Dr. Anton M. Koekemoer

Hubble Space Telescope /
Space Telescope Science Institute (STScI)
Baltimore, MD, USA

 

Professional Information

I am a research astrophysicist with the Hubble Space Telescope at the Space Telescope Science Institute (located in Baltimore, MD, USA), and I have held a research position here since late 1996. Previous experience and education include: At the Space Telescope Science Institute, for my scientific research I have mostly used the Hubble Space Telescope, and for some years I was the team lead in charge of one of the imaging cameras onboard Hubble (the 'NICMOS' Near-Infrared Camera and Multi-Object Spectrometer). More recently I have also been working on the James Webb Space Telescope (JWST, launched in December 2021), as well as the Nancy Grace Roman Space Telescope (a future space telescope with a field of view 100 times larger than Hubble), and the Hubble Legacy Data Archives. I also work on astrophysics research programs on my areas of interest which include the properties of distant galaxies and black holes, and their growth over cosmic time.

Research Interests

My scientific research interests are mostly in extragalactic astrophysics, including: I have also been in charge of creating all the Hubble science-level imaging mosaics, for my science work in several large projects:

 

Current research publications (1994 - 2025)

 

Ongoing large projects with JWST (2022-2025 onwards)

I am involved in several large projects with the James Webb Space Telescope, with expertise in the imaging observations for these projects and new scientific research results on the formation and cosmic growth of distant galaxies and black holes being discovered in these projects, including:
JWST-ERO: JWST Early Release Observations
CEERS: JWST Cosmic Evolution Early Release Science Survey
COSMOS-Web
PEARLS: JWST Prime Extragalactic Areas for Reionization and Lensing Science
PRIMER: Public Release Imaging for Extragalactic Research
NGDEEP: The Next Generation Deep Extragalactic Exploratory Public Survey

 

Projects with the Nancy Grace Roman Space Telescope

I have recently been working on ultra deep field concept studies for the new Nancy Grace Roman Space Telescope, scheduled for launch later this decade, which could image an area of the sky about 100 times larger than the Hubble Space Telescope. A few relevant links are here:

 

BUFFALO (Beyond Ultra-deep Frontier Fields And Legacy Observations) 2018-2021

I am in charge of the Hubble imaging for the BUFFALO project (Beyond Ultra-deep Frontier Fields And Legacy Observations), where I leed the Hubble Science Data team, with responsibility for all the calibration, processing, and production of final science-grade mosaic images of these fields, as well as their public distribution to the community.

The first Press release, which took place on 13 September 2018, presents the initial observations of the first cluster Abell 370., which acts as a gravitational `lens' to amplify the distant galaxies behind it, so the amplification provided by the cluster therefore helps to reveal galaxies that may be much fainter than those that had been previously discovered in the Ultra Deep Field, and thus probing galaxy evolution and cluster physics up to the distant universe.

 

Hubble Frontier Fields 2014-2017

I was in charge of the Hubble imaging for the Hubble Frontier Fields project, where I led the Science Data Products team, with responsibility for all the calibration, processing, and production of final science-grade mosaic images of these fields, as well as their public distribution to the community via our Archive Pages.

The first Press release, which took place on 7 January 2014, presents the initial data relase of the first epoch of the cluster Abell 2744. The cluster acts as a gravitational `lens' to amplify the distant galaxies behind it, and we are observing this field to very deep limits (about 28-29th magnitude AB), so the amplification provided by the cluster therefore helps to reveal galaxies that may be intrinsically fainter even than those that had been previously discovered in the Ultra Deep Field. A total of 6 clusters, each with an accompanying `parallel field', are being observed as part of this program across a wide range of filters with ACS (F435W, F606W, F814W) and also WFC3/IR (F105W, F125W, F140W, F160W), yielding a legacy set of multi-wavelength scientific products for probing galaxy evolution and cluster physics up to the distant universe.

 

Hubble Ultra Deep Field 2013

I was responsible for prodcing the combined imaging for the Hubble Ultra Deep Field 2014 project, where I created all the final images. This new image of the Hubble Ultra Deep Field was obtained in 12 different wavelength bands, ranging from the far-ultraviolet (150nm) to the infrared (1.6 microns), with the new ultraviolet data coming from proposals 10403 and 12534 (PI.: H. Teplitz), providing much wider wavelength coverage ("more colorful") imaging of the Ultra Deep Field than was ever possible before, which therefore gives much more detailed information about all the galaxies that we observe in it.

The Press release presents the various images and other details about the program, after the public data release took place in 2014.

 

Hubble Ultra Deep Field 2012

I was in charge of the imaging for the Hubble Ultra Deep Field 2012 project, where I led the observations and created all the final images. This new image of the Hubble Ultra Deep Field is the deepest ever image of the sky at these wavelengths. By combining new data obtained by the UDF12 Team (PI. R. Ellis) with previous data obtained by the UDF09 Team (PI.: G. illingworth) as well as other Hubble programs (The CANDELS team, PI.: S. Faber and H. Ferguson, and the Supernova team, PI.: A. Riess), these new data enable us to use Hubble to probe to deeper cosmic epochs, looking further back in time, than ever before.

The Press release presents the various images and other details about the program, after the public data release took place on 12 December 2012.

