Mars Opposition Day

[t00fri]

Hi,

just to remind you that today, Mars is closest to Earth! Unfortunately, the weather has turned rather bad over here...

But two days ago, I watched Mars around 1:30 local time [11:30 UT] with my 8 inch Celestia telescope. Unfortunately, there is a lot of frustration around here, at 53.5 degs north, about Mars' low transit altitude of only about 20.5 degs!

Nevertheless, it was quite a spectacular sight in my telescope, despite blue/red fringes due to atmospheric dispersion at such low altitudes. I managed to spot Mars around 1:30 MEST in between the branches of the many huge trees around my house;-).

Without optical aids, it looked like an amazingly bright redish lantern in the sky, at -3 mags!

By incorporting the appropriate Gaussian blur corrresponding to my (ideal) resolution (0.6") and using Mars' opposition size of 26", I prepared an image for you that is very close indeed to what I saw. Note the rose-white color! Mars was so bright in the telescope that it hurt in my eyes and I mostly used a blue or orange Wratten filter both to enhance the surface details and to reduce the glare.



Bye Fridger

PS: In the original post of the above image, I had forgotten to add the polar ice cap as it is seen today. Nobody seemed to have realized, though;-). Anyway, now it's there.

For texture freaks: Mars is RED and not muddy brown. If you take the above color and brightness reduce it, you get very close in color to what the HST photos look like...

[chris]

But two days ago, I watched Mars around 1:30 local time [11:30 UT] with my 8 inch Celestia telescope.

An 8 inch Celestia? Excellent choice of instrument!

--Chris

[JackHiggins]

But two days ago, I watched Mars around 1:30 local time [11:30 UT] with my 8 inch Celestia telescope.

I knew there was something up with that statement...

With 40x magnification, I can just make out mars' south polar cap, and a tiny bit of other detail on the surface, but it's really just a large orange dot...

I REALLY need to get a better telescope... I don't want to get a "beginners" one though, because in a few years i'll just want a bigger one again- why have 2 when I only really need 1?

Must have a look out later though, hopefully the weather has cleared up some bit since earlier!

[t00fri]

But two days ago, I watched Mars around 1:30 local time [11:30 UT] with my 8 inch Celestia telescope.

I knew there was something up with that statement...

With 40x magnification, I can just make out mars' south polar cap, and a tiny bit of other detail on the surface, but it's really just a large orange dot...

I REALLY need to get a better telescope... I don't want to get a "beginners" one though, because in a few years i'll just want a bigger one again- why have 2 when I only really need 1?

Must have a look out later though, hopefully the weather has cleared up some bit since earlier!

Jack,

you might care to look at ElPelado's thread, where I gave some general advice about telescopes from my very long-term perspective as an amateur astronomer. I built my fist telescope spotting a single 5cm lens at the age of 12;-).

My first 8" Celestron telescope I bought many years ago. Then, suspecting there was something wrong with the optics, I used sophisticated Laser interferometry in my basement, to prove that the Schmidt corrector plate was faulty. Altogether Celestron supplied 3 brand new optics sets and finally, after 10 years a brand new telescope free of charge that I still own;-)

No wonder that they are in financial difficulties...


Bye Fridger

[t00fri]

But two days ago, I watched Mars around 1:30 local time [11:30 UT] with my 8 inch Celestia telescope.

An 8 inch Celestia? Excellent choice of instrument!

--Chris

Hi, hi...Celestia forever...Incidentally, we also use Celestia toilet paper;-)

Bye Fridger

[ElPelado]

I 've been wathcing mars for more then a month now. first wit ha borrowed scope, and now with my own scope. i know that its only 3" of diameter are not enough to see many details, but i saw the polar cap and some dark areas. and today i use also the barlow, so i was useing this: scope 700mm
ocular 4mm
barlow 3x
getting a magnification of 525x. it looses cuality, but i can still see some dark areas and the polar cap. its beautiful!!!
today(wensday) i will be able, with a little help of the wheter, to see it trough an 8" (or 6", i dont rememeber) Schmidt-cassegrein, and to hear a class about mars(?). but its free so....
good look to everyone!
bye

[ElPelado]

what a waste of time!!!! 45 minutes waiting to see mars with an 8" telescope, but using a very low magnification!!! i can see the same and more with my only 3" one.
i am very disapointed...
at least I didnt have to pay anything.
well, i'll keep using my own scope now.
bye

[Adelvunegv_waya]

Well, i have it on good authority that the lenses and mirrors that i ordered for the unit im building will be here some time this week....

Granted they were supposed to be here MONDAY!!!!!

[t00fri]

I 've been wathcing mars for more then a month now. first wit ha borrowed scope, and now with my own scope. i know that its only 3" of diameter are not enough to see many details, but i saw the polar cap and some dark areas. and today i use also the barlow, so i was useing this: scope 700mm
ocular 4mm
barlow 3x
getting a magnification of 525x. it looses cuality, but i can still see some dark areas and the polar cap. its beautiful!!!
today(wensday) i will be able, with a little help of the wheter, to see it trough an 8" (or 6", i dont rememeber) Schmidt-cassegrein, and to hear a class about mars(?). but its free so....
good look to everyone!
bye

ElPelado,

525x is by far what one calls an empty magnification for your small scope! 'Empty' means that you do not see more detail but only get a bigger size with less sharpness. The rule of thumb is that the maximal useful magnification should not exceed twice the diameter of the scope in millimeters. In your case this would be 2x76 ~ 150x! In moments of exceptionally clear air one might try 3x the diameter, i.e the absolutely maximal mag that makes sense is 3x76 ~250x.

