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From: TerryMoselaol.com
Date: Sat, 17 Jul 2004 18:40:33 EDT
Subject: More on occultation, Sunspots

Hi all,

1. OCCULTATION, night of 20/21 July.
I have now done a more accurate plot of the track, using the exact latitudes &
 longitudes, rather than just using the rather small scale & foreshortened 
map on that website.

The central line runs from "The Raven Point" which is the promontory jutting 
out on the N side of Wexford Harbour, to Kilglass (just N of Inniscrone, Mayo) 
exiting near the NE corner of Killala Bay. 
   The following towns are within 1-2 km of the centre line: Enniscorthy, 
Portlaoise & Tobercurry. 
   Roscommon & Ballaghadereen are within 5km to the SW of the line, and 
Carlow, Mountmellick, Tullamore, Clara, Moate, Frenchpark & Easky are within 10km 
of the NE of the line, and Wexford, Athlone & Castlerea are within 10 km SE of  
the line. 

Correction to earlier email: using the more accurate track above, Sligo is 
now within the overall predicted track limits, though near the NE edge.

As a very rough guide, the SW limit runs from Tramore (Co Waterford) to 
Westport and the Mullet peninsula, and the NE limit from Wicklow to Bundoran, but 
you may still see an occultation if you are outside these limits, given the 
uncertainty in the track. Concommitantly, you might NOT see an occultation even 
if you ARE within the predicted limits, as the track might actually pass a bit 
to either side of the predicted limits.

So if you observe, and DON'T see any occultation, and you are fairly sure of 
that, then REPORT THAT! That will set a limit to the edge of the track, and 
hence to the maximum diameter of the asteroid.

Ideally, it would be good if every amateur astronomer between the lines 
joining Youghal to Clifden, and Balbriggan to Falcarragh, could observe that star 
for at least 5 minutes before & after 02.19 BST on 21 July! I know it's late, 
but you can go back to sleep again afterwards. ("Time for bed", said Zebedee. 
"OK" said Irmintraud. Any Magic Roundabout fans out there?)

For all reports, give your exact position: i.e. map reference, lat & long, or 
some other unambiguous & accurate description. Also state what instrument & 
timing method you used, your time reference source (the most convenient might 
be the speaking clock, tel 1191) the observing conditions, and your confidence 
in your observation. If you see a definite disappearance lasting for 5-10 secs 
that's fine; but if you only see a short disappearance lasting for a second 
or less, say how sure you are that it was real. One way to check that any 
disappearance is 'real' is to check the visibility of 32 Piscium, just 1/2 degree 
to the South - if it remains visible throughout, then any disappearance of the 
other star is probably real. 

PERSONAL EQUATION: As Tolis has pointed out, you also need to allow for your 
reaction time if using a stopwatch, i.e. the short delay between you seeing 
the event, and your pressing the button on the stopwatch. You can practice 
reacting quickly by getting a friend to switch a small torch on & off at random. 
Try to estimate your reaction time, and say whether you have, or have not, 
applied it to your actual reported recorded times.

There are at least two, and maybe three, 'proper' amateur observatories 
within the predicted limits, so it would be good if they could participate (I'll 
not embarass them by naming them!).

I would be glad to receive all reports, both positive & negative (or even if 
you tried, but were clouded out), but please also copy them all to Tolis 
Christou at Armagh Observatory 

2. Giant sunspot. That big spot coming over the E limb has now been split 
into two by a very bright prominent 'bridge', running approximately N-S. It was 
obvious even using low power on my 70mm Lidl refractor! It's worth keeping an 
eye on (safely, of course!)

Clear Skies,

Terry Moseley










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