Exposure Time Calculator
ETC User Manual
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Welcome
Release Notes for ETC 33.1
New Features
General
ACS
COS
STIS
WFC3
Documentation
Under the Hood
Resolved Issues
Known Issues
Basic Use
Examining the Results
Detailed Results
Plots and Tables
Approximating ETC Results in pysynphot
Calculations
SNR
Calculating Time
Imaging
Optimal SNR
Spectroscopy
Specifying the Wavelength
Extended Sources
Target Acquisition
COS Target Acquisition
Imaging Target Acquisition
Spectroscopic Target Acquisition
STIS Target Acquisition
Reference
Spectral Distributions
Castelli & Kurucz Models
Pickles Models
Kurucz Models
Bruzual Spectra
HST Standard Star spectra
PHOENIX M dwarf Models
Non-Stellar Spectra
Black-body
Power-law
Flat continuum
Castelli & Kurucz Models
The Atlas9 Stellar Atmosphere Models by Castelli and Kurucz 2004
Pickles Models
A Stellar Spectral Flux Library By A.J. Pickles (1998) (PASP 110, 863)
Other Spectra
Available Spectra Which Cannot be Used Directly by the ETC
The Complete Set of HST Standard Spectra (CALSPEC and CALOBS)
User-Supplied Spectra
Prepare your file
Spectrum File Format
Specify your spectrum
E(B-V) and the Interstellar Extinction Curves
Redshift
Normalizing the Source Flux
Adding Emission Lines
Using pysynphot to modify emission lines
SNR/Time Calculations at emission lines
Specifying the Appropriate Background
External Background
Thermal Background and Noise
CCD parameters
Postflash
Gain
ACS CCD Parameters
Quantum Yield correction for CCD detection of UV photons
STIS CCD Parameters
WFC3 CCD Parameters
Extraction Regions
The ETC Request ID
Retrieving Previous Calculations
Appendix B -
instruments
ACS Filters and Dispersers
HRC Filters
SBC Filters
WFC Filters
Ramp Filters
COS Dispersers
COS Dark current
COS FP-POS
Calculations with BOA at wavelengths shorter than 1200 Å
Wavelength dependence on the Exposure Times and S/N calculated by the ETC for the G130M/1055 and G130M/1096 Settings due to changing resel size.
COS Tables
Detector Count Rate Restrictions
COS Count Rate Screening Limits
Detector Dark Background
Detector background count rates (per second) for COS
STIS Filters and Dispersers
Comparisons of Imaging Mode Throughputs
Choosing a filter for imaging observations or slitless spectroscopy
STIS Brightest Pixel EE table with narrow slits
STIS Modes
Selecting a Slit/Filter
Plate Scales for Different Gratings
Detector Countrate Restriction
CCD Saturation Limits
MAMA Countrate Restrictions for Different Modes
Detector Binning
Detector Background
Selecting a Checkbox Size for STIS Target Acquisitions
WFC3IR Minimum Exposure Times and Subarrays
WFC3 Filters and Dispersers
WFC3 UVIS Filters and Grism
WFC3 IR Channel Filters and Grisms
WFC3 Scan Mode
Appendix C -
Browser Issues
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