Will Starlink satellite tracks pollute my observation?

If you read this post, you certainly already know that the constellations of Starlink satellites is expanding at an incredible pace.

As of July 2024, there are 6,281 Starlink satellites in orbit, of which 6,206 are working, according to Astronomer Jonathan McDowell who tracks the constellation on his website.
(space.com)

For astronomers, it means that many more data frames will be polluted with tracks. And not mentionning how this new type of visual pollution adds up with the “classical” light pollution which degrades our access to clear night skies (see the fantastic Dark Sky website for more on light pollution what you can do about it).

It’s always quite hard to predict with precision if a satellite track will hit the field-of-view (FOV) of your observation.

With Arcsecond, you can do it.

Using the latest official data, from CelesTrak.org and space-track.org. Here’s how.

First, login (or register) to Arcsecond. Then, open the Night Plans page. Night Plans are Arcsecond’s observations planner. Then create or open an existing plan.

Choose the observing date and the telescope. Then create observations by importing targets, and edit their start time and duration. Below is an example, where most observations have a one-hour (3600 seconds) duration.

At that point, Arcsecond provides a global visualisation of all Starlink tracks that will cross your sky on that night (that is, all tracks above 5º above horizon, between the times of the two astronomical twilights). The white track is that of the Moon. It may looks a bit scary, but it doesn’t necessarily mean your specific observation at a given time will be polluted.

Every observation row has a “Starlinks” hits column with a button indicating the number hits by Starlinks tracks Arcsecond has estimated on your FOV. Click the little “eye” button to see your FOV in Aladin Lite, with the tracks that Arcsecond has computed.

Simple, isn’t it? Try it!

Clear skies!

P.S. This feature is still under active improvement, as we have identified an issue with a small number of tracks which turn into tracks with jumping coordinates. You can follow the discussion here.