Jason Wang


Image courtesy of Heising-Simons Foundation

I am a 51 Pegasi b postdoc at Caltech. I take images of faint exoplanets by removing the glare of their host stars so that we can trace out their orbits and measure the properites of their atmospheres. I also study their atmospheres through low and high resolution spectroscopy.

I grew up in Dublin, Ohio, got my B.A. in Physics with a Minor in Computer Science from Cornell University, and my PhD in Astrophysics from UC Berkeley.

Cahill 150
Social Media


The Gemini Planet Imager (GPI)

I am part of the team working on the Gemini Planet Imager (GPI), a near-infrared extreme-AO system that will directly image and take spectra of young Jovian-sized planets and the debris disks in which they form.

I led the development of the software infrastructure to automate the data processing for the GPI Exoplanet Survey (see our JATIS paper). My main contributions are building the GPIES Data Cruncher (poster pdf), an automatic data reduction system for our survey, and pyKLIP (Bitbucket repo), a PSF subtraction library written in python.

The software infrastrucutre I developed allowed us to discover GPI's first exoplanet!

Previously, I examined how well we could measure the star that is blocked by the coronagraph mask, in particular to measure the location and spectrum of the occulted star. This work was presented in a poster and conference proceeding at the 2014 SPIE Astronomical Instrumentation conference.


Improved Astrometry and Orbital Parameters of β Pictoris b

I developed a new technique for more precise astrometry of directly imaged exoplanets. This technique is based off the mathematical framework developed by Pueyo (2016) which allows us to forward model the signature of an exoplanet through the data reduction process. It allows us to use artifacts of the data reduction process which we used to consider nuisances to better constrain the position of the planet. In addition, I developed a Bayesian framework that properly accounts for the correlated nature of the noise in the data with Gaussian process regression, allowing us to obtain an accurate posterior distribution on the location of an exoplanet.

I applied this method on multi-epoch data of β Pictoris b taken with the Gemini Planet Imager. I published a paper showing that I could fit a Keplerian orbit to my measured astrometry with well-behaved fit residuals. Our measured positions of β Pictoris b were a factor of 2-4 more precise than previously published values that used same data. We also were able to improve some of the orbital parameters by a factor of 2. Using this method, we showed the probability of the planet transiting the star was ruled out at 10-σ confidence. However, the Hill sphere of the planet will transit the star, and we will be monitoring the star in 2017 with both the Hubble Space Telescope and ground based observatories to look for circumplanetary material such as disks, rings, and moons.

Probing the AU Microscopii Debris Disk

I worked on observations of AU Microscopii (AU Mic) taken by GPI during the comissioning of the instrument. We observed AU Mic using both integral field spectroscopy to search for planets and broadband imaging polarimetry to characterize the disk. Using the state-of-the-art adaptive optics system of GPI, we are able to look closer in towards the star than ever before (~0.2" or 2 AU away from the star).

In an ApJ Letter I wrote, I presented analysis of this data. I showed that the SE and NW sides of the disk are asymmetric. I find that the SE side of the disk has a bump at around 1" (10 AU) that is roughly double the vertical scale height elsewhere. I also find that both sides of the disk look to be offset from the disk midplane, creating what looks to be a warp in the disk of ~2°.

Airborne Observing in the Mid-IR

Jupiter Callisto and Io

In my undergrad career at Cornell, I worked with Professor Terry Herter on FORCAST, a mid-infrared camera for SOFIA. I am thrilled to have the unique opportunity to fly on SOFIA three times. Science wise, my work on FORCAST has invovled working on calibrating FORCAST, improving the reduction pipeline, and studying the atmosphere of Jupiter.

My research on Jupiter also involved Professor Peter Gierasch. We used FORCAST images of Jupiter to look at ortho-para hydorgen ratios and how they vary across Jupiter. The ortho-para ratio is a good tracer for convection on Jupiter and we want to show that FORCAST is capable of performing this measurement.


