ETC Model Spectra
This page describes the reference and model spectra used with the Exposure Time Calculators.
Kurucz Models
These model spectra are calculated from the Kurucz database (Dr. R. Kurucz, CD-ROM No. 13, GSFC) which have been installed in the Calibration Database System (CDBS). These are the same spectra used in the paper by Leitherer, et. al. 1996, MAMA Bright Object Limits for Astronomical Objects, ISR ACS 96-024.
These spectra are available in CDBS
HST Standard Stars
These spectra are available in CDBS, and were chosen from the paper Turnshek, et. al 1990, An Atlas of HST Photometric, Spectrophotmetric, and Polarimetric Calibration Objects.
Non-Stellar Objects
The galaxy models were selected from the Kinney-Calzetti Atlas. These and the galactic object models are also available in CDBS.
Other models used by the ETC can be found in here.
Sky Background
The sky background is composed of Zodiacal light, and Earthshine in the form of scattered light and (in the UV) Geo-coronal emission. The spectrum of each component is parameterized for low, average, and high values that will be encountered at one time or another, depending upon the target location, the HST orbital phase of the exposure, and other, seasonal factors.
These models are described in a WFC3 instrument science report, WFC3 ISR 2002-12.
