A NuSTAR observation of the center of the Coma Cluster
  We present the results of a 55ks NuSTAR observation of the core of the Coma
Cluster. The global spectrum can be explained by thermal gas emission, with a
conservative 90% upper limit to non-thermal inverse Compton (IC) emission of
$5.1 \times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ in a 12 arcmin $\times$ 12 arcmin
field of view . The brightness of the thermal component in this central region
does not allow more stringent upper limits on the IC component when compared
with non-imaging instruments with much larger fields of view where claims of
detections have been made. Future mosaic NuSTAR observations of Coma will
further address this issue. The temperature map shows a relatively uniform
temperature distribution with a gradient from the hot northwest side to the
cooler southeast, in agreement with previous measurements. The temperature
determination is robust given the flat effective area and low background in the
3-20 keV band, making NuSTAR an ideal instrument to measure high temperatures
in the intracluster medium.
