[time-nuts] telling time without a clock

Jim Palfreyman jim77742 at gmail.com
Thu Jan 26 19:52:39 EST 2012


Download Occult4 by Dave Herald. You can list off all Lunar Occultations
for your location and choose a minimum magnitude to show. Start at 3.0, but
probably 2.0 or above is a binocular viewing - depending on your skies.

Note that Occult4 is an extensive piece of astronomical software for the
experienced amateur. It can do a *lot*. So be prepared to be patient with
it - however once mastered it is very very useful for accurate timing of
astronomical events.

The hardest and yet most satisfying for astronomical time nuts are
asteroidal occultations. This is where a faint asteroid passes in front of
a star and blocks it out for a few seconds. Hard to accurately predict and
hard to observe. It took me 40 attempts over 30 years to see my first.

But when a bunch of amateur astronomers observe and accurately time the
same event you can build up a profile of the shape of the asteroid.

It is a fun but dark path to go down...

Jim


On 27 January 2012 11:35, Jim Lux <jimlux at earthlink.net> wrote:

> On 1/26/12 2:55 PM, Jim Palfreyman wrote:
>
>> As a reasonably experienced occultation observer (and the very reason I
>> got
>> into being a time-nut - so I could time these observations), the main
>> problem is that the number of binocular-observable occultations is
>> actually
>> quite rare. When the star appears or disappears behind the bright limb it
>> is actually hard to see - even if the star is very bright. When the moon
>> is
>> nearly full, even disappearances behind the dark limb are hard.
>>
>
> Yes, that's what I observed when I was trying it a while ago..
>
>
>
>> So ideally you want bright star disappearences on a dark limb with a moon
>> before first quarter. (Last quarter as well - but then it's a reappearance
>> and you don't quite know where to look).
>>
>
> that would sort of limit you to 1 week out of 4. But better than nothing,
> for a technique that requires no outside assistance.
>
>
>
>> This limits the number of bright stars quite drastically. And then you
>> have
>> clouds...
>>
>>
> Yeah, that is something I don't have a feel for.. How many stars are
> candidates? I assume you could get a moon RA/declination list, and then run
> that against the star list.
>
>  This is one of those things that  I was hoping there's probably someone
> who has a program that can do the search trivially.
>
> I have a moon ephemeris, but I haven't found a convenient star catalog
> (something in ASCII that has ID, RA, Dec, Mag would be nice)
>
>
>
>
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