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Database

Database#

speXtra come with a in-built database of spectral libraries, astronomical filters and extinction curves. The database is constinously growing and we are happy to include additional data that can be useful for your research

The database organized through yaml files which describe the contents of the different data files.

The inner workings of the database are transparent to the user and generally the user does not need to deal with the database when working with speXtra.

There are however few things that might be useful to the user, specially when working in interactive mode (e.g. Jupyter Notebooks)

The database is organized within a directory tree. Depending on what you are requesting, a spectra template, a extinction curve or a filter, it will look for it at that particular place. The syntax is standard:

  • "library_name/template_name" for a spectral template

  • "extinction_curve_family/extinction_curve_name" for extinction curves

  • "filter_system/filter_name" for astronomical filters

Below you can find the contents of the database

Browsing the Database#

from spextra import spextra_database as db

print(db) 

Spextra Database:
  Remote URL: https://scopesim.univie.ac.at/spextra/database/
  Local path: /home/docs/.spextra_cache
Database contents:
├─libraries: 
│ ├─ref: A library of reference stars
│ ├─kc96: Kinney-Calzetti Atlas
│ ├─pickles: Pickles Stellar Library
│ ├─dobos: SDSS galaxy composite spectra
│ ├─irtf: IRTF spectral library
│ ├─agn: AGN templates
│ ├─nebulae: Emission line nebulae
│ ├─brown: Galaxy SEDs from the UV to the Mid-IR
│ ├─kurucz: Subset of Kurucz 1993 Models
│ ├─sne: Supernova Legacy Survey
│ ├─moehler: flux/telluric standards with X-Shooter
│ ├─madden: High-Resolution Spectra of Habitable Zone Planets
│ ├─bosz/hr: BOSZ stellar atmosphere Grid - High Resolution
│ ├─bosz/mr: BOSZ stellar atmosphere Grid - Medium Resolution
│ ├─bosz/lr: BOSZ stellar atmosphere Grid - Low Resolution
│ ├─assef: Low-resolution spectral templates for AGN and galaxies
│ ├─sky: Paranal sky background spectra
│ ├─shapley: Rest-Frame Ultraviolet Spectra of z ∼ 3 Lyman Break Galaxies
│ ├─etc/kinney: ESO ETC version of the Kinney-Calzetti Atlas
│ ├─etc/kurucz: ESO ETC subset of the Kurucz 1993 models
│ ├─etc/marcs/p: ESO ETC subset of the MARCS Stellar Models with Plane Parallel Geometry
│ ├─etc/marcs/s: ESO ETC subset of the MARCS Stellar Models with Spherical Geometry
│ ├─etc/misc: Other templates, nubulae and qso
│ └─etc/pickles: ESO ETC subset of the Pickles stellar library
├─extinction_curves: 
│ ├─gordon: LMC and SMC extinction laws
│ ├─cardelli: MW extinction laws
│ └─calzetti: extragalactic attenuation curves
└─filter_systems: 
  ├─elt/micado: MICADO filters
  ├─elt/metis: METIS filters
  └─etc: ESO ETC standard filters

The last will print basic information regarding local and distant storage.

To list all available libraries we can also use:

db["libraries"]

{'ref': 'A library of reference stars',
 'kc96': 'Kinney-Calzetti Atlas',
 'pickles': 'Pickles Stellar Library',
 'dobos': 'SDSS galaxy composite spectra',
 'irtf': 'IRTF spectral library',
 'agn': 'AGN templates',
 'nebulae': 'Emission line nebulae',
 'brown': 'Galaxy SEDs from the UV to the Mid-IR',
 'kurucz': 'Subset of Kurucz 1993 Models',
 'sne': 'Supernova Legacy Survey',
 'moehler': 'flux/telluric standards with X-Shooter',
 'madden': 'High-Resolution Spectra of Habitable Zone Planets',
 'bosz/hr': 'BOSZ stellar atmosphere Grid - High Resolution',
 'bosz/mr': 'BOSZ stellar atmosphere Grid - Medium Resolution',
 'bosz/lr': 'BOSZ stellar atmosphere Grid - Low Resolution',
 'assef': 'Low-resolution spectral templates for AGN and galaxies',
 'sky': 'Paranal sky background spectra',
 'shapley': 'Rest-Frame Ultraviolet Spectra of z ∼ 3 Lyman Break Galaxies',
 'etc/kinney': 'ESO ETC version of the Kinney-Calzetti Atlas',
 'etc/kurucz': 'ESO ETC subset of the Kurucz 1993 models',
 'etc/marcs/p': 'ESO ETC subset of the MARCS Stellar Models with Plane Parallel Geometry',
 'etc/marcs/s': 'ESO ETC subset of the MARCS Stellar Models with Spherical Geometry',
 'etc/misc': 'Other templates, nubulae and qso',
 'etc/pickles': 'ESO ETC subset of the Pickles stellar library'}

which also works for db["filter_systems"] and db["extinction_curves"] which will print the extinction curves and filter systems available

The class SpecLibrary and its equivalents FilterSystem and ExtinctionCurve hold the information regarding a particular library

from spextra import SpecLibrary, FilterSystem, ExtCurvesLibrary

lib = SpecLibrary("ref")

print(lib)

Downloading file 'libraries/ref/index.yml' from 'https://scopesim.univie.ac.at/spextra/database/libraries/ref/index.yml' to '/home/docs/.spextra_cache'.

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Spectral Library 'ref': Reference library for objects
  spectral coverage: uv, vis, nir, mir
  wave_unit: Angstrom
  flux_unit: FLAM
  Templates: vega, vegaLR, sirius, sun, sunHR

and basic information about the library will be printed

If you are only interested in the template names, just use

list(lib)

['vega', 'vegaLR', 'sirius', 'sun', 'sunHR']

Finally to obtain one of these templates just call Spextrum

from spextra import Spextrum

sp = Spextrum("ref/sun")

Downloading file 'libraries/ref/sun.fits' from 'https://scopesim.univie.ac.at/spextra/database/libraries/ref/sun.fits' to '/home/docs/.spextra_cache'.

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sp.plot()
../_images/8e07d559f53bb2a2e947de254eed5ddea16b70a75b3212eee64c53005d3f65f0.png
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