read the data with the idl routine read_slice.pro in the directory.
Example:

IDL>file='slice_0029.dat'
IDL>read_slice,file,nph,nth,time,ph,lat,br,bth,bph,vr,vth,vph

the data read in are:

nph: dimension in phi
nth: dimension in latitude
time: time in sec
ph(nph): phi grid location (in rad)
lat(nth): latitude grid location (in rad)
br(nph,nth): Br in G
bth(nph,nth): Bth in G (positive southward)
bph(nph,nth): Bph in G
vr(nph,nth): Vr in cm/s
vth(nph,nth): Vth in cm/s (positive southward)
vph(nph,nth): Vph in cm/s

I have written 15 snapshots at 12 hour intervals, tracking an area
centered on the emerging region (relative to a rotation rate of 477 nhz),
with data (Br, Bth, Bph, Vr, Vth, Vph) written on a phi-latitude grid
of about 30 degree (or about 400 Mm) widths.