H92     identifies a source of similar brightness and within 2" of a variable
        star identified by Haller (1992, Ph. D. thesis, Univ. of Arizona).
Cool    identifies a star with CO 2.3 mm absorption based on K-band spectra; see
        LRT (Lebofsky et al., 1982ApJ...263..736L), Sellgren et al.
        (1987ApJ...317..881S), Krabbe et al. (1995ApJ...447L..95K), and Paper II
        (Blum et al., 1996AJ....112.1988B).
He I    identifies a star with 2.06mm emission based on K-band spectra or
        narrow-band imaging; see Allen et al. (1990MNRAS.244..706A), Krabbe et
        al. (1991ApJ...382L..19K, 1995ApJ...447L..95K), Libonate et al.
        (1995ApJ...439..202L), Blum et al. (1995ApJ...441..603B), and Tamblyn et
        al. (1996ApJ...456..206T)
Red     identifies a star with a very red, nearly featureless spectrum based on
        K-band spectra; see Libonate et al. (1995ApJ...439..202L), Blum et al.
        (1995ApJ...441..603B), and Krabbe et al. (1995ApJ...447L..95K).
WC9     (NAME BSD WC9 in Simbad) identifies a star with C III and C IV emission
        lines based on K-band spectra; see Blum et al. (1995ApJ...440L..17B) and
        Krabbe et al. (1995ApJ...447L..95K).
b       Photometry derived from the DePoy & Sharp (1991AJ....101.1324D,
        hereafter DS91) data set. J and H presented from DS91 data only if no
        value from the OSIRIS data was available (except for IRS 7, 9, and 12N;
        see note e below); see Appendix. The DS91 data were flux calibrated by
        assuming the IRS 7 magnitudes of Becklin et al. (1978ApJ...220..831B)
        which are uncertain by less than 0.1mag at each wavelength. Good average
        agreement between the DS91 photometry and OSIRIS photometry argues that
        the assumed magnitudes of IRS 7 at the time of the DS91 observations
        were correct, despite the variability of IRS 7 (see text).
c       K magnitude derived from narrow-band filters at 2.2mm; see text.
d       IRS 2 and 10E label the bright sources at K. IRS 2L and 10EL label the
        nearby, but not coincident, bright sources at L. For IRS 2L and 10EL we
        give K from OSIRIS and L from DS91. IRS 10EL has been identified as a
        variable star by Tamura et al. (1996ApJ...467..645T) which they call IRS
        10*. It may also be the OH/IR star OH 359.946-0.047 in the list of
        Lindqvist et al. (1992, Cat. <J/A+AS/92/43>).
e       See discussion in text on IRS 7, 9, and 12N variability. DS91 magnitudes
        for IRS 7 are from Becklin et al. (1978ApJ...220..831B) as adopted by
        DS91. Uncertainty is less than +0.1mag at each wavelength. OSIRIS H
        magnitude for IRS 7 is from lower resolution image taken 2 months prior
        (1993 May 11) to the primary OSIRIS images; see text.
f       OSU Hel (IRS A22) is an He I emission-line star; OSU F1 (IRS A15) is
        featureless, both based on unpublished K-band spectra.
g       He I emission-line star identified by Tamblyn et al.
        (1996ApJ...456..206T) narrow-band photometry, confirmed by our
        unpublished K-band spectrum.