- The standard data format used in astronomy
- Stands for 'Flexible Image Transport System'
- Endorsed by NASA and the International Astronomical Union
- Header keywords provide descriptive information about the data
- Band SeQuential (BSQ) storage format
- Compatible with PDS archiving constraints
- Efficient projection (World Coordinate System) description (but for 3D systems)
- Community driven processing libraries (e.g. astropy)
- The Vatican Library has adopted FITS data format for long-term digital preservation of books and manuscripts!
Did you say FITS?
https://fits.gsfc.nasa.gov/
Cubes, tables and MEF
- 2D, 3D (cubes), ..., nD Rasters
- Binary tables
- Multi Extension Mosaics (MEF)
Multi Extensions Files
Is that really different?
Tools: astropy
http://www.astropy.org
#!/usr/bin/env python
from astropy.io import fits
hdulist = fits.open('my-fits-file-name')
hdulist.info()
hdulist.close()
The Astropy paper
The Astropy problem
>> hdulist.info() Filename: ESP_011265_1560_RED.fits No. Name Type Cards Dimensions Format 0 PRIMARY PrimaryHDU 4 () 1 ImageHDU 17 (2048, 100000) uint8 2 ImageHDU 17 (2048, 100000) uint8 3 ImageHDU 17 (2048, 100000) uint8 4 ImageHDU 17 (2048, 100000) uint8 5 ImageHDU 17 (2048, 100000) uint8 6 ImageHDU 17 (2048, 100000) uint8 7 ImageHDU 17 (2048, 100000) uint8 8 ImageHDU 17 (2048, 100000) uint8 9 ImageHDU 17 (2048, 100000) uint8 10 ImageHDU 17 (2048, 100000) uint8
Header Data Unit
#!/usr/bin/env python
from astropy.io import fits
hdulist = fits.open('my-fits-file-name')
hdr=hdulist[0].header
print hdr
hdulist.close()
SIMPLE = T / conforms to FITS standard BITPIX = 8 / array data type NAXIS = 0 / number of array dimensions EXTEND = T END
XTENSION= 'IMAGE ' / Image extension BITPIX = 8 / array data type NAXIS = 2 / number of array dimensions NAXIS1 = 2048 NAXIS2 = 100000 PCOUNT = 0 / number of parameters GCOUNT = 1 / number of groups CTYPE1 = 'MALG-AZP' / see Calabretta and Greisen (2002) CTYPE2 = 'MALN-AZP' / see Calabretta and Greisen (2002) CRPIX1 = 1.0 CRPIX2 = 1.0 CRVAL1 = 0.0 CRVAL2 = 1.0 CD1_1 = 1.0 CD2_2 = 1.0 CD1_2 = 0.0 CD2_1 = 0.0 END
>> hdulist.info() Filename: orb0413_1.IR1.fits No. Name Type Cards Dimensions Format 0 PRIMARY PrimaryHDU 23 (128, 1784, 128) int16 1 WCS-TAB BinTableHDU 17 1R x 2C [228352D, 228352D] 2 INCIDENCE ImageHDU 8 (128, 1784) float64 3 EMISSION ImageHDU 8 (128, 1784) float64 4 PHASE-ANGLE ImageHDU 8 (128, 1784) float64
Special thanks to David Berry (East Asian Observatory, Hilo, Hawaii)
See the Starlink software
>> hdulist[0].header SIMPLE = T / conforms to FITS standard BITPIX = 16 / array data type NAXIS = 3 / number of array dimensions NAXIS1 = 128 NAXIS2 = 1784 NAXIS3 = 128 EXTEND = T CTYPE1 = 'MALN-TAB' / See Greisen et al. (2006) CTYPE2 = 'MALG-TAB' / See Greisen et al. (2006) CRPIX1 = 1.0 CRPIX2 = 1.0 CRVAL1 = 1.0 CRVAL2 = 1.0 CD1_1 = 1.0 CD2_2 = 1.0 CD1_2 = 0.0 CD2_1 = 0.0 PS1_0 = 'WCS-TAB ' PS1_1 = 'COORDS1 ' PS2_0 = 'WCS-TAB ' PS2_1 = 'COORDS2 ' PV1_3 = 1.0 PV2_3 = 2.0 END
Accessing header - Accessing data
>> hdr=hdulist[0].header
>> print hdr.keys()
>> print hdr.values()
>> scidata = hdulist[0].data
>> print scidata.shape
>> print scidata.dtype.name
>> print scidata[30:40, 10:20, 30:40]
Official Astropy FITS IO documentation
<Thank You!>