DEEP SURFACE PHOTOMETRY OF SPIRAL GALAXY NGC-5383 - OBSERVATIONAL TECHNIQUES AND HALO CONSTRAINTS

The photometric profile of the spiral galaxy NGC 5383 is traced with c onfidence to visual surface brightness mu(V)=29.92, more than one magn itude arcsec(-2) fainter than any previous study. Such depth is achiev ed by very carefully removing stars and by taking great care to accura tely determine the sky level. The radial light distribution of NGC 538 3 decreases monotonically until it reaches almost three times the Holm berg radius, where the profile is lost in the noise of the night sky. The profile shows neither a separate component which can be identified as an extended low-surface-brightness halo nor any truncation of the galaxy's disk. The observations are used to set limits on the properti es of a putative halo composed of cool Population III white dwarfs. (C ) 1997 American Astronomical Society.