Lunar Eclipse 2019
On 21 January 2019 a total Lunar Eclipse was visible in large parts of the world. A total lunar eclipse is an infrequent event, so this was an ideal situation to experience and capture this unique phenomenon. As the Earth stands in between the sun and the moon, the shadow of the Earth covers the moon in darkness for a short while. Diffraction of sunlight in the Earth’s atmosphere causes the moon to get a deep red colour during total eclipse, also known as blood-moon.
There are different ways to capture a lunar eclipse and two approaches were applied. First, the TOA-130 telescope was setup with a regular photo camera attached, to make detailed images every 15s. The series of images were combined into a time-lapse video, to create a sense of the total event. A second approach was with a regular photo camera with 21mm wide-angle lens in stationary position. Making regular exposures would allow for a composite image showing the moon’s orbit while being eclipsed. Together, a total of more than 1300 images were shot. 736 Images found their way into the following time-lapse video.
Planning
Eclipse times (altitude)
Start eclipse: 04:34 (34º)
Start total eclipse: 05:41 (25º)
Maximum eclipse: 06:12 (20º)
End total eclipse: 06:44 (16º)
End eclipse: 07:51 (6º)
Conditions
Astr. night: 19:00
Astr. dawn: 06:29
Moon: 100%
Moon set: 08:40
The eclipse took place on the early morning of January 21, 2019. From 4:34h onwards an increasing part of the lunar surface was covered by the earth’s shadow. At the start of the eclipse, the altitude was still fairly high at 34º, allowing the full eclipse cycle to remain well visible above the horizon. At the end of the eclipse, the moon was still 6º above the horizon. But by that time, dawn had set in and it became fairly bright.
Capturing
The images were not captured in the backyard, but on a dark open-field location near Gasteren, The Netherlands. This location is often used by members of the local astronomical society. Together with another member, the eclipse was observed and photographed. The conditions were fairly poor at the start of the evening, with a lot of fog hanging over the fields. Fortunately the sky cleared up just before the eclipse started. It was very cold, with temperatures around -8 ºC. Hot clothing, heated socks and warm coffee were critical ingredients.
The camera used was a Leica SL, a regular mirrorless photo camera. This allowed for full-colour images. The moon is an extremely bright object in astronomy terms. Exposures of 1/250s at ISO100 were sufficient to capture a bright and detailed image of the moon. However, during the eclipse, brightness obviously reduced significantly. At total eclipse, exposures were 5s each at ISO400. This is approximately a 12 stop difference! So as the eclipse progressed, exposure settings had to be constantly adjusted. The camera was used tethered to the laptop, so exposures could be assessed in real-time using Capture One RAW editing software. The Leica SL applies Long Exposure Noise Reduction (LENR) to images of 1s and longer. Essentially this is a dark frame that is subtracted from the light frame. Unfortunately this function cannot be turned off. In order to make a time-lapse video, a capture was made every 15s. This was based on a maximum exposure of 5s followed by 5s of LENR and a little extra time, for the camera to get ready and just to be safe. When exposures had to be longer than 5s, the ISO was increased instead. In total the ISO was increased to 400 during total eclipse.
Technical details
Takahashi TOA-130 + 35 flattener
10Micron GM1000HPS
Leica SL
-8ºC (ambient temperature)
Telescope
Mount
Camera
Sensor Temp.
Exposures
OSC
Total duration (time-lapse)
736 x 1/250 - 5s @ ISO 100-400
3h 16m
As observations across the globe were made, an interesting event was reported. During the eclipse, a meteor had hit the moon! During a full moon, this would have never been noticed, but on a very dark moon surface, the flash of the impact was clearly visible. Based on reported timelines and locations, the relevant images from the time-lapse were analysed and yes, this meteor impact had been recorded! Above are three sequential images, 15s apart. Clearly in the middle one, at 05:41:36 there was a flash visible on the moon surface. It’s only a handful of pixels, but time and location was verified with other observers, this really was the meteor impact.
Processing
All images were captured in native RAW format, which for this camera is a DNG format. Processing of images was done in Capture One, a RAW editor. During capture, exposure was corrected from time to time. But for a time-lapse it was important to keep the overall brightness of the image somewhat comparable and create a smooth transition from the very bright full moon to the dark blood moon. This means that manually the exposure for each frame had to be corrected so that the overall brightness of the image would remain more or less constant. This was a tedious, manual process involving 736 frames. Apart from exposure changes, saturation was increased a little and shadows were lifted. Files were then exported as JPEGs. In Affinity Photo all files were aligned using the File>New Stack.. option. This is a fully automated process and aligns the images on the moon. Registration in PixInsight would also have been possible, but it would typically be done on the stars and would require a lot of tweaking of the integration parameters to register on the moon. Then they were cropped and exported again.
Registered and cropped images were loaded into Final Cut Pro. Each photo was given a length of three frames on a 24 fps timeline. This created a time-lapse of 8 images per second. With a total of 736 images this meant approximately 1.5 min of relatively smooth video. The video was then edited further with intro, credits, music etc. to the result as can be seen at the top of this page.
For the compilation image, for each of the three eclipse stages, a stack of 6 images was made in PixInsight to enhance structure and reduce noise. Images were then combined into one image using Affinity Designer.
The images of the second camera with the wide-angle view did not come out very well. The focus was a bit off, exposures were not very well controlled and overall the moon was very small on the 21mm lens, resulting overall in a very underwhelming experience.
In the early morning hours, the world woke up over a frosty landscape with the moon still low above the horizon. Nothing reminded of the exciting event that had happened that night, other than some astrophotography equipment.