Aims. We investigate the intermediate-age asymptotic giant branch stellar population of two Local Group dwarf irregular galaxies to characterize their carbon star population in near-infrared (IR). Methods. Our work is based on near-IR photometry complemented with optical ground based and Hubble Space Telescope (HST) photometry. Near-IR photometry is based on our and archival J and Ks-band image...

The absolute flux calibration of the standard WFC and HRC filters is derived from the available constraining observations of spectrophotometric standard stars. Values for the encircled energy (EE) of one arcsec radius relative to an infinite aperture radius are derived for hot stars and compared to the EE for cooler stars. The sensitivity degradation for the five year ACS lifetime is defined an...

We present the results of a search for strong Hα emission line galaxies (rest frame equivalent widths greater than 50Å) in the z ≈ 0.23 cluster Abell 2390. The survey contains 1189 galaxies over 270 ⊓⊔′, and is 50% complete at Mr ≈ −17.5 + 5 log h. The fraction of galaxies in which Hα is detected at the 2σ level rises from 0.0 in the central regions (excluding the cD galaxy) to 12.5±8% at R200....

We have constrained the age of the globular cluster S312 in the Andromeda galaxy (M31) by comparing its multicolor photometry with theoretical stellar population synthesis models. This is both a check on the age of this globular cluster, as well a check on our methodology. Main-sequence photometry has been the most direct method for determining the age of a star cluster. S312 was observed as pa...

The involvement of elements in the pathological process of primary hypertension has been established. The serum levels of copper, iron, zinc, sodium, potassium and calcium were studied by atomic absorption spectrophotometery and flame photometry in hypertensive and normal subjects. Serum copper and zinc levels were increased in hypertensive patients (25.5% and 14.7% respectively) as compar...