pro writefit, image, fname, notes=notes, obs=obs, inst=inst, tele=tele, obj=obj, date=date, filter=filter, $
              itype=itype, expo=expo, xbin=xbin, ybin=ybin, xmic=xmic, ymic=ymic, antime=antime, anframe=anframe, $
              focal=focal,  diam=diam,   help=help
     
IF KEYWORD_SET(help) THEN BEGIN
  PRINT,'pro writefit, image, fname, notes=notes, obs=obs, inst=inst, tele=tele, obj=obj, date=date, filter=filter, $
  PRINT,'             itype=itype, expo=expo, xbin=xbin, ybin=ybin, xmic=xmic, ymic=ymic, antime=antime, anframe=anframe, $
  PRINT,'             focal=focal,  diam=diam,  help=help
  PRINT,'
  PRINT,'    This procedure saves  <image> to a file caled <fname> in the MaximDL style FITS format.
  PRINT,'The header can contain optional information as below.
  PRINT,'
  PRINT,'USAGE:   writefit, image, fname, obs="Dr. Rob Suggs", antime=times, anframe=100
  PRINT,'HELP:    writefit,/help    Prints these notes
  PRINT,'
  PRINT,'Parameters:
  PRINT,' image     2-dimensional array of almost any type but string.  Default = indgen(150,100)+100
  PRINT,' fname     String, name of FITS file to be written.  Default = WriteFit.fit
  PRINT,'
  PRINT,'                ---    Optional    ---
  PRINT,'notes      String of length <69 char.  Longer will be truncated.
  PRINT,'obs        String of length <69 char.  Longer will be truncated. (observer name)
  PRINT,'inst       String of length <69 char.  Longer will be truncated. (camera name)
  PRINT,'tele       String of length <27 char.  Longer will be truncated. (telescope name)
  PRINT,'obj        String of length <69 char.  Longer will be truncated. ( object name)
  PRINT,'date       YYYY-MM-DDThh:mm:ss observation start, UT  See <antime> below
  PRINT,'filter     String of length <27 char.  Longer will be truncated. (filter name)
  PRINT,'itype      String of length <27 char.  Longer will be truncated. (light, dark, flat)
  PRINT,'expo       Scalar length of exposure in seconds
  PRINT,'xbin       Integer,  Binning factor in width
  PRINT,'ybin       Integer,  Binning factor in height
  PRINT,'xmic       Scalar, Pixel Width in microns (after binning)
  PRINT,'ymic       Scalar, Pixel height in microns (after binning)
  PRINT,'Focal      Focal lenght, mm
  PRINT,'diam       Aperture in mm
  PRINT,'antime     Structure, frame time from Boulder Imaging AN file.  If array, anframe is required
  PRINT,'anframe    Integer,  Frame number for antime. If absent and required, 0 is assumed
  PRINT,'
RETURN
ENDIF ;  help    
     

IF N_ELEMENTS(image) LT 10 THEN image = indgen(150,100)+100
IF N_ELEMENTS(fname) EQ 0 THEN fname = 'WriteFit.fit'

IF N_ELEMENTS(anframe) EQ 0 AND N_ELEMENTS(antime) GT 1 THEN BEGIN
    anframe = 0
    PRINT,'WriteFit:  WARNING, anframe assumed zero, start time will be for frame 0'
ENDIF


s = SIZE(image)
naxis = S(0)
naxis = STRING(naxis, FORMAT='(A20)')
naxis1 = S(1)
naxis1 = STRING(naxis1, FORMAT='(A20)')
IF naxis GE 2 THEN naxis2 = S(2) ELSE naxis2 = 0
naxis2 = STRING(naxis2, FORMAT='(A20)')
CASE S(naxis+1) OF
1: bitpix = 8
2: bitpix = 16
3: bitpix = 32
4: bitpix = -32
5: bitpix = -64
12: bitpix = 16
13: bitpix = 32
14: bitpix = 64
15: bitpix = 64
ELSE: bitpix = 0
ENDCASE
bitpix = STRING(bitpix, FORMAT='(A20)')
cblack = FIX(MIN(image))
cblack = STRING(cblack, FORMAT='(A20)')
cwhite = FIX(MAX(image))
cwhite = STRING(cwhite, FORMAT='(A20)')

