Configure Galactic dust maps

File-based and batch workflows apply Galactic dereddening before all other processing. The default is the Planck Collaboration (2016) GNILC map with the Fitzpatrick (1999) law and \(R_V=3.1\).

Configure the external dustmaps directory after installation:

from dustmaps.config import config

config["data_dir"] = "/path/to/dustmaps"

from dustmaps import planck, sfd
planck.fetch(which="GNILC")
sfd.fetch()

The configured directory should contain planck/ and sfd/. If correction is enabled, missing map files or missing RA/Dec fail fast rather than silently fitting uncorrected data.

Common alternatives

Use SFD with the Schlafly & Finkbeiner (2011) recalibration:

extinction = qsospec.GalacticExtinctionConfig(map_name="sfd")

Supply a known E(B-V) without querying a map:

extinction = qsospec.GalacticExtinctionConfig(ebv_override=0.035)

Disable the step explicitly:

extinction = qsospec.GalacticExtinctionConfig(enabled=False)

Pass the object as galactic_extinction_config=extinction to file, host, or batch workflows. Array spectra are uncorrected by default. High-level fit_object_to_store prepares them automatically; before low-level fitting, call:

prepared = qsospec.prepare_spectrum(
    spectrum,
    galactic_extinction_config=extinction,
)

Use galactic_extinction_corrected=True when constructing arrays that were already dereddened.

See Preprocessing order for the order of operations and qsospec.GalacticExtinctionConfig for every field. The complete single-object example is Fit J001554.18+560257.5.