S-band Spotlight

Observ-a-thon reveals comet nucleus, holiday asteroid, and more!

(left) Arecibo radar observations reveal details of Comet 46P/Wirtanen, including the first definitive measurements of its size! (right) Additionally, using a bistatic configuration, where Arecibo emitted and the Green Bank telescope in West Virginia received, the team captured detailed radar images of near-Earth asteroid 2003 SD220, a slow rotator first imaged by Arecibo in 2015. Find out more here!

About Us


The Planetary Radar Science group is a department of the Arecibo Observatory, which is an NSF facility operated under cooperative agreement by the University of Central Florida (UCF), Yang Enterprises, Inc. (YEI), and la Universidad Metropolitana (UMET). The Arecibo Observatory Planetary Radar program is fully funded by NASA's Near-Earth Object Observations program.

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Recently Observed Objects


For media inquiries, please contact our communications lead, Ricardo Correa

All observations in 2019 - most recent first

1999 VF22
2019 CT1
2019 CN2
2013 CW32
2019 BJ1
2019 BG3
2019 AP11
433 Eros
2019 AV2
2018 XN
2019 AK3
2018 XV
2019 AR2
2019 AW7 - taken from Minor Planet Center's confirmation page as C00GG11
2019 AX5
2016 AZ8

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.

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
2016 AZ8 Jan 02-04 High-res Imaging 21.1 Y Y BINARY!, period unknown
433 Eros Jan 25-Feb 16 Imaging 10.5 Y 5.27-h period
455176 (1999 VF22) Feb 19-21 Imaging 20.6 Y PHA, period unknown
2015 EG Mar 05-07 Imaging 25.7 5 arcmin Y NHATS, 1.29-h period
88254 (2001 FM129) Mar 13-14 Imaging 17.6 Y PHA, period unknown
522684 (2016 JP) Apr 16-23 High-res Imaging 21.1 Y PHA, 37.4-h period

The following may be detectable if scheduled for radar observations. 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 it is potentially hazardous or NHATS-compliant, 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
2019 BF1 Feb 22-25 Astrometry 22.6 0.5 arcmin Medium Period unknown
2019 CT4 Feb 27-Mar 01 Astrometry 24.2 10 deg Low Period unknown
2016 EO84 Feb 25-Mar 05 Astrometry 22.3 22 arcmin Low Period unknown
2018 VX8 May 10-11 Imaging 22.4 46 arcmin High Period unknown

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