header = [$
'SIMPLE  =                    T                                                  ', $ ; 0
'BITPIX  = '+bitpix+' /8 unsigned int, 16 & 32 int, -32 & -64 real     ', $ ; 1
'NAXIS   = '+naxis+' /number of axes                                  ', $ ; 2
'NAXIS1  = '+naxis1+' /fastest changing axis                           ', $ ; 3
'NAXIS2  = '+naxis2+' /next to fastest changing axis                   ', $ ; 4
'BSCALE  =   1.0000000000000000 /physical = BZERO + BSCALE*array_value           ', $ ; 5
'BZERO   =   0.0000000000000000 /physical = BZERO + BSCALE*array_value           ', $ ; 6
'OBJECT  =                                                                       ', $ ; 7
'TELESCOP=                            /telescope used to acquire this image      ', $ ; 8
'INSTRUME=                                                                       ', $ ; 9
'OBSERVER=                                                                       ', $ ;10
'NOTES   =                                                                       ', $ ;11
'DATE-OBS=                            / YYYY-MM-DDThh:mm:ss observation start, UT', $ ;12
'EXPTIME =   0.0000000000000000 /Exposure time in seconds                        ', $ ;13
'EXPOSURE=   0.0000000000000000 /Exposure time in seconds                        ', $ ;14
'SET-TEMP=   0.0000000000000000 /CCD temperature setpoint in C                   ', $ ;15
'CCD-TEMP=   0.0000000000000000 /CCD temperature at start of exposure in C       ', $ ;16
'XPIXSZ  =   0.0000000000000000 /Pixel Width in microns (after binning)          ', $ ;17
'YPIXSZ  =   0.0000000000000000 /Pixel Height in microns (after binning)         ', $ ;18
'XBINNING=                    1 /Binning factor in width                         ', $ ;19
'YBINNING=                    1 /Binning factor in height                        ', $ ;20
'XORGSUBF=                    0 /Subframe X position in binned pixels            ', $ ;21
'YORGSUBF=                    0 /Subframe Y position in binned pixels            ', $ ;22
'FILTER  =                            /Filter used when taking image             ', $ ;23
'IMAGETYP=                      /Type of image                                   ', $ ;24
'FOCALLEN=  0.00000000000000000 /Focal length of telescope in mm                 ', $ ;25
'APTDIA  =  0.00000000000000000 /Aperture diameter of telescope in mm            ', $ ;26
'APTAREA =  0.00000000000000000 /Aperture area of telescope in mm^2              ', $ ;27
'SWCREATE= "IDL WriteFit by W swift"/Name of software that created the image     ', $ ;28
'SBSTDVER= "SBFITSEXT Version 1.0" /Version of SBFITSEXT standard in effect      ', $ ;29
'FLIPSTAT=                                                                       ', $ ;30
'CBLACK  = '+cblack+' /Initial display black level in ADUs             ', $ ;31
'CWHITE  = '+cwhite+' /Initial display white level in ADUs             ', $ ;32
'PEDESTAL=                    0 /Correction to add for zero-based ADU            ', $ ;33
'SWOWNER = "NASA / MSFC EV44"   /       Licensed owner of software               ', $ ;34
'END                                                                             ']   ;35


IF cwhite GE 32768 THEN BEGIN  ;   to fit into signed integer
  tmp = header(6)
  STRPUT, tmp, STRING(32768.0), 11
  header(6) = tmp
  image = image - 32668
ENDIF

IF KEYWORD_SET(notes) THEN BEGIN
  tmp = header(11)
  STRPUT, tmp, notes, 11
  header(11) = tmp
ENDIF


IF KEYWORD_SET(obs) THEN BEGIN
  tmp = header(10)
  STRPUT, tmp, obs, 11
  header(10) = tmp
ENDIF

IF KEYWORD_SET(inst) THEN BEGIN
  tmp = header(9)
  STRPUT, tmp, inst, 11
  header(9) = tmp
ENDIF

IF KEYWORD_SET(tele) THEN BEGIN
  tmp = header(8)
  tele = STRTRIM(STRING(tele, FORMAT='(A26)'),2)
  STRPUT, tmp, tele, 10
  header(8) = tmp
ENDIF

