Several science websites, such as ScienceAlert, Space and SciTechDaily, have reported on the results of a survey of the Milky Way which was two years in the making, and released to the public on Jan. 18. It involved more than 10 terabytes of data from 21,400 individual exposures, that identified approximately 3.32 billion objects. And, this is only the beginning—these data represent a mere 6.5% of the night sky.
The National Science Foundation’s NOIRLab released a statement on Jan. 18: “This unprecedented collection was captured by the Dark Energy Camera (DECam) instrument on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF’s NOIRLab. CTIO is a constellation of international astronomical telescopes perched atop Cerro Tololo in Chile at an altitude of 2200 meters (7200 feet). CTIO’s lofty vantage point gives astronomers an unrivaled view of the southern celestial hemisphere, which allowed DECam to capture the southern galactic plane in such detail.
“DECaPS2 is a survey of the plane of the Milky Way as seen from the southern sky taken at optical and near-infrared wavelengths. The first trove 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° in length. While it might sound modest, this equates to 13,000 times the angular area of the full Moon.” (https://noirlab.edu/public/news/noirlab2301/)
“‘One of the main reasons for the success of DECaPS2 is that we simply pointed at a region with an extraordinarily high density of stars and were careful about identifying sources that appear nearly on top of each other,’ said Andrew Saydjari, a graduate student at Harvard University, researcher at the Center for Astrophysics | Harvard & Smithsonian and lead author of the paper. ‘Doing so allowed us to produce the largest such catalog ever from a single camera, in terms of the number of objects observed,’” NOIRLab continued.
Since the DECam sees in both the optical and near-infrared bandwidth of light, it has the ability to see through dust scattered throughout the galaxy, allowing for greater clarity in identifying individual stars.
“‘When combined with images from Pan-STARRS 1, DECaPS2 completes a 360° panoramic view of the Milky Way’s disk and additionally reaches much fainter stars,’ said Edward Schlafly, a researcher at the AURA-managed Space Telescope Science Institute and a co-author of the paper describing DECaPS2 published in the Astrophysical Journal Supplement. ‘With this new survey, we can map the three-dimensional structure of the Milky Way’s stars and dust in unprecedented detail.’”
The Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) began operations in May 2010, using a 1.8-metre telescope called Pan-STARRS1 or PS1. It observes the sky from the Haleakala Observatory in Hawaii.
“’Imagine a group photo of over 3 billion people and every single individual is recognizable!’ Debra Fischer, division director of Astronomical Sciences at the NSF, said in a statement. ‘Astronomers will be poring over this detailed portrait of more than three billion stars in the Milky Way for decades to come’,” reported ScienceAlert. “The research has been published in the Astrophysical Journal Supplement Series.” [https://iopscience.iop.org/article/10.3847/1538-4365/aca594]. (https://www.sciencealert.com/the-latest-milky-way-survey-shows-off-an-incredible-3-32-billion-celestial-objects)
Given that science estimates that there are at least 2 trillion galaxies in the universe, the potential number of celestial bodies is truly mind-boggling.
