Re: Challenge of Mercury
- From: W. H. Greer <sendnomail@xxxxxxxx>
- Date: Fri, 06 Apr 2007 10:12:46 -0600
On Thu, 5 Apr 2007, "Michael Martin-Smith" wrote:
Many of us have never seen Mercury, I believe; even at its favourable times
it is usually low in the sky - behind trees or hidden by cloud /murk near
the horizon.
However, I have now proved to myself that it IS visible in broad daylight-
with good setting circles and a bit of fancy footwork between features on
the horizon! At 09-20 BST ( 08-20 UT) today I had a clear view using a Meade
8" SCT ,40mms eyepiece, with an ornage filter. Sure, I saw no craters - but
the clear white disc stood out as a clearly visible pinprick first against
the azure sky , but then well enhanced with an orange filter.
From now on, April 5 will not just be the start of a new Tax Year ( in theUK!) , but also the "Day I saw the planet Mercury"
It is a nice little challenge for the urban telescope user
Congratulations! Mercury is an easy planet to miss (or ignore) -- as
most of us are well aware.
When seeing conditions permit, the planet will be better at somewhat
higher magnifications. The planet's phase should be discernable most
of the time. Under suitable conditions subtle, large-scale surface
markings may be visible as well.
It might help to have the telescope in the shade while making daytime
observations of planets -- particularly when using an SCT. A method
that can work well during eastern elongations is to set the telescope
up on the sunlight side of a shadow line, focus on the sun (using an
objective filter and low power eyepiece), then wait until the shadow
moves over the telescope (You could make a solar observation in the
meantime if there's anything interesting to see on the Sun.) Next,
using the known coordinates of the Sun and Mercury, shift the scope
over to Mercury's location and remove the solar filter. This method
works reasonably well with equatorial as well as alt-az mounts as long
as reasonably accurate setting circles are available. Of course,
those with computer-assisted pointing can 'tell' a telescope to point
at a planet in the daytime sky with a minimal use of their gray
matter; but why let a computer have all the fun? ;-)
--
Bill
Celestial Journeys
http://cejour.blogspot.com
.
- References:
- Challenge of Mercury
- From: Michael Martin-Smith
- Challenge of Mercury
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