ISS transits of the Moon and Sun

ISS Lunar transit in daylight

Video of the ISS recorded transiting the Moon as viewed from south Wales on the morning of 19th December at 09:20 using a Sony ZV-E10 camera fitted with a 350mm zoom lens. In this animation of 101 frames, the ISS can be seen as a small white spec travelling diagonally upwards from the bottom right of the frame. At the time of transit the ISS was some 678 miles away with an angular size of just 25.3 arc seconds, crossing the Moon at an altitude of just 18 degrees from the horizon and taking just under 3 seconds to cross the Moon's disc. The camera was placed on an MSM tracker so as to keep the Moon in the frame long enough to record the video at the predicted time which was calculated from the site ISS Transit Finder. An extract of the video was edited in Grass Valley Edius to apply a stabilisation filter to reduce the effect of camera shake resulting from high winds at the time of the transit. The video was then imported into Adobe Photoshop to make individual frames which were then exported into Adobe LightRoom where the frames were sharpened to give sightly higher contrast and then saved as jpegs which were subsequently aligned and cropped in AstroCrop before being re-imported into Adobe Photoshop to further crop and resize the frames and create a gif animation.

ISS transit video

Following the ISS lunar transit, I was lucky enough to be able to also image the ISS transiting the Sun on the very next orbit of the ISS around the Earth in the opposite part of the sky. Once again the ISS was tiny due to it being some 817 miles away, which made its angular size just 21 arc seconds, resulting in the ISS taking 2.2 seconds to traverse the Sun which was at an altitude of just 13 degrees above the horizon. Dodging a rain shower, I set up my rig comprising an iOptron CEM26 mount with a William Optics ZS71 refractor fitted with a Herschel Wedge used for safe solar imaging with an Apollo-M Mini camera. At the published time of transit I used Astro DMx Capture to take an SER of the Sun in white light which also recorded the ISS transiting the Sun. Using SER Player to enhance the contrast and crop the SER, I was able to export an AVI file to show the transit in real time. I also output a series of 183 frames as individual Tiffs for further editing in Adobe Lightroom and Photoshop to create a false colour gif slowed down to show the transit more clearly. Also attached is a montage of the rig being used at the time of the Solar transit and an image of the camera and tracker being used for the earlier lunar transit at the precise time the ISSS transited the Moon.

ISS Transit video

The Sun in White Light:

Prior to shooting the ISS transit across the Sun I had a clear sky and was able to capture a 3,300 frame SER in Astro DMx Capture using the ZS71 fitted with Herschel Wedge and Apollo-M Mini camera. The data were stacked in Autostakkert!4, wavelet processed in Registax and further processed using Pixinsight and Adobe 2024.

Chris Bowden