PM1EPHND is the Aqua Near Real Time (NRT) daily spacecraft definitive ephemeris data file in native format. This is MODIS Ancillary Data. The data collection consists of PM1 Platform Attitude Data that has been preprocessed by ECS to an internal standard supported by the ECS SDP Toolkit. This data is typically used in determining the geolocation of earth remote sensing observations.The file name format is the following:

PM1EPHND_NRT.Ayyyyddd.hhmm.vvv

where from left to right:
PM1 = PM1 (Aqua);
EPH = Spacecraft Ephemeris;
N = Native format;
D = Definitive;
A = Acquisition;
yyyy = data year,
ddd = Julian data day,
hh = data hour,
mm = data minute;
vvv = Version ID.