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Experiences Of Wfpc-2 Photometry And Psf Modelling, Nial Tanvir, David Robinson, Ted Von Hippel
Experiences Of Wfpc-2 Photometry And Psf Modelling, Nial Tanvir, David Robinson, Ted Von Hippel
Publications
The wide-field chips in WFPC-2 have ~0.0996 arcsec pixels, which is larger than the FWHM of the point spread function (PSF). This poor sampling of WFPC-2 images, means that simple stellar aperture photometry is competitive with profile fitting for moderately crowded fields. One of the problems which must be addressed with profile fitting photometry is that of allowing for variations of the PSF as a function of position on the image. The equivalent problem for aperture photometry is obtaining aperture corrections as a function of position. The aperture correction must be added to each aperture magnitude in order to account …
An Independent Calibration Of Stellar Ages: Hst Observations Of White Dwarfs At V=25, Ted Von Hippel, Gerard Gilmore, D.H.P. Jones
An Independent Calibration Of Stellar Ages: Hst Observations Of White Dwarfs At V=25, Ted Von Hippel, Gerard Gilmore, D.H.P. Jones
Publications
The white dwarf luminosity function of a stellar cluster will have a sharp trunca- tion at a luminosity which is determined by the time since formation of the first white dwarfs in that cluster. Calculation of the dependence of this limiting luminosity on age requires relatively well-understood physics and is independent of stellar evolutionary models. Thus, measurement of the termination of the white dwarf luminosity func- tion provides an independent method to determine the age of a cluster, and thereby to calibrate stellar evolutionary ages. We have obtained HST WFPC2 data in two open clusters, identified the white dwarf sequence, …