Green Bank Observer – Vol II, Issue 3

News from the Director

The students and interns have gone home, the cafeteria staff all got to take last weekend off, and last night the temperature here dropped into the 40s (Fahrenheit). Green Bank’s summer is coming to an end. The summer itself was busy in a wonderful way – we had 10 summer students taking part in our REU, PING, and internship programs and an additional 36 other summer staff who worked on everything from painting the GBT to site maintenance and providing tours, food, and rooms to all the visitors on site. We were excited to welcome back the Governor’s STEM Institute to the site this year, as well as holding another PING camp for rising 9th graders, a digital signal processing workshop for high school teachers, Chautauqua Short Courses, Earth-Space science training for West Virginia teachers, StarQuest, SARA, Star Parties, and much more, all activities that kept the staff busy and gave many different groups of students, teachers, and the general public the opportunity to learn more about STEM, astronomy, and exciting new discoveries than they would through just a normal half day visit.

But with summer over we can now start looking forward to the fall and the increase in GBT observing time that comes with the end of summer maintenance and the increase in the number of beautiful, clear nights for high frequency observing. This fall we will be holding another observer training workshop as well as a workshop aimed toward people either planning on in the middle of large surveys on the GBT, looking for ways to optimize the science from these surveys. We are also in the planning stages for a couple of new instruments on the GBT which will increase the telescope’s scientific output at a variety of frequencies, and we will announce those plans as soon as they are fully in place.

Karen O’Neil
Director, Green Bank Observatory

Science News

Even Phenomenally Dense Neutron Stars Fall like a Feather

Harnessing the exquisite sensitivity of the National Science Foundation’s Green Bank Telescope (GBT), astronomers have given one of Einstein’s predictions on gravity its most stringent test yet. By precisely tracking the meanderings of three stars in a single system – two white dwarf stars and one ultra-dense neutron star – the researchers determined that even phenomenally compact neutron stars “fall” in the same manner as their less-dense counterparts, an aspect of nature called the “Strong Equivalence Principle.”

Einstein’s understanding of gravity, as outlined in his general theory of relativity, predicts that all objects fall at the same rate, regardless of their mass or composition. This theory has passed test after test here on Earth, but does it still hold true for some of the most massive and dense objects in the known universe, an aspect of nature known as the Strong Equivalence Principle? An international team of astronomers has given this lingering question its most stringent test ever. Their findings, published in the journal Nature, show that Einstein’s insights into gravity still hold sway, even in one of the most extreme scenarios the Universe can offer.

Read more …

Observatories Team Up to Reveal Rare Double Asteroid

New observations by three of the world‘s largest radio telescopes have revealed that an asteroid discovered last year is actually two objects, each about 3,000 feet (900 meters) in size, orbiting each other.

Near-Earth asteroid 2017 YE5 was discovered with observations provided by the Morocco Oukaimeden Sky Survey on Dec. 21, 2017, but no details about the asteroid’s physical properties were known until the end of June. This is only the fourth “equal mass” binary near-Earth asteroid ever detected, consisting of two objects nearly identical in size, orbiting each other. The new observations provide the most detailed images ever obtained of this type of binary asteroid.

Read more …

eXtra Large Proposal Reminder

The Green Bank Observatory (GBO),  Long Baseline Observatory (LBO), and National Radio Astronomy Observatory (NRAO), invite submission of brief Expressions of Interest (EoIs) in Principal Investigator-led “eXtra Large Proposals” (X-Proposals) for the Green Bank Telescope, Very Long Baseline Array, and Very Large Array (VLA) requiring 1000 hours or more of telescope time, and running over multiple semesters (and possibly multiple VLA configurations).

Responses will be used to gauge the level of community interest in such proposals, and their scientific potential. GBO, LBO and NRAO will seek advice from their advisory committees and the joint Time Allocation Committee on the EoIs submitted. It is important to note that the observatories may not proceed to a Call for X-Proposals if, for example, there is judged to be insufficient community interest, scientific merit, or differentiation from Large Proposals.

Expressions of Interest can be submitted using the web form at:

The deadline for submissions is 31 August 2018.

