blanksky_add_time.py 文件源码

def add_time_column(fitsfile, blockname="EVENTS"):
    """
    Add a time column to the specified block of the input fits file.
    The time data are generated with a uniform distribution
    between TSTART and TSTOP.

    Return:
        A fits object with the new time column.
    """
    if isinstance(fitsfile, str):
        fitsfile = fits.open(fitsfile)
    table = fitsfile[blockname]
    tstart = table.header["TSTART"]
    tstop = table.header["TSTOP"]
    counts = len(table.data)
    time_data = np.random.uniform(tstart, tstop, counts)
    time_col = fits.Column(name="time", format="1D", unit="s", array=time_data)
    # NOTE: append the new time column to the *last*!
    # Otherwise the TLMIN??/TLMAX?? keyword pairs, which record the
    # minimum/maximum values of corresponding columns, will become
    # *out of order*. Therefore the output FITS file causes weird problems
    # with DS9 and DM tools.
    newtable = fits.BinTableHDU.from_columns(
            table.columns + fits.ColDefs([time_col]))
    fitsfile[blockname].data = newtable.data
    # update header
    fitsfile[blockname].header.update(newtable.header)
    return fitsfile