The latest Milky Way survey reveals an incredible 3.32 billion celestial objects: ScienceAlert

If you check in regularly at ScienceAlert, you’ll be familiar with quite a few amazing space images, but a recently published image has to be one of the best yet: 2 years in the making, 10 terabytes of data, 21,400 individual exposures combined, and a final image showing a whopping 3.32 billion celestial bodies.

We have the Dark Energy Camera (DECam) to thank for this beautiful room, part of the Víctor M. Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO), about 2,200 meters (7,218 feet) above sea level in Chile.

The image was issued as part of the Dark Energy Camera Plane Survey (DECaPS2) and it gives us more detail than ever before of this part of space – it accounts for about 6.5 percent of the entire night sky, focusing on the galactic plane . The Milky Way where the bulk of the galaxy’s mass is located.

Deep space map
Part of the new survey. (DECaPS2/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA; Image processing: M. Zamani & D. de Martin (NSF’s NOIRLab))

“One of the main reasons for the success of DECaPS2 is that we simply pointed to a region with an extraordinarily high density of stars and were careful to identify sources that appear almost on top of each other,” says astronomer Andrew Saydjari of Harvard University in Massachusetts.

“Doing so allowed us to produce the largest such catalog ever from a single camera, in terms of the number of objects observed.”

The high density brings with it a couple of problems: The huge chunks of space dust and the glow of brighter stars can completely block out the light of fainter objects. By measuring both optical and near-infrared wavelengths, DECam overcomes these problems.

The team also used a special computing technique to better estimate what the background of each star should look like, allowing more stars to be observed with greater clarity, improving the overall accuracy of the image.

Combined with other sky surveys – such as the Pan-STARRS project – the latest telescope technology gives us an unprecedented look at the universe beyond our planet, which of course gives us clues about how it came to be.

“When combined with images from Pan-STARRS 1, DECaPS2 completes a 360-degree panoramic view of the Milky Way disk and also reaches much fainter stars,” says astronomer Edward Schlafly of the Space Telescope Science Institute in Maryland.

“With this new survey, we can map the three-dimensional structure of the Milky Way’s stars and dust in unprecedented detail.”

The results are simply amazing and worth the two-year wait. The data collected in the survey is freely available for other researchers and the general public to use.

DECam was originally built to conduct a dark energy survey and to better understand this mysterious force believed to drive the universe. It continues to produce incredibly detailed images of deep space, and there will be much more to come.

“This is quite a technical feat,” says astronomer Debra Fischer of the National Science Foundation (NSF) in the US, who was not directly involved in the research. “Imagine a group photo of over three billion people, and every single individual is recognizable!”

“Astronomers will scrutinize this detailed portrait of more than three billion stars in the Milky Way for decades to come. This is a wonderful example of what partnerships across federal agencies can accomplish.”

The research is published in Astrophysical Journal Supplement Series.

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