BuildMasterBias

Bases: KPFFunction

Combine a set of bias files to make a master bias.

Parameters:
  • files (list) –

    A list of files to combine.

  • output (str) –

    The output combined filename to write.

KTL Keywords Used:

  • kpf_expmeter.BIAS_FILE
Source code in kpf/expmeter/BuildMasterBias.py 
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class BuildMasterBias(KPFFunction):
    '''Combine a set of bias files to make a master bias.

    Args:
        files (list): A list of files to combine.
        output (str): The output combined filename to write.

    KTL Keywords Used:

    - `kpf_expmeter.BIAS_FILE`
    '''
    @classmethod
    def pre_condition(cls, args):
        check_input(args, 'files', allowed_types=[list])

    @classmethod
    def perform(cls, args):
        biasfiles = [Path(biasfile) for biasfile in args.get('files')]
        log.debug(f"Combining {len(biasfiles)} bias frames:")

        biases = []
        timestamps = []
        for biasfile in biasfiles:
            log.debug(f"  {biasfile.name}")
            this_bias = CCDData.read(biasfile, unit="adu")
            biases.append(this_bias)
            timestamps.append(this_bias[0].header.get('DATE-BEG'))

        combiner = ccdproc.Combiner(biases)
        combiner.sigma_clipping(low_thresh=5, high_thresh=5)
        combined_average = combiner.average_combine()
        for i,timestamp in enumerate(timestamps):
            combined_average[0].header[f'DATEBEG{i:02d}'] = (timestamp,
                                       'DATE-BEG of file {i:02d}')
        utnow = datetime.utcnow()
        combined_average[0].header['DATEMADE'] = (utnow.isoformat(),
                                   'UT timestamp of file creation')

        if args.get('output', None) not in [None, '']:
            outputfile = Path(args.get('output')).expanduser()
        else:
            match_fn = re.match('([\w\d_]+)(\d{6})\.(\d{3})\.fits', biasfiles[0].name)
            if match_fn is not None:
                frameno = match_fn.group(2)
                outputfile = Path(f'/s/sdata1701/ExpMeterMasterFiles/MasterBias_{frameno}.fits')
            else:
                now_str = utnow.strftime('%Y%m%dat%H%M%S')
                outputfile = Path(f'/s/sdata1701/ExpMeterMasterFiles/MasterBias_{now_str}.fits')

        log.info(f"Writing {outputfile}")
        combined_average.write(outputfile, overwrite=True)
        if args.get('update', False) is True:
            bias_file = ktl.cache('kpf_expmeter', 'BIAS_FILE')
            bias_file.write(f"{outputfile}")

    @classmethod
    def post_condition(cls, args):
        pass

    @classmethod
    def add_cmdline_args(cls, parser):
        parser.add_argument('files', nargs='*',
                            help="The files to combine")
        parser.add_argument("--output", dest="output", type=str,
                            default='',
                            help="The output combined bias file.")
        parser.add_argument("--update", dest="update",
                            default=False, action="store_true",
                            help="Update the bias file in use with the newly generated file?")
        return super().add_cmdline_args(parser)