Magnification is generally of inferior importance as compared to the scope's diameter [and optical perfection, of course].

Bye Fridger

[t00fri]

what a waste of time!!!! 45 minutes waiting to see mars with an 8" telescope, but using a very low magnification!!! i can see the same and more with my only 3" one.
i am very disapointed...
at least I didnt have to pay anything.
well, i'll keep using my own scope now.
bye

There may have been various reasons for that:

-- perhaps the 8 inch was bad optically and they knew that it would work reasonably only with low mag;-). Just take a refractor of d=100mm ~ 4 inch that has really good optics. Such scopes easily cost $2000 (!) and more, despite a size that is not much larger than your 76mm, $50 telescope...

--since it was a class, they perhaps thought that a low mag was easier to handle for unexperienced observers...

-- perhaps the air was not quiet which is a most important factor for larger scopes. In such a case you generally see more with smaller telescopes!

You cannot imagine what a huge difference my observations of Mars showed in Switzerland at 1850 m of altitude and 46 degs latitude (mars got up to 30 degs at transit!) as compared to what I can see here (up north and at sea level) with those color fringes due to atmospheric dispersion!

And this with the same 8 inch telescope and despite the fact that in Switzerland Mars was still only 20 arcsecs in size while here it was at opposition, i.e. 26 arcsecs!

On the other hand this makes astronomical observations so thrilling, since almost every night the conditions of observation are quite different. Every astronomer continuously hopes for the "super night", of course;-).


Bye Fridger

[ElPelado]

well, where to start. i'll start from your first reply:

525x is by far what one calls an empty magnification for your small scope! 'Empty' means that you do not see more detail but only get a bigger size with less sharpness. The rule of thumb is that the maximal useful magnification should not exceed twice the diameter of the scope in millimeters. In your case this would be 2x76 ~ 150x! In moments of exceptionally clear air one might try 3x the diameter, i.e the absolutely maximal mag that makes sense is 3x76 ~250x.

Magnification is generally of inferior importance as compared to the scope's diameter [and optical perfection, of course].

Bye Fridger

all what you said in this reply i 've already known it. and i wrote it in my post. i said "it looses cuality". i know that. but i wanted to try, and i saw something. today i tryed again and i didn't saw even the polar cap with the barlow. that means that maybe the previous day, the atmosphere was better. but i know that the max magnification is 2xDiameter.

and about the second reply:

There may have been various reasons for that:

-- perhaps the 8 inch was bad optically and they knew that it would work reasonably only with low mag;-). Just take a refractor of d=100mm ~ 4 inch that has really good optics. Such scopes easily cost $2000 (!) and more, despite a size that is not much larger than your 76mm, $50 telescope...

as far as i know, this cope costs more than $2000. and its a very very very good 8" Schmidt-Cassegrain telescope with computer. so thats not the reason.

--since it was a class, they perhaps thought that a low mag was easier to handle for unexperienced observers...

what do you mean when you say easier to handle?? no one toched te telescope, there was only one man moving the telescope, and i think that for begginers, is much more beautiful to see it bigger than that. i heard about many people that were disapointed after seeing just a small dot.

-- perhaps the air was not quiet which is a most important factor for larger scopes. In such a case you generally see more with smaller telescopes!

the air was good enough to see at least with 150x, believe me.

You cannot imagine what a huge difference my observations of Mars showed in Switzerland at 1850 m of altitude and 46 degs latitude (mars got up to 30 degs at transit!) as compared to what I can see here (up north and at sea level) with those color fringes due to atmospheric dispersion!

i am at ~30? lat and at the sea's level, and at transit mars got up to ~42?, so there is not such difference. in argentina, when i was there some weeks ago, at 1 am it was almost at 90?.

bye Uriel.

[t00fri]

ElPelado,

then perhaps you should have asked the man (telescope operator) why he did not put at least 250x in? With such a small mag as you describe, the glare is very high in an 8" telescope such that you can barely see details. It hurt my eyes to look at Mars with 100x only...You would need blue or orange filters. In good air, indeed 500-600x is best with my 8 inch. Then Mars appears really big, about like a small (party) tomato;-). The illumination is still bright, but the glare is entirely gone.

Bye Fridger

[ElPelado]

why in the mars' texture i have, the south polar cap is so small??? it should be bigger than that, shouldn't be?

[t00fri]

why in the mars' texture i have, the south polar cap is so small??? it should be bigger than that, shouldn't be?

It varies with the seasons...

Bye Fridger

[ElPelado]

so, your texture in the texfoundry is for what season?

[Guest]

i got to look at mars through a 22" telescope.

[ElPelado]

WOW!!! and how did it look?? what did you see?