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Howard Isaacson

Academic Researcher, Specialist Series

213 Campbell Hall



Home Institution:

UC Berkeley

Academic Researcher, Specialist


Exoplanets, Blackholes, Life in the Universe

I currently hold a research position split between two research groups: The Search for Extra-Terrestrial Intelligence with Breakthrough Listen, and the California Planet Search.

I am interested in the study of planets that orbit around stars other than our sun,  exoplanets!  With the California Planet Search team, I work to characterize the size, mass, density and composition of the exoplanets discovered that are the most like the Earth. Our team accomplishes this by combining photometric measurements of stars’ brightness collected by Kepler with radial velocity measurements of individual stars collected with the Keck Telescope and HIRES spectrometer located on the top of Mauna Kea on the Big Island of Hawai’i. The overarching goal of my research is to try to find planets that most resemble the Earth in their size, composition, and distance from their host star. I have worked with NASA’s Kepler Spacecraft team, as well as the K2 and TESS exoplanet missions.

I am keenly interested in stellar activity, specifically measured by the spectral features produced in the outer stellar atmosphere, called a star’s chromosphere. By studying these features, we can improve our radial velocity measurement precision, and uncover patterns in other stars that are similar to the different stellar activity cycles that we observe in the sun. Stellar activity on timescales of days, months, and years can be used to determine the rotation period, and timescale of stellar activity cycles.

My collaborators in the California Planet Search include Andrew Howard (CalTech), Fei Dai (CalTech), Erik Petigura (UCLA), Lauren Weiss (Notre Dame),  and BJ Fulton (CalTech/NExSci) as well as graduates , Sarah Blunt (CalTech), Ryan Rubenzahl (Caltech).  Our new collaboration to measure planet masses around host-stars identified by NASA’s TESS mission (The TESS Keck Survey or TKS)  includes collaborators across the University of California, the University of Hawaii and Kansas University.

Past collaborators include Lea Hirsch (now at University of Toronto, Mississsauga), former graduate students Evan Sinukoff, Molly Kosiarek (UCSC), Lee Rosenthal (CalTech),  Aida Behmard (CalTech), among many many others.


In my work with the Berkeley SETI Research center and Breakthrough Listen and the Search for Extraterrestrial Intelligence(SETI) I work with data from the Automated Planet Finder (APF) and the Levy Spectrometer from Lick Observatory. We search the high resolution spectra for laser emission lines that could originate from beyond the Earth. Such laser signals are very narrow in wavelength, allowing for detection against the broadband energy emitted by the observed stars. Breakthrough Listen has an extensive undergraduate research program taking place both in the summer and during UCB semester.

My collaborators at BSRC include Andrew Siemion, Vishal Gajjar, Matt Lebofsky, Steve Croft, Julia DeMarines, Dave MacMahon, Daniel Czech, Dave DeBoer, Brian Lacki, Danny Price (Curtain University in Australia), Sofia Sheikh* (SETI Institute), John Hoang(UCB/UCSC) and Bryan Brzycki*. Current students include Anna Zuckerman* (University of Colorado, GS), Zoe Ko* (UCB, UG).

*Indicates former Breakthrough Listen Summer Interns.


I am currently pursuing my PhD at the University of Southern Queensland, Australia in collaboration with Stephen Kane (UC Riverside) and Brad Carter (USQ). That work is focused on exoplanets and stellar activity.


I was born and raised under the dark skies of Butte Montana. My interest in Astronomy began when I was shown Saturn through a telescope by Lloyd Magnuson, my 8th grade science teacher. After meandering through interest in different sciences, I landed at the Physics and Astronomy Department at San Francisco State University in San Francisco, California. There I collected both an undergraduate and Master’s Degree working with Dr. Debra Fischer, focusing my research on exoplanet detection and stellar activity metrics. After graduation, I began with working at UC Berkeley on the Kepler Space Mission operated out of NASA Ames Research Center, where I continue the search for life in the cosmos. I live with my wife Missy, and our dog Ripley, in the Mission District of San Francisco.