function subtense,telescope
;+
; NAME:				SUBTENSE
;
; PURPOSE:			Returns the angular subtense (arc sec/pixel)
;				for the requested telescope
;
; CATEGORY:			REDUCTION
;
; CALLING SEQUENCE:		Result = SUBTENSE (Telescope)
;
; INPUTS:			Telescope = Number of the telescope that the
;					    angular subtense is desired
;                                           Either (C1..C4/EIT) or (0..3)
;
; OPTIONAL INPUTS:		None
;	
; KEYWORD PARAMETERS:		None
;
; OUTPUTS:			Result = angular subtense of a pixel in arc 
;					 seconds
;
; OPTIONAL OUTPUTS:		None
;
; COMMON BLOCKS:		reduce_history
;
; MODIFICATION HISTORY:		Written,  RAH, NRL
;   Version 1  rah  5 Nov 1995
;   Version 2  rah  13 Apr 1996		Added test for telescope as string
;   Version 3  rah   6 May 1997		Changed C2 and C3 based on star transits
;   Version 4  sep  16 Dec 1997		Changed EIT from 2.8 to 2.59
;   Version 4  rah  26 Feb 1998		Changed C2 from 12.4 to 12.1
;   Version 5  sep   7 Apr 1998		Changed C1 from 5.6 to 5.8
;   Version 6  sep  28 Aug 1998		Mods for telescope being a structure
;   Version 7  rah  12 Nov 1998		Mods for MLO MK3 k-coronameter
;   Version 8  rah  20 Nov 1998		Changed C2 from 12.1 to 11.9
;   Version 9  dab  14 Jan 2000		Mods for MLO MK$ k-coronameter
;	nbr	26 Jul 2000	Use SCCS version for reduce_history common block
;
; SCCS variables for IDL use
; 
version= '@(#)subtense.pro	1.14 09/13/10' ; LASCO IDL LIBRARY
;
;-
;
COMMON reduce_history, cmnver, prev_a, prev_hdr, zblocks0
cmnver = strmid(version,4,strlen(version))

;ver = 'V9'

CASE DATATYPE(telescope) OF
'UND':  BEGIN
           sz = SIZE(telescope)
           IF (sz(1) EQ 0)  THEN BEGIN
              PRINT,'%SUBTENSE:  Telescope not defined'
              tel = 0
           ENDIF
        END
'STR':  BEGIN
           IF (STRUPCASE(telescope) EQ 'EIT') THEN tel=4 $
           ELSE IF (STRUPCASE(telescope) EQ 'MK3') THEN tel=5 $
	   ELSE IF (STRUPCASE(telescope) EQ 'MK4') THEN tel=6 $
                           ELSE tel= FIX(STRMID(telescope,1,1))
        END
'INT':  tel = telescope+1  ; convert camera=0,1,2,3, to c1,c2,c3,eit
'STC':  BEGIN
        END
ELSE:   
ENDCASE
CASE tel of
     1:   f=5.8                      ; C1 04/07/98
     2:   f=11.9                     ; C2 2/26/98
     3:   f=56.0                     ; C3 5/22/97
     4:   f=2.59                     ; EIT approximate
     5:   f=9.19                     ; MK3 approximate
     6:   f=9.19		     ; MK4 approximate
     ELSE:   BEGIN
                f=0
                PRINT,'%SUBTENSE:  Telescope not defined'
             END
ENDCASE
RETURN,f
END