  A complete sample of 174 M giants classified by Blanco (1986) and later than
subtype M0 in the NGC6522 Baade's Window clear field has been investigated to
establish some general properties of cool Bulge stars. Photometric information
has been obtained from the MACHO database to search for variability and, where
possible, to determine periods. Near- and mid-IR magnitudes have been extracted
from DENIS and ISOGAL. 46 semi-regular variables and 2 irregulars were found a
mongst the 174. Many M5 and all stars M6 or later show variation, whereas
earlier subtypes do not. The DENIS I-J and J-K_S colours and the luminosities
of the M stars increase with M sub-class. K tends to increase with log P among
M-type SR variables. Almost all the variables were detected at 7 microns during
the ISOGAL programme. Excess radiation at 15 microns, indicative of heavy mass
loss, is associated with very high luminosity and late spectral type. The limit
of sensitivity of the ISOGAL survey was such that the non-variables were not
detected. Four probable M stars not listed by Blanco (1986), two of which are
semi-regular variables, were detected by ISOGAL. In the case of doubly-periodic
SR variables, the longer periods have K mags which place them close to the D
line of Wood (2000) in a K,log P diagram. The unusual MACHO light curve of one
particular star, Blanco 26, shows the commencement of a long-period variation
with an anomalously short and sharp event and appears to rule out a pulsational
model for this phenomenon.
