Hi! I'm Eric.

I'm an astrophysicist.


I am a Postdoctoral Scholar in Astronomy at Caltech.

I am Project Scientist for the Zwicky Transient Facility. I am using variability data from large sky surveys to better understand the formation and evolution of neutron star binaries.

My research includes observation, instrumentation, and large-scale data analysis.

Eric Bellm


I am the Project Scientist for the Zwicky Transient Facility (ZTF), a next-generation optical time-domain survey based on the Palomar Transient Factory (PTF). With the benefit of a new camera with a 47 square degree field of view and faster readout, ZTF will survey more than an order of magnitude faster than PTF and conduct an unprecedented high cadence, wide area survey.

ZTF will discover a young supernovae every night, identify rare classes of transients, and produce an all-sky variability catalog with more than 250 epochs per field each year. First light is expected in 2017.

ZTF Cryostat

Fermi has discovered many millisecond pulsars eclipsing and ablating low-mass companions--"Black Widow" and "redback" systems. I am conducting photometric and radial-velocity followup to model these systems, measure the masses of the neutron stars, and understand their evolutionary history.

My study of the unique redback MSP binary PSR J2129-0429 revealed that it has a heavy neutron star of 1.7 solar masses as well as an unexpected optical dimming on a timescale of years. The system sits in an unusual region of binary evolution phase space, exactly at the bifurcation period between converging and diverging binaries

NuSTAR's high-sensitivity and continuous energy coverage enables some of the best spectroscopy of X-ray binaries. My analysis of the cyclotron line in the Be/X-ray binary GRO J1008-57 confirmed its high magnetic field.

Compact Binary

Repeated optical imaging of the Galactic Plane can probe Galactic Structure with variable star populations and identify rare outbursting sources, but crowded fields makes automated photometry difficult.

With the benefit of a new PSF image-differencing pipeline, we are conducting what is currently the best variability survey of the Northern Galactic Plane.

I am using these data to identify compact binaries as part of a larger project to classify unidentified X-ray sources with optical variability.

Galactic Plane

Increasingly sensitive measurements of gamma-ray bursts continue to reveal new complexity in the emission mechanisms.

With NuSTAR, I discovered an unusual extra component in the late-time X-ray afterglow of the ultra-long GRB130925A. In contrast, NuSTAR data for the bright nearby GRB130427A was consistent with emission by a single mechanism.

In my dissertation, I evaluated multi-component "quasi-thermal" spectral models of the GRB prompt emission using RHESSI and Swift.


As part of my dissertation work, I participated in two campaigns of the balloon-borne gamma-ray Nuclear Compton Telescope. I maintained the flight control software and calibrated its effective area and polarization response for future observations of GRBs.

Our 2009 New Mexico flight yielded the first image of the Crab Nebula by a compact Compton telescope. I led our 2010 Alice Springs campaign, directing shipping logistics, field operations, and interfaces with NASA and the media.

My campaign blog chronicled these adventures.

Balloon launch


Postdoctoral Scholar, Caltech 2011-
Ph.D., Physics, U.C. Berkeley 2011
A.B., Physics & Astronomy, Harvard2005


My papers on ADS.

Complete CV (pdf).


Office:Cahill 216
MC 249-17
1200 E. California Blvd.
Pasadena, CA 91125


Email:ebellm ∝ caltech.edu