I'm a Principal Staff Scientist in the ACS (Advanced Camera for Surveys) Group in the Instruments Division
at the Space Telescope Science Institute
(STScI)
located in Baltimore, MD. The STScI is operated by
AURA for
NASA and is a multimission operations and research center
whose primary mission originally involved supporting science
with the Hubble Space
Telescope which is still operating and producing forefront science.
STScI is also the science and operations center for the larger infrared
successor to HST's UV/Optical/Infrared legacy, the
James Webb Space Telescope (JWST), and more here,
which was launched on 25 December, 2021. In addition to that, STScI is to be the operations center and one of the partners in a new mission to fly an exciting new HST-sized (in terms of the primary mirror diameter) infrared survey telescope now in development, the
Nancy Grace Roman Space Telescope, with launch at present set to a nominal date of late August or early September 2026. It is exciting because it is designed to have the same resolution as Hubble's newest infrared camera WFC3/IR but with ~200 times the area imaged on the sky with each image taken, so it will be a true survey telescope and a real discovery machine which will identify targets for further study with larger telescopes in the infrared and other wavelengths.
Since July 1985, I have worked on a variety of tasks at STScI, including:
Image processing and catalog generation/object classification and calibration
for the original Hubble Guide Star Catalog and the Digitized Sky Survey (the
original Archive at STScI)
Proposal development and TAC and peer review support
Observer support
Phase II observing program design/development and implementation
Designing and writing the SM1 (1st Servicing Mission, in 1993) Early Release Observations (ERO) Phase II observing program on
distant galaxy cluster CL0939+4713 (Abell 851) for Alan Dressler et al. at the time of the initial "rescue/optical correction"
of Hubble. At the time, these observations were some of the deepest optical images ever taken of the night sky, and helped reveal
that, contrary to predictions, the "repaired" HST with its new WFPC2 camera's corrective optics was a superb tool for the study
of the morphologies of distant galaxies. These observations helped inspire the idea of the Hubble Deep Field and all subsequent
deep and wide survey fields observed by HST.
Helping develop the original Director's Discretionary Time community programs HDF-N and HDF-S programs as member of the original HDF-N and later HDF-S Working Groups. Also did WFPC2 data processing
for HDF-N and HDF-S flanking fields, including drizzling all of HDF-S WFPC2 flanking fields. First author for large HDF-S flanking
fields data paper. (Many more flanking fields than for HDF-N, and in 3 imaging instruments: WFPC2, STIS, and NICMOS. I am very
grateful to all my many colleagues who did much work on that large paper, especially including Ed Smith, Harry Ferguson, and Richard Hook.)
Helping design the Director's Discretionary Time community Hubble ACS Ultra-Deep Field as an original member of the HUDF Working Group, and its parallel ultra-deep fields in WFPC2
(deepest UV images ever at the time) and NICMOS (deepest near-IR images ever at the time) with Massimo Stiavelli. Later, post-2004, while in INS, was an early Working Group Member and co-I on and helped to initially define the Hubble Frontier Fields DD program and later took part in the HFF data group.
Taking part as co-I in design and development of GOODS, HUDF05, and CANDELS surveys
Panel Chair for 1 E/PO NASA peer review panel and panel member for 2 others, at STScI, at NASA HQ, and remotely.
Testing JWST Design Reference Mission observing programs of several types, especially Deep Fields DRM observing programs, with
Massimo Stiavelli and others, modifying as needed for testing purposes.
Since switching to INS (the Instruments Division at STScI) in 2004, I have worked on a variety of instrument-related tasks, including:
Creation and delivery of ACS calibration reference files to CDBS; former lead for ACS CDBS deliveries;
former lead ACS partner for automated population of ACS CDBS reference file web pages;
creation, testing, and delivery of first post-SM4 ACS/WFC biases and darks, with Max Mutchler
ACS and WFPC2 calibration in general, and former lead partner for ACS in the
original automated ACS superbias and superdark calibration pipeline (with Mike Swam,
Max Mutchler, and Marco Sirianni).
Worked with CDBS staff to automate population of ACS reference file web pages.
Helped verify Boomerang Nebula as good target for ACS polarimetry calibration program; helped design/create polarimetry calibration observing program which also became a Hubble Heritage image release.
Calculated new BOP limits for ACS/SBC, plotting IUE spectra to verify stellar type, finding a typo of spectral type for one star in original ~1945 Keenan paper in the process.
Created, tested, and delivered new heavily modified/rearranged MDRIZTAB, new CCDTABs, SPOTTABs, and some other calibration files for ACS.
Former OPUS pipeline regression tester for ACS
Served as chief investigator of failed observations for ACS.
Former ACS+WFPC2 Help Desk Lead
Former ACS webmaster
WFC3 Thermal Vacuum testing for SM4 at NASA's GSFC
ACS replacement electronics testing for SM4 at NASA's GSFC
Astronaut EVA support on console during SM4 at NASA's GSFC for SM4 astronaut repair of ACS
Testing, re-commissioning, and early science release observations of ACS post-SM4
(I suggested the ACS SM4 ERO target galaxy cluster Abell 370...)
I am particularly interested in and involved in calibration studies of CTE
(Charge Transfer Efficiency) in on-orbit CCD detectors, especially for extragalactic
extended sources in WFPC2 and ACS data.
JWST NIRCAM thermal vacuum testing in Palo Alto, CA as part of the Extended NIRCAM Team has also taken some of my time.
I have also been a long-time user and tester of drizzling software (since original
versions in the mid-1990s) for HST imaging and continued in this role with the new AstroDrizzle
software and related software, such as TweakReg, and the associated use of SourceExtractor software.
