zogy.py 文件源码

def fits2ldac (header4ext2, data4ext3, fits_ldac_out, doSort=True):

    """This function converts the binary FITS table from Astrometry.net to
    a binary FITS_LDAC table that can be read by PSFex. [header4ext2]
    is what will be recorded as a single long string in the data part
    of the 2nd extension of the output table [fits_ldac_out], and
    [data4ext3] is the data part of an HDU that will define both the
    header and data parts of extension 3 of [fits_ldac_out].

    """

    # convert header to single (very) long string
    ext2_str = header4ext2.tostring(endcard=False, padding=False)

    # if the following line is not added, the very end of the data
    # part of extension 2 is written to a fits table such that PSFex
    # runs into a segmentation fault when attempting to read it (took
    # me ages to find out!).
    ext2_str += 'END                                                                          END'

    # read into string array
    ext2_data = np.array([ext2_str])

    # determine format string for header of extention 2
    formatstr = str(len(ext2_str))+'A'
    # create table 1
    col1 = fits.Column(name='Field Header Card', array=ext2_data, format=formatstr)
    cols = fits.ColDefs([col1])
    ext2 = fits.BinTableHDU.from_columns(cols)
    # make sure these keywords are in the header
    ext2.header['EXTNAME'] = 'LDAC_IMHEAD'
    ext2.header['TDIM1'] = '(80, {0})'.format(len(ext2_str)/80)

    # simply create extension 3 from [data4ext3]
    ext3 = fits.BinTableHDU(data4ext3)
    # extname needs to be as follows
    ext3.header['EXTNAME'] = 'LDAC_OBJECTS'

    # sort output table by number column if needed
    if doSort:
        index_sort = np.argsort(ext3.data['NUMBER'])
        ext3.data = ext3.data[index_sort]

    # create primary HDU
    prihdr = fits.Header()
    prihdu = fits.PrimaryHDU(header=prihdr)
    prihdu.header['EXPTIME'] = header4ext2['EXPTIME']
    prihdu.header['FILTNAME'] = header4ext2['FILTNAME']
    # prihdu.header['SEEING'] = header4ext2['SEEING'] #need to calculte and add
    prihdu.header['BKGSIG'] = header4ext2['SEXBKDEV']


    # write hdulist to output LDAC fits table
    hdulist = fits.HDUList([prihdu, ext2, ext3])
    hdulist.writeto(fits_ldac_out, clobber=True)
    hdulist.close()

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