pro zen_plot,date,takeoff_time,takeoff_gmt,poam_times,sage_times,haloe_times,noerase=noerase,position=position,open_axis=open_axis,$
    title=title,nomoon=nomoon

; does the base plot of zenith angle window plot including satellite overpasses
    yrange=[60.,120.]
    xrange=takeoff_time+[0,10]
    if n_elements(position) eq 0 then position=[.15,.15,.85,.85]
    if keyword_set(open_axis) then yst=9 else yst=1
    if n_elements(title) eq 0 then title='Solar/Lunar Zenith Angle '+nicedate(date)
    plot,[0],[0],title=title,xrange=xrange,yrange=yrange,$
    xtitle='Flight Time (local)',ytitle='Zenith Angle',xst=1,yst=yst,xticks=10.,noerase=noerase,position=position
;      oplot,xrange,[78.,78.], linest=2
      oplot,xrange,[90.,90.], linest=0
      clip=[takeoff_time,60,takeoff_time+10,120]
      if n_elements(poam_times) gt 0 then xyouts,takeoff_time+poam_times,yrange(1)-4.+poam_times*0.,'P',col=80,/data,noclip=0
      if n_elements(sage_times) gt 0 then xyouts,takeoff_time+sage_times,yrange(1)-3.+sage_times*0.,'S',col=150,/data,noclip=0
      if n_elements(haloe_times) gt 0 then xyouts,takeoff_time+haloe_times,yrange(1)-4.+haloe_times*0.,'H',col=200,clip=clip,/data,noclip=0
      gmts=takeoff_gmt+findgen(10.)
      n=where(gmts gt 24.)
      if n(0) gt 0 then gmts(n)=gmts(n)-24.
      xinc=takeoff_time+findgen(10)
      xyouts,xinc,yrange(0)+2.+fltarr(10),string(gmts,format='(f4.1)')
      xyouts,takeoff_time-1.2,yrange(0)+2.,'GMT',size=0.9
      xyouts,xinc,yrange(0)+5.+fltarr(10),string(findgen(10),format='(i2)')
      xyouts,takeoff_time-1.2,yrange(0)+5.,'FLT',size=0.9
      oplot,(takeoff_time+8.)*[1.,1.],yrange
      if not keyword_set(nomoon) then legend,['solar','lunar'],lines=[0,1],box=0
 

return
end