Potentially Hazardous Asteroid 2008 BT18

[Dennis]

Hello,

The attached image shows the trail of Potentially Hazardous Asteroid 2008 BT18 (mag 13) as recorded from Brisbane on 20th July, 2008 from 4:38am to 5:23am AEST. Tak Mewlon 180 F12 with ST7E ccd.

Data about this PHA can be found here (http://ssd.jpl.nasa.gov/sbdb.cgi):

Its approximate diameter is 770 metres and its closest approach to Earth was approx. 5.8 Lunar Distances, on 15th July 2008. So, while you were all sleeping in the wee hours of today, I was out there, at my station, on PHA look out, watching your backs!

Another great NEO/PHA website is here (http://hohmanntransfer.com/#top):

Cheers

Dennis

[AlexN]

Glad someone is out there standing guard.. :D

My question is this.. Whilst you are 'watching our backs, If it all goes pair shaped, what are you going to do to protect us from a 770m asteroid? Got some superman abilities that your not telling us about hmm??


All seriousness though, its a good image.. The asteroid sure traveled a long way in the field of view.. Any ideas of what its made of? Surely NASA have some idea, but whether or not its public is another thing..

[Dennis]

Hi Alex

I’ve got Bruce Willis on speed dial, just in case we need him and his crew to change the orbit of any rogue NEOs (Near Earth Objects) or worse still, PHAs (Potentially Hazardous Asteroids)! LOL!

I periodically obtain forward looking data on these events from SpaceWeather (http://spaceweather.com/) as I find it quite interesting, and challenging, to record their fleeting passage against the fixed back ground stars.

What is quite fascinating is that when I first started this as a sub-set of astro photography, the number of PHAs were around 600 and I note from SpaceWeather, the count is now up to 962 as of the date of this post!

From a vague (and tired) memory, I think they are mainly rocky bodies?

Cheers

Dennis

[Dennis]

Hello

I was going over some of the frames of 2008 BT18 when I noticed that several appeared to suggest some type of gap or discontinuity in the “dashes” recording the passage of 2008 BT during each 60 second exposure.

I selected one frame and ran a contour plot in MIRA AP with an interesting result. On Frame 2008_BT18.00000029, a Contour plot in MIRA AP shows a gap between peaks of around 10 pixels.

At an image scale of 0.81 arcsec/pixel, this would suggest a separation of some 8 arcsecs between two components of 2008 BT18, if this is a real effect and not a system or processing artefact.

On the other hand, maybe this can be attributed to some periodic error in the mount?

SpaceWeather (http://www.spaceweather.com/archive.php?view=1&day=13&month=07&year=2008) on 13th July 2008 mentions the binary nature of this asteroid.

Cheers

Dennis

[sheeny]

Very interesting, Dennis. Well done.



And I thought you would blasted it to smithereens with your trusty 5mW green laser pointer...:rolleyes:

Al.

[jjjnettie]

Have no fear, Dennis is here!

Very nice capture too.
Lots of detail considering how small it is.
I made an 8 frame .gif showing the rotation. It could be done better using all the images, maybe I'll work on it tonight.

[Dennis]

Whoops! Forget my gibberish from the previous post!:doh:

2008 BT18 distance from Earth was over 10 LD’s, so being very conservative, let’s put it at 3,780,000kms. Now if I can dredge up some very, very rusty trigonometry, I think that:

Tan ⊖ = Opposite/Adjacent.

Assume a peak to peak separation of 600 metres. Half this is 300 metres.

So we get Tan ⊖ = 0.3/3,780,000 = 0.000000079 degrees

Which is a meagre 0.00028 arcsecs, much, much smaller than my estimate of 4 arcsecs.

Oh well, back to kindergarten for me!:lol::lol:

Cheers

Dennis

[h0ughy]

awesome result Dennis!!

[Dennis]

Why thank you Dave - glad to see you up and about again!

Cheers

Dennis

[John K]

Amazing images Dennis, well done on the capture. Scary looking object. Lets hope it does not come any closer!