About Us


The Planetary Radar Science group is a department of the Arecibo Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by the University of Central Florida (UCF), Yang Enterprises, Inc. (YEI), and Universidad Ana G. Mendez (UAGM).

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The Arecibo Observatory Planetary Radar program is fully funded by NASA's Solar System Observations program and proudly supports NASA's efforts to track and characterize near-Earth objects for planetary defense. For information about asteroid and comet orbits, including close approaches to Earth, please see the websites of the NASA Center for Near-Earth Object Studies and the NASA Planetary Defense Coordination Office.

S-band Spotlight

Arecibo Continues Operations through Pandemic to Observe Potentially Hazardous Asteroid 1998 OR2

Arecibo, Puerto Rico - April 23, 2020

The Arecibo Observatory is using its powerful radar system to track (52768) 1998 OR2, a near-Earth asteroid that will safely pass the Earth at a distance 16 times further than the distance to the Moon on April 29.

The radar data confirm that 1998 OR2 is approximately 2 km in diameter and rotates once every 4.1 hours, as was suggested by optical observations. The range-Doppler images uniquely revealed the overall shape of the asteroid and some smaller-scale topographic features, such as hills and ridges.

(Left) Mosaic of range-Doppler radar images of (52768) 1998 OR2 obtained on April 19-20 UT reveal the near-Earth asteroid to be approximately 2 km in diameter (7.5 m/pixel vertically) with a crater-like concavity rotating across the radar-illuminated side (top of image) during roughly 2 hours of radar imaging. (Right) Animation of delay-Doppler images from Apr 18 UT. Image credit: Arecibo Observatory/NASA/NSF.

The scientists and telescope operators at the observatory have been adhering to health and safety guidelines, limiting the number of observing scientists at the telescope and wearing masks during the observations in response to the COVID-19 pandemic.

Arecibo radar observations were collected April 13th and every day between April 16th through April 23rd. The team of observers includes Drs. Anne Virkki, Flaviane Venditti, and Sean Marshall from UCF/Arecibo Planetary Group, Dr. Patrick Taylor (remotely) from the Lunar and Planetary Institute in Houston, TX, and the Arecibo telescope operators Israel Cabrera, Elliot Gonzalez, and Daniel Padilla.

In an international collaborative effort, the Svetloe Radio Astronomical Observatory near St. Petersburg, Russia, has also been receiving the AO radar waves that were bounced off of 1998 OR2 with their 32-meter radio telescope.

Click here for the press release about these observations!

Recently Observed Objects


Past Observations

Upcoming Radar Targets

The following tables list: (1) targets with submitted observing proposals, including those from our annual high and medium priority proposals and (2) possible radar targets, often newly discovered asteroids, that may be detectable, but have not yet been scheduled for observation. Further details on these objects are available including SNR estimates, specific observing tracks, and pointing, Doppler, and range uncertainties.

These tables are not comprehensive lists of all asteroids visible from Arecibo. For more complete lists of possible targets of opportunity and long-term future radar targets, updated daily, see: all asteroids visible today (SNR > 2/day), this month (SNR > 2/day), and in the next five years (SNR > 100/day). Note that these tables inevitably include objects that are currently "lost," often suggested by "1d" in the Type column, which stands for "one apparition with a days-long arc," so observer beware!

Requests for Optical/Infrared Observations

Astrometry: optical astrometry is specifically requested for objects with three-sigma plane-of-sky pointing uncertainties (from the JPL Horizons database) of tens of arcseconds or more. The plane-of-sky uncertainties refer to the first date of the radar observing window listed. Often these are lower limits as the pointing uncertainty often grows with time, especially for newly discovered objects; however, in some cases the pointing uncertainty is much lower prior to the object entering the Arecibo field of view. Optical observers are asked to submit astrometry to the Minor Planet Center as soon as possible after observations.

Lightcurves: optical lightcurves and period estimates are specifically requested for objects that will produce high-resolution images (i.e., possible shape models), for targets of IRTF thermal-infrared observations, for candidate binary asteroids, and for potential human-exploration targets. Lightcurve observers are asked to relay period estimates to the radar team to help with the planning of radar observations. During the analysis and modeling process, the radar team may request to use available lightcurve data.

Spectra: spectra refers broadly to optical or infrared spectra and colors, which are most important for completeness of the strongest radar targets, for candidate binary asteroids, and for potential human-exploration targets. Observers are asked to relay probable spectral-class information to the radar team to compare with characteristics suggested by radar.

Object Dates Expected
H mag Request
441987 (2010 NY65) Jun 19-28 High-res Imaging 21.5 Y Y PHA, 5.5-h period, Yarkovsky?
144411 (2004 EW9) Jun 21-04 High-res Imaging 16.6 Y Y 49.9-h period
242450 (2004 QY2) Jul 08 Astrometry 14.7 PHA, period unknown
2016 YO3 Jul 09 Astrometry 20.1 Period unknown
2006 NL Jul 10-11 Imaging 20.0 Y Period unknown
2004 XP14 Jul 10-19 Astrometry 19.4 PHA, long period?
8014 (1990 MF) Jul 13-17 High-res Imaging 18.7 Y Y PHA, period unknown
480936 (2003 QH5) Jul 17 Astrometry 20.1 PHA, period unknown
85989 (1999 JD6) Jul 23-24 Imaging 17.1 Y PHA, 7.7-h period
2015 FP332 Jul 25 Astrometry 17.3 Period unknown
2002 BF25 Jul 26-27 Imaging 22.2 Y NHATS, period unknown

The following may be detectable if scheduled for radar observations. Further details on these objects are available including SNR estimates, specific observing tracks, and pointing, Doppler, and range uncertainties. Requests for optical astrometry are indicated where the pointing uncertainties are a significant fraction of, or larger than, our 2 arcmin pencil beam. Priority level (high, medium, low) is noted: high = likely to propose urgent radar observations, medium = may observe as a target of opportunity during other scheduled observations, low = unlikely to pursue. Priority level is subjective and is based on how detectable the object is, whether the object is potentially hazardous, NHATS-compliant, or on the SENTRY list of possible impactors, and how likely it is to be scheduled. Objects may move from this table to the table above as they are scheduled on the telescope.

Object Dates Expected
H mag Request
Priority Level Notes
2020 MX3 Jul 26-29 Astrometry 23.6 1 deg! Medium Period unknown

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