IF KEYWORD_SET(obj) THEN BEGIN
  tmp = header(7)
  STRPUT, tmp, obj, 11
  header(7) = tmp
ENDIF

IF KEYWORD_SET(date) THEN BEGIN
  tmp = header(12)
  date = STRTRIM(STRING(date, FORMAT='(A26)'),2)
  STRPUT, tmp, date, 10
  header(12) = tmp
ENDIF

IF KEYWORD_SET(filter) THEN BEGIN
  tmp = header(23)
  filter = STRTRIM(STRING(filter, FORMAT='(A26)'),2)
  STRPUT, tmp, filter, 10
  header(23) = tmp
ENDIF

IF KEYWORD_SET(expo) THEN BEGIN
  expo = STRING(expo, FORMAT='(A20)')
  tmp = header(13)
  STRPUT, tmp, expo, 10
  header(13) = tmp
  tmp = header(14)
  STRPUT, tmp, expo, 10
  header(14) = tmp
ENDIF

IF KEYWORD_SET(itype) THEN BEGIN
  tmp = header(24)
  itype = STRING(itype, FORMAT='(A26)')
  STRPUT, tmp, itype, 10
  header(24) = tmp
ENDIF

IF KEYWORD_SET(xmic) THEN BEGIN
  tmp = header(17)
  xmic = STRING(xmic, FORMAT='(A20)')
  STRPUT, tmp, xmic, 10
  header(17) = tmp
ENDIF

IF KEYWORD_SET(ymic) THEN BEGIN
  tmp = header(18)
  ymic = STRING(ymic, FORMAT='(A20)')
  STRPUT, tmp, ymic, 10
  header(18) = tmp
ENDIF

IF KEYWORD_SET(xbin) THEN BEGIN
  tmp = header(19)
  xbin =  STRING(xbin, FORMAT='(A20)') 
  STRPUT, tmp, xbin, 10
  header(19) = tmp
ENDIF

IF KEYWORD_SET(ybin) THEN BEGIN
  tmp = header(20)
  ybin =  STRING(ybin, FORMAT='(A20)') 
  STRPUT, tmp, ybin, 10
  header(20) = tmp
ENDIF

IF KEYWORD_SET(focal) THEN BEGIN
  tmp = header(25)
  focal =  STRING(focal, FORMAT='(A20)') 
  STRPUT, tmp, focal, 10
  header(25) = tmp
ENDIF

IF KEYWORD_SET(diam) THEN BEGIN
  tmp = header(26)
  diam =  STRING(diam, FORMAT='(A20)') 
  STRPUT, tmp, diam, 10
  header(26) = tmp
ENDIF

;IF KEYWORD_SET(gain) THEN BEGIN
;  tmp = header(33)
;  gain =  STRING(gain, FORMAT='(A20)') 
;  STRPUT, tmp, gain, 10
;  header(33) = tmp
;ENDIF


IF KEYWORD_SET(antime) THEN BEGIN
    IF N_ELEMENTS(antime) GT 1 THEN BEGIN
    ansave = antime
    antime = antime(anframe)
    ENDIF
     date=STRTRIM(antime.year,2)+'-'+STRTRIM(antime.month,2)+'-'+STRTRIM(antime.day,2)+' '
     sec = antime.sec + antime.msec/1000.0 + antime.usec/1.0e6
     time = STRTRIM(antime.hr,2)+':'+STRTRIM(antime.minute,2)+':'+STRING(sec,FORMAT='(f9.6)')
     tmp = header(12)
     date = STRTRIM(STRING(date+time, FORMAT='(A26)'),2)
     STRPUT, tmp, date, 10
     header(12) = tmp
     IF N_ELEMENTS(ansave) NE 0 THEN antime=ansave
ENDIF

ON_IOERROR, ioerror
OPENW, lun, fname, /GET_LUN
WRITEU, lun, BYTE(header)
WRITEU, lun, SWAP_ENDIAN(REVERSE(image,2))
CLOSE, lun
GOTO, done

ioerror:
PRINT, 'WriteFit:   '+!ERR_STRING 

done:
IF N_ELEMENTS(lun) NE 0 THEN FREE_LUN, lun



END  ;   pro writefit, image, fname