Fits File Format

The Fits file format, like it is written by WinScan:

Sample of the fits data header, written by WinScan, when a drift scan image was taken:
SIMPLE = T
BITPIX = 16
NAXIS = 2
NAXIS1 = 765
NAXIS2 = 2000
OBJECT = 'OBJECT'
DATE = '2001-12-09'
DATE-OBS= '2001-12-09'
TIME-OBS= '17:11:18.09'
INSTRUME= 'SBIG ST-7'
TELESCOP= 'TELESCOP'
OBSERVER= 'Christoph Flohr'
BZERO = 32768
BSCALE = 1
ORIGIN = 'WinScan 1.01'
EXPTIME = 84.1345751799128
SNAPSHOT= 1
EACHSNAP= 84.1345751799128
PIXWIDTH= 0.009
PIXHEIGH= 0.009
CCD-TEMP= 25.63
RESPONSE= 2000
GAIN = 2.3
FOCALLEN= 29.567
APERTURE= 28.22
FILTER = 'None'
BACKGRND= 200
RANGE = 1000
HISTORY = 'R'
PEDESTAL= 0
TRAKTIME= 0
DATAMAX = 65535
SHIFTIME= 0.16496975525473
DECLINAT= 5
RIGHTACE= 1000
CTYPE1 = 'RA---CAR' / RA - plate carree projection
CTYPE2 = 'DEC--CAR' / DEC - plate carree projection
CRVAL1 = 116.61197040000 / RA in decimal degrees.
CRVAL2 = 5.23835475300 / DEC in decimal degrees.
CRPIX1 = 382.50000 / X pixel of tangent point
CRPIX2 = 1000.00 / Y pixel of tangent point
CDELT1 = 0.0006866182017850 / X degrees per pixel
CDELT2 = -0.000686632196636 / Y degrees per pixel
CROTA1 = 90.00 / rotation of the axis
CROTA2 = 90.00 / rotation of the axis
EQUINOX = 2000.0000
KINDIMG = 'DriftScan'
COMMENT Sekunden je Reihe 0.164969755254731
COMMENT ANote1
COMMENT -
COMMENT -
COMMENT Y2KYear=2001
END

Some explanations :

SIMPLE = T
BITPIX = 16
NAXIS = 2
NAXIS1 = 765
NAXIS2 = 2000
OBJECT = 'OBJECT'
DATE = '2001-12-09'
DATE-OBS= '2001-12-09'
TIME-OBS= '17:11:18.09'
-should be UT
-In drift scan images:
-The Time and Date in UT the first line of the image file
- was read out form the active image area of the CCD
( in WinScan <= 2.7 it was the time, the first line of the image file was read out form the CCD)
INSTRUME= 'SBIG ST-7'
-set by WinScan
TELESCOP= 'TELESCOP'
OBSERVER= 'Christoph Flohr'
BZERO = 32768
BSCALE = 1
ORIGIN = 'WinScan 1.01'
EXPTIME = 84.1345751799128
- in seconds:
- drift scan images: effective exposure time, =
the time, a star needs to move over the CCD=
number of lines of the CCD * Shiftime
if there are read in fewer lines, with open
shutter, as lines are on the CCD
- EXPTIME = Shiftime * lines read in while shutter open
- Standard image: Time the shutter is open
- sub array image: The time, one sub array is exposed
- speckle image: The time one sub array of the speckle image is exposed
- fast scan image: The time, to read out one line, same as Shiftime
SNAPSHOT= 1
EACHSNAP= 84.1345751799128
-same as EXPTIME, as WinScan does not support track and accumulate
PIXWIDTH= 0.009
PIXHEIGH= 0.009
CCD-TEMP= 25.63
RESPONSE= 2000
GAIN = 2.3
FOCALLEN= 29.567
- in inch
APERTURE= 28.22
- in inch^2
FILTER = 'None'
BACKGRND= 200
RANGE = 1000
HISTORY = 'R'
PEDESTAL= 0
TRAKTIME= 0
DATAMAX = 65535
SHIFTIME= 0.16496975525473
- The time to read out one line
not used for Standard images and sub array images
This is calculated in the settings form for drift scan images form focal length, declination, pixel height and sidereal rate.
For speckle images and fast scan images this is filled in in the settings form. To check, if the shifttime is reached, check the timestamp data.
DECLINAT= 5
- form the settings form
RIGHTACE= 1000
- in the settings information's form the RA of the start of the image can be filled in, processing the image in ViewScan may change this
if unknown, set to 1000
CTYPE1 = 'RA---CAR' / RA - plate carree projection
CTYPE2 = 'DEC--CAR' / DEC - plate carree projection
CRVAL1 = 116.61197040000 / RA in decimal degrees.
CRVAL2 = 5.23835475300 / DEC in decimal degrees.
CRPIX1 = 382.50000 / X pixel of tangent point
CRPIX2 = 1000.00 / Y pixel of tangent point
CDELT1 = 0.0006866182017850 / X degrees per pixel
CDELT2 = -0.000686632196636 / Y degrees per pixel
CROTA1 = 90.00 / rotation of the axis
CROTA2 = 90.00 / rotation of the axis
EQUINOX = 2000.0000
KINDIMG = 'DriftScan'
-kind of image:
- 'DriftScan' for drift scan images
- 'Standard' for standard images
- 'SubArray' for sub array images
- 'Speckle' for speckle images
- 'FastScan' for fast scan images
COMMENT Sekunden je Reihe 0.164969755254731
COMMENT ANote1
COMMENT -
COMMENT -
COMMENT Y2KYear=2001
COMMENT -
END
WinScan always stores a 5760 byte file header for fits images.