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Tuesday, October 27, 2015

 

UPDATED: Watching NEO 2015 TB145 from Australia (31 October, 2015)

NEO 2015 TB145 at midnight on 31 October 2015, it is just above the shield of Orion. Click to embiggen.NEO 2015 TB145 at astronomical twilight on 31 October 2015, it has moved towards the bottom of the shield of Orion. Click to embiggen.

UPDATED! with charts based on the latest ephemeris. 

Near Earth Asteroid 2015 TB145 with an  estimated diameter of around 460 m will come relatively close to Earth on 17:01 UT, 31 October (4:01 am 1 Nov AEDST) at distance of 0.003 AU (around 1.3 Earth-Moon distances, ie it is further away from us than the Moon, so there is no chance it will hit us). It is brightest at 14:30 UT on the 31st though (1:30 am 1 Nov AEDST).

At this time the asteroid will be a reasonably bright magnitude 10.1, easily visible in small telescopes and strong astronomical binoculars. Unfortunately from Australia we will be unable to see it as it is in the northern sky, only visible from the northern hemisphere.
Black and white chart suitable for printing showing the track of the asteroid from midnight to sunrise and beyond on 31 October. The circle shows the field of view of 10x50 binoculars (although you will not be able to see it in binoculars, this simulates the FOV of a finder scope).

The asteroid is near Orion's Shield. Tick marks are an 30 minutes apart. Click to embiggen and print. Use the charts up above to orient yourself first.

NEO 2015 TB145 moves from Taurus to Orion, then back into Taurus (crossing the horns of the Bull), into Auriga (where it is brightest) then on to Lynx and beyond.

Australia's best  view is on the morning of the 31st, when the asteroid brightens from magnitude 13 to magnitude 12.5. It will be visible in amateur telescopes (as a faint dot), however, the still bright waning Moon 17 degrees away will make it a bit tricky to spot (probably reflectors of 6" and up are needed, not sure about refractors, the bigger the better). Its movement should be obvious over several minutes in a medium power telescope eyepiece.
Black and white chart suitable for printing showing the track of the asteroid from midnight to sunrise and beyond on 31 October. This chart is suitable for telescopes. The chart is inverted with respect to the finder chart above.

The circle is the field of view of a 20 mm eyepiece with a  4" Newtonian reflector scope. Tick marks are 30 minutes apart. Click to embiggen and print. Use the binocular charts up above to orient yourself first

The asteroid is currently magnitude 16.5, and  will not really be accessible to modest amateur equipment until the 30th. You can get an accurate ephemeris for your location from the Minor Planet Ephemeris Centre or JPL horizons. While the orbit is pretty well established, it is still best  to wait a few more days to generate an ephemeris as even better position data is gathered.

Stellarium chart showing the location of the asteroid at 4:40 am on 31 October. The chart is in the same orientation and shows most of the same stars, at a slightly different magnification, as the printable chart above. Click to embiggen.

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Comments:
Why does Neodys say that the close approach probability is 1.00e-0 on Oct. 31? And why does the minimum distance to from .014 to .007AU on Nov. 1?
 
Hi friends . I captured this wonderful planetary conjunctions of Venus, Jupiter and Mars! Early morning on 28 October. 3 planets so close together are 'rare and beautiful sight'. Would like to share it with you.
https://youtu.be/UklZq12xSj8
 
Hi friends . I captured this wonderful planetary conjunctions of Venus, Jupiter and Mars! Early morning on 28 October. 3 planets so close together are 'rare and beautiful sight'. Would like to share it with you.
https://youtu.be/UklZq12xSj8
 
Revo, the close approach probability means that it actually makes a close approach (in the other cases there is uncertainty whether it will come within 5 Earth-Moon distances). The decreased Nov 1 disturbance is simply due to the better understanding of the orbit as we get more observations, the asteroid still comes no closer than 0.0032 AU at its closest (still around 1.3 Earth-Moon distances)
 
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