a) Time profile in different RHESSI energy ranges of the flare starting around 23:55 UT on 2002 April 14. The vertical lines indicate the five time intervals for which the spectral fitting and visibility-based imaging were performed. b) The spatially integrated RHESSI X-ray spectrum fitted with an isothermal plus thick-target nonthermal model for the third time interval (00:06 − 00:08 UT). c) An example of a photon flux map (for the third time interval and energy bin 18 − 20 keV) obtained by the Clean method (Hurford et al. 2002).