1.5 TB of James Webb Space Telescope data just hit the internet

Online catalog gives open science access to data from early universe

A NASA-backed project using observations from the James Webb Space Telescope (JWST) has released more than 1.5 TB of data for open science, offering the largest view deep into the universe available to date.

The Cosmic Evolution Survey (COSMOS), a joint project from the University of California, Santa Barbara and Rochester Institute of Technology, has launched a searchable dataset for budding astrophysics enthusiasts worldwide.

As well as a catalog of galaxies, the dataset includes an interactive viewer that users can search for images of specific objects or click them to view their properties, covering approximately 0.54 square degrees of sky with the Near Infrared Camera (NIRCam) and a 0.2 square degree area with the Mid Infrared Instrument (MIRI).

Although the raw data was already publicly available to the science community, the aim of the COSMOS-Web project was to make it more usable for other scientists.

"Those raw data are public, but it takes a lot of work to do all of the calibrations and correct for all of the different types of artifacts that you can get in the imaging... such as the background light, so that you end up with a final image that's clean and usable for science," said Jeyhan Kartaltepe, associate professor at Rochester Institute of Technology and lead researcher of COSMOS-Web.

Artifacts are elements of the images that don't come from an astrophysical source, such as "snowball" ghost images caused by light from bright stars bouncing around the JWST.

One of about 100 projects each year to gain time on the $10 billion JWST, COSMOS-Web aims to observe very high redshift galaxies in a relatively large region of sky.

"So many surveys observe a very small area or an intermediate area, but there's a trade-off: you can either look in one spot and stare for a really long time and see the deepest things possible, or you can try to cover a large area. COSMOS doesn't observe quite as deeply to see the faintest things possible, but it does cover a large area, which lets us cover a very large cosmic volume. We still detect very high redshift galaxies, but we're able – because of the size of the imaging – to measure the scale of structures at high redshift," Kartaltepe said.

Light from distant galaxies and stars shifts to the red end of the spectrum because they are moving away from the Earth. "A higher redshift means they're moving away from us the fastest, which means they're the furthest away; and we are seeing them as they were in the very, very early universe," Kartaltepe said.

The project relied on French supercomputer CANDIDE at the Institut d'Astrophysique de Paris to combine images into the single mosaic, and then actually run the catalog, which makes around 1.5 TB of data available.

The COSMOS project, which began in 2007, will use the catalog to continue its mission to understand a dramatic change in state in the early universe, about 200 million years after the Big Bang, or about 13.5 billion years ago. During this period, the early universe transitioned from being filled with neutral hydrogen – which blocked light – to ionized gas that allowed light to travel freely. This process, known as reionization, marked the moment the universe became transparent to photons.

"We want to understand that structure and how where galaxies are relative to that structure has affected the process of reionization in the early universe," Kartaltepe said.

But COSMOS-Web is open to other projects from around the world, she said. "Our person-power is limited, so there's only so much time in the day. Certainly, having the broader community dig into the data will be fantastic… and people will have ideas that we don't have and have completely different science projects that they want to do."

NASA has funded the project so far through its Space Telescope Science Institute project, although that is set to come to an end. COSMOS has also applied for funding in Europe. ®