Re: Venus issues

On Sat, 10 Mar 2007 03:32:34 GMT, AstroApp
<Astro-App@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Wed, 07 Mar 2007 20:05:01 GMT, "Steve & Lizzie"
<steveandlizzie@xxxxxxxxxxxxxxxx> wrote:

Dear All

I have been told that I should be able to resolve Venus
easily - what am I doing wrong?

I am not getting any new posts at all via my ISP's newsgroup server,
so I've had to read them via Google.

Some comments recently appended to my last long statement, by Brian
Tung and W. H. Greer, seem to me to be highly accurate and
informative.

But I'd like to remind others that the original poster who asked a
question about Venus is a BEGINNER.

The usual thing observed here by me, over the years, is that a
beginner asks a pretty clear and obvious question that has a simple
answer, but the response often given is highly obscure. People dredge
up all kinds of arcane possibilities that SOMEBODY, SOMEWHERE has once
explored by means of the most advanced techniques imaginable.

Now I know that this kind of reply is quite self-reinforcing and
enjoyable for the poster. It's fun to think of this stuff, and we all
get a kick out of reminding others on the board about how much we
might know.

But, remember who you are addressing.

A beginner who has just started using a telescope is NOT going to be
able, suddently, to start doing ultraviolet imaging, nor benefit from
personal experience of a lengthy project to observe Venus under the
highest conditions of equipment sensitivity and trained visual acuity.

So, when you make your "learned" replies to a beginner, it might be
helpful to him or her to divide them into reasonable categories of
usefulness. I know I am just blathering away into the wind as nobody
will agree with me and it won't change anything nor help the poor
beknighted beginners who are bamboozled and confused by the non
sequitur replies that NEVER seem to address their own particular
questions. Let's just say that I'm getting this off my chest, and
move on from there.

This came up years ago when I TRIED my best to give advice to a
beginner about which type of filter to use to photograph less sky
fogging. I of course recommended the Deep Sky filter and not an OIII
or UHC type. But, a spectroscopist who worked for a university, who
did lots of experimentation with narrowband photography -- admitting
that he liked to make pictures that showed virtually no stars -- took
me to task, saying my advice was preposterous and incorrect.

The fact is: there is practical advice to give for people who are
STARTING OUT to make their own experiments, and also advice for those
who have already done the first steps and want to learn more advanced
techniques.

As I said from the beginning, Venus shows next to no detail. At best,
the limb or the edge of the shadow during certain aspects of the
phases can be discerned in moments of excellent seeing. I believe
firmly that this is what the OP had in mind. I think that he or she
was seeing a boiling blob, and wondering why it was not -- in the word
of the poster -- 'resolved', and what to do about it.

The point is: you can't do anything about it, other than to wait for
perfect seeing. And, even then, you just see a blindingly bright
image with no detail -- UNLESS you take the special pains that a tiny
obscure minority of Venus imagers and visual specialists have done.

To confim all this, I looked again at Venus on the evening of Saturday
17 March with my C-11, at dusk both before and after the Sun had set,
from an altitude of 3,400 feet above sea level at my regular observing
site south of San Jose, CA. At this site, in good seeing, I have
confirmed that my telescope performs very well after using it there
for nearly two years -- and I have used the exact same spot for more
than twenty years previously. The seeing is pretty much the same as
at Lick Observatory at Mt. Hamilton, not far away.

Venus was -- ahem -- a "boiling blob". Due to the particular phase
condition, no "cusps" could be seen, as the planet was perhaps 70%
illuminated (hard to judge because it would not steady down enough to
really be able to tell, and I did not bother to check Calsky
afterward.) The limb would not steady down and resolve at all; colors
constantly flashed, and the site almost blinded my eye.

Yet, Saturn was almost perfect, and hours later, nearing dawn, I got a
fantastic, highly detailed view of Jupiter, with loops and festoons
and a remarkably high contrast view of the equatorial belts.

So, to repeat (ad nauseum): Venus is problematical, even for an
experienced observer with a very good telescope. It is very bright,
and atmospheric disturbance tends to make it look worse than Saturn or
Jupiter.

The beginner who tries a smaller aperture, less expensive scope, in a
site that has even poorer conditions than mine generally does will,
therefore, have even WORSE results than I had.

This is NORMAL.

There is nothing wrong with the original poster's telescope, then, if
Saturn and Jupiter look good, but Venus looks poor.

I do believe that this is the information that the poster was seeking.

Now, I am fully expectant that NOBODY ELSE will agree with me in the
slightest bit; and that almost everybody will take great offense. It
is par for the course, and this realization has tended to discourage
me from posting here.

AstroApp
.

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