Proposal Call Results

A total of 97 proposals requesting NSF funded “open skies” time were submitted to the Green Bank Observatory’s Robert C. Byrd Green Bank Telescope (GBT)  for semester 18B.  Proposals are reviewed on a competitive basis with a panel review system (see Proposal Review System).  Below are the statistics by proposal count and hours.  The oversubscription is the ratio of the number of submitted proposals to the number of approved proposals.  The pressure is the ratio of the requested time to the available time in hours.  Here we only include proposals submitted for the 18B semester that have been reviewed by the Green Bank Observatory Telescope Allocation Committee (TAC).

A description of the 18B proposals accepted can be found at 2018B Science Program.

Recent GBO Publications

From time to time, we update our list of publications on the GBO Web site. Here are a few listed alphabetically below:

Anderson, L.D. et al. 2018 ApJS, 234, 33.
“A Green Bank Telescope Survey of Large Galactic HII Regions”

Andrews, J.J. et al. 2018 RNAAS, 2, 60.
“A Serendipitous Pulsar Discovery in a Search for a Companion to a Low-mass White Dwarf”

Archibald, A.M. et al. 2018 Nature, 559, 73.
“Universality of free fall from the orbital motion of a pulsar in a stellar triple system”

Arzoumanian, Z. et al. 2018 ApJ, 859, 47.
“The NANOGrav 11-year Data Set: Pulsar-timing Constraints On The Stochastic Gravitational-wave Background”

Bhattacharyya, B.; 2018 MNRAS, 477, 4090.
“A Long-term study of three rotating radio transients”

Bietenholz, M.F. et al. 2018 MNRAS, 475, 1756. SN 2014C:
“VLBI images of a supernova interacting with a circumstellar shell”

Burkhardt, A.M. et al. 2018 MNRAS, 474, 5068.
“Detection of HC$_5$N and HC$_7$N Isotopologues in TMC-1 with the Green Bank Telescope”

A complete list may be found on our Publications Page.

Optimizing Science from Green Bank Telescope Surveys

Since its commissioning, the Green Bank Telescope (GBT) has been used for a number of surveys that have produced unique data of lasting value. Recent GBT surveys are measuring star-forming molecular clouds in the Gould Belt, searching for new chemical species in Taurus, determining the HI properties of galaxies in the local Universe, determining the distribution of dense gas in galaxies and hot gas in galaxy clusters, searching for H2O megamasers in nuclear disks, and searching for new pulsars toward the north celestial pole.

The Green Bank Observatory (GBO) is interested in assisting its users who perform surveys. The assistance could take many forms: hosting a survey website; arranging team meetings; training student observers; organizing the observing; curating the final data products. To explore the ways that the GBO might assist survey science there will be a workshop “Optimizing Science from Green Bank Telescope Surveys” at the Green Bank Observatory on November 13-14, 2018. The goal of the workshop will be to develop practical policies for GBO support of survey science, but there will also be time set aside for survey team meetings, discussion with GBO staff on technical issues, or any other activity that might benefit current and future GBT surveys.

This workshop is intended for scientists and students who are involved with current or past GBT surveys, or who are planning future GBT surveys.

Logistics at the GBO limit the workshop to about 40 participants. There will be no registration fee, and all on-site expenses, include lodging and meals, will be covered by the GBO.

Workshop information page

Summer Students Wrap Up Their Work

Green Bank Observatory recently bid a fond farewell to our 2018 class of undergraduate summer students. Eight students, three from the Research Experience for Undergraduate program, four from the Physicists Inspiring the Next Generation program, and one from GBO’s research assistant program, spent the summer living and working at the observatory. Their projects focused on pulsars and fast radio bursts, Galactic and Local Group HI, the conditions for water on Mars, new instrumentation for the GBT, and RFI mitigation. Our students were active members of the observatory community, participating in numerous education and outreach programs and local community events, in addition to their research projects. We look forward to seeing many of them at upcoming professional meetings – including the 2019 Winter AAS meeting, and as observers at the GBT – and wish them success in their future endeavors.

