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

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)
  

Acknowledgement

This project is supported by the CSST scientific data processing and analysis system of the China Manned Space Project and Shanghai Academic/Technology Research Leader (22XD1404200).

Reference

• JWST ETC Pandeia
• HST/STIS spectroscopic ETC