ifs-etc 0.0.1

exposure time calculator

CSST-IFS ETC

Description

Exposure time calculator for CSST-IFS. The Python module is constructed by modifing the JWST ETC (Pandeia), which would be easily imported into Python programs.

Installation

via pip:

pip install ifs_etc

Usage

• Creating a default configuration dictionaray:

  from ifs_etc.etc1d.config import build_default_calc
  config = build_default_calc()
  

• Editing the configuration:

  # changing the spectrum of the source  
  config['source']['spectrum']['name'] = 'SFgal_texp_FeH0_tau5_Ew10_AGN1.fits'
  
  # changing the surface brightness of the source
  config['source']['normalization']['value'] = 17.7
  

• Running the code:

  from ifs_etc.etc1d.perform_calculation import perform_calculation
  report = perform_calculation(calculation)
  

• The output results:

  • report.__dict__ lists all the information in the result
  • report['snr'] contains the signal-to-noise ratio generated by the calculation
  • report['readnoise], report['darknoise'], report['sourcenoise'] contain different types of noise.
  • report['mockwave'], report['mockflux'], report['mockerror'] provide the mock spectrum of the observation

• Two Examples:

  • S/N ratio reached in a exposure time of 900 seconds for an extended source with sdss g-band surface brightness of 18 mag/arcsec² and AGN spectrum

    from ifs_etc.etc1d.config import build_default_calc
    from ifs_etc.etc1d.perform_calculation import perform_calculation
    
    config = build_default_calc()
    config['obst'] = 300
    config['repn'] = 3
    config['source']['normalization']['value'] = 18.0
    config['source']['spectrum']['name'] = 'SFgal_texp_FeH0_tau5_Ew10_AGN1.fits'
    report = perform_calculation(config)
    print(report.snr)
    

  • Exposure time needed to obtain a S/N ratio of 10 for an elliptical galaxy with SDSS r-band surface brightness of 18 mag/arcsec²

    from ifs_etc.etc1d.config import build_default_calc
    from ifs_etc.etc1d.perform_calculation import perform_calculation
    
    config = build_default_calc()
    config['targetsnr'] = 10
    config['obst'] = 300
    config['source']['normalization']['value'] = 18.0
    config['source']['spectrum']['name'] = 'SFgal_texp_FeH0_tau1_Ewd.fits'
    report = perform_calculation(config, calculation_mode='snr2exptime')
    print(report.exptime)
    

Reference

• JWST ETC Pandeia
• HST/STIS spectroscopic ETC