    First Author Publications

  • Wang, J. J., Graham, J. R., Dawson, R., et al. (2018) Dynamical Constraints on the HR 8799 Planets with GPI. AJ, 156, 192.
  • Wang, J. J., Perrin, M. D., Savransky, D., et al. (2018) Automated data processing architecture for the Gemini Planet Imager Exoplanet Survey. JATIS, 4, 018002.
  • Wang, J. J., Graham, J. R., Pueyo, L., et al. (2016) The Orbit and Transit Prospects for β Pictoris b constrained with One Milliarcsecond Astrometry. AJ, 152, 97W.
  • Wang, J. J., Graham, J. R., Pueyo, L., et al. (2015) Gemini Planet Imager Observations of the AU Microscopii Debris Disk: Asymmetries within One Arcsecond. ApJL, 811, L19.
  • Wang, J. J., Rajan, A., Graham, J. R., et al. (2014) Gemini Planet Imager Observational Calibrations VIII: Characterization and Role of Satellite Spots. Proc. SPIE, 9147, 55.
  • Co-author Publications (Selected)

  • Greenbaum A. Z., Pueyo, L., Ruffio, J.-B., Wang, J. J., et al. (2018) GPI Spectra of HR 8799 c, d, and e from 1.5 to 2.4 μm with KLIP Forward Modeling. AJ, 155, 226.
  • Nielsen, E. L., De Rosa, R. J., Rameau, J., Wang, J. J., et al. (2017) Evidence that the Directly-Imaged Planet HD 131399 Ab is a Background Star. AJ, 154, 218.
  • Ruffio, J.-B., Macintosh, B., Wang, J. J., et al. (2017) Improving and Assessing Planet Sensitivity of the GPI Exoplanet Survey with a Forward Model Matched Filter. AJ, 842, 14.
  • Nielsen, E. L., De Rosa R. J., Wang, J., et al. (2016) Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager. AJ, 152, 175N.
  • Millar-Blanchaer, M. A., Wang, J., Kalas, P., et al. (2016) Imaging an 80 AU Radius Dust Ring Around the F5V Star HD 157587. AJ, 152, 128M.
  • Konopacky, Q. M., Rameau J., Duchêne, G., et al. (2016) Discovery of a Substellar Companion to the Nearby Debris Disk Host HR 2562. ApJL, 829, 4,.
  • Perrin, M. D., Ingraham, P., Follette, K. B., et al. (2016) Gemini Planet Imager observational calibrations XI: pipeline improvements and enhanced calibrations after two years on sky. Proc. SPIE, 9908, 37.
  • Kalas, P. G., Rajan, A., Wang, J. J., et al. (2015) Direct Imaging of an Asymmetric Debris Disk in the HD 106906 Planetary System. ApJ, 814, 32.
  • De Rosa, R. J., Nielsen, E. L., Blunt, S. C., et al. (2015) Astrometric Confirmation and Preliminary Orbital Parameters of the Young Exoplanet 51 Eridani b with the Gemini Planet Imager. ApJL, 814, L3.
  • Millar-Blanchaer, M. A., Graham, J. R., Pueyo, L., et al. (2015) β Pictoris' inner disk in polarized light and new orbital parameters for β Pictoris b. ApJ, 811, 18.
  • Macintosh, B., Graham, J. R., et al. (2015) Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager. Science, 350, 64.
  • All Other Co-author Publications

