;+
;       NAME:
;               single_eph.Pro
;
;       PURPOSE:
;		Returns a structure with the following information:
;                 {et, ra, dec, radot, decdot, ephinfo} where ephinfo
;                 contains the observer range and observer range rate.
;
;	DESCRIPTION:
;              Calculates the ra, dec, radot, decdot, observer range
;              and range rate using the NAIF ICY routines.
;
;       CALLING SEQUENCE:
;               eph = single_eph( target, et, neph, observer=observer,
;               testing=testing)
;
;       INPUTS:
;		et - the ET at which you want to know the
;                        coordinates
;       KEYWORDS
;               observer - the keyword argument that indicates the
;                          observer location, default to Earth.
;              verbose - a keyword argument.  If set, it
;                        will print out error messages.
;       OUTPUTS:
;              eph - a structure with the following elements
;              eph.ra - the Pluto RA in radians
;              eph.dec - the Pluto Dec in radians
;              eph.radot - the RA rate in radians/s
;                          (d(ra)*cos(dec)/dt)
;              eph.decdot -- the Dec rate in radians/s
;              eph.ephinfo.delta - the observer range (in km)
;              eph.ephinfo.deltadot - the observer range rate (in km/s)
;              eph.ephinfo.target - the target
;              eph.ephinfo.observer - the observer name
;
;
;       REVISON HISTORY:
;       17-January-2005 CBO SwRI
;       2005 Mar 3 Moved to $idl/layoung/naif  LAY
;                  Also put long lines onto 2 lines
;       2005 Apr 26 Return 1 for neph under usual circumstances
;                   Bypass bodn2c if target or observer are integers
;                   Change verbose = 0 for quiet, 1 for verbose,
;                   and removed testing
;-

function	single_eph, target, et, neph, observer=observer, $
                   verbose = verbose

;check to see if optional arguments are set by the user.  If not assign values.
        IF not keyword_set(observer) THEN observer = "Earth"
        IF not keyword_set(verbose) THEN verbose = 0

; Load naif kernels.  If they are already loaded, naifinit will not
; reload them.
        naifinit

; Look up the naif id's for the observer and target
        case datatype(observer) of
            'STR': begin
                CSPICE_BODN2C, observer, obscode, found            
                IF found EQ 0 THEN BEGIN
                    neph = 0
                    eph = -1
                    IF keyord_set(verbose) THEN $
                      PRINT, "Observer not understood by CSPICE_BOD2N"
                    RETURN, eph
                ENDIF
            end
            'INT': obscode = observer
            'LON': obscode = observer
            else: begin
                neph = 0
                eph = -1
                IF keyword_set(verbose) THEN $
                  PRINT, "Observer must be a string or an integer"
                RETURN, eph
            end
        endcase

        case datatype(target) of
            'STR': begin
                CSPICE_BODN2C, target, targetcode, found            
                IF found EQ 0 THEN BEGIN
                    neph = 0
                    eph = -1
                    IF verbose NE "False" THEN $
                      PRINT, "Target not understood by CSPICE_BOD2N"
                    RETURN, eph
                ENDIF
            end
            'INT': targetcode = target
            'LON': targetcode = target
            else: begin
                neph = 0
                eph = -1
                IF verbose NE "False" THEN $
                  PRINT, "Target must be a string or an integer"
                RETURN, eph
            end
        endcase

; Get the RA and Dec of the target
	abcorr = 'LT' ;only correcting for light time
	frame='J2000'

	CSPICE_SPKEZ, targetcode, et, frame, abcorr, obscode, $
          stateTarget, ltime

; Convert X, Y, Z to RA, Dec and distance
        radTarget = rec6rad6(stateTarget)
        delta = radTarget[0]
        ra = radTarget[1]
        dec = radTarget[2]
        deltadot = radTarget[3]
        radot = radTarget[4]
        decdot = radTarget[5]
        
        ephinfo = $
          {delta:delta, deltadot:deltadot, target:target, observer:observer}
        eph = {et:et, ra:ra, dec:dec, radot:radot, decdot:decdot, $
               ephinfo:ephinfo, state:stateTarget}
        neph = 1


        RETURN, eph

 END

;+