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Discovery of PHA 2009 BD81

Animated Discovery Image of 2009 BD81

 

On January 31, 2009 a Potentially Hazardous Asteroid (PHA) 2009 BD81 was discovered at ARO by Observer R. Holmes, measurers S. Kirby, K. Dankov, H. Devore and was published in MPEC 2009-C09 on February 2nd 2009.  At the time of discovery the ARO 0.61-m telescope was performing routine follow-up astrometric observations on NEO 2008 EV5.  Immediately I knew any unknown object at a declination of 72 degrees north had to be an interesting object with an unusual orbit.  2009 BD81 was discovered at 0225 UT on 31 January by the Astronomical Research Observatory which observed it at January 31.10 and February 2.30.  The NEO discovery was confirmed by Silver Spring Observatory on February 2.13, Sandlot Observatory on February 2.15 and Magdalena Ridge Observatory on February 2.28.  After checking the Minor Planet Center's NEO rating page, the measures returned an indication of 100% and there was no known objects with this speed and position angle in the region.  Additional data was obtained before sending the astrometry to the MPC using the Find Orb, Orbit Determination Software.  Initial indications returned a MOID of 0.0683 with perihelion expected on 2009 03 20.55 which immediately revealed an indication that this might be a near earth object.  The phase angle at the time of discovery was 62.3 percent at a unfiltered magnitude 19.10.  The discovery observation span a total of 29 minutes. 

Discovery Image - PHA 2009 BD81 (left)   -   PHA 2008 EV5 (right)

2009 BD81 will make its closest approach to Earth on this opposition on February 27th 2009. 

 

 

Based on data at the NASA/JPL risk web page the object has a diameter 0.314 km (H = 20.2) and currently has a potential of 10 impact risks over the next 100 years beginning in the year 2042-03-04.58.  On that date, it is calculated that 2009 BD81 will pass about 5.5 earth radii from earth.  At the time of writing the chances of an impact are extremely low at 1 in 2,439,000.   Currently there are 1,015 known PHAs including 2009 BD81. 

The orbital period is 1,643.87 days with a semi-major axis larger that Earth's making this an Apollo class class object with a very elliptical orbit extending nearly to the planet Jupiter.  Furthermore this object has a Minimum Orbit Intersection Distance (MOID) with earth that is 0.05 astronomical units (roughly 7,480,000 km or 4,650,000 mi) or less with an absolute magnitude greater than H = 22 (150-m or about 500 feet in diameter).

 

Note:  H - Absolute Magnitude, a measure of the intrinsic brightness of the object.