We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

Astrosat: forecasting satellite transits for optical astronomical observations

Osborn, James and Blacketer, Laurence and Townson, Matthew J and Farley, Ollie J D (2022) 'Astrosat: forecasting satellite transits for optical astronomical observations.', Monthly notices of the Royal Astronomical Society, 509 (2). pp. 1848-1852.


The impact of large-scale constellations of satellites, is a concern for ground-based astronomers. In recent years there has been a significant increase in the number of satellites in low-Earth orbit and this trend is set to continue. The large number of satellites increases the probability that one will enter the field of view of a ground-based telescope at the right solar angle to appear bright enough that it can corrupt delicate measurements. We present a new tool ‘Astrosat’ that will project satellite orbits onto the RA/Dec. coordinate system for a given observer location and time and field of view. This enables observers to mitigate the effects of satellite trails through their images by either avoiding the intersection, post-processing using the information as a prior or shuttering the observation for the duration of the transit. We also provide some analysis on the apparent brightness of the largest of the constellations, Starlink, as seen by a typical observatory and as seen with the naked eye. We show that a naked eye observer can typically expect to see a maximum of 5 Starlink satellites at astronomical twilight, when the sky is dark. With the intended 40 000 satellites in the constellation that number would increase to 30.

Item Type:Article
Full text:(VoR) Version of Record
Available under License - Creative Commons Attribution 4.0.
Download PDF
Publisher Web site:
Publisher statement:© 2021 The Author(s) Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Date accepted:No date available
Date deposited:01 February 2022
Date of first online publication:20 October 2021
Date first made open access:01 February 2022

Save or Share this output

Look up in GoogleScholar