NASA Goddard/CUA) report: The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite observed the prompt emission of GRB 130427A (Maselli et al. , GCN 14448), with usable data over the approximate range 50 keV to 15 MeV, and a time resolution of 1us on each photon recorded. Absolute timing accuracy is ~1ms. Since the GRB was 122 degrees from the Sun, the photons entered through the rear of the spectrometer. The lightcurve of the main outburst in three energy bands is shown binned to 25ms resolution at: http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_longplot.gif The black, red, and orange lightcurves represent the energy ranges 50 keV to 1 MeV, 1-5 MeV, and 5-15 MeV, respectively. The lightcurve of the slower, fainter peak of the GRB, about two minutes after the primary outburst, is shown here: http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_lateplot.gif The black, red, and orange lightcurves in this case represent the energy ranges 50-200 keV, 200-500 keV, and 500 keV to 1 MeV, respectively. RHESSI data are publicly available. We invite anyone intending to use the RHESSI data to consult with us about instrumental issues associated with the observation.