  • Ruffio, J.-B., Mawet, D., Czekala, I., et al. (2018) A Bayesian Framework for Exoplanet Direct Detection and Non-Detection. AJ, in press.
  • Bailey, V. P., Bottom, M., Cady, E., et al. (2018) Lessons for WFIRST CGI from ground-based high-contrast systems. Proc. SPIE, 10698, 6P.
  • Savransky, D., Shapiro, J., Bailey, V., et al. (2018) Mining the GPIES database. Proc. SPIE, 10703, 0H.
  • Esposito, T. M., Duchêne, G., Kalas, P., et al. (2018) Direct Imaging of the HD 35841 Debris Disk: A Polarized Dust Ring from Gemini Planet Imager and an Outer Halo from HST/STIS. AJ, 156, 47.
  • Mékarnia, D., Chappellier, E., Guillot, T., et al. (2017) The δ Scuti pulsations of β Pictoris as observed by ASTEP from Antarctica. A&A, 608, L6.
  • Rajan, A., Rameau, J., De Rosa, R. J., et al. (2017) Characterizing 51 Eri b from 1-5 μμ m: a partly-cloudy exoplanet. AJ, 154, 10.
  • Follette, K. B., Rameau, J., Dong, R., et al. (2017) Complex Spiral Structure in the HD 100546 Transitional Disk as Revealed by GPI and MagAO. AJ, 153, 264.
  • Rameau, J., Follette, K. B., Pueyo L., et al. (2017) An Optical/Near-infrared Investigation of HD 100546 b with the Gemini Planet Imager and MagAO. AJ, 153, 244.
  • Johnson-Groh, M., Marois, C., De Rosa, R. J., et al. (2017) Integral Field Spectroscopy of the Low-mass Companion HD 984 B with the Gemini Planet Imager. AJ, 153, 190.
  • Chilcote, J., Pueyo, L., De Rosa, R. J., et al. (2017) 1-2.4 μm Near-IR Spectrum of the Giant Planet β Pictoris b Obtained with the Gemini Planet Imager. AJ, 153, 182.
  • Blunt, S., Nielsen, E. L., De Rosa, R. J., et al. (2017) Orbits for the Impatient: A Bayesian Rejection-sampling Method for Quickly Fitting the Orbits of Long-period Exoplanets. AJ, 153, 229.
  • Bailey, V. P., Poyneer, L. A., Macintosh, B. A., et al. (2016) Status and performance of the Gemini Planet Imager adaptive optics system. Proc. SPIE, 9909, 0V.
  • Millar-Blanchaer, M. A., Perrin M. D., Hung, L., et al. (2016) GPI observational calibrations XIV: polarimetric contrasts and new data reduction techniques. Proc. SPIE, 9908, 36.
  • Hung, L., Bruzzone, S., Millar-Blanchaer, M. A., et al. (2016) Gemini planet imager observational calibration XII: photometric calibration in the polarimetry mode. Proc. SPIE, 9908, 3A.
  • Esposito, T. M., Fitzgerald, M. P., Graham, J. R., et al. (2016) Bringing "The Moth" to Light: A Planet-Sculpting Scenario for the HD 61005 Debris Disk. AJ, 152, 85E.
  • Draper, Z. H., Duchêne, G., Millar-Blanchaer, M. A., et al. (2016) The Peculiar Debris Disk of HD 111520 as Resolved by the Gemini Planet Imager. ApJ, 826, 147D.
  • Rameau, J., Nielsen, E. L., De Rosa, R. J., et al. (2016) Constraints on the architecture of the HD 95086 planetary system with the Gemini Planet Imager. ApJL, 822, L29.
  • De Rosa, R. J., Rameau, J., Patience, J., et al. (2016) Spectroscopic characterization of HD 95086 b with the Gemini Planet Imager. ApJ, 824, 121.
  • Wolff, S. G., Perrin, M., Millar-Blanchaer, M. A., et al. (2016) The PDS 66 Circumstellar Disk as seen in Polarized Light with the Gemini Planet Imager. ApJL, 818, L15.
  • Poyneer, L. A., Palmer, D. W., Macintosh, B., et al. (2016) Performance of the Gemini Planet Imager’s adaptive optics system. Applied Optics, 55, 323.
  • Hung, L., Duchêne, G., Arriaga, P., et al. (2015) First Scattered-light Image of the Debris Disk around HD 131835 with the Gemini Planet Imager. ApJL, 815, L14.
  • Perrin, M. D., Duchêne G., Millar-Blanchaer, M., et al. (2015) Polarimetry with the Gemini Planet Imager: Methods, Performance at First Light, and the Circumstellar Ring around HR 4796A. ApJ, 799, 182.
  • Maire, J., Ingraham, P. J., De Rosa, R. J., et al. (2014) Gemini Planet Imager Observational Calibrations VI: Photometric and Spectroscopic Calibration for the Integral Field Spectrograph. Proc. SPIE, 9147.
  • Konopacky, Q. M., Thomas, S. J., Macintosh B. A., et al. (2014) Gemini Planet Imager Observational Calibrations V: Astrometry and Distortion. Proc. SPIE, 9147.
  • Perrin, M. D., Maire, J., Ingraham, P., et al. (2014) Gemini Planet Imager Observational Calibrations I: Overview of the GPI Data Reduction Pipeline. Proc. SPIE, 9147.
  • Macintosh, B. A., Chilcote, J. K., Dillon, D., et al. (2014) The Gemini Planet Imager: First Light and Commissioning. Proc. SPIE, 9148.
  • Herter, T. L., Vacca, W., Adams, J. D., et al. (2013) Data Reduction and Early Science Calibration for FORCAST, A Mid-Infrared Camera for SOFIA. PASP, 125, 1393.
  • Adams, J. D., Herter, T. L., Gull, G. E., et al. (2012) The FORCAST Mid-Infrared Facility Instrument and In-Flight Performance on SOFIA. Proc. SPIE, 8446.
  • All Publications: ADS Link




In the Fall of 2016, I co-taught the pedagogy course for first time graduate and undergraduate student instructors in teh astronomy program. The course is focused more on the practical side of teaching astronomy, emphasizing how to apply techniques such as group work in astronomy discussion sections. The syllabus, lesson plans, and materials for the course are available online.


