Seeing Asteroid 2005 YU55

[ravnostic]

Space.com was nice enough to provide a little sky map of where to find the asteroid that’s whizzing by us tonight:

http://www.space.com/13541-asteroid-2005-yu55-close-approach-earth-preview.html

Basically, around 10:30pm EST, 9:30 CST, 8:30MST, or 7:30 PST, it will be about 4 degrees north of Markab, in the constellation Pegasus, moving counter-clockwise with respect to the poles and background stars, in a line nearly parallel to that between Markab and Algenib, at a rate of around 4 degrees per hour (about the width of 8 moons).

I did the mathz, and even with my 11″ Celestron, I don’t think it will appear as anything more than a point of light (but I think I’ll try to prove me wrong on that!).

But if you have a tripod, multiple shots of the great square of Pegasus taken 15 or so minutes apart should reveal it. I’d suggest a high ISO, noise reduction and mirror-lock-up turned ‘on’, and as long an exposure as you can take without star trails (600 divided by effective lens focal length–don’t forget to compensate for smaller sensor sizes!!)

Alternately, a 15 minute exposure with star trails would reveal it, also–it would be the ‘star’ that moves out-of-step with the other star trails (by about the width of the moon over that period of time–which should be noticeable, though with some difficulty. At 11th magnitude, it may be necessary for an exposure this long to capture it (11th magnitude is some 100 times dimmer than what the human eye can see).

Pegasus will be in the northwest on the east coast at that time, and very nearly directly overhead on the west coast; it looks very much like the big and little dippers, only bigger–it’s ‘bowl’ (the great square) is pretty evident as 4 bright stars, quite nearly square in shape.

For Farktographer et al in London’s time zone, 3 hours earlier when Pegasus is high above your head, it will be north of Enif (hold your right arm out, make a fist, put your thumb out like you were a hitchhiker and place over Markab; it’s the bright star near your pinky knuckle.) For Plama out in Hawaii, at 9:30 it will be 4 or so degrees N. of Algenib having moved across the Square of Pegasus in the 4 hours between.

Hope some of you out there will try to get some shots. I’m pretty certain at this point that I will be breaking out the scope to try to do the same, and will post if I get anything worth posting about.

//edit: fixed a trajectory error.

[Farktographer]

I was reading up on this earlier today. The article on BBC said a 15-inch telescope lens would get you an okay look, but it’s still going to be quite a ways off. I’ll see if I can find a nook outside the city that’s plenty dark for me to get starlight, then try to get the asteroid as per your very helpful suggestions.

[ravnostic]

I had to amend the post (twice!), to clarify something about it’s path. With respect to the stars and the pole star, it will be moving clockwise (easterly). But with respect to the sky and our view of it, it will be moving counter clockwise (westerly). As it happens, Markab and Algenib are each about the same distance away from Polaris, and since the asteroids path is tangent to those two stars, there are some goods and bads that will be associated with capturing it on film (or sensor, which would be easier), I think.

I’m no astrophysicist (can we have an astrophysicist to the podium, please, Plama?), but I’m thinking since it’s moving against, yet parallel to, the background sky, then in a 15 minute exposure, the stars will have moved about 4 degrees, but the asteroid (at 8:30 MST) only 3 (these are loose approximations). So the asteroid will be spending some 33% more time in a given point in the sky than the background stars–this should make it appear some 33% brighter in long exposure (or technically short exposure too) photos.

Unfortunately, that difference isn’t much–about some .3 magnitudes? And in the photo, since the movement would more-or-less follow the same arc of the stars, it might be trickier to identify. I’m hoping for a counter-arc appearance, or at least a measurable difference in trailing.

Since I think A-focal via the telescope would be very difficult for me (and it’s cold outside), I’ll piggyback the 70-300 on the scope. I’ll still suffer from axis rotation (a lot–when objects are high in the sky, the alt-az can almost spin of it’s own accord), but should be able to get enough FOV and enough light to be able to ID the thing. I hope. It doesn’t help that the moon is so strong.

Fingers crossed. My application is strong this year–a condemnation from the mayor…:-D

[Farktographer]

I have rainy skies and clouds covering the area around me. No shooting for the next couple nights -_-

[Kestrana]

We have a pretty significant telescope here if we can make it work right (apparently when we tried it in Connecticut it thought it was still in upstate New York; now that we know that, it should solve some problems). Should have clear, cold skies tonight.

[olavf]

Any of you astro-nuts know of anything worth watching for from Southern CA around the 19th of this month? Other than any potential clouds, the sky isn’t going to be any darker for me for a while…

[Plamadude30k]

I’m no astrophysicist (can we have an astrophysicist to the podium, please, Plama?), but I’m thinking since it’s moving against, yet parallel to, the background sky, then in a 15 minute exposure, the stars will have moved about 4 degrees, but the asteroid (at 8:30 MST) only 3 (these are loose approximations). So the asteroid will be spending some 33% more time in a given point in the sky than the background stars–this should make it appear some 33% brighter in long exposure (or technically short exposure too) photos.

Short answer: Yes. Long answer: Yes, but it’s still pretty dim. I think that IRTF is very probably going to go for it (3 meter) and I think I know somebody who is going to try it on the UH88 (2.2 meter). It’s cloudy enough here in Manoa that it’s a moot point for me.

[orionid]

Any of you astro-nuts know of anything worth watching for from Southern CA around the 19th of this month? Other than any potential clouds, the sky isn’t going to be any darker for me for a while…

Yes. A last quarter moon.

Seriously, though, the Leonids meteor shower usually peaks on the 17th and 18th, and is generally one of the better shows. It’s on a down year, but the comet that provides this show produces lots of yellow and green fireballs, and has been known to show a couple fractured meteors. In the high desert with a last quarter moon, you could probably expect to see 20-30 an hour (40-60 on a peak year).

Edit to add: Look to Leo after midnight. He looks like a question mark in the eastern* sky.

/* direction is based on memory, may be entirely wrong.

[olavf]

orionid Sweet, thanks!

I don’t even know where to look for this kind of info, let alone interpret half of it :/

[orionid]

np

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