S-band Spotlight

Arecibo radar tracks close flyby of asteroid 2019 OK

On July 24, 2019, the near-Earth asteroid 2019 OK passed by the Earth at 1/5 of the distance to the moon. The object is between 50 - 130 meters in size, but was detected just 24 hours before its close flyby. Arecibo radar was used to greatly refine the asteroid's predicted orbit so that it can be tracked for the next century.

The figure on the left shows the detection of the asteroid from Arecibo radar. The 30 Hz offset of the reflected radio signal is used to refine the velocity and predicted trajectory of 2019 OK. The width of the observed signal is used to determine its rotation period. On the right, a schematic from JPL Horizons shows the proximity of 2019 OK to Earth during its close flyby.

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

2019 QY1
2010 JG
2019 UN12
481394 (2006 SF6)
2005 WD
2019 UL8
2015 JD1
2019 UG12
2019 UT7
2016 TH94
2019 UF5
162082 (1998 HL1)
2019 SL7
2019 TM
2019 SX3
2019 SU3
2019 SD8
2019 SE8
2019 SW5 - taken from Minor Planet Center's confirmation page as A10gg2c
2019 SH3
2019 SP
537342 (2015 KN120)
354030 (2001 RB18)
2017 SL16
2019 RC
465617 (2009 EK1)
523934 (1998 FF14)
2019 RX1
2019 QZ3
2019 RA
2100 Ra-Shalom (1978 RA)
237805 (2002 CF26)
2019 GT3
2016 PD1
153814 (2001 WN5)
2019 PZ2
141593 (2002 HK12)
525364 (2005 CL7)
66146 (1998 TU3)
454094 (2013 BZ45)
2019 OK
2019 OD
10145 (1994 CK1)
2019 KD3
2016 OF
2019 NE2
2019 NN3
2019 NX1
2019 MF1
2019 MT
494999 (2010 JU39)
2019 LV1
90403 (2003 YE45)
418900 (2009 BE2)
11500 Tomaiyowit
441987 (2010 NY65)
2019 LU
2019 KZ3
2019 KA4
2019 KG2
2011 HP
66391 (1999 KW4) - BINARY!
68950 (2002 QF15)
2019 KV
2019 JL3
2019 JU5
528159 (2008 HS3)
2019 JN2
2019 JG1
12538 (1998 OH)
2018 VX8
2009 FU23
2019 JJ3 - taken from Minor Planet Center's confirmation page as C0MDCQ2
2019 GT1
2019 JE
152931 (2000 EA107)
2018 XG5
2019 FN2
2019 GM4
522684 (2016 JP)
2019 GN4
2019 GO4
2016 GW221
2019 GL4
2019 GJ4
2019 FU
2019 EN
2019 CL2
88254 (2001 FM129)
2019 CD5
525477 (2005 FC3)
2019 DN
2015 EG
455176 (1999 VF22)
2019 CT1
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
162082 (1998 HL1) Oct 25-28 High-res Imaging 18.9 Y Y PHA, period unknown, Q/Sq?
2015 JD1 Nov 01-04 High-res Imaging 20.6 Y Y PHA, period unknown
481394 (2006 SF6) Nov 10-14 High-res Imaging 19.9 Y Y PHA, NHATS, 5.75 or 11.5 h period?
2005 WD Nov 10 Astrometry 21.9 PHA, period unknown
2010 JG Nov 11-12 Imaging 20.9 Y PHA, period unknown
2011 YS62 Nov 13-17 High-res Imaging 19.7 Y Period unknown
85236 (1993 KH) Nov 13 Astrometry 18.6 Period unknown
2011 WN15 Dec 12-13 Imaging 19.6 Y PHA, period unknown
216258 (2006 WH1) Dec 13-14 Imaging 20.2 Y PHA, period unknown
264357 (2000 AZ93) Dec 17 Astrometry 21.0 PHA, period unknown

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 VN Nov 09-13 Astrometry 25.3 Low Period ~ 0.02 h
2019 QY1 Nov 09-15 Astrometry 20.7 Medium PHA; period unknown
2019 VF1 Nov 23-25 Astrometry 23.0 10 arcmin Medium Period unknown
2019 VK Nov 25-27 Astrometry 24.6 Medium Period unknown
2019 UO Dec 25-30 Astrometry 19.8 2 arcmin Medium PHA; period ~ 7.79 h
2019 UO9 Apr 26-27 Astrometry 19.7 3 deg! Medium PHA; period unknown

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