JWST's PEARLS

Welcome to the public website for the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (“PEARLS”) project!

The main goal of PEARLS is to study the epoch of galaxy assembly, AGN growth, and First Light using the James Webb Space Telescope (JWST) . This 110 hour GTO program  (#1176 and 2738) is lead by JWST Interdisciplinary Scientist Rogier Windhorst, from Arizona State University, in collaboration with a team of astronomers from around the world.

PEARLS uses NIRCam to survey three prime extragalactic survey areas including two at the North Ecliptic Pole (NEP), seven gravitationally lensing clusters, two high redshift proto-clusters, and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. Three fields, JWST NEP Time-Domain Field (TDF), the IRAC Dark Field (IDF), and two lensing clusters, will be observed in up to four epochs over a year, to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. We designed PEARLS to be of lasting benefit to the community.

Full observing details for the programs can be found at Program Information: #1176 and Program Information: #2738.

Recent Highlights

NASA’s Webb, Hubble Combine to Create Most Colorful View of Universe


NASA’s James Webb Space Telescope and Hubble Space Telescope have united to study an expansive galaxy cluster known as MACS0416. The resulting panchromatic image combines visible and infrared light to assemble one of the most comprehensive views of the universe ever taken. Located about 4.3 billion light-years from Earth, MACS0416 is a pair of colliding galaxy clusters that will eventually combine to form an even bigger cluster.

The image reveals a wealth of details that are only possible to capture by combining the power of both space telescopes. It includes a bounty of galaxies outside the cluster and a sprinkling of sources that vary over time, likely due to gravitational lensing – the distortion and amplification of light from distant background sources.

This cluster was the first of a set of unprecedented, super-deep views of the universe from an ambitious, collaborative Hubble program called the Frontier Fields, inaugurated in 2014. Hubble pioneered the search for some of the intrinsically faintest and youngest galaxies ever detected. Webb’s infrared view significantly bolsters this deep look by going even farther into the early universe with its infrared vision.

“We are building on Hubble’s legacy by pushing to greater distances and fainter objects,” said Rogier Windhorst of Arizona State University, principal investigator of the PEARLS program (Prime Extragalactic Areas for Reionization and Lensing Science), which took the Webb observations.

For more details, see the Nov 9 2023 NASA Webb press release!

This is based on our articles

Webb Spotlights Gravitational Arcs in ‘El Gordo’ Galaxy Cluster


A new image of the galaxy cluster known as “El Gordo” is revealing distant and dusty objects never seen before, and providing a bounty of fresh science. The infrared image, taken by NASA’s James Webb Space Telescope, displays a variety of unusual, distorted background galaxies that were only hinted at in previous Hubble Space Telescope images. El Gordo is a cluster of hundreds of galaxies that existed when the universe was 6.2 billion years old, making it a “cosmic teenager.” It’s the most massive cluster known to exist at that time. (“El Gordo” is Spanish for the “Fat One.”)

In our El Gordo images we have studied galaxies such as “El Anzuelo” (The Fishhook), “La Flaca” (the Thin One), a single red giant star nicknamed Quyllur, and many ultra-diffuse galaxies. For more details, see the Aug 2 2023 NASA Webb, ESA Webb, ASU, UofA and Chandra press releases!

This is based on our articles

The public data and mosaics for El Gordo can be found on our Data Products page. 

SN H0pe: a triply-detected SN Ia in the central region of galaxy cluster G165

As detailed in AstroNote 2023-96 (April 21, 2023; Frye et al.), a  new transient was discovered in JWST NIRCam exposures of the massive galaxy cluster PLCK G165.7+67.0 (G165) taken as part of the PEARLS program on UT 2023 March 30.  The source was not detected in earlier deep HST WFC3/IR images. 

The transient is associated with a galaxy host at z ~ 1.8 estimated by its NIRCam-based photometric redshift and by a lens model prediction (Frye et al. 2019; Pascale et al. 2022).  This single transient is detected in three different locations (a, b, and c, ordered from North to South) as a result of strong lensing by the foreground galaxy cluster G165.  Our lens model predicts that light of the transient arrived first in image "a", followed by "c", and then "b".  This transient, nicknamed "SN H0pe" by the team, is a probable supernova of which the type is not yet established via spectroscopy, but is likely  to be a SN Ia based on the redshift and intrinsic brightness (after correcting for the magnification due to gravitational lensing) and the inferred age of the host galaxy.  Follow-up observations, including spectroscopy, have been scheduled with JWST (DD-4446; PI: B. Frye). 

