TRMM orbits where the station is within the swath of PR (Precipitation Radar) during the period 16 May -- 15 June 1998.
Search results at
http://www-tsdis.gsfc.nasa.gov/tsdis/PredictOrbit.html
on 9 December 2002 (7 June 2003 for Chiang Mai).
[Exercise with TRMM data (in Japanese)] [Earth Observation 2006 (in Japanese)]