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frank5817
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Re: Venus 05.04.07 new [Re: CarlosEH]
      #1600097 - 05/12/07 09:40 AM

Sol and Michael,

Your gibbous phase Venus sketches stack up nicely together.
Frank

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Special Ed
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Re: Venus 05.04.07 and 5.9.07 new [Re: Sol Robbins]
      #1601332 - 05/12/07 11:02 PM

Quote:


I don't wish to start a Venusian mutual admiration society, but I have to admit I am a bit excited about the prospect of trading Venus observations.

I don't remember Venus being so high up in the sky as it is now. Additionally scope cool down is a cinch and we don't have to freeze in order to catch a good view. Don't even need a flashlight to draw by either.




Yes, I hope we can continue to post complementary observations while Venus is so favorably placed and outdoor conditions are so confortable and easy to work in. I hope others reading this will join in, too.

I have studied up some on Venus (using Fred Price's The Planet Observer's Handbook) and learned some interesting things--some of which are very confusing to think about. Re: the direction of rotation---while it is true that Venus rotates in retrograde motion, i.e., east to west, its axial tilt is 177 degrees. That means that Venus is almost upside down and when you look at a correct image view as with binoculars for instance, the south pole is on top. With a reflector, the north pole would be on top. With my SCT, what I thought was the north pole was actually the south pole, so the N-S directions on my sketch are inaccurate. I do think the direction of rotation is towards the terminator. I thought the ALPO Venus Section template directions were set up for a reflector but maybe I'm wrong. Or maybe with the cloud cover on Venus so thick, it doesn't matter which end is up and one should just use celestial N-S-E-W.

Re: the speed of rotation and changes in the cloud cover albedo---while it is true that Venus rotates slowly (one rotation on its axis every 243 Earth days), the clouds make one complete rotation every 4 Earth days. This was first observed in 1957 and confirmed in 1973 by Mariner 10. And Taras is correct---the winds on Venus are blowing in the cloudtops at ~200 mph (100 meters/second).

Re: seeing detail in the clouds---some say one can't see anything that is really there even with Wratten filters and only UV imaging works---others say one can see the albedo features,depending on the observer, seeing conditions and filters used, also that some people's eyesight is more sensitive in the UV range.

Quote:


I also recommend sending a copy of this to ALPO's Venus coordinator as Venus images are always a bit small in number compared to the other planets. I think there is also a downloadable page of observing tips as well.




I will send my observations to the Venus Section coordinator and I downloaded the observing tips a little while ago.

People have put telescopes on Venus since Galileo in 1610, spacecraft have visited our sister planet, yet there is much about Venus that is still unknown. I know now there is a lot I don't know about it. Once again, observing an object (or a feature) leads one into learning.

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Michael Rosolina
Celestron CGE Pro 1400 f/11 SCT
1980 Orange Tube C8 f/10 SCT
4.25" f/4.2 Astroscan Reflector
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Edited by Special Ed (05/15/07 11:35 AM)


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LivingNDixie
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Re: Venus 05.04.07 and 5.9.07 new [Re: Special Ed]
      #1603793 - 05/14/07 01:12 PM

Sol,

Great sketch! I have been sketching Venus for the last month for the AL planetary pin. It is fun watching the phase change and the apparent diameter grow as the weeks pass.

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Preston
Meade 10in LX200R GPS UHTC
blog (updated 02/15/2013)




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frank5817
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Re: Venus 05.04.07 and 5.9.07 new [Re: LivingNDixie]
      #1605047 - 05/15/07 12:57 AM Attachment (98 downloads)

I made a rather crude sketch of Venus this evening and posted it below. I began observing at 0:00 U.T. 5/15/2007.
I noted the seeing and transparency were both above average. I intended to sketch the planet with a Wratten 47 violet filter but before I did that I looked at Venus with every filter in my collection. The violet filter provided the only view of any albedo features. The features must have changed while I was drawing (30 minutes) because when I finished the features no longer matched my sketch. For experienced planetary sketchers like Sol and Michael Venus sketching may go smoothly. I was challenged but fascinated. I have photographed Venus and even sketched it in the past but I have never looked at it through any filter other than a polarizing pair until this night. I labelled this sketch with 2 letters H is the direction of the horizon and Z the direction of the zenith. For this sketch I used a protractor to draw a 3 inch semi-circle and freehand sketched the terminator. I used white sketching paper, black Conte' crayons filed sharp, index finger for blending and inverted the drawing after scanning and cropping.I sketched for about 30 minutes between 0:30- 1:15 U.T.
10 inch Dobsonian f/5.7 at 241X

Frank McCabe

Attachment

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Edited by frank5817 (05/15/07 01:29 AM)


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CarlosEH
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Re: Venus 05.04.07 and 5.9.07 new [Re: frank5817]
      #1605215 - 05/15/07 05:44 AM

Frank,

An excellent observation/rendering of Venus. I am glad that you were able to detect albedo features using the Wratten 47 (Violet) filter. Venus is a challenging object to detect detail over. The cloud tops actually rotate in a period of approximately four days (versus the 243 days retrograde rotation and 225 days orbital period).

