Flying over Jenny Jump: the ISS

On Saturday, May 18 a group of us witnessed a very nice flyover of the International Space Station from Jenny Jump State Park in New Jersey. This view was from the UACNJ facility, which is open to the public on Saturday evenings. The ISS was scheduled to clear the southwest horizon at 9:25 pm and set to the east-northeast at 9:36 pm, quite a long flyover.

I wanted to try to photograph the station as it headed across the field of a very wide-angle lens. In a dark site you can photograph the ISS as a streak in the sky for two to three minutes and often longer. Two things were working against that on Saturday: the full moon would be lighting up the sky to the east and there would be about 40 minutes of faint light remaining until the start of astronomical twilight, when the sky is as dark as it will get.

Looking at a star chart from Heavens Above, a great website and app that gives information on ISS and satellite passes, I saw the trace of the flyover go right near the star Arcturus. Preston Stahly also pointed this out on SkySafari on his iPad, and we looked up to see Arcturus in the southeast. Using the star I could properly align my lens to include that part of the sky.

I used a Nikon 16mm full-frame fisheye lens on my Nikon D850 to get as much of the sky in as possible. This lens has a 180-degree field of view from side to side in a horizontal image.

Exposure was tricky since the view was directly into the rising moon. I took a few test shots and settled on ISO 800, 8 seconds at f2.8. My plan was to not shoot a long streak but many shorter ones to keep the sky and surroundings dark as they appeared and give the ISS the appearance of movement across the sky.

The key to getting the ISS to show up well in a wide-angle shot is as wide an aperture as possible at as high an ISO as possible. The shutter speed doesn’t matter since it is moving, unlike stationary stars where you can gain an advantage with longer shutter speeds. A bright flyover helps, too. This one would be better than magnitude – 1.0 when I start photographing, -3.8 at the maximum, second only to the moon in brightness, and just under -2.0 when I shoot the last frame.

I set it up like shooting a star trail shot, a series of exposures one right after another. The remote timer was set for a 2 second interval. I had tried that once before and it gave a nice gap between the streaks. To be safe, the number of frames that the timer would shoot was set to 40.

At UACNJ there are trees to the southwest so it was a matter of guessing when the ISS would clear them. At 9:27 pm it was supposed to be 10 degrees above the horizon and no sighting yet. I started the timer about 9:29 pm and about 15 seconds later the station appeared above the trees.

The total time it was visible above the trees was over 4 minutes while we watched transfixed as the ISS made its steady track across the sky.

At home I combined 22 of the frames into a composite, similar to star trail composites, and the resulting image showed the path across the New Jersey sky that the station took. Members of the public and our class and their equipment can be seen in the foreground adding to the atmosphere. The total time presented here is 3 min, 30 seconds. Stars appear as streaks due to their movement between the first and last frames. Arcturus is the bright streak just below the ISS streak at top center of the photo.

 

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