2015BK515 | Kleinplaneten Entdecker Erwin Schwab

Discovery of the hazardous asteroid 2015 BK515 in collaboration with ESA

2015 February – The potentially hazardous asteroid 2015 BK515 was found by amateur astronomer Erwin Schwab (Germany), working as volunteer scientist with ESA’s Space Situational Awareness programme. He conducted his asteroid hunt in January 2015 during an observation slot at the European Space Agency’s Optical Ground Station (ESA OGS) in Tenerife, Spain.

Detlef Koschny, head of ESA’s Near Earth Objects Segment in the Space Situational Awareness (SSA) programme, determined Erwin Schwab to plan and analyze the searching for lost hazardous asteroids. His scheduled target was the Near Earth Object (NEO) 2013 GD34, which Schwab could find 0.4° away (about the apparent size of the Moon) from the predicted position. After this successful recovery by releasing a Minor Planet Electronic Circular announcing the new observations, Schwab checked the picture for unknown objects using the software Astrometrica. Very close to the edge of the field he found an unidentifiable fast moving object and submitted the position measurements to the US-based Minor Planet Center, which collect all asteroid measurements from observers worldwide.

When the discovered asteroid belongs with high probability to the class of Near Earth Objects, follow-up observations must be done extremely fast to ensure it is not subsequently lost. Therefore the Minor Planet Center had listed this new NEO candidate immediately as Schw684 (the discoverer’s reported designation) onto the Near Earth Objects Confirmation webpage to inform other Observatories as quickly as possible. But the high star density in the area of the new object made follow-up observations very difficult.


Animation of Discovery images from 19.1.2015 credit: ESA / E. Schwab Detail of 5×5 arc minutes, unedited original field has 47×47 arc minutes	Animation of Confirmation images from 27.1.2015 credit: DLR / S. Hellmich & S. Mottola

Fortunately a week after discovery the confirmation succeed by Stephan Hellmich and Stefano Mottola using the 1.2m reflector at the Calar Alto Observatory in Spain. On 2015 February 7. the discovery was published in the Minor Planet Electronic Circular and the result of orbit determination showed that 2015 BK515 is a hazardous Asteroid, which can approach the Earth closer than about 7 million km.

: sky view of recovery field for 2013 GD34 together with discovered 2015 BK515

Detailed article of the discovery story published in VdS-Journal 4/2015 (Nr. 55), page 46-49 in german

Table of the next close approaches, brighter 22. magnitude, calculated with FINDORB after 24-day-arc elements:

Date	distance to Earth	magnitudes
2015 June	0,261 AU	20,6 mag
2022 April	0,090 AU	19,4 mag
2029 February	0,204 AU	19,9 mag
2036 August	0,820 AU	21,9 mag
2052 July	0,430 AU	21,7 mag
2059 June	0,115 AU	18,6 mag
2066 March	0,058 AU	17,0 mag