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How are you going to capture the December 7th Mars / Moon Occult?

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#1 MachMike

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Posted 05 December 2022 - 09:04 PM

I'm asking because I'm not sure if I should use the Fuji XT1 with the CPC1100 HD or the ASI462 with the CPC1100HD to capture the moments. I would love to hear the pros and cons of each method.

 

Thanks in advance.


 

#2 Lumix.guy

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Posted 05 December 2022 - 09:29 PM

I'm wondering the same thing!

 

For a narrow field of ASI462 (or similar), I'm wondering how the surface brightness of Mars will compare to the Moon.  Can they both be faithfully captured in one exposure setting?

 

John


 

#3 MachMike

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Posted 05 December 2022 - 09:51 PM

I'm wondering the same thing!

 

For a narrow field of ASI462 (or similar), I'm wondering how the surface brightness of Mars will compare to the Moon.  Can they both be faithfully captured in one exposure setting?

 

John

Yeah, I am not sure. The CCD (I could be wrong) is focused to infinity, so they should both make it...I am going to assume a 13% filter is a must. 

So I was starting to lean towards my Fuji XT1. Honestly I have no clue so thats why I'm posting, Maybe one of the gurus will provide some tidbits of knowledge.


 

#4 bthrel

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Posted 05 December 2022 - 10:09 PM

I'll be capturing it in my imagination and vicariously through you guys as the forecast here is dismal next 5 days frown.gif Cant wait to see pictures here


 

#5 gregghallinan

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Posted 05 December 2022 - 10:15 PM

Both Mars and the Moon are reflecting sunlight,  so the apparent surface brightness, and therefore the number of photons per pixel of your camera, is inversely proportional to the square of the distance from the Sun and linearly proportional to the albedo (fraction of photons reflected). Mars is at 1.5 AU from the Sun and the moon is 1 AU, so 2.25x more photons per square cm are hitting the Moon than Mars. In other words, the flux of sunlight is 2.25 higher at the Moon than Mars. The visual geometric albedo is 17% for Mars and 12% for the Moon - that is the fraction of photons in the visible band reflected back at the Earth. Therefore,  the flux of photons per pixel of your camera will be 2.25*12/17 = 1.6 times higher for the Moon then Mars. This does not account for color effects.  For example Mars geometric albedo reaches 0.4 at 1 micron and it may be brighter than the Moon in the near infra-red, for example.  To summarize,  this is very easy to capture with a single camera setting.  This would not be the case for any other planet! Venus is too bright and the rest are too faint. Mars is the Goldilocks planet to be occulted by the Moon! 


 

#6 TOMDEY

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Posted 05 December 2022 - 10:41 PM

The best way --- with my eyes and a telescope!    Tom


 

#7 Lumix.guy

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Posted 05 December 2022 - 10:57 PM

Both Mars and the Moon are reflecting sunlight,  so the apparent surface brightness, and therefore the number of photons per pixel of your camera, is inversely proportional to the square of the distance from the Sun and linearly proportional to the albedo (fraction of photons reflected). Mars is at 1.5 AU from the Sun and the moon is 1 AU, so 2.25x more photons per square cm are hitting the Moon than Mars. In other words, the flux of sunlight is 2.25 higher at the Moon than Mars. The visual geometric albedo is 17% for Mars and 12% for the Moon - that is the fraction of photons in the visible band reflected back at the Earth. Therefore,  the flux of photons per pixel of your camera will be 2.25*12/17 = 1.6 times higher for the Moon then Mars. This does not account for color effects.  For example Mars geometric albedo reaches 0.4 at 1 micron and it may be brighter than the Moon in the near infra-red, for example.  To summarize,  this is very easy to capture with a single camera setting.  This would not be the case for any other planet! Venus is too bright and the rest are too faint. Mars is the Goldilocks planet to be occulted by the Moon! 

I like your math, but do we need to consider the relative distances from Earth also?  Moon is 230K miles and Mars is 82M miles!


 

#8 Lumix.guy

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Posted 05 December 2022 - 10:59 PM

Yeah, I am not sure. The CCD (I could be wrong) is focused to infinity, so they should both make it...I am going to assume a 13% filter is a must. 

So I was starting to lean towards my Fuji XT1. Honestly I have no clue so thats why I'm posting, Maybe one of the gurus will provide some tidbits of knowledge.

A C11 at f/10 should not need any filter.  In fact the filter will reduce your frames per second which is a bad thing.


 

#9 RedLionNJ

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Posted 05 December 2022 - 11:37 PM

This is the third time this topic has been raised in this forum in the last few weeks. Locking this thread and suggesting people learn to use 'search' to come up with a link like:

 

https://www.cloudyni...ies/?p=12325731


 


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