  On 25 October 2012 the Reuven Ramaty High Energy Solar Spectroscope Imager
(RHESSI) and the Tropical Rainfall Measuring Mission (TRMM) satellites passed
over a thunderstorm on the coast of Sri Lanka. RHESSI observed a terrestrial
gamma ray flash (TGF) originating from this thunderstorm. Optical measurements
of the causative lightning stroke were made by the lightning imaging sensor
(LIS) on board TRMM. The World Wide Lightning Location Network (WWLLN) detected
the very low frequency (VLF) radio emissions from the lightning stroke. The
geolocation from WWLLN, which we also assume is the TGF source location, was in
the convective core of the cloud. By using new information about both RHESSI
and LIS timing accuracy, we find that the peak in the TGF light curve occurs
230 $\mu$s before the WWLLN time. Analysis of the optical signal from LIS shows
that within the uncertainties, we cannot conclude which comes first: the gamma
emission or the optical emission. We have also applied the new information
about the LIS timing on a previously published event by {\O}stgaard et al.
(2012). Also for this event we are not able to conclude which signal comes
first. More accurate instruments are needed in order to get the exact timing
between the TGF and the optical signal.

Space Physics;Instrumentation and Methods for Astrophysics