Astronomers have released a massive galactic plane survey of the Milky Way. The new dataset contains a staggering 3.32 billion celestial bodies – arguably the largest such catalog to date. Data for this unprecedented survey was taken using the Dark Energy Camera, built by the US Department of Energy, at the NSF Cerro Tololo Inter-American Observatory in Chile, a program of NOIRLab.
The Milky Way contains hundreds of billions of stars, shimmering star-forming regions, and towering dark clouds of dust and gas. Imaging these objects and cataloging them for study is a daunting task, but a newly released astronomical dataset known as the Dark Energy Camera Plane Survey Data Release 2 (DECaPS2) reveals a staggering number of these objects in unprecedented detail. The DECaPS2 survey, which took two years to complete and yielded more than 10 terabytes of data from 21,400 individual exposures, identified nearly 3.32 billion objects – arguably the largest catalog compiled to date. Astronomers and the public can explore the dataset here.
This unprecedented cluster was captured by the Dark Energy Camera (DECam) instrument on the 4-meter Víctor M. Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO), a program of the NSF NOIRLab. CTIO is a constellation of international astronomical telescopes perched atop Cerro Tololo in Chile at an altitude of 2,200 meters (7,200 feet). CTIO’s lofty vantage point provides astronomers with an unparalleled view of the southern celestial hemisphere, allowing DECam to capture the galaxy’s southern plane in such detail.
DECaPS2 is a plane-plane survey of the Milky Way as seen from the southern sky taken at optical and near-infrared wavelengths. The first set of data from DECaPS was released in 2017, and with the addition of the new data release, the survey now covers 6.5% of the night sky and spans a staggering 130 degrees. While it may sound modest, this is equivalent to 13,000 times the angular area of the full moon.
The DECaPS2 dataset is available to the entire scientific community and is hosted by NOIRLab’s Astro Data Lab, which is part of the Data and Community Science Center. Interactive access to pan/zoom imaging within a web browser is available from Legacy Survey Viewer, World Wide Telescope and Aladin.
Most of the Milky Way’s stars and dust lie in its disk — the bright band running across this image — where the spiral arms lie. While this large amount of stars and dust makes for beautiful pictures, it also makes the galactic plane difficult to spot. The dark tendrils of dust seen through this image absorb starlight and completely wipe out the faint stars, and light from diffuse nebulae interferes with any attempts to measure the brightness of individual objects. Another challenge arises from the sheer number of stars, which can overlap in the image and make it difficult to separate individual stars from their neighbours.
Despite the challenges, astronomers have delved to the galactic level to gain a better understanding of our Milky Way. By observing near-infrared wavelengths, they were able to bypass much of the light-absorbing dust. The researchers also used an innovative approach to data processing, which allowed them to better predict the background behind each star. This helped mitigate the effects of crowded nebulae and starfields on such large astronomical images, ensuring that the final catalog of processed data would be more accurate.
said Andrew Sedgarry, a Harvard graduate student and researcher at the Center for Astrophysics | Harvard and Smithsonian and lead author of the paper. “Doing this allowed us to produce the largest catalog of this type ever from a single camera, in terms of the number of items spotted.”
“When combined with images from Pan-STARRS 1, DECaPS2 complements a panoramic 360-degree view of the Milky Way’s disk and also reaches for fainter stars,” said Edward Schlafly, a researcher at the AURA-run Space Telescope Science Institute and colleagues. -Author of the paper describing DECaPS2 published in The Astrophysical Journal Supplement. “With this new survey, we are able to map the 3D structure of the Milky Way’s stars and dust in unprecedented detail.”
“Since my work on the Sloan Digital Sky Survey two decades ago, I’ve been looking for a way to make better measurements over complex backgrounds,” said Douglas Finkbeiner, professor at the Center for Astrophysics and co-author of the paper. , the principal investigator behind the project. “This business accomplished that and more!”
“This is a very technical feat. Imagine a group photo of over three billion people and everyone is recognizable!” says Debra Fisher, director of the Division of Astronomy Sciences at NSF. “Astronomers will look at this detailed picture of more than three billion stars in the Milky Way for decades to come. This is a great example of what partnerships across federal agencies can achieve.”
DECam was originally built for the Dark Energy Survey, which was conducted by the Department of Energy and the US National Science Foundation between 2013 and 2019.