Extending

Implementing a New Spectrograph

For each supported spectrograph, there is a unique spectrograph.py file within the module pychell.data. This file contains all of the necessary details for each spectrograph. The great thing about Python is this file can be modified at runtime. In order to implement a spectrograph not officially supported, one has two options:

1. Create a new file pychell/data/spectrograph.py where spectrograph is the desired name of the spectrogaph (must be lowercase).

2. Use the generic spectrograph (especially useful for a one-off analysis) module by defining a few specific functions within ones own runtime.

It’s also possible to start from an currently supported spectrograph and only modify the necessary methods or classes.

Below are default method names currently used in pychell.

Reduction

categorize_raw_data(data_input_path: str, output_path: str) -> dict

correct_readmath(data: Echellogram, data_image: np.ndarray) -> np.ndarray

gen_master_calib_filename(master_cal: MasterCal) -> str
gen_master_calib_header(master_cal: MasterCal) -> Header

group_darks(darks:list<MasterCal>)
group_flats(flats:list<MasterCal>)

pair_master_bias(data: RawEchellogram, master_bias: list<MasterCal>)
pair_master_dark(data: RawEchellogram, master_darks: list<MasterCal>)
pair_master_flat(data: RawEchellogram, master_flats: list<MasterCal>)
pair_order_maps(data: RawEchellogram, order_maps: list<RawEchellogram>)

parse_exposure_start_time(data: Echellogram)
parse_fiber_nums(data: RawEchellogram)
parse_image(data: Echellogram)
parse_image_header(data: Echellogram)
parse_image_num(data: RawEchellogram)
parse_itime(data: Echellogram)
parse_object(data: RawEchellogram)
parse_sky_coord(data: Echellogram)
parse_utdate(data: Echellogram)

Spectral Forward Modeling

compute_barycenter_corrections(data: Union[Spec1d, RawEchellogram], star_name: str)
compute_exposure_midpoint(data: Union[Spec1d, RawEchellogram])
estimate_wls(data: Union[Spec1d, RawEchellogram], order_num=None, fiber_num=None)
parse_spec1d(data: Spec1d)

Below is an example of how one may implement or override: parse_itime.

def parse_itime(data):
    return float(data.header["ITIME"])

spectrograph.parse_itime = parse_itime