What is this dark line in the sky?
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Hi everyone, yesterday I was shooting a timelapse of the Milky Way using a 720nm infrared filter to reduce light pollution from the city. My sky is Bortle Class 8, so the Milky Way is barely visible without the filter. During my test shots, I noticed a distinct dark line in the sky. Initially, I thought it might be dirt on the sensor. To test, I changed the framing. If it were dust, the band would have remained in the same position relative to the sensor, but it moved along with the stars as I adjusted the composition. I also excluded reflections, as they would have shifted relative to the sky. I took a photo without the filter, and it wasn't visible in visible light. I then continued with the timelapse, and in the video, you can see the band shift slightly and then gradually fade after a few minutes in real time. Toward the end of the timelapse, an irregular cloud-like structure began to appear, slowly moving across the field of view. I thought it might be airglow? I remember watching a video on how to capture airglow, but that video used a specialized camera sensitive to wavelengths above 1500 nm. My setup is 720 nm. Is it possible to capture airglow at that wavelength, or is it more likely something else? submitted by /u/GianlucaBelgrado |
