XraySpectrum1D class with loaders

specutils/io/default_loaders/chandra_hetg.py

@@ -0,0 +1,54 @@
+from astropy.io import fits
+from astropy.units import Unit
+
+from specutils.io.registers import data_loader
+from specutils import XraySpectrum1D
+
+__all__ = ['chandra_hetg_identify', 'hetg_spectrum_loader']
+
+def chandra_hetg_identify(origin, *args, **kwargs):
+    """Check whether given file contains Chandra HETG spectral data."""
+    with fits.open(args[0]) as hdu:
+        # Check that it is a Chandra spectrum file
+        if hdu[0].header['TELESCOP'] == 'CHANDRA' and 'SPECTRUM' in [h.name for h in hdu]:
+            # Check that it's an HETG file
+            if hdu['SPECTRUM'].header['GRATING'] == 'HETG':
+                return True
+    return False
+
+@data_loader(label="chandra_hetg", identifier=chandra_hetg_identify, extensions=['pha','pha2', 'PHA', 'PHA2', 'FITS', 'FIT', 'fits', 'fit'])
+def hetg_spectrum_loader(file_name, arf=None, rmf=None):
+    """
+    Load Chandra HETG spectral data from a file into a spectrum object.
+
+    Parameters
+    ----------
+    file_name: str
+        The path to the FITS file
+
+    arf : str OR AreaResponse
+        Filename for the area response file (ARF) or a pre-loaded AreaResponse object
+
+    rmf : str OR ResponseMatrix
+        Filename for the response matrix file (RMF) or a pre-loaded ResponseMatrix object
+
+    Returns
+    -------
+    data: XraySpectrum1D
+        The spectrum that is represented by the data in this table.
+    """
+
+    with fits.open(file_name) as hdu:
+        header = hdu[0].header
+        meta   = {'header': header}
+        data   = hdu[1].data
+
+        bin_unit = Unit(data.columns['BIN_LO'].unit)
+        bin_lo   = data['BIN_LO'] * bin_unit
+        bin_hi   = data['BIN_HI'] * bin_unit
+
+        counts   = data['COUNTS'] * Unit('ct')
+        exposure = hdu[1].header['EXPOSURE'] * Unit('second')
+
+    return XraySpectrum1D(bin_lo, bin_hi, counts,
+                          exposure=exposure, arf=arf, rmf=rmf)

specutils/spectra/__init__.py

@@ -6,3 +6,5 @@
 from .spectral_region import *  # noqa
 from .spectrum_collection import *  #noqa
 from .spectrum_list import * #noqa
+
+from .xrayspectrum1d import *