Re: asteroids

[hjohnson@pluto.njcc.com (Herbert R Johnson)]

On Tue, 6 Jan 1998 11:27:52 -0600, Bill Dillon <bdillon@houston.geoquest.slb.com> wrote:
*>Arne wrote:
*>> They say that "the set of known asteroids is complete to about absolute
*>> magnitudes 12.75, 12.25 and 11.25 in the inner, middle and outer regions
*>> of the belt respectively."
*>
*>Forgive me for dropping out of lurker space, but these "absolute"
*>magnitudes are NOT opposition magnitudes, but the magnitude the
*>asteroid would have if were 1 A.U. from the sun and 1 A.U. from
*>the earth.

*>That's not to say that TASS can't be valuable in catching earth-crossing
*>or approaching asteroids (or comets!).  But you'll have to go much
*>fainter than 15th magnitude to discover lots of Main Belt asteroids 
*>these days.
*>
*>Bill Dillon

This is probably true. TASS may be able to reacquire some asteroids with
poorly determined orbits and thus be of some use. I think it's good practice,
myself, to look for some in the database and to keep them in mind when
possible.

My best guess, incidently, is that main belt asteroids will be moving slowly
enough that the Mark III survey will see them as point sources, not streaks.
"Next camera" or "next day" algorithms may find such objects. Earth
approaching asteroids would be moving faster, and may be bright enough
depending on phase and relation to the Earth.

Speaking of asteroids: inclement weather killed my chances of seeing
asteroid 93 Julia occult a 12th mag star last night over NJ. Fog
clamped down over an otherwise good opportunity to look straight up
near Algol and time this event out. An hour's delay in the fog may
have helped: two hours absolutely! (sigh)

Herb Johnson

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Herbert R. Johnson                      voice/FAX 609-771-1503 day/nite
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                 amateur astronomer and astro-tour guide
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