I'm a postdoctoral research fellow at UC Berkeley's Department of Astronomy and Miller Institute. I'm interested in detecting exoplanets and characterizing their atmospheres using a wide range of techniques. Currently, I'm leading a demonstration of predictive wavefront control at W. M. Keck Observatory in order to push our sensitivity to extremely faint exoplanets located at small angular separations from their host stars. I also use GPI and SPHERE to hunt for polarized thermal emission from previously imaged planets — an as yet unexploited means of studying the clouds that shroud their atmospheres. I pursue my interests in space-based and collaborative exoplanet science as member of NASA's ExoPAG Executive Committee and the High Contrast Testbed Community Homepage.

Update: In January of 2020, I will be joining the UC Santa Cruz Department of Astronomy and Astrophysics as an assistant professor!


Predictive Wavefront Control Demo

Fewer than 20 of the 3000+ known exoplanets have been directly imaged, in part due to time lags between measuring and correcting for atmospheric turbulence in adaptive optics systems. A large body of theoretical work indicates that compensating for this time lag with predictive wavefront control has enormous potential to improve our planet detection limits. Supported by the Heising-Simons Foundation, I am collaborating with the W. M. Keck Observatory to demonstrate predictive wavefront control at the Keck II telescope by 2021.

Exoplanet Polarimetry in the Near-IR

Scattering by grains in the atmospheres of cloudy, self-luminous exoplanets induces the polarization of thermally emitted radiation in the near-infrared. Detecting these polarization signatures may shed light on the details of cloud physics that have proven challenging to constrain via the planets' spectra. In Jensen-Clem et al. 2016, I showed that such detections are feasible with the Gemini Planet Imager. Stay tuned for follow-up results!

Robo-AO Commissioning and Science

Robo-AO is a robotic laser guide star adaptive optics instrument on the Kitt Peak 2.1-m telescope. Observing every clear night through 2018, Robo-AO at Kitt Peak is the first dedicated adaptive optics observatory. Since commissioning in the winter of 2015, I’ve been developing imaging processing pipelines and characterizing the instrument’s performance. I’m also studying the origins of stellar angular momentum by resolving hundreds of Pleiades and Praesepe binaries with Robo-AO and relating their separations to K2’s photometrically determined rotation periods. See Jensen-Clem et al. 2018b for details!

Signal Detection Theory

As planning for the next generation of high contrast imaging instruments matures, it is imperative that the performance of different designs, post-processing algorithms, observing strategies, and survey results be compared in a statistically robust framework. In Jensen-Clem et al. 2018a, I proposed a new figure of merit, the performance map, that incorporates three fundamental concepts in signal detection theory: the true positive fraction, false positive fraction, and detection threshold.

CV and Publications

PhD Astrophysics, Caltech, 2017
MSc Astrophysics, Caltech, 2014
BS Physics, MIT, 2012

To download my full CV, click here.
For a complete list of publications, see NASA ADS here.

Selected Publications

Jensen-Clem, R.; Bond, C. B.; Cetre, S.; McEwen, E. et al. 2019, Proc. SPIE 11117, Techniques and Instrumentation for Detection of Exoplanets IX, 111170W, "Demonstrating Predictive Wavefront Control with the Keck II Near-Infrared Pyramid Wavefront Sensor"

Jensen-Clem, R.; Mawet, D.; Gomez Gonzalez, C. A.; Absil, O. et al. 2018, AJ, 155, 19, "A New Standard for Assessing the Performance of High Contrast Imaging Systems"

Jensen-Clem, R.; Duev, D.; Riddle, R.; Salama, M.; Baranec, C.; Law, N.; Kulkarni, S.; Ramprakash, A. N. 2018, AJ, 155, 32, "The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1 m Telescope"

Jensen-Clem, R.; Millar-Blanchaer, M; Mawet, D; Graham, J. R. et al. 2016, ApJ, 820, 111J, "Point Source Polarimetry with the Gemini Planet Imager: Sensitivity Characterization with T5.5 Dwarf Companion HD 19467 B"

Jensen-Clem, R.; Muirhead, P. S.; Bottom, M.; Wallace, J. K.; Vasisht, G.; Johnson, J. A. 2015, PASP, 127, 1105J. "Attaining Doppler Precision of 10 cm/s with a Lock-in Amplified Spectrometer"

Jensen-Clem, R.; Wallace, J. K.; Serabyn, E. 2012, IEEE Aerospace Conference, Big Sky, MT, pp. 1-7. "Characterization of the phase-shifting Zernike wavefront sensor for telescope applications"

Contact Me

rjensenclem (at) berkeley (dot) edu