Good Job!

Carlos

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Special Ed
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Re: Venus 05.04.07 and 5.9.07 new [Re: CarlosEH]
      #1605747 - 05/15/07 11:56 AM

Frank,

Great observation and sketch! I like the appearance of the planet in your rendering.

I also like how you solved the problem of orientation. I was hoping that someone would be able to answer my questions about that. I might e-mail the ALPO Venus coordinator and ask him.

Eric Jamison posted an observation report of Venus on the StarryNights Yahoo group. His observation was made on Sunday evening--he said the seeing wasn't good and he didn't mention using any filters but he reported noticing some dusky markings along the terminator.

Regards,

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Michael Rosolina
Celestron CGE Pro 1400 f/11 SCT
1980 Orange Tube C8 f/10 SCT
4.25" f/4.2 Astroscan Reflector
50mm f/10 Galileoscope
40mm PST f/10
APM Germany HD 15x70 binoculars
Canon 12x36 IS II binoculars
Mark I Eyeball
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rodelaet
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Re: Venus 05.04.07 and 5.9.07 new [Re: frank5817]
      #1606212 - 05/15/07 04:13 PM

Frank,

That is a very cool sketch!!

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Rony

'The Casual Sky Observer's Guide.'

My Astronomical Sketches

My Binocular Sketches

Callibrate your Monitor with this little strip.



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frank5817
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Re: Venus 05.04.07 and 5.9.07 new [Re: rodelaet]
      #1606294 - 05/15/07 04:47 PM

Carlos, Michael and Rony,

Thank you for the kind remarks. I anticipated I would need to take a good long look. Venus is so brilliant it needs filtering to see well after it gets dark. I have rarely ever used the Wratten 47 filter but I'll be using it now with Venus.
Michael, I took your suggestion on the orientation. I wouldn't want to guess the other positions (rotational poles, direction of rotation, and the like). I'll need to brush up on Venus to fill my knowledge void.

Frank

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Tommy5
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Re: Venus 05.04.07 and 5.9.07 new [Re: frank5817]
      #1606709 - 05/15/07 08:02 PM

Great sketch of Venus,I looked at Venus on the 13th from chicago and had very steady skies,with my #47 violet I saw some albedo markings as well. darker toward the terminator and lighter towards the edge with my 6" achro refractor,I'm in the process of scanning/posting my sketch it is remarkably similiar to yours and these marking are strange,they seemed to come and go,yet they are diffinatly there with the filter and gone without it.

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Sol Robbins
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Re: Venus 05.04.07 and 5.9.07 new [Re: Tommy5]
      #1606932 - 05/15/07 09:48 PM

Great sketch. Looks like seeing some kind of detail on Venus has found its workaround.

Bad weather is setting in on me for the moment. Hopefully others will get a shot at Venus. This seems to be a first time a bunch of sketches of Venus over short periods of time has been put together.

At the risk of making a super-long thread, I would find it interesting and fun to see a whole folio of Venus sketches during this favorable apparition.

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S.R.


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frank5817
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Re: Venus 05.04.07 and 5.9.07 new [Re: Sol Robbins]
      #1606957 - 05/15/07 09:57 PM

Sol and Tommy,
Thanks!
______________
Sol,
That sounds like a plan

Frank

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Tommy5
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Re: Venus 05.04.07 and 5.9.07 new [Re: Sol Robbins]
      #1607055 - 05/15/07 10:53 PM Attachment (112 downloads)

Good idea about the sketches around this years Venus show .I've read that the cloud marking are easiest to see between superior conjunction and eastern elongation and are more difficult as the planet goes into a cresent phase but we will see, here is my sketch from 5/13/07,the markings were there during the twilight calm and more prominent toward's the terminator they didn't extend as far out as sol's or Micheal's sketch, but since i have only 6" aperture maybe that is why.They were only visible during the steadier moments on a calm twilight and only seen in the #47 violet filter which I thought was useless in my scope.The markings were easier to see then to sketch, the unlit part of the disk was invisible of course, i blacked out a disk from alpo.#47 filter,200x.

Attachment

Edited by Tommy5 (05/15/07 11:03 PM)


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Special Ed
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Re: Venus 05.04.07 through 05.16.07 new [Re: Tommy5]
      #1607165 - 05/16/07 12:06 AM Attachment (101 downloads)

Here's my latest sketch to add to the collection. It was done this evening during twilight (16 May UT). I diagrammed my eyepiece observation using the 0.0=completely black to 10.0=brightest scale and immediately did the sketch on a Venus Section ALPO form using HB and 2B pencils and a loaded stump.

