Date of Award

Spring 1-1-2013

Document Type


Degree Name

Doctor of Philosophy (PhD)


Astrophysical & Planetary Sciences

First Advisor

Webster Cash

Second Advisor

Andrew Hamilton

Third Advisor

Steve Osterman

Fourth Advisor

Jeff Forbes

Fifth Advisor

Randall McEntaffer


The CODEX sounding rocket payload was designed and flown to significantly improve spectral resolution of the Vela supernova remnant (SNR) in the soft x-ray (0.1 − 1.0 keV) bandpass. High spectral resolution (E/ΔE > 40) across its 3.25° ×3.25° field of view would disentangle thermal emission from nonthermal or line emission components to constrain the age when SNRs stop emitting nonthermal x-rays. Relatively recent observations have found significant nonthermal emission from remnants up to several kyr old, but CODEX encountered concurrent problems of higher noise and lower signal than expected, leaving the thermal versus nonthermal question unanswered in the 11 kyr-old Vela SNR. This thesis covers the motivation, design, and post-flight analysis of the CODEX instrument and data from its flight.