The overview reference papers for this survey are:

A. M. Koekemoer et al., 2013, Astrophysical Journal Supplement, 209, 3
R. S. Ellis et al., 2013, Astrophysical Journal Letters, 763, 7

 

Hubble Ultra Deep Field 2004

I was in charge of the imaging for the Hubble Space Telescope / Advanced Camera for Surveys (HST/ACS) original Hubble Ultra Deep Field (UDF) project in 2004, where my role was to calibrate, combine and analyse the 800 ACS/WFC exposures to produce a set of final, cleaned "drizzled" images in each of the four filters, providing the deepest view of the universe that had ever been obtained at that time, and revealing fainter galaxies at earlier cosmic epochs than had ever been observed before.

The Press release presents the various images and other details about the program, after the public data release took place on 9 March 2004.

 

CANDELS: Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey

I am responsible for all the Hubble imaging for the CANDELS project, where I led the calibration and processing, and created all the final mosaic images. This project is designed to document the first third of galactic evolution from between redshifts 1.5 and 8, via deep imaging of more than 250,000 galaxies with WFC3/IR and ACS, as well as discovering Type Ia supernovae beyond redshift 1.5 in order to establish their accuracy as standard candles for cosmology. The survey targets five premier multi-wavelength sky regions; each has multi-wavelength data from Spitzer and other facilities plus extensive spectroscopy of the brighter galaxies. The use of five widely separated fields mitigates cosmic variance and yields statistically robust and complete samples of galaxies to faint limitsout to redshift 8.

The first Press release presents initial discoveries from the program.

The overview reference papers for this survey are:

N. A. Grogin et al., 2011, Astrophysical Journal Supplement, 197, 35
A. M. Koekemoer et al., 2011, Astrophysical Journal Supplement, 197, 36

 

Hubble Wide Field Camera 3 / Early Release Science (WFC3 / ERS)

I was part of the team for the new Early Release Science Program obtained with the Hubble Space Telescope / Wide Field Camera 3 (HST/WFC3), which was installed on Hubble by the Astronauts during Servicing Mission 4 in May 2009. This program uses the new Wide Field Camera 3 to obtain extensive new, deep near-infrared data on the GOODS-South Field (part of the "Great Observatories Origins Deep Survey" / "GOODS" project).

The Press release presents the various images and other details about the program, after the public release took place on 5 January 2010.

 

The Hubble COSMOS Survey

I was also in charge of combining all the Hubble imaging data for the COSMOS project, which used 600 orbits of Hubble time to produce the largest single mosaic ever obtained with HST (about 2 square degrees, or about 10 times the area of the full moon, and covering about 2 million galaxies); my science interest in this project is to search for supermassive black holes in the very early universe.

The overview reference papers for the COSMOS HST data are:

A. M. Koekemoer et al., 2007, Astrophysical Journal Supplement, 172, 196
N. Scoville et al., 2007, Astrophysical Journal Supplement, 172, 38

 

"EXO's" - Extreme X-ray / Optical sources

This is a new class of galaxies which I discovered in 2004, that are well detected in deep X-ray studies with the Chandra and XMM telescopes, but completely undetected at optical wavelengths in deep observations with Hubble and large ground-based telescopes (VLT, Gemini, Subaru, Keck etc). They are detected at infrared wavelengths, particularly with Spitzer in the 3 - 8 micron and 24 micron wavelength bands.

The Press release presents the various images and other details about the program, after the public release took place on 1 June 2004.

The original discovery paper is:

A. M. Koekemoer et al., 2004, Astrophysical Journal Letters, 600, L123

 

"MultiDrizzle" - Software for Combining Hubble Imaging Data

I originally wrote and developed the MultiDrizzle software, which uses the "drizzle" software (Fruchter & Hook 2002) to perform automatic registration, cosmic ray rejection and combination of dithered HST images.

The original paper describing MultiDrizzle is:

A. M. Koekemoer, A. S. Fruchter, R. Hook, W. Hack, 2002 HST Calibration Workshop, 337

This also served as the foundation for the subsequent "AstroDrizzle" software, which is now implemented as a successor to it.

Some of my other related research webpages

  • Hubble Space Telescope staff webpage Anton Koekemoer
  • Linked-in member profile Anton Koekemoer Anton Koekemoer
  • IAU member webpage Anton Koekemoer
  • Google-Scholar page Anton Koekemoer
  • About.me page Anton Koekemoer
  • Scopus page Anton Koekemoer
  • OrcID web page Anton Koekemoer Anton Koekemoer
  • ResearcherID page Anton Koekemoer
  • Research.com page Anton Koekemoer
  • ResearchGate page Anton Koekemoer
  • Academia.edu page Anton Koekemoer

    • Other Astronomy Sites

    Astroweb [deprecated]:
  • CDS, [NRAO, STScI, MSSSO, ST-ECF, Villafranca, WWW Virtual Library]

    • Anton Koekemoer Anton Koekemoer Anton Koekemoer Anton Koekemoer Jochem Koekemoer Anton Koekemoer
    Disclaimer: Any views expressed on this webpage are strictly personal and are not intended in any way to necessarily represent those of, or be endorsed by, any other entity or organization.