Randall McEntaffer

Assistant Professor

The science team of EXOS poses in front of the Athena launcher prior to the 2009 flight.  EXOS, its predecessor CyXESS, and 2 future payloads are carried to space on Black Brant IX rockets to observe hot, diffuse galactic sources.


Computer Aided Design (CAD) model of the Off-plane Grating Rocket Experiment (OGRE) slated for launch on 2017.  The project is led by Iowa and involves graduate and undergraduate students as well.


A false-color image of SNR G272.2-3.2 in X-rays.  Red covers the energy range 0.3--1.2 keV with green from 1.2--1.7 keV, and 1.7--8.0 keV for blue.  The outer regions of this remnant are shock heating clouds in the local environment while the predominantly blue emission in the center is enriched with ejected metals from a Type Ia supernova explosion

Ph.D., Astronomy, University of Colorado 2007

Contact Information

Department of Physics and Astronomy

University of Iowa, 704 Van Allen Hall

Laboratory B08 Van Allen Hall

Phone: 319-335-3007, FAX: 319-335-1753

Email: randall-mcentaffer [at] uiowa.edu

Biographical Information

I am a native Iowan, born in Sioux City, which brought me to the University of Iowa where I obtained a B.S. in Physics and a B.S. in Astronomy.  This provides me with a unique insight when teaching courses and mentoring students in the same department that I attended.  Following my undergrad work I went to the University of Colorado in Boulder to pursue my doctorate in astrophysics.  My thesis project was the design, fabrication, calibration, and launch of a suborbital rocket.  The payload was a high resolution X-ray spectrometer for soft X-ray spectral observation of the Cygnus Loop supernova remnant.  In my free time I enjoy relaxing with my family and working around the house.  In my free-free time I enjoy fishing, hunting, gaming, and playing ultimate frisbee. 

Research Interests

My current research interests are driven by high resolution spectroscopy in the soft X-ray bandpass (E <2keV). I design, fabricate, test and fly high resolution X-ray spectrographs for use on sub-orbital rocket payloads and as concept hardware for future NASA missions. Associated science topics include shock and plasma physics in the blast wave/interstellar medium interaction sites of supernova remnants,properties of pulsar wind nebulae and their interaction with the supernova reverse shock, and characterization of the spectral and temporal properties of the ubiquitous soft X-ray background.

Current Research Projects

• PI on a 5-year suborbital rocket project to develop critical technologies for future NASA X-ray missions.  The payload is named the Off-plane Grating Rocket Experiment (OGRE) and will incorporate optics from Goddard Space Flight Center, a CCD camera from collaborators at the Open University in the UK, and diffraction gratings made via nanofabrication techniques here at Iowa.  The payload will obtain the highest resolution soft X-ray spectrum to date.  The observation target is Capella, a binary giant star system with intense coronal activity, and a common X-ray calibration source.  Launch is scheduled for 2017.

• Recipient of the 2011 NASA Nancy Grace Roman Technology Fellowship and PI of the associated X-ray diffraction grating fabrication study.  The goal of this study is to formulate a novel method of X-ray reflection grating fabrication and implement these techniques at the University of Iowa.  This leverages heavily from our existing microfabrication facilities in the Optical Science and Technology Center at the Iowa Advanced Technology Laboratories.

• Reduction and analysis of Chandra X-ray Observatory data of various supernova remnants in the galaxy and Magellanic Clouds. This effort is supported by three graduate students – Tom Brantseg, Quentin Roper, and Casey DeRoo.

• PI on a Strategic Astrophysics Technology program to increase the flight readiness of soft X-ray spectrometers for future NASA X-ray missions. Contributing institutes include Goddard Space Flight Center, Marshall Space Flight Center, Northrop Grumman Aerospace Systems, the University of Colorado, and the Open University in the UK.

