Szeptember 6-án (287) Nephthys elfedi a HIP 84012 = eta OPH 2,4
magnis csillagot! A fedés sávja a Pireneusok környékén
látszik, de a kisbolygónak van egy holdja, amely 0,5-1 másodperces
okkultációt okozhat Európa bármely részén!
Az egyetlen bökkeno, hogy a fedésre nappali égen kerül sor!
Bár a csillag látszik még kis távcsövekben is, de hogyan lehet
megtalálni? Elozo este meg kell keresni valamelyiket a lent felsorolt
csillagokból x idovel a fedés után (a deklináció megegyezik, a
rekta különbséget pedig csak ki kell vonni egymásból), majd
mozdulatlanul kinn hagyni a távcsövet.
Azért a fedés elotti hetekben ezt a módszert próbáljuk ki,
mennyire látszik az éta Oph a távcsoben nappal?
A fedés ideje 15:22-15:26 UT szeptember 6-án.
Szabó Sándor
A CHALLENGE !
How to observe NEPHTHYS in the afternoon of Sep. 6th ?
In the afternoon of 2004.09.06, (287) Nephthys will occult HIP
84012 = eta OPH around UTC 15h30 (see Goffin´s prediction for area #6
; this opportunity was first noticed by Francois Colas).
Nephthys has already been seen possibly satellited (with Very Large
Telescope + Adaptative Optics, Jerome Berthier, personal communication),
but there is no confirmation for an orbit. So ANY OBSERVER IN EUROPE can
be lucky enough to catch a satellite occultation when observing on Sep
6th.
The star is bright, mag = 2.4 (actually a double star with
components around mag 3), and with enough magnification (to dim the
background blue sky) it can be seen even with a small telescope. But how
to find it in full daylight ?
If you have not a precise aiming system, here is a simple road to
success.
During the night before, just aim your telescope at a star of about
the same declinatio, and let it stands still at a known time until the
next afternoon (remind that AR is in sidereal time, not UT). For an
example, aiming at the mag 5.6 star HIP 7345 and stopping any drive at
UTC 23h26m49s (the day before) will make eta OPH be in the field at UTC
15h00m00s. The magnification of the scope weakens the brightness of the
daylight sky, whereas the aperture improves the light of the star.
Here are 6 selected stars suitable to try this method, with the
time interval in UT to wait between this star and the target eta OPH =
HIP 84012. Note that the event is not expected very high over the
south-east horizon in western Europe : aiming at a bright star is
better. And it is better to find the target at UT 15 than at the last
minute.
HIP113136 m=3.3 RA 22 54 39 DE -15°49´ m 3.3 : 18h12m44s UT before
the target (5´ north)
HIP 7345 m=5.6 RA 01 34 38 DE -15°41´ m 5.6 : 15h33m11s UT before
the target (3´ south)
HIP 6589 m=6.2 RA 01 24 40 DE -15°40´ m 6.2 : 15h43m08s UT before
the target (4´ south)
HIP109822 m=6.6 RA 22 14 38 DE -15°49´ m 6.6 : 18h52m39s UT before
the target (5´ north)
HIP 5840 m=7.3 RA 01 14 54 DE -15°49´ m 7.3 : 15h52m52s UT before
the target (6´ north)
HIP 15868 m=7.5 RA 03 24 25 DE -15°39´ m 7.5 : 13h43m42s UT before
the target (5´ south)
Please try to make a rehearsal of the method a few days before !
Finder charts (thanks to J. Schwaenen & E. Frappa) for those 6 stars
will be available here soon.
The target eta OPH = HIP 84012 is at RA 17 10 27 DE -15 43 29
Raymond Dusser, on behalf of EAON.
----- Original Message -----
From:
To: "planoccult"
Sent: Tuesday, August 17, 2004 12:54 AM
Subject: [PLANOCCULT] Call to observe 287
> ... in the afternoon of september 6th, the bright star eta Ophiuchi
= HIP
> 84012 will be occulted by the main body (for max duration ~4 seconds)
or by
> a possible satellite (0.5s ?), with a ~1 magnitude drop, between UTC
15h 22m
> and 15h 26m . (The main body shadow will run over the Pyrenees
mountains,
> the satellite could be observed at some places somewhere in Europe).
> The target, visual magnitude 2.4 , is easy to see in daylight with
a
> 15cm or even 10cm scope (with enough magnification to dim the blue
> background sky).
> If you have not a precise aiming system :
>
> Here attached is a finding chart for delta Aquarii = HIP 113136,
mag
> 3.3, RA 22h 54m 39s DEC -15d 49´ .
> If you aim this star, the scope standing still the target eta OPH
will
> be find at ~ the same place (5´ north) 18h 12m 44s UT later.
>
> Example : if you want to find the target at UTC 15h 00m, find HIP
113136
> in the evening the day before, and stop the drive of the scope at UTC
20h
> 47m 16s . A lot of time to wait, but in the afternoon at UT 15h the
target
> will be in your field.
>
> Clear skies !
>