About

Bruce Alan Macintosh serves as the Director of the University of California Observatories (UCO), a multi-campus research unit that operates and supports key telescope facilities including Lick Observatory, the W.M. Keck Observatory, and the proposed Thirty Meter Telescope. In this role, he supervises the observatories and instrumentation labs at UCSC and other campuses, overseeing research and educational activities related to these facilities. His personal research focuses on the study of extrasolar planets, particularly through direct imaging techniques that involve blocking, suppressing, and subtracting the light of bright parent stars to observe planets that are hundreds of thousands of times fainter. Dr. Macintosh co-led the team that imaged the first extrasolar planets and was the Principal Investigator of the Gemini Planet Imager, an advanced adaptive optics planet-finder for the Gemini South telescope. He has been actively involved in astrophysics science policy, including serving on the Steering Committee of the 2020 Decadal Survey of Astronomy and Astrophysics. Additionally, Dr. Macintosh is committed to making astronomy and physics more inclusive, diverse, and supportive.

Research topics

• Physics
• Optics
• Astrophysics
• Astronomy
• Astrobiology
• Computer Science
• Remote sensing
• Operating system
• Geology
• Aerospace engineering
• Engineering

Selected publications

• Progress toward a demonstration of high contrast imaging at ultraviolet wavelengths

  ArXiv.org · 2025-09-11

  preprintOpen access

  NASA's Habitable Worlds Observatory (HWO) aims to achieve starlight suppression to the $10^{-10}$ level for the detection and spectral characterization of Earth-like exoplanets. Broadband ozone absorption features are key biosignatures that appear in the 200-400nm near-ultraviolet (UV) regime. Extending coronagraphy from visible wavelengths to the UV, however, brings with it a number of challenges, including tighter requirements on wavefront sensing and control, optical surface quality, scattered light, and polarization aberrations, among other things. We aim to partially quantify and address these challenges with a combination of modeling, high-resolution metrology to the scales required for UV coronagraphy, and ultimately a demonstration of UV coronagraphy on the Space Coronagraph Optical Bench (SCoOB) vacuum testbed. In these proceedings, we provide a status update on our modeling and contrast budgeting efforts, characterization efforts to understand performance limitations set by key optical components, and our plans to move toward a demonstration of UV coronagraphy.

  PublisherOA PDFDOI

• Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet system

  Nature · 2025-06-10 · 16 citations

  articleOpen access
  PublisherOA PDFDOI

• Cross-Model Validation of Coronagraphic Exposure Time Calculators for the Habitable Worlds Observatory: A Report from the Exoplanet Science Yield sub-Working Group

  ArXiv.org · 2025-02-25

  preprintOpen access

  Estimating the exoplanet scientific productivity of the Habitable Worlds Observatory requires estimating science exposure times. From exoplanet yields to spectral retrievals, exposure times are at the heart of our understanding of the capabilities of this future mission. As such, ensuring accuracy and consistency between different exposure time calculators (ETCs) is critical. We summarize the efforts of the Exoplanet Science Yield sub-Working Group's ETC Calibration Task Group, which conducted a calibration study from March 4 to June 30 of 2024. We compare three commonly-used coronagraphic exposure time calculators. We find that the ETCs use a broad variety of differing methods, assumptions, and inputs that produce variation in the final exposure times at the ~60% level. The causes for the disagreement have largely been identified, flagged for further development efforts, and in some cases retired since the conclusion of this effort. We expect that addressing the flagged efforts will bring the ETCs to within better than ~30% agreement.

  PublisherOA PDFDOI

• Developments on LLNL’s high contrast testbed and Lick/ShaneAO

  2025-09-18

  articleSenior author

  LLNL has recently setup a High Contrast Testbed (HCT) for AO and exoplanet imaging technology development. We present the various HCT technologies currently under development, including (1) a Wynne corrector, (2) multi-wavefront sensor (WFS) single conjugate AO (SCAO) control. We present HCT testing results of a first Wynne corrector prototype with a self-coherent camera. We present updates on development efforts to design and apply multi-WFS SCAO control to our HCT setup. We also present ongoing HCT deformable mirror and WFS upgrades. Lastly, we present developments for REDWOODS, a project to deploy many of these technologies on-sky on a sub-bench of the Shane AO system at Lick Observatory.

