Simulating the behaviour and performance of instrumentation is required, in different forms, at several different times during the development of an astronomical research project, from preliminary studies of an instrument to the planning of its observations to the assessment of their quality.
This is a compilation of mostly trivial and boring but (hopefully!?) useful stuff related to the simulation of astronomical instrumentation behaviour and performance.
In Section 1 some basic optical concepts are reviewed. Section 2 discusses energies involved in light propagation, its breaking down in photons and blackbody emission. In Section 3 reviews some typical representations of the spectrum of astronomical objects. Sections 4 and 5 discuss sources of instrumental and sky background, respectively. Section 6 reports a few formulae which can be used to compute the SNR to be expected from an observation. In Appendices A and B, the units of measure used for angular and photometric quantities, the adopted conventions about their abbreviations, some useful conversion factors and formulae are given. Appendix D lists further useful astrophysical constants and conversion factors.
Léna et al. (1998), Schlessinger (1995), and Vaccari (2000) are good starting points for the adoption of a consistent set of units of measures, names and symbols.
SI units are generally used throughout the document. Approximate numerical values of constants (generally given with 4 significant figures) and analytical relations are indicated by the $\simeq$ symbol, whereas the $=$ symbol is used to indicate exact ("by definition") relations and physical constants.