A comparison of raw and processed images of the Andromeda galaxy reveals how astronomers remove Earthly artifacts from long-exposure photography.
Key facts
- •The raw image is a stack of 223 individual 300-second exposures.
- •The data was collected from a garden observatory in Portugal in 2019.
- •Common artifacts in the raw data included airplane trails, satellite tracks, and cosmic ray streaks.
- •Software used to reduce artifacts included Astro Pixel Processor, DeepSkyStacker, and PixInsight.
- •The goal of the processing was to minimize Earthly interference to better reveal the true likeness of M31.
NASA's Astronomy Picture of the Day for September 27, 2026, features a comparison of raw and processed images of the Andromeda galaxy (M31). The raw image captures the galaxy through Earth's atmosphere, revealing various digital and environmental imperfections.
By the numbers
Capturing the Raw Data
The raw image of the Andromeda galaxy was created by stacking 223 individual photographs, each taken with a 300-second exposure. These images were captured from a garden observatory in Portugal during 2019. The resulting composite included several artifacts, such as bright parallel airplane trails, continuous satellite tracks, cosmic ray streaks, and bad pixels.
Processing and Artifact Reduction
To improve the clarity of the image, the raw data was processed using software packages including Astro Pixel Processor, DeepSkyStacker, and PixInsight. This process was intended to minimize Earthly artifacts rather than create a digital fantasy, allowing for a more accurate representation of the galaxy's actual appearance.
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This article was independently rewritten by ManyPress editorial AI from reporting originally published by NASA Breaking News.