The seeing wasn't the greatest, but in steady moments I could clearly see the dusky features rendered in the sketch. To lessen my confusion, I kept the mirror-reversed orientation of the SCT and used celestial directions.

As Sol said, compiling this series of observations is a good thing--I'm glad to be part of it. And I'm looking in the mail every day for my #47 filter.

Attachment

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Michael Rosolina
Celestron CGE Pro 1400 f/11 SCT
1980 Orange Tube C8 f/10 SCT
4.25" f/4.2 Astroscan Reflector
50mm f/10 Galileoscope
40mm PST f/10
APM Germany HD 15x70 binoculars
Canon 12x36 IS II binoculars
Mark I Eyeball
My CN Gallery

Edited by Special Ed (05/16/07 10:19 PM)


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frank5817
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Re: Venus 05.04.07 through 05.16.07 new [Re: Special Ed]
      #1607601 - 05/16/07 09:25 AM

Tommy and Michael,
Skillful Venus sketches guys.
Frank

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Special Ed
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Re: Venus 05.04.07 through 05.16.07 new [Re: frank5817]
      #1609112 - 05/16/07 10:17 PM

Thanks, Frank.

I commented on a Venus observation by Eric Jamison posted on the StarryNights Yahoo group and he and Geoff Gaherty (the moderator) had some information in response to my questions about labeling the directions on Venus observations. According to Geoff, the convention for identifying preceding is the direction that an object (planet, double star, etc.) drifts when the tracking drive is turned off--in other words, celestial west. This holds true regardless of retrograde rotation. The fact that most of the planets appear to rotate towards the west is a happy circumstance. Likewise, north-south is celestial north-south, even if the planet is upside down like Venus, or on its side like Uranus. I have edited the last sketch accordingly.

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Michael Rosolina
Celestron CGE Pro 1400 f/11 SCT
1980 Orange Tube C8 f/10 SCT
4.25" f/4.2 Astroscan Reflector
50mm f/10 Galileoscope
40mm PST f/10
APM Germany HD 15x70 binoculars
Canon 12x36 IS II binoculars
Mark I Eyeball
My CN Gallery

Edited by Special Ed (05/17/07 06:23 AM)


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CarlosEH
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Re: Venus 05.04.07 through 05.16.07 new [Re: Special Ed]
      #1609213 - 05/16/07 11:13 PM

Michael and Tommy,

Excellent observations of Venus showing albedo features over the venusian atmosphere. I am glad to see such an effort on the part of observing Venus which is normally ignored. Detail is easier to note between superior cojunction and eastern/western elongation due to the increase in brilliance (irradiation) of the crescent phase (and therefore reduction in contrast; the planet's apparent diameter is larger during the crescent phase but the increased irradiation diminishes the contrast of albedo features). This is why it is easier to detect albedo features closer to the terminator.

Keep up the good work!

Carlos

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frank5817
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Re: Venus 05.04.07 through 05.16.07 new [Re: CarlosEH]
      #1611908 - 05/18/07 01:16 PM Attachment (92 downloads)

Viewing conditions 1.5 hours before sunset were shaping up to be be very good. I set up my telescope for evening and nightime viewing just before sundown. Venus was clearly visible and I retrieved my Wratten 47 violet filter to view and sketch the albedo features of Venus if visible.

Equipment: 18" f/5 Dob., 6mm ortho eyepiece (381X)
Wratten 47 filter
Seeing: Pickering 8
Transparency: Excellent
Time: 1:10-1:35 UT 5-18-2007
Sketching:
9"x12" black Strathmore Artagain paper
white pastel Conte' crayons, blending
stump, gum eraser, contrast and brightness
adjusted using Microsoft Paint.

Frank McCabe

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cildarithModerator
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Re: Venus 05.04.07 through 05.16.07 new [Re: frank5817]
      #1611936 - 05/18/07 01:36 PM Attachment (99 downloads)

Great sketches of Venus everyone! Here is a sketch of our sister-planet made just over a month ago:

Attachment

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Eric
6" f/6 Parks Newtonian
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CarlosEH
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Re: Venus 05.04.07 through 05.16.07 new [Re: cildarith]
      #1612153 - 05/18/07 03:55 PM

Eric and Frank,

Excellent observations of Venus! You both have recorded a good amount of detail over our sister planet. Thank you for sharing them with us all.

Carlos

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Sol Robbins
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Re: Venus 05.04.07 through 05.16.07 new [Re: CarlosEH]
      #1612400 - 05/18/07 06:31 PM

Ditto!

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S.R.


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