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Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence


Computer Sciences, 1.3 PHYSICAL SCIENCES

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Monthly Notices of the Royal Astronomical Society, Volume 498, Issue 3, November 2020, Pages 3720–3729,


This paper presents a catalogue of optimised pointings for differential photometry of23,779 quasars extracted from the Sloan Digital Sky Survey (SDSS) Catalogue and ascore for each indicating the quality of the Field of View (FoV) associated with thatpointing. Observation of millimagnitude variability on a timescale of minutes typicallyrequires differential observations with reference to an ensemble of reference stars. Foroptimal performance, these reference stars should have similar colour and magnitudeto the target quasar. In addition, the greatest quantity and quality of suitable refer-ence stars may be found by using a telescope pointing which offsets the target objectfrom the centre of the field of view. By comparing each quasar with the stars whichappear close to it on the sky in the SDSS Catalogue, an optimum pointing can be cal-culated, and a figure of merit, referred to as the “score” calculated for that pointing.Highly flexible software has been developed to enable this process to be automatedand implemented in a distributed computing paradigm, which enables the creationof catalogues of pointings given a set of input targets. Applying this technique to asample of 40,000 targets from the 4th SDSS quasar catalogue resulted in the produc-tion of pointings and scores for 23,779 quasars. This catalogue is a useful resourcefor observers planning differential photometry studies and surveys of quasars to selectthose which have many suitable celestial neighbours for differential photometry


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