International Halley Watch Wide Field Network for Large-Scale Phenomena, Calibration of Schmidt Plates Using Star Profiles

Abstract

The International Halley Watch Wide Field Network for Large-scale Phenomena (Niedner, Rahe and Brandt, 1982) will be receiving several thousand original or first copy images of the large scale structure of comet Halley. These images will be coming from over 90 telescopes at 70 different observatories around the world. Some but not all of the photographic material will have associated sensitometry. It is anticipated that since this network is looking for changes in the plasma tail structure most, if not all, observations will be made with unfiltered Kodak IIaO emulsion. One of the major tasks of the network will be to study the plasma tail variations at the highest time resolution possible. In order to do this, it will be necessary to combine photographs taken at many observatories. This implies creating calibrated intensity images from a sequence of diverse photographic plates. We will need to provide a method for calibrating individual photographic plates, that is not only fast but also accurate using only information that can be obtained on a single Schmidt plate.