Don’t miss the close flyby of bright space rock 1998 HL1, 25–29 October

By Ade Ashford

Believed to be 440–990 metres in size, Apollo asteroid 162082 (1998 HL1) passes just 6.2 million kilometres or slightly more than 16 lunar distances from Earth on the UK evening of Friday, 25 October. The body is predicted to peak at magnitude +12.4, making it a viable target for 15-cm (6-inch) telescopes and larger. Click the graphic to be taken to an interactive HTML5 applet. Image credit: Orbit Viewer (JPL)/ Ade Ashford (AN).
If any clear skies occur during the last week of October, don’t miss any opportunities to view a 700-metre-wide space rock with the catchy designation 162082 (1998 HL1) as it hurtles past our planet slightly more than sixteen lunar distances away at 17:20 UT (6:20pm BST) on 25 October 2019.

Predicted to reach a peak magnitude of +12.4 on 27 October, this near-Earth asteroid is a viable target for 6-inch (15-cm) aperture telescopes and larger for five nights as it zips through the constellations of Triangulum, Aries and into Cetus at rates of up to 9 degrees/day relative to the background stars. (See the bottom of this page for a table of predicted positions at hourly intervals for observers in the UK and Western Europe.)

Classed as a Potentially Hazardous Asteroid (PHA), 162082 (1998 HL1) is magnitude +13 or brighter as it speeds southeast through the constellations of Triangulum, Aries and Cetus between 25 and 29 October. At its closest to Earth on the 25th, 1998 HL1 is travelling at a rate of 9 degrees/day against the background stars. The asteroid passes just 0.4° – less than a lunar diameter – east of Uranus around 13:30 UT on 27 October, an event observable from the antipodes. Click the graphic for a scaleable PDF version with stars to magnitude +7 suitable for printing. AN graphic by Ade Ashford.
Although classified as a Potentially Hazardous Asteroid (PHA), there is no chance that 1998 HL1 could collide with Earth for at least 120 years. The next time it passes closer to Earth than this apparition is on 26 October 2140 when it zips by our planet at a distance of 6.18 million kilometres, or 3.8 million miles.
Asteroid 162082 (1998 HL1) moved 40 arcseconds against the constellation backdrop of Cetus during this 2-minute exposure (ISO1600) with an astromodified Canon 550D DSLR at the focus of a SharpStar 150mm f/2.8 hyperbolic Newtonian astrograph on 27 October 2019, 22:17-22:19UT. The 700-metre-wide body was close to its peak magnitude of +12.5 and stars to magnitude +17 are shown across a cropped 0.4-degree field. Image credit: Ade Ashford.
Discovered by the Lincoln Near-Earth Asteroid Research (LINEAR) project at Socorro, New Mexico on 18 April 1998, 162082 (1998 HL1) is an Apollo-type asteroid that loops the Sun once every 508 days in an eccentric orbit inclined by 20 degrees to the ecliptic.
The table above shows the position of asteroid 1998 HL1 every hour for the interval that it is brightest and visible from the UK and Western Europe. Universal Time (UT) is used, so add one hour for British Summer Time (BST) until 02h UT on 27 October. Topocentric central UK equatorial coordinates are for the current epoch (J2019.8) for direct entry into digital setting circles or GoTo mount hand controllers. The asteroid’s predicted visual magnitude (Mag.) and distance in astronomical units (delta) are also shown. Data credit: Minor Planet Center / NASA HORIZONS / Ade Ashford.