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Daytime Mars: March 26, 2010; 23:50 UT

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#1 frank5817

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Posted 27 March 2010 - 01:51 AM

Well before sunset in the late afternoon I began observing Mars. I was using a polarizing filter, as Mars has entered that part of the sky in the daytime where the sky can be darkened by a polarizing filter to good effect when transparency is above average and it was.
I began this sketch before sunset and the seeing was average but the advantage gained by using a single polarizing was dramatic.
The North Polar Cap was clearly seen and it shrinkage has slowed. Utopia was seen south of the pole and Syrtis major was on the sunrise limb. Between Syrtis major and minor, Hesperia was visible in the direction of the South Polar region. Mare Cimmerium appeared as a dark line projecting toward the central meridian. The region of Elysium appeared darker than the surroundings and the region of Amazonis looked to be under clouds or haze or both near the preceding limb.
For a time I was able to add a barlow to the eyepiece and see Mars fairly well at about 600x.

Sketching:

The eyepiece sketch is the one on top in graphite pencil. The second color sketch was made indoors.
White sketching paper 8" x 11"; HB graphite pencil, blending stumps for blending orange, brown and red Crayola pencil shavings.
Date 3/26/2010 – Time 23:30-0:10 UT
Telescope: 10 inch f/5.7 Dobsonian and 4mm eyepiece 362 x, polarizing filter
Temperature: 2°C (35°F)
partly cloudy, calm, dry air conditions
Transparency 4/5
Seeing: Average-Above average 3/5

Frank McCabe :)

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#2 S1mas

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Posted 27 March 2010 - 02:09 AM

I like subtle details and colors here Frank :)

#3 frank5817

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Posted 27 March 2010 - 02:13 AM

S1mas,

Thank you. :thanx: Although Mars and Earth are now getting well seperated; this is one of the best views I have had this year.

Frank :)

#4 Uwe Pilz

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Posted 27 March 2010 - 02:51 AM

I never observed Mars at daytime but Jupiter. I had the feeling that I saw more of detail with some blue in teh background. You saw mauch detail at a tiny Mars.

#5 dweller25

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Posted 27 March 2010 - 04:04 AM

Excellent Frank, loads of detail considering how far away it is now.

#6 Kris.

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Posted 27 March 2010 - 04:40 AM

impressive detail in your sketch Fank :waytogo:

i wonder how you find mars back in the daylight with a dobson (or do you have a go-to system?).

in 2005 i've observed mars once untill the sun was above the horizon in the summer, so i could see the difference between a dark background to blue. i found the blue background was more relaxed for my eyes, and perhaps it also made it easier to see color differences on the disk...

#7 frank5817

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Posted 27 March 2010 - 10:10 AM

Uwe, dweller, Kris:

Thank you all. :thanx:
You all need to try observing Mars on a clear, late afternoon. If the atmosphere is reasonable steady you will be surprised at the results.
-----
Kris,
Shortly after I built my 10" scope (early 1980's) I wrote a short computer program in Q basic to convert RA and Dec to Alt/Az. Then I added a circular protractor to the altitude bearing and I made a large circular ground Azmuth circle.
Using a computer planetarium program (I use Stellarium-free on-line) you can point your scope at any target in the sky day or night. You can also use Heavens-Above.com. to get Mars location in the daytime.

Frank :)

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#8 Kris.

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Posted 27 March 2010 - 11:17 AM

thanks frank, i might try that too. so if you are pretty well alligned to the north star (using a compass at daytime?) you can actually spot tiny mars in daylight using the lowest power eyepiece? i've got a pan24 which yields 62x with the 12" dob. is it so accurate that your target is immediately in view?

stupid question: why do you need to convert declination :question: isn't it in degrees already?

can i use my rotating star chart for the azimuth (it's alo given in 'hours' as on heavens above. or is there a program available to convert ra to az.

#9 dweller25

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Posted 27 March 2010 - 12:26 PM

Kris, the declination of Mars during the night will stay the same but it's altitude will change due to the Earths tilt.

#10 Kris.

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Posted 27 March 2010 - 01:30 PM

:foreheadslap: offcourse! that's why i said it was a stupid question :grin:

#11 roadi

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Posted 27 March 2010 - 04:39 PM

Frank,
Thats a great sketch and an impressive view! ;)

#12 Tommy5

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Posted 27 March 2010 - 07:51 PM

very nice Mars sketch and great idea to catch Mars in the afternoon, i observe jupitr sometines at dusk and this can improve contrast but never mars maybe i will give it a go.

