NAME:
       xgif
 PURPOSE:
       preview gif files
 CALLING SEQUENCE:
       xgif,file
 INPUTS:
       file 
 OUTPUTS:
       none
 CALLS: ***
	LOC_FILE [1], LOC_FILE [2], LOC_FILE [3]
 PROCEDURE:
       spawns local previewer
 HISTORY:
       Written Jun'94 (DMZ,ARC)

 Project     : SDAC
                   
 Name        : XJUMPER2
               
 Purpose     : This procedure looks for counter overflow in the GRS XRAY data and then adjusts
		it to the true rate.  
               
 Category    : SMM, GRS
               
 Explanation : The algorithm looks for abrupt changes in the compressed
		rate, OVERFLOW, of more than 128. It is assumed that these jumps are produced 
		by overflow.  Moreover, we believe that the GRS algorithm which wrote the USER
		file then used the cnts*(cnts+1) algorithm on these data, so first they must
		be corrected back to the cnts value and the appropriate number of overflows
		added.  After finding these jumps it is simply bookkeeping to reset the 
		data to the true rate.
               
 Use         : XJUMPER2, Overflow, Reset
    
 Inputs      : Overflow - Raw GRS Xray counter values.
               
 Opt. Inputs : None
               
 Outputs     : Reset    - Corrected counter values.

 Opt. Outputs: None
               
 Keywords    : SUMMED_ROLLS - Total rollovers, positive and negative.
		ERR_NTOT - If set, the rollovers aren't balanced.  Possible error.
		W- indices of the jumps
 Calls       :
 CALLED BY:
	GRS_JUMPER
 Common      : None
               
 Restrictions: 
               
 Side effects: None.
               
 Prev. Hist  :

 Modified    : Version 1, RAS, 1992
		Version 2, RAS, 21-mar-1997, completed documentation

 NAME:
	XRPOFF
 PURPOSE:
	Return XRP pitch and yaw offsets
 CALLING SEQUENCE:
	XRPOFF, TIME, P_OFF, Y_OFF, T_OFF
 INPUTS:
	TIME	time in seconds since 1979/1/1
 OUTPUTS:
	P_OFF	pitch offset in arcsec
	Y_OFF	yaw offset in arcsec
       T_OFF   actual time of offset (secs since 1979/1/1)
 CALLED BY:
	RDFCS, RDFIS, rdfis_img
 PROCEDURE:
	The returned pitch and yaw offset correspond to the catalog time
	preceding the input time, except for times between the last pre-repair
	offsets and the first post-repair offsets (in which case the time
	nearest to input time is used).
 MODIFICATION HISTORY:
	APR-1991, Paul Hick (ARC)

 pro xy0
 XY0 sets input x axis range and y axis range to [0,0] for autoscaling.
 AKT

 NAME: 
      XYTOLB
 PURPOSE:  
      convert solar cartesian coordinates to heliographic
 CATEGORY:  
      utility
 CALLING SEQUENCE:  
      xytolb,x,y,l,b,radius,bangle,roll,/inverse
 INPUTS: 
      x,y = cartesian coords of points (arcsecs)
      radius = solar radius (arcsecs)
      bangle = solar bangle (deg)
 OUTPUTS
      l,b = heliographic coords of points (degrees)
 OPTIONAL INPUT
      roll = spacecraft roll (deg) clockwise from solar north 
 KEYWORDS:
      /inverse: if set then conversion is from (l,b) to (x,y)
 CALLED BY:
	HELIOG, PLOTMAP, drot
 PROCEDURE:  
      uses heliographic formulae from "Textbook on Spherical Astronomy", by
      W.M. Smart (see page 174).
 MODIFICATION HISTORY:      
      Written by DMZ (ARC) Aug 1991