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What are reasonable expectations of a 4" apo on mars this year's opposition?

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#76 contrailmaker

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Posted 21 March 2020 - 10:44 AM

Two oppositions ago I had a great time observing Mars using an Orion 100ED.  All the mayor albedo features as well as the polar caps and, when present, clouds/dust are clearly visible with small telescopes and plenty of details with a 100mm. Olympus Mons has remained elusive with the 100mm. If my recollection is accurate, the best I have done is observing the clouds that sometimes form on top of the volcanoes using a 6” refractor. Filters help a lot with that as they are usually low contrast. Keep in mind that the duration of the Martian day is almost exactly that if a day on earth. So if one observes at the same time each evening one gets to see the same side of Mars. 

Really looking forward to the next opposition. The last one was a bust. 

 

CM
 


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#77 mikeDnight

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Posted 21 March 2020 - 11:42 AM

Two oppositions ago I had a great time observing Mars using an Orion 100ED.  All the mayor albedo features as well as the polar caps and, when present, clouds/dust are clearly visible with small telescopes and plenty of details with a 100mm. Olympus Mons has remained elusive with the 100mm. If my recollection is accurate, the best I have done is observing the clouds that sometimes form on top of the volcanoes using a 6” refractor. Filters help a lot with that as they are usually low contrast. Keep in mind that the duration of the Martian day is almost exactly that if a day on earth. So if one observes at the same time each evening one gets to see the same side of Mars. 

Really looking forward to the next opposition. The last one was a bust. 

 

CM
 

Yet by observing at the same time the following night, you'll get a second pop at detecting that illusive Olympus Mons. 


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#78 Brent Campbell

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Posted 21 March 2020 - 12:01 PM

The polar caps, Syrtis, Hellas, & Argyre should be easy in a quality 4" refractor.  I've seen clouds over / around Olympus Mons with my 3" F15 achromatic, and I've imaged Sinus Sabaeus & Meridiani with a 60mm F15 refractor.  But, I've had near-perfect planetary seeing here at The Swamp.

 

This map is good for identifying the features commonly seen:

 

attachicon.gifMars - Visual Features Map.jpg

Bomber Bob.  Where can I download a copy of that map?



#79 BillP

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Posted 21 March 2020 - 12:02 PM

I still remember Ken Fulton's advice about sketching an egg.

???



#80 t.r.

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Posted 21 March 2020 - 12:15 PM

The polar caps, Syrtis, Hellas, & Argyre should be easy in a quality 4" refractor. I've seen clouds over / around Olympus Mons with my 3" F15 achromatic, and I've imaged Sinus Sabaeus & Meridiani with a 60mm F15 refractor. But, I've had near-perfect planetary seeing here at The Swamp.

This map is good for identifying the features commonly seen:

Mars - Visual Features Map.jpg

I’ve never been able to resolve the paint runs of Gomer Sinus in up to 140mm refractors...anyone lay claim to it with like aperture?

Edited by t.r., 21 March 2020 - 12:15 PM.


#81 contrailmaker

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Posted 21 March 2020 - 01:47 PM

Yet by observing at the same time the following night, you'll get a second pop at detecting that illusive Olympus Mons. 

Challenge accepted, Olympus Mons will be one of my goals this year. 
 

CM


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#82 Bomber Bob

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Posted 21 March 2020 - 10:59 PM

Bomber Bob.  Where can I download a copy of that map?

Can't recall where I found it, but you can save the CN copy that I posted to your PC, Laptop, tablet, or other device...



#83 m9x18

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Posted 22 March 2020 - 01:42 AM

???

Boiled down (pun intended), he said that you would be surprised at how many features can be found on the surface of an egg if you just look for them. Sketching forces us to be more observant. To the casual observer, the egg's exterior may appear uniform and bland. But, if we can get good at finding and sketching the minute details on an eggshell, imagine how well we could do with the things found in our telescope's eyepiece. It's just a way of training the eye as well as a method to improve our sketches.  


Edited by m9x18, 22 March 2020 - 11:54 AM.

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#84 stanislas-jean

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Posted 22 March 2020 - 05:19 AM

If you replace this famous boiled egg by Something else more evaluating like a resolution grid placed at a distance sothat some area come to a resolution limit of the 4" aperture,

this will bring a lot to you:

- quality of the optics (well characterised),

- response through the seeing,

- response to the light level of the target, testing during day, at dawn, during night, Under moonlight lighting.

The scope is not all the question but also the ability of the observer even using the best of the best scope.

Performing such, when comparing OTA with different design and construction you see quickly that with "minimal" optical acuracies fullfilled the major limiting factor is the observer equation.

 

Olympus mons is not a big concern through a 4" aperture, because possible also through a 3" aperture, when mars is 12-13" of disk and lefting the limb and the Terminator of the planet.

Stanislas-Jean


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#85 daquad

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Posted 22 March 2020 - 09:44 AM

Boiled down (pun intended), he said that you would be surprised at how many features can be found on the surface of an egg if you just look for them. Sketching forces us to be more observant. To the casual observer, the egg's exterior may appear uniform and bland. But, if we can get good at finding and sketching the minute details on an eggshell, imagine how well we could do on the things found in our telescope's eyepiece. It's just a way of training the eye as well as a method to improve our sketches.  

I recall reading that sketching the full moon with the naked eye is excellent practice for sketching at the telescope.

 

Dom Q.


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#86 m9x18

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Posted 22 March 2020 - 07:46 PM

Yes, all true. Plus, we can try sketching boring things like a wall other such mundane subjects/objects. We would be sure to benefit from exercises like that as they cannot help but to improve our observational skills and sharpen our sketching abilities all at the same time. So watch out Mars, we're getting ready for you!     


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#87 stanislas-jean

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Posted 23 March 2020 - 04:41 AM

Better things to observe when targets to test are typically unknown, sketched then compared with the target at final.

An other game.

Stanislas-Jean


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#88 laedco58

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Posted 23 March 2020 - 09:08 AM

I’m hoping the weather is favorable. Planetary observation through a refractor is a new experience for me. Well actually any non terrestrial observation with a refractor is a new experience for me, lol. 


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#89 mike bacanin

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Posted 28 March 2020 - 12:35 PM

After reading of Don Pensack and his experience of observing mars with the Baader Contrast Booster filter, I think i'll probably give it a try.

 

Mike




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