Editor-in-Chief of ACS Data Handbook (2016-2022), including conversion from IRAF/PyRAF to Python etc.; Assistant Editor (2023)
Co-Editor of most recent HST Data Handbook 5-chapter Introduction for all HST instruments (2019), including conversion from IRAF/PyRAF to Python, etc.
I am currently the INS Phase II User Support Technical Lead, coordinating the INS User Support observing program
review tools requirements and process for all of the INS Science Instrument Groups, working with OED
programming staff to develop and implement new web-based tools for this process, plus documenting the
procedures and conducting the training for new Contact Scientists and Instrument Scientist observing
program reviewers who review GO, GTO, and calibration etc. observing programs. I also help advise and consult on plans for JWST required reviews of ERS and Cycle 1 GTO and GO programs.
Here are some of my various research projects in which I am or have been involved including the original Guide Star Catalog, and other projects, as author, observer, and/or co-Investigator or Principle Investigator:
Nancy Grace Roman Space Telescope
(NGRST 2001): Roman eXtreme Deep Field (RXDF): Transformative Science at Roman's Limit
(NGRST 19067): A Census of Black Hole Evolution Using High-Ionization Emission Lines
James Webb Space Telescope
(JWST 9493): SN Eos: A Multiply-Imaged, 30x Magnified SN Near the Epoch of Reionization
(JWST 9478): SN Ares: A Strongly Lensed, High-z CCSN with Remarkable Time Delays
(JWST 8559): SPAM: Star-formation from Photometry through the Addition of Medium-bands
(JWST 8410): A Census of Galaxy Kinematics and Outflows to z ~ 7
(JWST 6882): VENUS: Vast Exploration for Nascent Unexplored Sources
(JWST 6368): The CANDELS-Area Prism Epoch of Reionization Survey (CAPERS)
(JWST 5507): Deep Spectroscopy of Galaxies at z=4-14: Uncovering Drivers of Early Galaxy Formation and Black Hole Growth
(JWST 5407): MEOW: The MIRI Early Obscured-AGN Wide Survey
(JWST 5398): POPPIES: The Public Observation Pure Parallel Infrared Emission-Line Survey
(JWST 4291): Galaxy angular momentum alignment with filaments at z ~ 3: The effect of large scale structure on galaxies
(JWST 3305): Analyzing Giant Clumps in JWST Images of Star-Forming Galaxies to Constrain Feedback
(JWST 2750): Spectroscopic follow-up of ultra-high-z candidates in CEERS: Characterizing true z > 12 galaxies and z~4-7 interlopers in preparation for JWST Cycle 2
(JWST 2123): JWST Spectroscopic Pathfinder, a large program to test innovative ways of doing spectroscopic observations of the internal kinematics of some distant, early galaxies in the Hubble Ultra-Deep Field region.
(JWST 1837): PRIMER: A large JWST imaging survey program to observe two of our HST CANDELS fields with the MIRI and NIRCAM instruments on JWST.
(JWST 1721): An Archival Study of the Interstellar Medium in some of our JWST CEERS ERS galaxies...
(JWST 1345): CEERS: A JWST Early Release Science (ERS) observing program on distant galaxies in the early universe. I am a listed "science collaborator" on this new program which is to be observed in the early days of JWST operations, as a guide to others in the community, helping show what science can be done with JWST studies of distant galaxies, and how, etc.
Hubble Space Telescope (Many more observing and archival programs...)
(HST): Hubble Deep Fields-North and South, GOODS, Hubble Ultra-Deep Field, HUDF0
CANDELS, the Hubble Frontier Fields Massive Galaxy Clusters Lensing and "Blank" Extragalactic Surveys, and UV-CANDELS; performed original preliminary feasibility and design studies for HDF-N, HDF-S, and GOODS, in addition to SM1 ERO CL0939+4713 (Abell 851).
(HST): Distant Galaxy Clusters and Gravitational Lensing, Hubble Frontier Fields Galaxy Clusters and Lensing Survey; member of original STScI study and program definition/design team.
(HST): Lockman Hole HST imaging
(HST, NOT-La Palma): HST WFPC2 and NICMOS snapshots of ULIRGs and Nordic Optical Telescope (La Palma) observations of LIRGs (VLIRGs)
(CTIO, KPNO, HST): Polar Ring Galaxies and Collisional Ring Galaxies including original HST Cartwheel Galaxy observations; Galaxy interactions and mergers
(HST): Globular Cluster Populations in galaxies
(HST): ULX and comet-like gas clouds in the Cartwheel Galaxy
(HST): Hoag's Object Hubble Heritage imaging - served as the scientist/observer for this at request of Hubble Heritage Team.
(HST): High-z Supernovae
(HST): Gamma Ray Bursts
VLA and NVO
(VLA): VLA observations of Steep-Spectrum Radio Sources (PI) - VLA snapshot program of ~70+ galaxies with co-I Ken Chambers
(VLA radio, UK Schmidt optical, various X-ray): Funded Multiwavelength Virtual Observatory investigations of Radio Galaxies (PI) -
reduced data (HI maps produced by Neal Miller's pipeline) delivered to MAST as HLSP; with Neal Miller & others
Some other relevant experience over the years...:
In addition to Hubble, I have also done some work on testing James Webb
Space Telescope Design Reference Mission proposals (especially the
"Deep Fields" ones), and in addition to being a Hubble observer, I have
also used a variety of optical and radio telescopes in the US and abroad,
including observations at CTIO in Chile and La Palma in the Canary Islands
and at the VLA, as well as being a visiting researcher at the IAC on Tenerife,
and have also visited the Keck, Subaru, Gemini, and CFHT, etc. telescopes on
Mauna Kea in Hawai'i, and have been a part of teams getting data from the VLT,
Keck, Subaru, and others.
You can find more about all of this at my home page.