  The unusually narrow X-ray source imaged with RHESSI during an impulsive
spike lasting for $\sim$10~s during the GOES C7.9 flare on 25 September 2011
(SOL2011-09-25T03:32) was only $\sim$2~ arcsec wide and $\sim$10~arcsec long.
Comparison with HMI magnetograms and AIA images at 1700~\AA~shows that the
X-ray emission was primarily from a long ribbon in the region of positive
polarity with little if any emission from the negative polarity ribbon.
However, a thermal plasma source density of $\sim$10$^{12}~cm^{-3}$ estimated
from the RHESSI-derived emission measure and source area showed that this could
best be interpreted as a coronal hard X-ray source in which the accelerated
electrons with energies lass than $\sim$50~keV were stopped by Coulomb
collisions in the corona, thus explaining the lack of the more usual bright
X-ray footpoints. Analysis of RHESSI spectra shows greater consistency with a
multi-temperature distribution and a low energy cutoff to the accelerated
electron spectrum of 22 keV compared to 12 keV if a single temperature
distribution is assumed. This leads to a change in the lower limit on the total
energy in electrons by an order of magnitude given the steepness of the
best-fit electron spectrum with a power-law index of $\sim$6.