#13 frank5817

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Posted 27 March 2010 - 10:41 PM

dweller, Rodi, and Tommy:

Thank you all for your comments and kind words.:thanx:
----
Kris,

As dweller said the coordinate system of Alt/Az is fixed at your location[stars and planets move in the background] but the RA/Dec coordinate system move across the sky [stars and planets move with the coordinates] as the earth rotates so you need to continuously update with respect to time in both.
Using low power I have 3/4 of a degree of a field of view. So when I guess due north I can get within 1 or 2 degrees of my target when pointing the scope. With a little motion up and down or back and forth I'm there. The important thing is to have the eyepiece in focus before you start. If the moon is in the sky your in business or you can do what I do put the scope away with the eyepiece in place and focused.
I have done this so many times and from exactly the same observing spot that I believe I can point the scope to within 3 degrees of Altitude and Azimuth without using the circles. The altitude bearing was the only one I used Friday and I swept back and forth to get to Mars (just a few seconds). I'm not kidding when I say anyone can easily do this.

Frank :)

#14 Nick Lloyd

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Posted 28 March 2010 - 07:57 AM

wow... didn't know mars looked like this in the daytime. very nice sketches!

#15 Special Ed

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Posted 28 March 2010 - 11:26 AM

Frank,

Excellent sketches. The color is very well rendered--the Martian deserts have that pinkish-orange hue when seen agianst a blue sky in my experience. How you acquire Mars is a neat trick. :cool:

I've never looked at Mars in the afternoon, but have observed it several times in the morning twilight and even after sunrise to take advantage of the steady air that sometimes happens then. The glare is no longer a problem and the planet has a look and color that is unusual and memorable. Every Mars observer should try it. :)

#16 Sol Robbins

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Posted 28 March 2010 - 11:32 AM

Very well done Frank!

#17 frank5817

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Posted 28 March 2010 - 11:51 AM

Nick, Michael and Sol,

Thank you.

The filter does change the color of Mars and darken it a bit. Yes Michael the loss of glare in daylight does help a great deal as it does with Venus and even Jupiter.

Frank :)

#18 JayinUT

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Posted 28 March 2010 - 01:13 PM

Frank,

I really like the subtle colors and details in this sketch. What a wonderful way to gather more on the red planet! Well done as always.

#19 mikesemmler

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Posted 28 March 2010 - 03:20 PM

Frank - what a great scetch - i like day time planetobserving too, but until now only jupiter and saturn.

Michael

#20 frank5817

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Posted 28 March 2010 - 07:05 PM

Michael S.,

Thank you for the words and comments. :thanx:
Venus is the easiest but near the Sun requires care to prevent an accidental pointing at the sun. I use a large building on the side with increasing shade. Saturn is very difficult unless the sky is pristine.

Frank :)

#21 mikesemmler

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Posted 29 March 2010 - 04:28 AM

frank - thanks for the info, I will try your tips soon

Michael

#22 niteskystargazer

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Posted 29 March 2010 - 11:06 AM

Frank,

:waytogo: nice sketch, in the day light, You have to know where Mars is. :).

:thanx:,

Tom

#23 frank5817

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Posted 29 March 2010 - 08:48 PM

Tom,

Thanks,
I hope your getting in some observing on clear nights.

Frank :)

#24 frank5817

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Posted 01 April 2010 - 01:24 AM

I began observing Mars about 2 hours before sunset (5pm local daylight savings time). The view was pretty good but I could not begin sketching until after sunset because of the high winds. During the daylight, observing Mars was easy because it was in the darkest part of the sky through the single polarizing filter.

Sketching:

The eyepiece sketch is the one on top in graphite pencil. The second color sketch was made indoors.
White sketching paper 8" x 11"; HB graphite pencil, blending stumps for blending orange, brown and yellow Crayola pencil shavings.
Date 3/31/2010 – Time 7:45-8:25 CDT
Telescope: 10 inch f/5.7 Dobsonian and 4mm eyepiece 362 x, polarizing filter
Temperature: 21°C (70°F)
partly cloudy, very windy, dry air conditions
Transparency 3/5
Seeing: Average-Above average 3/5

Frank McCabe :)

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#25 frank5817

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Posted 01 April 2010 - 01:51 AM

I took these two images of the sky before beginning my Mars observing session as an example of how well the single polarizing filter can darken the daytime sky. The first image without the filter sheet and the second with the polarizing filter in front of the camera.

Frank

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