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Calculated Standard Star Flux Densities for Michelle Filters

A text file containing flux densities of standard stars calculated for the Michelle filters can be found at this link.The values in the file are in-band flux densities in Jy unless there is a "*" after the name, in which case the values in mJy. Those stars with values in mJy are calibration stars for SPITZER and so are unlikely to be used by Michelle. All values are calculated for zero airmass (i.e. outside the atmosphere).

Some standards are in the table more than once, because several lists of standard stars for the mid-infrared are used to compile it. These include the TIMMI2 and MIRAC standard stars, where spectral energy distribution tables are available, and the series of papers on "Spectral Irradiance Calibration in the Infrared" by Martin Cohen and various others. The latter series of papers is the source of the large majority of the objects listed here. The formal uncertainties in the values are of order 2% to 4% for the Cohen spectral irradiance values, but it depends on how much data is available for any given star. The best standards have uncertainties of 1.5% or so in the spectral irradiance values.

The first entry in the table, "zero_mag", gives the assumed zero magnitude flux density, calculated from the alpha CMa in-band fluxes and the magnitude values as a function of wavelength in Cohen et al. (1992) [AJ, vol. 104, 1650, 1992]. Comparison of these values with those for alpha Lyr itself, which in the Cohen et al. (1992) paper is assumed to be of magnitude 0.0 at all wavelengths provided that the dust shell does not contribute any emission, gives an idea of the real precision of the calculations used to produce the table, which is seen to be about 0.4% or better. The number of decimal places in the table is therefore somewhat excessive.



Last update Oct 25, 2005; K Volk