查看“Fits文件”的源代码

=[[astro_lib]]中的fits文件读写=

== mrdfits 和 mwrfits ==
mrdfits都入fits文件，存为一个结构数组，结构的tag从header得到。比较简易方便。
 a = mrdfits('TEST.FITS', 0, header)

mwrfits将一个结构数组写成fits文件，header根据结构的tag名自动生成.
 mwrfits,a,'TEST2.fit'

*默认的写入在HDU1，不是PRIMARY HDU
*默认的数组写入的是BINARY格式。可以用/silent变成ASCII格式。

==readfits 和 writefits==
 data = READFITS( Filename, Header)
 WRITEFITS, filename, data , header,
这一组命令将fits文件分成data（数组）和header（字符串数组）处理，相对没有mrdfits 和 mwrfits方便，但是有较多的配套命令可修改fits文件。

=[[astro_lib]]中的fits文件的修改=

==ASCII 表格的修改==
修改之前，需要readfits都入data和header

*FTADDCOL： Add a new column to a FITS ASCII table 
*FTPUT： Update or add data to a field in a FITS ASCII table array 
*FTAB_EXT Extract specified columns of a FITS table extension into IDL vectors 
FTDELCOL Delete specified column from a FITS ASCII table data array 

==BINARY 表格的修改 ==
BINARY表格的修改（如删除一列）相对较为复杂。但是可以较为方便的构造

例：Write a binary table 'sample.fits' giving 43 X,Y positions and a 21 x 21 PSF at each position:

(1) First, create sample values
     x = findgen(43) & y = findgen(43)+1 & psf = randomn(seed,21,21,43)

(2) Create primary header, write it to disk, and make extension header
      fxhmake,header,/initialize,/extend,/date
      fxwrite,'sample.fits',header
      fxbhmake,header,43,'TESTEXT','Test binary table extension'

(3) Fill extension header with desired column names
      fxbaddcol,1,header,x[0],'X'             ;Use first element in each array
      fxbaddcol,2,header,y[0],'Y'             ;to determine column properties
      fxbaddcol,3,header,psf[*,*,0],'PSF'

(4) Write extension header to FITS file
      fxbcreate,unit,'sample.fits',header

(5) Use FXBWRITM to write all data to the extension in a single call
      fxbwritm,unit,['X','Y','PSF'], x, y, psf
      fxbfinish,unit                 ;Close the file

=其他=

==fitsdir==
可以读入一个文件夹下所有fits文件头中的信息