About Me

My name is Justin Robinson, and I am a third year graduate research assistant at Georgia State University. My research interests include extragalactic distance measurements, supermassive black hole mass measurements, and relationships between active galaxies and supermassive black holes.

Green Bank Radio Telescope

The Robert C. Byrd Green Bank Telescpoe is located in the national radio quiet zone in West Virginia. It is the largest steerable instrument in the world, with a dish 300 feet in diameter and height 485 feet above the ground. I've used this telescope to observe 21cm radiation from neutral hydrogen in nearby galaxies hosting an active galactic nucleus.

Arecibo Radio Telescope

The 305m (1000ft) Arecibo Telecope was once the world's largest single-aperture telescope. It has since been overtaken by the Five Hundred Meter Aperture Spherical Telescope (FAST) in China. Arecibo is of the premier instruments for extragalactic radio astronomy. I've also used this telescope for 21cm observations with the Arecibo Legacy Fast ALFA (ALFALFA) survey, a huge collaboration of astronomers measuring distances, masses, and velocities of thousands of galaxies in the local universe.

My Work


"HI Spectroscopy of Reverberation-Mapped Active Galactic Nuclei," Justin H. Robinson, Misty C. Bentz, Megan C. Johnson, Hélène M. Courtois, Benjamin Ou-Yang 2019, ApJ, 880, 68



GOT Space Outreach Event

Maynard Holbrook Jackson High School
I am one of the pilot graduate ambassadors for the new Georgia Outreach Team for Space (GOT Space). GOT Space's mission:  to inspire an appreciation of STEM and STEM careers in Georgia K-12 students through the delivery of interactive presentations by graduate and undergraduate students, highlighting innovative science and engineering research.

Extragalactic HI
Learn more

Cold, neutral hydrogen (HI) exists in a configuration where the spins of the  proton and electron are parallel. When the electron flips its spin, the atom enters into a lower energy state, and a photon is emitted with the difference in energy, which corresponds to a wavelength of 21cm, or a frequency of 1420 MHz.
    Energy emitted by these spin-flipped HI atoms helps us study nearby galaxies.  The width of the emission lines (like the one from nearby galaxy MCG+08-11-011 shown above) gives us information about the rotational velocity of the galaxy. The integrated flux along with the distance to the galaxy allows the total mass in neutral hydrogen to be determined as well. The center-line velocity measurements also yield one of the most reliable redshift measurements in extragalactic astronomy.

Astronomy 1020 Lab Materials

Here you will find all materials and documentation for your Astronomy 1020 lab section. Click on each link to view/download.

Possible project topics and short summaries. Due dates for outlines, presentations, and projects listed.

Outline of due dates and details on each step of the project.

Summary and requirements for each type of possible project.


The Tully-Fisher Relation

Image credit: NOAO
The Tully-Fisher relation shows a correlation between the rotational velocity of a spiral galaxy (the width of the emission line, corrected for the inclination of the galaxy) and its absolute magnitude. Therefore, if the rotational velocity is known, then the true brightness of a galaxy can be achieved.
    The Tully-Fisher relation's main importance to extragalactic astronomy is distance measurement. Because the relation gives absolute magnitude, if we compare that value to the measured apparent magnitude of the same galaxy, then the distance can be measured (in short, comparing how bright something actually is to how bright it appears to be shows how far away it must be).


We are are working to expand West Virginia's currently established Science Public Outreach Team (SPOT) program with participation from Georgia State University, Georgia Institute of Technology, and Kennesaw State University, and association with the Georgia Space Grant Consortium.

For more information on GOT Space, or to request a presentation, please visit our website: 


My talk, "HI Spectroscopy of Reverberation-Mapped Active Galactic Nuclei," given at the 2018 Georgia Regional Astronomers Meeting

Contact Me


jrob (at) astro.gsu.edu


25 Park Place South
Suite 605
Atlanta GA, 30303-2911