A&A Supplement series, Vol. 127, January II 1998, 327-333
Received January 31; accepted May 9, 1997
M. Sodemann and B. Thomsen
Send offprint request: bt@obs.aau.dk
Institut for Fysik og Astronomi, Aarhus Universitet, Ny
Munkegade, DK-8000 Århus C, Denmark
We present a thorough investigation of stellar photometry based
on HST imaging of crowded fields at 
and 
from the centre of the high-surface brightness elliptical galaxy M 32.
The Principal Investigators of the present archive data have elsewhere
presented an impressive colour-magnitude diagram of the field at .
Based on the same data we enlarge on their photometric analysis
and supplement with error estimators that more clearly show the
implications of severe image crowding on the stellar photometry.
We show that the faintest stars (
, 
) are found too
bright by several tens of a magnitude.
For the field at we conclude that
it is not possible to obtain reliable stellar photometry,
standard deviations being larger than 0.4 mag.
Artificial-star experiments show that only very few of the brightest stars
of the luminosity function can be expected to represent single objects,
the majority being either spurious or not as bright as measured.
The paper as such introduces and demonstrates
basic guide lines which may be used when dealing with stellar photometry of
severely crowded fields.
keywords: methods: data analysis -- galaxies: elliptical -- galaxies: individual: M 32 -- galaxies: stellar content