Webb Glimpses Field of Extragalactic Pearls Studded with Galactic Diamonds

NASA's JWST has captured one of the first medium-deep wide-field images of the cosmos, featuring a region of the sky near the North Ecliptic Pole. “I was blown away by the first PEARLS images,” said Rolf Jansen, Research Scientist at ASU and a PEARLS co-investigator. “Little did I know, when I selected this field, that it would yield such a treasure trove of distant galaxies, and that we would get direct clues about the processes by which galaxies assemble and grow. I can see streams, tails, shells, and halos of stars in their outskirts, the leftovers of their building blocks.” See the Dec 14 2022 NASA Webb blog, ESA Webb blog, ASU News press release, and our team blog .

This is based on our article "JWST's PEARLS: Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results", by  Rogier Windhorst & the PEARLS team. Published in (the Jan 2023 issue of) The Astronomical  Journal, Vol. 165, 13 [preprint].

The public data and mosaics for the first of four ``spokes'' within the JWST  NEP Time Domain Field can be found on our Data Products page.  Once completed, the PEARLS program will image a 4 times larger area within this NEP field, and provide spectroscopy over part of that area.

These and other versions  of these images are available from http://lambda.la.asu.edu/jwst/pr22/ 

Webb, Hubble Team Up to Trace Interstellar Dust Within a Galactic Pair

We got more than we bargained for by combining data from NASA’s James Webb Space Telescope and NASA’s Hubble Space Telescope! Webb’s new data allowed us to trace the light that was emitted by the bright white elliptical galaxy, through the winding spiral galaxy – and identify the effects of interstellar dust in the spiral galaxy. This image of galaxy pair VV 191 includes near-infrared light from Webb, and ultraviolet and visible light from Hubble. See our press release on NASA's JWST blog here!

This is based on our article "Webb's PEARLS: dust attenuation and gravitational lensing in the backlit-galaxy system VV 191", by Bill Keel & the PEARLS team, accepted for publication in ApJ and available at this ADS Link.

For details on our papers, see Papers.

A full list of PEARLS team papers can be found in this ADS library. 

PEARLS Targets

Galaxy Cluster Lenses:

JWST GTO_ERS cluster lensing observations.pptx (Powerpoint)

Backlit Galaxy:

Blank Fields:

z > 1 Galaxy Clusters / Protoclusters

z=6 Quasars:

Team Members

Core team (PIs, CoIs and 'Builders'):
Rogier Windhorst, Seth Cohen, Rolf Jansen, Jake Summers, Jordan D'Silva,  Scott Tompkins, Christopher Conselice, Simon Driver, Haojing Yan, Dan Coe, Brenda Frye, Norman Grogin, Anton Koekemoer, Madeline Marshall, Mario Nonino, Rafael Ortiz III, Nor Pirzkal, Aaron Robotham, Russell E Ryan Jr, and Christopher Willmer

Current members (In alphabetical order):
Nathan J Adams, Duncan Austin, John F. Beacom, Rachana A. Bhatawdekar, Larry D. Bradley, Cheng Cheng, Liang Dai, Jose M Diego, Hervé Dole, Kenneth J Duncan, Giovanni G. Fazio, Giovanni Ferrami, Leonardo Ferreira, Steven L. Finkelstein, Lukas J. Furtak, Hansung Gim, Kevin C. Harrington, Nimish P. Hathi, Jia-Sheng Huang, Minhee Hyun, Bhavin A Joshi, Patrick S. Kamieneski, William C. Keel, Patrick Kelly, Rebecca L Larson, Juno J. Li, Zhiyuan Ma, Peter Maksym, Giorgio Manzoni, Ashish Kumar Meena, Rosalia D O'Brien, Justin D.R. Pierel, Maria del Carmen Polletta, Huub Rottgering, Ian Smail, Amber N Straughn, Louis-Gregory Strolger, James A. A. Trussler, Lifan Wang, Brian Welch, Stephen M. Wilkins, Steven P. Willner, J. Stuart B. Wyithe, Jiawen Yang, Min Yun, Erik Zackrisson, Jiashuo Zhang, and Adi Zitrin

In Memoriam

We dedicate our PEARLS papers to the memory of our dear colleague Mario Nonino (26/11/1959 - 21/07/2023). Mario was an astronomer at the INAF in Trieste and was a key contributor to the PEARLS team, in particular with a significant experience in carrying out and analyzing galaxy surveys. Mario was a gifted and dedicated scientist, and a generous person. Working alongside him has been a pleasure and a privilege, and he will be dearly missed.