The Panchromatic Hubble Andromeda Treasury (PHAT) is an HST multi-cycle treasury program that has mapped the resolved stellar populations of ∼1/3 of the disk of M31 from the UV through the near-IR. This data provides color and luminosity information for more than 150 million stars. Using stellar evolution models, we model the optical color-magnitude diagram to derive spatially-resolved recent star formation histories (SFHs) over large areas of M31 with 100 pc resolution. These include individual star-forming regions as well as quiescent portions of the disk. With these gridded SFHs, we create movies of star formation activity to study the evolution of individual star-forming events across the disk. We analyze the structure of star formation and examine the relation between star formation and gas throughout the disk and particularly in the 10-kpc star-forming ring. We find that the ring has been continuously forming stars for at least 500 Myr. As the only large disk galaxy that is close enough to obtain the photometry for this type of spatially-resolved SFH mapping, M31 plays an important role in our understanding of the evolution of an L* galaxy.

We present a preliminary analysis of known planetary nebulae (PNe) in M31 that were observed in the first year of the Panchromatic Hubble Andromeda Treasury HST Multi-cycle program. We use the properties of this sample to discuss PNe from this new multi-band survey.

We present the size-luminosity relation (SLR) for disk galaxies observed in eight clusters from the ESO Distant Cluster Survey (EDisCS). These clusters, at redshifts 0.4 < z < 0.8, were observed with the Hubble Space Telescope's Advanced Camera for Surveys. While we observe a change in the SLR with redshift, namely that there is an absence of low surface brightness galaxies at high redshift, we demonstrate that this could be a product of selection effects and thus is not a confirmation of evolution. We also compare the SLR for cluster and field galaxies in each redshift bin and see no significant effects of environment on the SLR.

We present a preliminary analysis of the properties of HI selected galaxies selected from the HIPASS and HIJASS surveys and that fall within the SDSS. Prom SDSS photometry in the early data release (EDR), we have obtained optical properties such as color, morphology, surface brightness and size. By comparing these with the HI properties derived from HIPASS/HIJASS, we are able to find relationships between the cool gas and the current generation of stars.

Given the difficulties in detecting even a single LSB, surveying statistically significant numbers of LSBs presents a daunting task. Large, systematic surveys with well understood selection criteria are necessary for assessing the full cosmological significance of the LSB population. Here I briefly review some of the progress which has been made in the last ten years, and suggest strategies which may prove fruitful in the future.