17 citations · 32 across the 5 of their papers we have counts for
5 papers
A general and practical method for calculating cosmological distances
Rainer Kayser, Phillip Helbig, Thomas Schramm
The calculation of distances is of fundamental importance in extragalactic astronomy and cosmology. However, no practical implementation for the general case has previously been av…
The light curve and the time delay of QSO 0957+561
Jaan Pelt, Rainer Kayser, Sjur Refsdal +1
We present a new analysis of the presently available photometric data for the gravitationally lensed quasar 0957+561 A,B with the aim of determining the time delay between its two…
The complex theory of gravitational lensing: Beltrami equation and cluster lensing
T. Schramm, R. Kayser
We introduce a new complex formalism to describe arclet fields in clusters of galaxies and derive the appropriate inversion techniques to find the related mass distribution of the…
The Hamburg Quasar Monitoring Program (HQM) at Calar Alto III. Lightcurves of optically violent variable sources
K. -J. Schramm. U. Borgeest, D. Kühl, J. von Linde +2
HQM is an optical broad-band photometric monitoring program carried out since September 1988. We use a CCD camera at the MPIA 1.2m telescope. Fully automatic photometric reduct…
A toolbox for general elliptical gravitational lenses
T. Schramm
We introduce a formalism to describe 2D-Potentials for 2D-matter (or charge) distributions with arbitrary elliptical symmetry including varying eccentricity and twisting of the iso…