  PublisherDOI

• Experimental validation of photonic lantern imaging and wavefront sensing performance

  2025-09-18 · 2 citations

  article

  Photonic lanterns (PLs) are fiber-based waveguides that are capable of focal-plane wavefront sensing while simultaneously directing light to downstream science instruments. The optimal choice of wavefront reconstruction algorithm has yet to be determined and likely depends on the particular observing scenario under consideration. Previous work in simulation suggests that PLs can be used for nonlinear wavefront sensing for several applications, including sensing the low-wind effect and correcting large-amplitude aberrations. We present the design of muirSEAL (miniature IR SEAL), a testbed designed to test PL wavefront reconstruction over Zernike modes and segmented-mirror offsets. We demonstrate throughput and linear wavefront reconstruction at multiple f-numbers. We further present initial laboratory imaging of a new photonic lantern fabricated at Lawrence Livermore National Laboratory.

  PublisherDOI

• Ground-based Mid-IR Direct Imaging: The Origin of the Thermal Background on the Keck II Telescope and Correcting Instrumental Systematics

  Publications of the Astronomical Society of the Pacific · 2025-09-01

  articleOpen accessSenior author

  Abstract Mid-IR wavelengths are of particular interest to exoplanet science due to the fact they can extend the searchable parameter space to planets that are older and/or colder. However, a significant source of uncertainty at mid-IR wavelengths on ground-based telescopes is the thermal background. This background comes from blackbody radiation in the atmosphere and telescope and is therefore dependent on instrument design and atmospheric conditions. When performing imaging observations, this background manifests as a slowly varying, inhomogeneous signal throughout the image, underlying our data. Photometry at mid-IR can greatly constrain atmospheric models but existing data are usually scarce or have significant error bars due to the difficulty of subtracting the background. Using M -band direct imaging observing sequences on NIRC2, we evaluate the thermal background of the Keck II telescope and attempt to subtract the background in a more comprehensive way. For our primary science target, the forming protoplanet AB Aur b, we present a contrast upper limit of 2 × 10 −4 in M -band and address the limiting factors in our observation due to the thermal background. We determine that the origin of the systematic components of the thermal background comes from the K-mirror and find that the thermal background is also strongly influenced by emission from the secondary spiders on Keck II.

  PublisherDOI

• Performance predictions and contrast limits for an ultraviolet high-contrast imaging testbed

  Journal of Astronomical Telescopes Instruments and Systems · 2025-05-14 · 1 citations

  articleOpen access

  NASA’s Habitable Worlds Observatory (HWO) concept and the 2020 Decadal Survey’s recommendation to develop a large space telescope to “detect and characterize Earth-like extrasolar planets” require new starlight suppression technologies to probe a variety of biomarkers across multiple wavelengths. Broadband absorption due to ozone dominates Earth’s spectrum in the mid-ultraviolet (200 to 300 nm) and can be detected with low spectral resolution. Despite the high value of direct ultraviolet (UV) exoplanet observations, high-contrast coronagraph demonstrations have yet to be performed in the UV. Typical coronagraph leakage sources such as wavefront error, surface scatter, polarization aberrations, and coronagraph mask quality all become more significant in the UV and threaten the viability of HWO to produce meaningful science in this regime. As a first step toward a demonstration of UV coronagraphy in a laboratory environment, we develop an end-to-end model to produce performance predictions and a contrast budget for a vacuum testbed operating at wavelengths from 200 to 400 nm. At 300 nm, our model predicts testbed performance of ∼3×10−9 contrast in a narrow 2% bandwidth and ⪅10−8 in a 5% bandwidth, dominated primarily by the chromatic residuals from surface errors on optics that are not conjugate to the pupil.

  PublisherOA PDFDOI

• Characterization of the Host Binary of the Directly Imaged Exoplanet HD 143811 AB b

  ArXiv.org · 2025-09-08

  preprintOpen access

  HD~143811~AB is the host star to the directly imaged planet HD~143811~AB~b, which was recently discovered using data from the Gemini Planet Imager and Keck NIRC2. A member of the Sco-Cen star-forming region with an age of $13 \pm 4$ Myr, HD~143811~AB is somewhat rare among hosts of directly imaged planets as it is a close stellar binary, with an $\sim$18 day period. Accurate values for the orbital and stellar parameters of this binary are needed to understand the formation and evolutionary history of the planet in orbit. We utilize archival high-resolution spectroscopy from FEROS on the MPG/ESO 2.2-meter telescope to fit the orbit of the binary, and combine with unresolved photometry to derive the basic stellar properties of the system. From the orbit, we derive precise values of orbital period of $18.59098 \pm 0.00007$ days, and mass ratio of $0.885 \pm 0.003$. When combined with stellar evolutionary models, we find masses of both components of $M_A = 1.30^{+0.03}_{-0.05}$ M$_\odot$ and $M_B = 1.15^{+0.03}_{-0.04}$ M$_\odot$. While the current data are consistent with the planet and stellar orbits being coplanar, the 3D orientations of both systems are currently poorly constrained, with additional observations required to more rigorously test for coplanarity.

