Billions of celestial objects in our Milky Way galaxy cataloged – rts.ch

It took 21,400 galactic photos to capture some 3.32 billion stars and galaxies in one of the largest surveys of the sky ever. The result is a gargantuan catalog of our galaxy produced by an American team.

“This is a real technical feat. Imagine a group photo of more than three billion people and each individual is recognizable!” Enthuses Debra Fischer, director of the division of astronomical sciences at the National Science Foundation (NSF). “Not just each individual, but also the color of their shirt,” adds lead researcher Andrew Saydjari, a PhD candidate in physics at Harvard University.

This image, which is full of stars and dark dust clouds, is just a small snippet – a pinhead!  – the entire DECaPS2 (Dark Energy Camera Plane Survey) study of the Milky Way. [M. Zamani & D. de Martin (NSF’s NOIRLab) - DECaPS2/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA]This image, which is full of stars and dark dust clouds, is just a small snippet – a pinhead! – the entire DECaPS2 (Dark Energy Camera Plane Survey) study of the Milky Way. [M. Zamani & D. de Martin (NSF’s NOIRLab) – DECaPS2/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA]

“Astronomers will be poring over this detailed portrait of more than three billion stars in the Milky Way for decades,” notes Debra Fischer in a communicated of NOIRLabwhich published the results of the study this week.

It’s here DECama dark energy camera installed at an altitude of 2200 meters on one of the telescopes of the Inter-American Cerro Tololo Observatory (CTIO), in Chile, which carried out these observations for two years, focusing on the sky of the southern hemisphere. The sky was observed in the light visible to the human eye and in the near infrared.

The study DECaPS2for Dark Energy Camera Plane Survey, of the Milky Way is accessible to everybody; this immense catalog full of details can be explored HERE or thanks to World Wide Telescope of the American Astronomical Society (AAS).

The gargantuan study of the Milky Way's galactic plane contains 3.32 billion celestial objects, arguably the largest catalog of its kind to date.  This image has a resolution of 4000 pixels in order to be accessible on smaller devices. [M. Zamani & D. de Martin (NSF’s NOIRLab) - DECaPS2/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA]The gargantuan study of the Milky Way’s galactic plane contains 3.32 billion celestial objects, arguably the largest catalog of its kind to date. This image has a resolution of 4000 pixels in order to be accessible on smaller devices. [M. Zamani & D. de Martin (NSF’s NOIRLab) – DECaPS2/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA]

Most of these Milky Way objects – 3.32 billion, so! – are stars and are shown in remarkable detail (read box). The tally also includes small, distant galaxies that could have been mistaken for individual stars: “Despite spending many hours looking at images containing tens of thousands of stars, I’m not sure my mind has grasped the magnitude of these numbers,” Andrew Saydjari said in an email to AP.

Only a small part of the night sky

This latest study now covers 6.5% of the night sky, according to the research team, an impressive 130 degrees. It includes the results of a investigation published in 2017 which cataloged 2 billion celestial objects, mostly stars.

The DECaPS2 study does not cover "that" 6.5% of the night sky... the elongated rectangle. [M. Zamani & D. de Martin (NSF's NOIRLab) - DECaPS2 / DOE / FNAL / DECam / CTIO / NOIRLab / NSF / AURA / E. Slawik]The DECaPS2 study covers “only” 6.5% of the night sky… i.e. the elongated rectangle. [M. Zamani & D. de Martin (NSF’s NOIRLab) – DECaPS2 / DOE / FNAL / DECam / CTIO / NOIRLab / NSF / AURA / E. Slawik]

With hundreds of billions of stars in the Milky Way, the cosmic catalog is sure to grow: “No further updates are planned for this particular survey,” says Andrew Saydjari, “but future telescopes will will attack even larger areas of the sky”.

>> Diving into the gargantuan cosmic catalog in video:

Stephanie Jaquet and AP

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