Astrophotographer Andrew McCarthy has taken an extraordinary photograph called “GigaMoon.” It is an incredibly detailed image of the Moon created from a whopping 280,000 photos. The image has a resolution of 1.3 gigapixels.
McCarthy had been wanting to capture this image for a long time, but his previous attempts were hindered by unfavorable conditions.
“I have numerous failed attempts at capturing GigaMoon saved on my hard drive,” McCarthy shared with PetaPixel. “I closely monitor the weather forecast every day, specifically looking for optimal viewing conditions. It’s a unique aspect of weather that isn’t typically included in regular forecasts. I rely on a specialized astronomy-oriented weather app called Astrospheric to stay updated on the constantly changing conditions of the upper atmosphere.”
To capture the image, McCarthy utilized an 11-inch telescope equipped with a 2.5x powermate. This combination resulted in a focal length of 7000mm. However, due to temperature differences between different atmospheric layers, the Moon can appear blurry and shaky when observed at such high magnification.
However, on the evening of April 29, the weather forecast was favorable, prompting McCarthy to make another attempt at capturing the image.
“Even under favorable conditions, it feels as if capturing the image is akin to doing so through water, given how much the atmosphere distorts each individual image,” he explained.
“To overcome this challenge, I capture around 2,000 images at once. I repeat this process for each section of the moon, adjusting the position of my telescope and capturing more images until I have covered the entire surface,” he explained the process of capturing these images.
Although the conditions were generally favorable, there were still some phases that were less than ideal. To account for this, McCarthy took photographs of the entire Moon twice to ensure he had coverage even in areas with potential issues. In the end, he captured an astounding 140 panels, resulting in a staggering total of 280,000 images.
Editing the GigaMoon
“Since I used a monochrome camera for this project, I still needed to capture the color information separately,” McCarthy explained.
“To accomplish that, I utilized my 12-inch Newtonian telescope paired with a full-frame CMOS camera. Although the camera was also monochrome, it had a filter wheel that enabled me to switch between red, green, and blue filters during the capturing process. This allowed me to gather high-quality color data that I later incorporated into the final image,” McCarthy elaborated.
Gathering all the necessary data is quite challenging, but assembling it into a coherent final image is an even more complex task. It requires significant computational power to accomplish.
Manually aligning each panel of a huge moon pic is a pain but it must be done for the best outcome. Sometimes I spend an entire day just getting this part right. It also gives me an intimate look at each panel, so I know which ones need to be reprocessed with different settings. pic.twitter.com/XGNJztn1TJ— Andrew McCarthy (@AJamesMcCarthy) April 30, 2023
Aligning each panel of a large moon picture manually can be a tedious task, but it is necessary to achieve the best possible outcome. Sometimes, I dedicate an entire day to ensure this step is done accurately. It also provides me with a close examination of each panel, helping me identify any that require reprocessing with different settings.
“I incorporated a technique called ‘drizzle’ into my images, where software was used to interpolate data between the pixels and produce an upscaled image from the stack of images. This process took several days to complete,” McCarthy explained.
After completing the previous steps, I manually assembled the entire image using Photoshop. I chose to do it by hand because it allowed me to carefully inspect each panel for any flaws and make precise adjustments to their orientation to accommodate the subtle angle change of the moon known as ‘libration’ that happened during the capturing process.
After spending several days assembling the image, McCarthy needed to make editing adjustments that are more familiar to terrestrial photographers, such as working on composition, contrast, and color. However, due to the large memory requirement, he had to divide the image into smaller pieces so that his computer could handle the editing process.
“Throughout the last week, I divided the image into sections and reassembled it around 10 to 15 times while making these relatively minor edits. This was done to ensure that the final result appeared flawless as a whole and maintained its quality even when zoomed in to view the moon’s surface,” McCarthy explained.
McCarthy encountered numerous computer crashes, approximately a dozen times, during the completion of GigaMoon. To view the entire 1.3-gigapixel image, you can visit the provided link. If you are interested in purchasing a fine art print of the image, you can visit McCarthy’s website. Additionally, the full image can be downloaded from McCarthy’s Patreon page.