HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot’s internal reliability are made using multiple observations of the same field, and tests of external reliability are made ...

The variation of sensitivity within a pixel of a CCD can be substantial and also substantially the same for each pixel of the CCD. Variations of the order of 10%, now being found for CCDs, can lead to errors in stellar photometry on the order of a few percent, dependent on the size of the stellar image and the position of its center within the pixel. An enhanced version of Starman, a proole tti...

We quantify the systematic effects on the stellar mass function which arise from assumptions about the stellar population, as well as how one fits the light profiles of the most luminous galaxies at z ∼ 0.1. When comparing results from the literature, we are careful to separate out these effects. Our analysis shows that while systematics in the estimated comoving number density which arise from...

Mayall II = G1 is one of the most luminous globular clusters (GCs) in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on farand near-ultraviolet GALEX photometry, broad-band UBV RI , and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G1 to date, spanning the wavelen...

We present our catalog of U , B, V , and I stellar photometry of the central 18 sq.◦ area of the Small Magellanic Cloud. We combine our data with the 2MASS and DENIS catalogs to provide, when available, U through KS data for stars. Internal and external astrometric and photometric tests using existing optical photometry (U , B, and V from Massey’s bright star catalog; B, V , and I from the micr...

We present a thorough investigation of stellar photometry based on HST imaging of crowded fields at 85 and 10 from the centre of the high-surface brightness elliptical galaxy M32. The Principal Investigators of the present archive data have elsewhere presented an impressive colour-magnitude diagram of the field at 85. Based on the same data we enlarge on their photometric analysis and supplemen...