In the Fall of 2014, I was a graduate teaching instructor for Introduction to Astrophysics with Professor Mariska Kriek. This is the first course for astrophysics majors at UC Berkeley (mainly sophomores). I lead two discussion sections, held weekly office hours, and facilitated to weekly group homework session.


In the Fall of 2013, I was a graduate teaching instructor for Professor James Graham for Ay120 (Optical/Infrared Astronomy Lab). I held office hours, gave mini-lectures on programming, and helped with data aquisition. Here are some technical primers I wrote up for Unix, LaTeX, and Python.

  • A quick introduction to UNIX: PDF
  • Example LaTeX document that demonstrates some basic functionality: .tex, PDF
  • LaTeX template for lab reports: .tex
  • Introduction to pip, the python package manager: PDF
  • An exploration of the different ways to iterate over some data: python code


CS 4410/4411

As an undergrad at Cornell, I was a TA for CS4410 (Operating Systems) and CS4411 (Operating Systems Practicum) in the Fall semester of 2012. My responsibilities included holding office hours, answering the constant flood of emails, grading exams and projects, and fixing configuration issues with Visual Studio.


Astronomy Software

  • pyKLIP - Python library to perform PSF subtraction following the KLIP algorithm and foward modelling using KLIP-FM. Supports GPI, P1640, MagAO, Keck/NIRC2, and SPHERE data. Bitbucket repo and ASCL Reference
  • GPIES Data Cruncher - The automated data processing system for the GPI Exoplanet Survey. Creates PSF-subtracted data and contrast curves in real time and is ported to also run on a supercomputer to reprocess the entire survey's worth of data in a few hours. JATIS Paper
  • GPI Pipeline - I am part of the team that is developing the tools to reduce and analyze data from the Gemini Planet Imager. Pipeline Documentation
  • nair - Python script to calculate the index of refraction for air in the near infrared. Github page
  • Fast Median Filtering - A bucket-sort implementation of Median Filtering that scales well and can handle floating point numbers. Written in Pascal for Terry Herter. Github page

Web Apps

I also run or help run several web applications.


I interned at Microsoft the summer of 2012 working in the Visual Studio group. I worked on developing the automated testing framework for testing. I also participated in the DevDiv Intern Hack-A-Thon and my group's project was voted best by the full time employees. Our group used the Kinect to simulate touchscreen grestures in Windows 8. You can check out a video of our project here.

Academic Programming Projects

  • P2Potato - A distributed Dropbox built upon Isis2 with no centralized data store. Github page
  • PortOS - Wrote my own operating system (concurrent scheduling, TCP/IP, UDP, Routing, UNIX Filesystem)


Exoplanet Orbit Movies

I use real footage of exoplanets taken with various telescopes and use motion interpolation to make smooth time-lapse movies. You can see them here.

My HR 8799 animation has been featured on Astronomy Picutre of the Day, Wikipedia Featured Pictures, National Geographic, Washington Post, and more. They have also been used at school both in educational software and in classroom activities.

See more movies here

Roasting marshmallows by focusing the power of the Sun

Events and Demos

I am involved in several hands-on astronomy outreach efforts.

  • I lead a crowdfunding campaign that successfully rasied funds to develop virtual reality demonstrations in astronomy. Stay tuned for more!
  • I am working on creating new outreach demonstrations, such as a parabollic mirror that can be used to roast marshmallows by focusing sunlight (as seen in this picture).
  • I helped start up Astro Night, a monthly public lecture and stargazing series hosted by the Berkeley Astronomy department.

Education Initiatives

Outside of astronomy, I have been involved with the Cornell Computer Reuse Association (CCRA) to refurbish old computers, donate them to education and community organizations, and expand computer literacy all around the world. I also helped start the Zambia Community Education Initiative (ZCEI), a 501(c)3 not-for-profit that aims to improve education in Zambia. If you are interested in these organizations, contact me!