function getalt,log,epoch

;This function returns the altitude in KM from the given test log
;at the passed mission time (epoch).  The epoch should be in minutes
;after T0.

; mtime = mission time (an array containing the mission time)
; alt = corresponding altitude info from the Science Summary

;if no data is found the program returns altitude = -1.


openr,lun,log+'Science_Summary_M',/get_lun

time = ''
name = ''
rest = ''
space=''
mtime=fltarr(350)
alt=fltarr(350)
i=0
altitude=-1000.	;if no data is found the program returns -1

; The first line is different
readf,lun,time,name,rest,format ='(a13,a8,a)'
goto, start

;___________________________________________________________________
;read in data from Science_Summary and place in arrays, mtime & alt

while not eof(lun) do begin
 readf,lun,space,time,name,rest,format ='(a1,a13,a8,a)'

 start:
 if sstr(name) ne 'Cycle' then goto, next


 hrs=float(strmid(time,0,2))
 min=float(strmid(time,3,2))
 sec=float(strmid(time,6,7))

 seconds=3600.*hrs+60*min+sec
 minutes=seconds/60.

 mtime(i)=minutes
 n=strpos(rest,'Alt:')
 alt(i)=float(strmid(rest,n+4,9))

 i=i+1

 next:
endwhile
;___________________________________________________________________
;clean up data

filtzero,mtime,alt,npoints	;eliminate 0,0 data points
if npoints eq 0 then begin & print,'No Altitude Data Found' & goto,exit & endif

;sort in ascending order
array=fltarr(2,npoints)
array(0,*)=mtime
array(1,*)=alt
col_sort,array,0
mtime=array(0,*)
alt=array(1,*)

;___________________________________________________________________
;interpolate within these arrays to get the actual altitude at the epoch.

if epoch gt max(mtime) or epoch lt min(mtime) then $
 print,'* WARNING * getalt.pro must extrapolate to determine altitude at time: ',sstr(epoch)

altitude=interpol(alt,mtime,epoch)


exit:
close,lun
return,altitude/1000
end