36 replies to this topic

[Sasa]

Mars tonight on September 11, 2018:

 

Edited by Sasa, 12 September 2018 - 02:35 AM.

[frank5817]

Alexander,

 

The very classic Mars view. Excellent sketch.

 

Frank

[niteskystargazer]

Alexander,

 

Very nice sketch of Mars  .

 

CS,KLU,

 

,

 

Tom

[Sasa]

Last night I set up my larger refractor. Before I started with sketch, view was quite sharp at 167x. As you can expect, once I started with the work it never came back at the same level. Being lazy I stayed at 167x.

 

Hellas was not that bright as night before. However I think I glimpsed in it a brighter smaller spot. Saw it only 3 times for very short time, it could be a trick played to my eyes.

 

 

[Sasa]

And more Mars from today. Conditions were awful, most of the time Mars was not visible by eye and when it was seeing was very bad. Still I was able to glimpse something:

 

[Sasa]

Tonight, it was another fight to see at least something:

 

[astronz59]

Big ups to you for persistence and sheer ability, Alexander! 

[Kris.]

Very good set of sketches, especially with such modest apertures!

[Sasa]

Thanks to all likes and comments. Here is another Mars under mediocre conditions from yesterday

 

[Sasa]

Finally, I run yesterday on little bit better conditions

 

[Sasa]

After stormy yesterday night atmosphere cleaned a lot from dust. It was still windy today (and tonight) with quickly changing weather between completely clear sky to rain, even hailstones occasionally. I saw through window bright Moon, the sky was almost clear with just some clouds quickly approaching from north. I knew I must be fast, luckily this is possible with 60mm refractor. At the end I got about 14 minutes of observing and sketching Mars before the sky got completely clouded. View was surprisingly reasonably good. In short moments I saw interesting texture with numerous darker and lighter patches. I wish I had more time to capture them more precisely:

 

[Sasa]

Two nights ago I took out my larger 82mm refractor. I wanted to explore in more detail those interesting patches I saw on previous night with 60mm refractor. Alas, I got usual bad seeing and I was happy to see at least something. Here is my best guess of what was going on the Mars globe:

 

[Sasa]

Finally I run with my larger refractor on very good sky, both transparency and seeing. In calm moments, the view was very sharp at 167x

 

[Sasa]

Mars is getting smaller and it seemed tonight like it was too small for 60mm telescope. It was hard to notice anything else beyond the two polar caps and Terra Sirenum. According to WinJUPOS, Solis Planum and Margaritifer Terra were supposed to be on western edge. All I could see in this area were just vague, very faint and slighlty darker undefinite patches

 

Edited by Sasa, 29 September 2018 - 02:38 PM.

[Aquarellia]

Good job Sasa, a nice souvenir for this opposition!

Michel

[Sasa]

Thanks Michel. I should go to Japan more often...

[azure1961p]

Wow, nice job!!!!

 

Pete

[Sasa]

Thanks Pete, here is another one from tonight. As I was half an hour late, Mars was showing the same face as previous night so one could compare the two observations. Tonight, Solis Planum and Margaritifer Terra were more pronounced, even with some hints of tips. But nothing definite:

 

Edited by Sasa, 30 September 2018 - 04:31 PM.

[agmoonsolns]

Very nice work!

[Sasa]

Thanks, btw I see all the time bright northern polar region. However on images, or in sketches through larger scopes (like recent one from Paul Abel), there is nothing. I was paying special attention to it last night. It was clearly there, I would say even much more pronounced than souther cap. So is this a trick played on my eyes, like in small telescopes the brighter edges somehow tend to be larger? I don't know. It is one of the most pronounced albedo features, I usually see first this northern cap and with more concentration the darker albedo features. To me it looks quite real.

[Kris.]

I have no clue why you see this, my only wild guess would be that it is some form of chromatic aberration? but only if you’re using an achromatic refractor, if your scopes are apochromatic this would be much less… but i don't know your telescopes ...  just a thought

[David Gray]

Thanks, btw I see all the time bright northern polar region. However on images, or in sketches through larger scopes (like recent one from Paul Abel), there is nothing. I was paying special attention to it last night. It was clearly there, I would say even much more pronounced than souther cap. So is this a trick played on my eyes, like in small telescopes the brighter edges somehow tend to be larger? I don't know. It is one of the most pronounced albedo features, I usually see first this northern cap and with more concentration the darker albedo features. To me it looks quite real.

Most of this apparition (16.3” D-K) I have been routinely getting a brightness – often very bluish – along/inside the N. limb: evidently the NP Hood.  As I indicate more an arc than a circular cap-like aspect; in fact many images are showing a similar arc. Tho’ I suspect some have processed it out???

 

With using an ADC I can confidently say bluish (and real!) and have posted several sketches here showing that.  The apodizer further cleans up the limb regions.

 

What you are getting accords well with my 3” refractor views……that rounder effect I feel is down to the diffraction effects of lo-res (perhaps some irradiation also) – much as we get larger Airy disks with smaller apertures as compared to larger.  In fact my most of my more recent views with the co-mounted 3”gave a very cap-like apparent ellipse ('NPC') effect and even more apparent with the 3” stopped down to 1½“(160x no ADC but a Ramsden ep for dispersion cancelling).  

 

To show an extreme example attached is a rendering from last apparition (posted here back then) where the SPC, sub-res in the 3”, mimicked a bright star complete with 1st diffraction ring!

 

Hope to post some of my recent Mars shortly – very busy time domestically lately, but hoping for an opportunity next weekend………

 

Dave.

Edited by David Gray, 03 October 2018 - 12:33 PM.

[Sasa]

Thanks David, you are the right person to answer my question as you routinely observe Mars with both large and small aperture. I'm glad that my sketches correspond to the view in your 3" refractor. It brings more confidence back to me. It was quite shaken by the absence of the bright north polar cap on many recent images and sketches.

 

I think you explanation as an effect of limited resolution of small refractor is spot on.

[Pbinder]

Very nice work

[Sasa]

Thanks Paul, after short period of bad weather, we had clean sky tonight. Mars is still ok even in the small telescope

 

 

Just for fun, here is a comparison with the situation at the end of August when I captured at the same position:

 

 

Edited by Sasa, 04 October 2018 - 03:43 PM.