Perseids in the Rockies
The annual Perseid meteor shower found me in Rocky Mountain National Park in northern Colorado, a great place to view them. At a minimum of around 8,000 feet in altitude and rising to over 12,000 feet at the Alpine Tundra Communities trail, stars sparkle in the thinner air (mountain peaks in the Rockies top 14,000 ft.) I was part of the parks’ Night Sky Festival on August 10-12, which happily coincided with Perseids.
I had scouted out a trail and a few locations earlier in the day with my wife, so I headed there the night of Aug 11. Upper Beaver Meadows trailhead is an area with an open view to the north and east, where Perseus and the meteor shower radiant was rising. I hiked in about a mile along a trail heading into a forested area.
After finding a place with an interesting foreground, setting up the equipment and shooting a few test shots, it was after midnight, Aug. 12. I thought I would do a test and shoot a series of frames over a period time to see how many meteors can be recorded by the camera. The equipment was a Nikon D850, 14-24mm lens at 14mm on a Manfrotto tripod. Settings were ISO 8000, 15 seconds, f2.8.
Meteors can appear bright to one’s eyes, but the duration is so short they are difficult to record with a camera. When you shoot photos at night with a long shutter speed, the stars are being recorded that whole time. A meteor, while many times the brightness of most stars and planets, whizzes by in a fraction of a second sometimes. For this reason, I keep the ISO high and the aperture (f-stop) wide open to let in as much light as possible. The shutter speed (15 seconds in this case) is irrelevant, a longer exposure time wouldn’t make the streaks brighter, you might possibly get more that one streak on a frame. I wasn’t using a tracking mount, so I went for the shorter exposure time to keep the stars sharp.
I set the remote trigger to an interval of one second between shots and to take 360 frames. At that number of frames, I estimated just over 90 minutes of shooting. From the time stamp on the first image, I started at 12:27 am and would be finished around 2:00 am, about my limit that night.
Polaris was placed off to the left side of the frame, Cassiopeia and the Andromeda Galaxy were a bit to the right and the northern part of the Milky Way crossing vertically. I had framed the shot with some trees in the foreground and on the right side, later realizing that as Perseus rose and the radiant moved, some of the trees and branches might interfere with the meteor streaks.
But I got a few images. The best had two streaks in it including one fairly close to M31 (Andromeda). Cropping in on the meteor and Andromeda made a dramatic picture. That first night, I got 16 frames with streaks in them out of a total of 360.
The next night, the supposed peak of the shower, I attended an astronomy night presentation at the same location, so I didn’t have to go far to set up. For a while a large crowd gathered to observe through telescopes and do naked-eye viewing of the Perseids. Many people lay on blankets to better see the sky. Occasionally a bright meteor would flash by and cheers broke out followed by applause.
I didn’t walk as far and found a nice clearing with a view of low mountains and a tree. Car lights in the trailhead parking lot and some on the nearby Trail Ridge Road created man-made streaks in the photos. Using the same equipment and settings as the night before I decided to shoot longer, from 12:55 am to 3:35 am. The trigger was set for 600 frames, a total of 2 hours 30 minutes of exposure. This night it looked like 33 frames had meteor streaks in them, many of them small or faint. Smoke from the recent California fires was visible along the horizon earlier in the evening and it may have interfered with the shower since the Sunday night ‘show’ was less interesting than the night before.
I assembled a composite of the best 13 frames that had 15 meteors in them from the Sunday night (Aug 12-13) session. Using an excellent video posted by member Michael Krypel on the Astrophotography Google Groups two years ago I proceeded in Photoshop to create the composite: https://www.youtube.com/watch?v=u7JVwSX1iAg
The main trick is to accurately rotate the star field as Perseus rises to keep all the meteors looking like they radiate from the constellation.