This file contains EPI-Lo direct event data for ion composition mode
as used in Desai et al (2021). Details of instrument operation are
described in Hill et al (2017), https://doi.org/10.1002/2016JA022614 .

These were processed on 2021-9-13 with the then-current EPI-Lo
calibrations (version 10), corresponding to ISOIS data release 9.

Data columns are:

DAY: YYYMMDD of ion detection

TIME: UTC (HH:MM:SS) of ion detection, converted from spacecraft
clock. The precision of the raw event data is about one second.

SPECIES: Species as identified by on-board lookup tables. X means
identified as not being a valid species (i.e., outside of tracks for
valid species.)

SPEED: Speed of the ion in the time-of-flight chamber, in km/s.

E_DEP: Energy deposited in the SSD, in keV.

E_C: Characteristic incident energy of the energy channel identified
by on-board lookup tables, in keV. This is the best estimate for
incident ion energy. -1 in this or E_LO, E_HI indicates no identified
species and thus no calculated incident energy.

E_LO: Minimum incident energy of the energy channel identified by
on-board lookup tables.

E_HI: Maximum incident energy of the energy channel identified by
on-board lookup tables.

QUAD: Quadrant of EPI-Lo where the ion entered, 0-3.

POS: Position within a quadrant (based on start pulse), 0-19. quad *
20 + pos == "L" look direction.

TOF: Time of flight (in ns). Note that the effective length of the TOF
chamber is look-direction dependent and this has not been corrected
(the SPEED column is corrected for this path length.)

SCSPEED: Spacecraft speed relative to the inertial frame, projected
along the look direction of ion arrival. This is the additional
velocity (km/s) imparted on the incident particles down the boresight
of the aperture. It is positive for particles that have had their
speed increased by the spacecraft motion (i.e. should be subtracted
from the SPEED column to get something closer to speed in the
non-moving frame, although SPEED is roughly speed through the TOF
chamber and may not be exactly incident.) Technically this is:
Spacecraft motion relative to the Sun in J2000 frame, rotated by a
J2000-to-look-direction-frame rotation matrix, Z component taken. The
+Z axis of each look direction's frame is out the boresight.