Selected Publications

McEntaffer, R. L., Grieves, N., DeRoo, C., & Brantseg, T., “A New X-ray View of the Supernova Remnant G272.2-3.2 and Its Environment,” The Astrophysical Journal, 774, 120, 13 pages, 2013.

McEntaffer, R. L., DeRoo, C., Schultz, T., Gantner, B., Tutt, J., Holland, A., O’Dell, S., Gaskin, J., Kolodziejczak, J., Zhang, W. W., Chan, K.-W., Biskach, M., McClelland, R., Iazikov, D., Wang, X., & Koecher, L., “First results from a next-generation off-plane X-ray diffraction grating,” Experimental Astronomy, 36, 389, 17 pages, 2013.

Brantseg, T., McEntaffer, R. L., Bozzetto, L., Filipovic, M., & Grieves, N., “0540-69.3: A Multi-Wavelength Look at a Young Composite SNR,” The Astrophysical Journal, accepted pending revisions, 2013.

Allured, R. & McEntaffer, R. L., “Analytical Alignment Tolerances for Off-Plane Reflection Grating Spectroscopy,” Experimental Astronomy, DOI:10.1007/s10686-013-9349-y, 2013.

Oakley, P., McEntaffer, R. L., & Cash, W., “Soft X-ray Spectroscopy of the Cygnus Loop Supernova Remnant,” The Astrophysical Journal, 766, 51, 6 pages, 2013.

Bautz, M.W., Cash, W. C., Davis, J. E., Heilmann, R. K., Huenemoerder, D. P., Schattenburg, M. L., McEntaffer, R. L., Smith, R., Wolk, S. J., Zhang, W. W., Jordan, S. P., Lillie, C. F., “Concepts for high-performance soft X-ray grating spectroscopy in a moderate-scale mission,” Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, Proceedings of the SPIE, 8443, 844315, 9 pages, 2012.

McEntaffer, R. L., Brantseg, T., & Presley, M., “SNR 0453-68.5: An Asymmetric Remnant and its Plerion in the Large Magellanic Cloud”, The Astrophysical Journal, 756, 17, 13 pages, 2012.

McEntaffer, R. L., & Brantseg, T., “Chandra Imaging and Spectroscopy of the Eastern XA Region of the Cygnus Loop Supernova Remnant”, The Astrophysical Journal, 730, 99, 11 pages, 2011.

McEntaffer, R. L., Cash, W., Lillie, C., Casement, S., Zhang, W., Holland, A., Murray, N., O’Dell, S., Schattenburg, M., Heilmann, R., Tsunemi, H., “Development of off-plane gratings for WHIMex and IXO,” Optics for EUV, X-ray and Gamma-Ray Astronomy V, Proceedings of the SPIE, 8147, 81471K, 11 pages, 2011.

Oakley, P. H. H., McEntaffer, R. L., & Cash, W., “A suborbital payload for soft X-ray spectroscopy of extended sources”, Experimental Astronomy, 31, 23, 22 pages, 2011.

McEntaffer, R. L., & Cash, W., “Soft X-ray Spectroscopy of the Cygnus Loop Supernova Remnant”, The Astrophysical Journal, 680, 328, 8 pages, 2008.


Part of the technology development occurring at Iowa involves high precision alignment of reflection grating arrays.  We are currently developing prototype substrates and module mounts that satisfy tight alignment tolerances thus enabling high performance requirements

Left: Raw infrared data of SNR 0453-68.5 taken with the Spitzer IR observatory.  Right: X-ray data from the Chandra X-ray Observatory is shown in green and plotted over this IR emission which is now shown in red.  This demonstrates either a swept up shell of material being heated by a blast wave or an interaction of the blast wave with a pre-blown cavity caused by the massive precursor star.


We are currently fabricating X-ray diffraction gratings using nanofabrication technology.  A pre-master grating is fabricated via e-beam lithography and subsequently nanoimprinted onto a resist coated off-axis cut Si wafer.  Post imprint etching techniques transfer the pattern into the wafer

Copyright University of Iowa 2015