All undergraduate and graduate students are encouraged to apply for the 2019 GBO/NRAO summer student programs. We’ll have an informational table at the 2019 Winter AAS undergraduate student reception and throughout the AAS meeting in the main exhibit hall.  Information about 2019 research opportunities will be available in December. The application deadline for the 2019 summer student programs will be Feb 1, 2019. Please visit our summer student program page for additional information on GBO and NRAO student programs.

Quick look display of a galactic center map from a 10 minute observation.

Twenty Meter Telescope Available for
Undergraduate Student Educational Use

The Green Bank Observatory is pleased to make the 20 Meter Telescope available for observational projects as part of college and university astronomy courses.

The 20 Meter Telescope was built in Green Bank by RSI, and funded by the US Naval Observatory (USNO) to be part of their Earth orientation observing program, and was operated by USNO from 1995-2000. In 2012, the 20 Meter was refurbished, and joined the Skynet Robotic Telescope Network project operated by the University of North Carolina, Chapel Hill.

The NRAO 20-meter telescope is the only radio telescope in the network, providing a unique capability to include radio astronomy as a lab component in university/college astronomy courses. Much of today’s professional astronomical research is multi-wavelength, with scientists using combinations of radio, optical, infrared, or other telescopes to gain a complete picture of the objects they study. The 20 Meter Telescope gives students the same ability and provides them with a better understanding of modern research.

Two receivers formerly used on the 140-foot telescope were revived and adapted for use on the 20 Meter, providing receivers sensitive to 1.3-1.8 GHz, and 8-10 GHz. The 1.3-1.8 GHz receiver is usually on the telescope providing access to studies of neutral hydrogen emission, OH emission as well as continuum observations to a declination limit of  about -45 degrees.

Telescope time may be purchased for both educational and research activities. The highly competitive educational rate requires the observations to be used for student training and education as the primary activity. Professors and teachers interested in learning more about educational observing projects can contact Sue Ann Heatherly at sheather–at– For detailed information regarding the 20 Meter capabilities visit [], or contact Frank Ghigo, 20 Meter Scientist, at fghigo–at–


Family Day and Open House – September 9, 1 – 5 P.M.

GBT Remote Observer Training Workshop – September 17-18

2018 Jansky Lecture by Professor Roger D. Blandford – November 1, 7:00 P.M., in the Science Center Auditorium

Optimizing Science from Green Bank Telescope Surveys – November 13-14

2019A Semester Call for Proposals is Now Live

The Green Bank Observatory invites scientists to participate in the 2019A Semester Call for Proposals for the Green Bank Telescope (GBT). The entire proposal call can be found here. The submission deadline for Semester 2019A proposals is Wednesday, 1 August 2018, at 17:00 EDT (21:00 UTC).

The Green Bank Observatory encourages proposals that take advantage of the GBT’s unique capabilities. Key science areas include, but are not limited to: astrochemistry, cosmology, fast radio bursts, galaxy and cluster evolution, HI (galactic and extragalactic), pulsars (searches and timing), radio recombination lines, solar system science, and star formation.

We encourage the submission of high risk, high reward proposals requiring moderate amounts of GBT observing time.

Filler time proposals which can take advantage of gaps in the GBT schedule are also encouraged.

Triggered proposals can be submitted for studies of transient objects such as fast radio bursts, near Earth asteroids, comets, and other transients.

All proposals should state why the GBT is necessary for the requested observations in both the abstract and science justification.

The Green Bank Observatory is hoping to start a fellowship program to support astronomical research by graduate and undergraduate students at U.S. universities and colleges. This program is intended to strengthen the proactive role of the Observatory in training new generations of scientists and telescope users. Information about this program, if it becomes available, will be included in the 2019A semester disposition letters.

We strongly encourage proposers to carefully read through the “News and Opportunities” section of the proposal call.

Learn more about proposing on the GBT on the Proposal Call page.

Diamond Dust Shimmering around Distant Stars

Nanoscale gemstones source of mysterious cosmic microwave light

Some of the tiniest diamonds in the universe – bits of crystalline carbon hundreds of thousands of times smaller than a grain of sand – have been detected swirling around three infant star systems in the Milky Way. These microscopic gemstones are neither rare nor precious; they are, however, exciting for astronomers who identified them as the source of a mysterious cosmic microwave “glow” emanating from several protoplanetary disks in our galaxy.