Today on the #arXiv:
Nolan et al. 2026, "Planetary Radar at the Arecibo Observatory" - arxiv.org/abs/2604.00332
@mikeynolan.bsky.social, @lynncarter.bsky.social, and @planettreky.bsky.social review everything that was done by #TeamRadar at Arecibo.
Today on the #arXiv:
Cannon et al. 2026, "The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations" - arxiv.org/abs/2603.16703
Led by Richard Cannon, working with @agastro.bsky.social and building on work @kaleybrauer.bsky.social did with me.
#TeamRadar
Shout-out to co-authors! @kaleybrauer.bsky.social @michael-w-busch.bsky.social @mikeynolan.bsky.social @sondy.com #TeamRadar 🪨
These results for Nereus are consistent with those from #TeamRadar in 2009 (11º pole direction offset with uncertainties of ±10º).
echo.jpl.nasa.gov/asteroids/46...
#TeamRadar approved.
#TeamRadar (and also one of my advisors' advisor).
FOURTH TEST OF GENERAL RELATIVITY: PRELIMINARY RESULTS Irwin I. Shapiro, Gordon H. Pettengill, Michael E. Ash, Melvin L. Stone, William B. Smith, Richard P. Ingalls, and Richard A. Brockelman Lincoln Laboratory, t Massachusetts Institute of Technology, Lexington, Massachusetts (Received ll March 1968) Several years ago it became evident that a new test of general relativity was technically feasi- ' ble. The proposed experiment was designed to verify the prediction that the speed of propaga- tion of a light ray decreases as it passes through a region of increasing gravitational potential. Far a radar pulse transmitted from the earth and reflected by another planet, the increase in the round-trip time delay, attributable to the predicted gravitational influence of the sun on the propagation, would be =200 p, sec if the path of the pulse were to graze the solar limb.
Shapiro et al tested the idea in 1966-67, first with Venus and then with Mercury, at MIT's Lincoln Laboratory Haystack radar site ( #TeamRadar ).
The results agreed with the predictions of general relativity to well within the expected uncertainties. (4/n)
journals.aps.org/prl/abstract...
As well as it being unavailable for spacecraft communications; #TeamRadar observations with DSS-14 have been canceled since September: echo.jpl.nasa.gov/asteroids/go...
#TeamRadar
Lazio et al. 2025, "The Next-Generation Ground-Based Planetary Radar" - www.kiss.caltech.edu/final_report...
Emerson Wittaker: talking about near earth asteroid binary 1999 KW4: Moshup 1.5km and Squannit 0.5km, mutual orbit in 17 hours. Measured by #TeamRadar from Arecibo (😭)
Evolution of system depends on YORP effect, relative spins of bodies, and shapes.
Doing shape-model libration simulations now […]
Today on the #arXiv :
White et al. 2025, "Ground-Based Radar Tracking of Near-Earth Objects With VLBI Radio Telescopes: 2024 MK Test Case" - arxiv.org/abs/2509.15684
#TeamRadar
Transmitting with DSS-43 and DSS-35 and receiving with antennas across Australia.
I have a 3D print of the old #TeamRadar #1998KY26 shape model, which was always suspiciously symmetric - because it turned out to be aliased.
Maybe I should order a new one.
bsky.app/profile/agas...
Check out our tiny rock featured by @eso.org !
Now available in Nature Comms: www.nature.com/articles/s41...
We measured the size using the new lightcurve shape models and old radar data #TeamRadar
📡🪨🔭🧪
#TeamRadar has a large block of presentations at #EPSCDPS2025:
Zambrano Marin reviews the Arecibo radar data archive - meetingorganizer.copernicus.org/EPSC-DPS2025...
Cannon et al. presents shape models of the contact binaries 2024 ON and 2000 RS11: meetingorganizer.copernicus.org/EPSC-DPS2025...
The #TeamRadar sessions at #EPSCDPS2025 begin with @avirkki.bsky.social reviewing the relationships between the properties of planetary surfaces and how they scatter radar beams: meetingorganizer.copernicus.org/EPSC-DPS2025...
Rick highlighted #TeamRadar radar astrometry of #Apophis and its role in ruling out any possibility of impact in the foreseeable future.
Per Brozovic et al. 2018 - echo.jpl.nasa.gov/asteroids/br...
For a very basic version of this:
When #TeamRadar does radar observations of objects in the solar system; we cycle between transmitter and receiver, switching every round-trip-travel-time to the target.
So we see radar light from Saturn's rings for a couple of hours after we turned off the source.
Neither 2I nor 3I passed close enough to Earth for #TeamRadar to detect, either with Goldstone or with Arecibo before it collapsed.
1I passed just close enough to potentially detect with Arecibo on 2017 October 15-16; but it was only discovered on October 19, by when it was too far out again.
I class radio and radar astronomy together.
#TeamRadar just does not rely upon the universe for our photons (to quote @sondy.com).
Also today on the #arXiv:
Fan, Wright, & Lazio 2025, "Detecting Extraterrestrial Civilizations That Employ an Earth-level Deep Space Network" - arxiv.org/abs/2508.15425
Updating studies of the radio leakage from spacecraft communications and #TeamRadar observations.
And, in case anyone is confused:
Speckle imaging as done here is entirely different from speckle tracking as done by #TeamRadar.
Since I was asked:
Interstellar object 3I / #A11pl3Z will not be passing close enough to Earth to be observed by #TeamRadar.
Alas for the loss of Arecibo (although depending on the exact size of 3I, even Arecibo might not have been enough).
Nice article about #TeamRadar by @astrowriter.bsky.social in Space.com today:
www.space.com/astronomy/as...
#TeamRadar presentations at #PDC2025, continued:
Pupillo et al., "Radar Observation of Asteroids 2005 LW3 and 2006 WB with European Radio Telescopes" - iaa.4hdt.ro/event/1/cont... .
Venditti et al., "The potentially hazardous binary asteroid (285263) 1998 QE2" - iaa.4hdt.ro/event/1/cont...
#TeamRadar presentations at #PDC2025, continued:
Calves et al., "Radar and optical tracking of Near-Earth Objects at the University of Tasmania" iaa.4hdt.ro/event/1/cont...
Horiuchi et al., "Southern Hemisphere Asteroid Radar Program (SHARP)" iaa.4hdt.ro/event/1/cont...
