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Eastern Limb Huggers: Humboldt and Hecataeus

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#1 frank5817

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Posted 04 November 2009 - 12:19 PM

Two old large craters near the eastern limb of the moon were putting on such a nice show at sunset that I could not resist sketching them. First was the floor fractured crater Humboldt (207 km.). This is an ancient Upper Imbrian period depression on the lunar surface. The mountain range in the center of this crater was catching the last rays of sunlight while the northeastern rim was already consumed by darkness as was most of the crater floor. Along the limb below Humboldt to the north in the eyepiece is the Nectarian walled plain crater Hecataeus (167 km.). The floor of this crater was completely in shadow while the inner, far, steep wall was directly illuminated by the sun and showing some interesting structure and texture.

Sketching:

For this sketch I used: white sketching paper 12”x 9”, HB, 4B, 6B graphite pencils, a blending stump and a plastic eraser the sky was darkened using black Conte' pencil. After scanning, Brightness was decreased (-2) and contrast increased (+2) using Microsoft Office Picture Manager.

Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241x
Date: 11-3-2009, 4:45 - 6:00 UT
Temperature: 7° C (45° F)
clear, calm, low humidity
Seeing: Antoniadi III
Colongitude 99.1°
Lunation 16 days
Illumination 99.8 %

Frank McCabe :)

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#2 Uwe Pilz

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Posted 04 November 2009 - 02:41 PM

Dear Frank,

the autumn give the chance to see the waning moon in the evening sky. We should not miss this chance!
Thank you for sharing your sketch.

#3 frank5817

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Posted 04 November 2009 - 06:51 PM

Uwe,

You are absolutely correct. We just need the sky to clear.

Frank :)

#4 Tommy5

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Posted 04 November 2009 - 07:44 PM

Cool sketch of these crators on the edge.

#5 markseibold

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Posted 05 November 2009 - 05:07 AM

Frank

Very nice revealing image of the light "hugging and breaking" on the stark terminators eastern limb! :bow: :bow: :bow:

You've reminded me again that I can do a smaller area. I have no excuse tonight as it is finally clear here, except it is near freezing now and late. I may try an earlier evening again.

Thanks for posting,

Mark

#6 Jef De Wit

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Posted 05 November 2009 - 08:07 AM

Frank
Congratulations with your ASOD! Beautiful sketch!

#7 kraterkid

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Posted 05 November 2009 - 10:13 AM

Frank,

This graphite sketch is a beautiful rendition of ancient Humbolt and Hecataeus! :bow: :rainbow: :bow: I love the sinuous curves that the terminator reveals right at the edge of darkness, simply a breathtaking view! :waytogo:

#8 frank5817

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Posted 05 November 2009 - 10:15 AM

T5, Mark and Jef,

Thank you all for your comments on my lunar sketch. :thanx: It was a fine scene to behold even though the longitudinal libration on this night was not showing these craters to best advantage.

Frank :)

#9 frank5817

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Posted 05 November 2009 - 10:26 PM

Rich,

Thank you so much. :thanx: I wish you could have been with me to see this great view. I really would have enjoyed sketching it in White Conte' and black graphite at the same time side by side. However, the risk of two incomplete sketches was too great. If you were with me you could have handled the Conte' sketch with ease.

Frank :)

#10 JayKSC

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Posted 06 November 2009 - 10:47 AM

Great sketch, Frank. You've captured these edge-features well. I've always found lunar edges trickier to work with due to the distortions in the view.

- Jay
South Florida

#11 niteskystargazer

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Posted 06 November 2009 - 11:46 AM

Frank,

:), nice sketch.

:thanx:,

Tom

#12 Shannon s

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Posted 06 November 2009 - 04:25 PM

Great sketch Frank. Do you find it hard to sketch when you have Moon blindness in one eye? :crazyeyes:

#13 frank5817

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Posted 06 November 2009 - 05:43 PM

Jay, Tom, and Shannon,

Thank you all for your kind words about my sketch.:thanx:
---------
Jay- Yes I too need to play with the shapes of the limb craters but I do this very lightly at first until I think I have it correct. As I sketch in the surrounding craters I can then tell how close I got. If it isn't good the spacing between the surrounding craters is all wrong. That happens to me frequently.
----
Shannon-- To answer your question --no not any more. I now do all my lunar sketching with bright lights on, including a bright book lamp. Just a few years ago moon blindness was a problem with a dim sketching lamp. The moon is so bright that you don't need dark adaption to sketch it. It is more comfortable to sketch the moon if your eyes are bright light adapted; plus you can see what you are doing.

Frank :)

#14 mickmrn1

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Posted 08 November 2009 - 11:27 PM

Excellent sketch Frank; Amazing what you can see with a 6mm eyepiece! Keep up the great work!

#15 frank5817

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Posted 09 November 2009 - 12:14 AM

Michelle,

Thank you.:thanx: 240x is plenty enough magnification on the moon. Even binoculars give great views.

Frank :)

#16 CarlosEH

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Posted 11 November 2009 - 04:59 PM

Frank,

An excellent observation of Humboldt and Hecataeus along the lunar eastern limb. Craters along the lunar limb are interesting as libration changes their appearance at times. Thank you for sharing it with us all.

Carlos

#17 frank5817

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Posted 11 November 2009 - 06:57 PM

Carlos,

Thank you much for your comments about my post. :thanx:

Frank :)






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