  PublisherOA PDFDOI

• Characterization of the Host Binary of the Directly Imaged Exoplanet HD 143811 AB b

  The Astrophysical Journal Letters · 2025-12-11 · 1 citations

  articleOpen accessCorresponding

  Abstract HD 143811 AB is the host star to the directly imaged planet HD 143811 AB b, which was recently discovered using data from the Gemini Planet Imager and Keck NIRC2. A member of the Sco-Cen star-forming region with an age of 13 ± 4 Myr, HD 143811 AB is somewhat rare among hosts of directly imaged planets, as it is a close stellar binary, with an ∼18-day period. Accurate values for the orbital and stellar parameters of this binary are needed to understand the formation and evolutionary history of the planet in orbit. We utilize archival high-resolution spectroscopy from FEROS on the MPG/ESO 2.2 m telescope to fit the orbit of the binary, and we combine with unresolved photometry to derive the basic stellar properties of the system. From the orbit, we derive precise values of orbital period of 18.59090 ± 0.00007 days and mass ratio of 0.886 ± 0.003. When combined with stellar evolutionary models, we find masses of both components of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">A</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1.3</mml:mn> <mml:msubsup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.05</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi mathvariant="normal">B</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>1.1</mml:mn> <mml:msubsup> <mml:mn>5</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.04</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.03</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ . While the current data are consistent with the planet and stellar orbits being coplanar, the 3D orientations of both systems are currently poorly constrained, with additional observations required to more rigorously test for coplanarity.

  PublisherDOI

• The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. III. Aperture Masking Interferometric Observations of the Star HIP 65426 at 3.8 <i>μ</i>m

  The Astrophysical Journal Letters · 2025-04-09 · 3 citations

  articleOpen access

  Abstract We present aperture masking interferometry (AMI) observations of the star HIP 65426 at 3.8 μ m, as part of the JWST Direct Imaging Early Release Science program, obtained using the Near Infrared Imager and Slitless Spectrograph instrument. This mode provides access to very small inner working angles (even separations slightly below the Michelson limit of 0.5 λ / D for an interferometer), which are inaccessible with the classical inner working angles of the JWST coronagraphs. When combined with JWST’s unprecedented infrared sensitivity, this mode has the potential to probe a new portion of parameter space across a wide array of astronomical observations. Using this mode, we are able to achieve a 5 σ contrast of Δ m F380M ∼ 7.62 ± 0.13 mag relative to the host star at separations ​​​​​≳0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 07 , and the contrast deteriorates steeply at separations ≲0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 07. However, we detect no additional companions interior to the known companion HIP 65426b (at separation ∼0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 82 or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>8</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>31</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>108</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">au</mml:mi> </mml:math> ). Our observations thus rule out companions more massive than 10–12 M Jup at separations ∼10–20 au from HIP 65426, a region out of reach of ground- or space-based coronagraphic imaging. These observations confirm that the AMI mode on JWST is sensitive to planetary mass companions at close-in separations (≳0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mtext>″</mml:mtext> </mml:mrow> </mml:mover> </mml:math> 07), even for thousands of more distant stars at ∼100 pc, in addition to the stars in the nearby young moving groups and associations, as stated in previous works. This result will allow the planning and successful execution of future observations to probe the inner regions of nearby stellar systems, opening an essentially unexplored parameter space.

  PublisherDOI

Recent grants

• Collaborative Research: The Gemini Planet Imager Exoplanet Survey

  NSF · $830k · 2014–2019

Frequent coauthors

• Christian Marois

  477 shared

• E. Nielsen

  360 shared

• Gaspard Duchêne

  University of California, Berkeley

  340 shared

• Robert J. De Rosa

  University of California, Santa Barbara

  288 shared

• Jeffrey Chilcote

  267 shared

• Quinn Konopacky

  251 shared

• Paul Kalas

  249 shared

• Marshall D. Perrin

  Space Telescope Science Institute

  221 shared

Education

• PhD, Astronomy

  UCLA

  1994