Presented is N, 8.7
m, 9.8m 12.5m and Q photometry on a
set of 26 stars which were measured on the IRTF. The errors in the measurements
are of the order 1 to 1.5% in the N, 8.7m, 9.8m 12.5m
and 3% at Q . The zero points in the 5 filters have been set using near IR photometry and the Kurucz model grid to predict the IR magnitudes
in the 5 filters. The probable error in the derived zero
points is 0.015 mags which is comparable to the current error in the more
direct methods of determining the zero points in this wavelength range.
The main problem with the method is that the Kurucz model grid,
which was used here, does not include the SiO bands and so stars hotter than
4500 K are needed to set the zero points in the N, 8.7m and 9.8m
filters. The results presented here do validate part of the proposed
method for calibration of ISO, at least between 8 and 26 m. These
26 stars now qualify as reliable, self-consistent set of mid IR standards.
Acknowledgements
We would like to thank the staff of the IRTF for their assistance during the observations. We thank Dr. M. Cohen for providing access to his composite spectra and spectral templates well as helpful comments on an original draft of the paper, and also thank the referee, A. Tokunaga, for useful suggestions.