Infrared standards for ISO

I. A new calibration of mid infrared photometry

¹ Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
² DESPA, Observatoire de Paris, Meudon, France
³ LAEFF, VILSPA, P.O. Box 50727, 28080 Madrid, Spain
⁴ Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
⁵ ESA, VILSPA, P.O. Box 50727, 28080 Madrid, Spain
⁶ European Southern Observatory, Casilla 19001, Santiago 19, Chile
⁷ IRTF, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI96822, U.S.A.

Send offprint request to: P.L. Hammersley

Received: 13 January 1997
Accepted: 17 June 1997

Abstract

We present N, 8.7 μm, 9.8 μm 12.5 μm and Q bolometry of 26 stars which were observed on the IRTF. These are primarily K giants which have been well measured at other wavelengths and are chosen to be single and non-variable. Hence the data presented provides a new homogeneous set of mid IR standards. As a test of part of the calibration strategy of ISO over this wavelength range, the zero points have been set using the Kurucz model grids (1993) to predict the mid IR magnitudes from near IR data. An analysis of the errors involved is presented and a comparison with more direct methods for the determination of the zero points suggest an possible error of 0.015 mags, although the source of this error is unclear as it is at the level of the uncertainty in the more direct methods. The effect of the SiO fundamental on the spectral energy distributions of K giants is discussed.