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


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
66391 (1999 KW4) May 29-Jun 04 High-res Imaging 16.5 Y Y BINARY, PHA, IAWN Campaign
11500 Tomaiyowit Jun 21 Astrometry 18.3 PHA, 73-h period
2009 BE2 Jun 23 Astrometry 19.2 Period unknown
441987 (2010 NY65) Jun 19-29 High-res Imaging 21.5 Y PHA, 5.5-h period, Yarkovsky?
494999 (2010 JU39) Jun 26-28 Imaging 19.6 Y PHA, period unknown
90403 (2003 YE45) Jun 26-Jul 08 High-res Imaging 17.6 Y PHA, 500-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 LU Jun 18-20 Astrometry 25.0 Medium Period unknown
2019 JF1 Sep 01-07 Astrometry 23.9 3 arcmin Medium NHATS, period unknown

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