Working with Spectra

Performing a Spectrum Query

To perform a spectrum query to SDSS and plot the result:

from ATK import query

sdss_query = query("spectrum", targets=587316166180416640, survey="sdss", path="example_spectrum.fits.gz")
sdss_query.show(show_types=True)
sdss_query.open()

<Spectrum DataSet>

.kind (str):        Spectrum
.targets (list):    587316166180416640 | 141.185° 8.031° (icrs, 2016-01-01T00:00:00.000, 3.0″)
.exception (bool):  False
.data (list):
          <sdss Spectrum>
                    survey (str):                  sdss
                    correction (str):              full
                    search_pos (astropy.SkyCoord): 141.185° 8.031° (icrs, 2017-01-01T00:00:00.000)
                    separation (astropy.Quantity): 0.387″
                    exposure (astropy.Quantity):   10505.0 s
                    wavelength (astropy.Quantity): [3803.64501953125, 3804.52197265625, ..., 9210.853515625, 9212.978515625] Å
                    flux (astropy.Quantity):       [20.667999267578125, 18.420000076293945, ..., 9.447999954223633, 10.515999794006348] 1×10⁻¹⁷ erg Å⁻¹ s⁻¹ cm⁻²

          <sdss Spectrum>
                    survey (str):                  sdss
                    correction (str):              full
                    search_pos (astropy.SkyCoord): 141.185° 8.031° (icrs, 2017-01-01T00:00:00.000)
                    separation (astropy.Quantity): 0.422″
                    exposure (astropy.Quantity):   2300.3 s
                    wavelength (astropy.Quantity): [3801.89306640625, 3802.77001953125, ..., 9212.978515625, 9215.09765625] Å
                    flux (astropy.Quantity):       [19.785999298095703, 16.702999114990234, ..., 11.475000381469727, 8.510000228881836] 1×10⁻¹⁷ erg Å⁻¹ s⁻¹ cm⁻²


Available Methods: .add(), .apply(), .from_target(), .merge(), .open(), .plot(), .save(), .show(), .split(), .store()

The returned DataSet’s data attribute is a list of Spectrum objects (one or multiple per target, subject to data availability). If multiple Spectrum objects are returned for a single target, these will be arranged in order of decreasing exposure.

Note

ATK supports queries to the following spectra surveys:

• SDSS - sdss

• DESI - desi

For a refresher on query() fundamentals, see here. For a refresher on plotting fundamentals, see here.

If the desired survey is not listed above, see here for a tutorial on utilising external data.

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