The Perseid Meteor Shower: 2021 Results

The Perseid Meteor Shower: 2021 Results

The Perseid Meteor Shower peak has come and gone for 2021. This year the Moon’s interference was minimal, setting early in the evening around the predicted peak days, but luck always plays a major role in anyone’s success. And this year, if you were out a couple of nights after the nominal peak, you would have been treated to a brief but intense above-normal peak rate (see published graph). This peak probably was due to a denser cloud of particles, perhaps ejected from the parent comet (109P/Swift–Tuttle) in an outburst when it warmed up on a close approach to the Sun. Unfortunately, I missed the outburst, but I did have good weather on the evening of the peak.

Since this year’s peak occurred in the middle of the week, I ran my cameras on the Saturday nights before and after the peak, as well as on Wednesday night. The result was some (low) activity on the Saturday night preceding the peak, some clouds but “normal” peak activity on Wednesday night, and heavy clouds on Saturday following the peak, resulting in only a single meteor recorded on that night.

I had two setups going (described below), one very wide (15mm fisheye) for time-lapse video, as well as composite shot, and a 105mm for a closer view of the radiant area of the shower, which contains a number of interesting deep sky objects.

Wide-Field Composite

The wide-field composite creates a bit of a problem since multiple frames from a fisheye lens can’t be simply rotated/translated to match up due to the extreme lens distortion. In this situation, I pick a suitable frame (one already with a meteor) and use it as a base to which other frames with meteors will be matched. 

To register the additional frames to the base frame, I use a program called Registar (not to be confused with Registax), which was originally designed to stack astrophotos taken on film. Because film is a flexible medium that is subject to curling and other distortions, Registar identifies each star in the base frame and the frame to be registered, determines the distortions required, and outputs a distorted version of the frame, which is extreme in the case of fisheye lens frames. Below is an example of a frame warped by Registar (top) to match the reference frame (bottom). Registar does not work on the landscape, only on star fields.

The registered frames can then be imported into Photoshop as layers so that the meteors can be extracted using a layer mask to produce a composite final image.

The wide-field frames can also be easily converted to a time-lapse video by Photoshop. Just open the first frame in Photoshop, be sure to check the “Image Sequence” box, and Photoshop will open the sequence of images and create a video sequence. To adjust exposure or any other details prior to creating a video, I first batch adjust the images in Lightroom. In addition, to save downstream processing time, I also crop to a 16:9 aspect ratio, and export JPEG files for processing into a video by Photoshop. When exporting the JPEG files from Lightroom, I also renumber the frames since it’s possible that the numbering of frames from the camera may have wrapped around (e.g. 9999 to 0000), interrupting the consecutive numbering Photoshop expects.

Wide-Field Video

When viewing the time-lapse video, keep in mind that not all of the objects streaking through the frame are meteors. True meteors will only appear in a single frame. Satellites are slower, and will appear in 2 or more consecutive frames, and aircraft are even slower and are visible in many frames.

A bonus from the wide-field image set was a very bright Perseid meteor (right side late in the time-lapse video) which was followed by some ionization trail wisps which could be seen in frames following the meteor. A cropped view was turned into a GIF animation.

Focus on the Meteor Shower Radiant

The narrower field view (105mm lens) was done by mounting the camera on a tracking mount. This makes creating a composite much less difficult since registration of frames that have not moved (much) between them doesn’t require lens distortion correction. In addition, so many frames can be stacked (255 in this case) that noise is not a problem in the final image.

Normally, a closeup of the radiant of a meteor shower is not of any particular interest, especially since the smaller field of view will make it less likely to catch a meteor, but in this case the radiant lies in an interesting area of the Milky Way. The tight cluster of stars in the upper right of the frame are NGC 869 and NGC 884. This pair of clusters, known as the Double Cluster, is easily visible in binoculars. To the lower left of the Double Cluster are ionized hydrogen clouds designated IC 1805 and IC 1848. These glow in the deep red light of hydrogen-alpha, and are not easily photographed by standard consumer cameras unless they have been modified for enhanced red spectral response.

Equipment Setup

The nice aspect of photographing a meteor shower is that the equipment takes care of itself, leaving you free to relax and just watch the show (or drift off to sleep). For this year, I ran two setups. Setup #1 was my standard setup -- a Nikon D850 with Sigma 15mm fisheye lens on a fixed tripod. This was set to shoot 15 second exposures at f/2.8, ISO 3,200 using the camera’s built-in intervalometer function.

Setup #2 was a “modified” Canon EOS RP on a Sky-Watcher Star Adventurer tracker. In this setup, a Nikon 105mm Micro Nikkor lens with a lens adapter for the Canon body was used since I'm normally a Nikon shooter and all of my lenses are F-mount lenses. The mirrorless Canon body was modified by a 3rd party (Hutech) for enhanced red sensitivity to include the hydrogen-alpha emission line visible in many astrophotos. The setup was run at f/2.8, ISO 1,600, with 30-second exposures, again using this camera’s built-in intervalometer.

Both setups were run with dummy batteries fed by power from AC adapters so battery changes were not necessary during the night and large enough memory cards were used to last the entire night, making the imaging session a completely hands-off effort.

Next Up

The next major meteor shower opportunities are the Leonid shower in November, and the Geminid shower in December. Unfortunately, both showers will be competing with a bright moon this year, but this does not make it impossible to get good results, so I'll be out there trying my luck again.


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