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 confidence to visual surface brightness mu_V = 29.92, more than one magnitude arcsec (-2) fainter than any previous study. Such depth is achieved by very carefully removing stars and by taking great care to accurately determine the sky level. The radial light distribution of NGC 5383 decreases monotonically until it reaches almost three times the Holmberg 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 properties of a putative halo composed of cool Population III white dwarfs.