Mars Feb 20th - Odd NPC ?

[DarkerSky]

Mars was stunning last night, even though we are on its more muted side in the evenings at the mo. I was using my 16" at x295 mag with a red filter. Seeing was mostly 2 but sometimes 3. The oddest thing though is that I couldn't make out the boundary of the NPC on the preceeding edge. It just seemed to 'merge' with a lighter area on the limb.

Here is the sketch:

22.00 to 22.45UT

CM 181 degrees approx

The NPC really is a slither of white light now compared to how it was a few weeks ago. Quite a difference. The dark area around the NPC also showed detail with one darker notch either side of the CM. The notch on the following side was more noticeable and seems to fit with Propontis II.

Further onto the disc there was alot of subtle shading. Three slightly darker areas caught my eye, these being (I think ) Euxinus Lacus, from which further lighter shading curved up around the Amazonia basin; Propontis I, which seemed to extend westwards; and Trivium Charontis. In fact Trivium was the darkest of these 3 markings. Elysium did not seem particularly bright, only really defined by its boundings of the 2 darker areas (Propontis I and Trivium).

In the South, Mare Sirenium was a dark slither high up near the southern limb. It showed a wavyness to it, with a distinct 'v' shape near the CM. Diving off the western limb was Mare Cimmerium.

[dweller25]

Very nice drawing.

I observed the same CM a few nights ago and also noticed a lot of lighter areas on the preceeding edge which I took to be cloud formations. Could these have been obscuring the NPC hood ???

[chrisrnuttall]

the cloud formations you have observed are also on my sketch, and i took them to be tharsis volcanoes - which is quite cool. See pete lawrences image of a similar CM on the imaging forum, it clearly shows the volcanoes. near there, plus other brightness on the limb

[chrisrnuttall]

actually, having checked on mars previewer there is a white splodge where both you and i drew it called arcadia! oh well.

by the way, i was examining the NPC closely and could not see any notchiness to the border, i checked because a few people have reported it recently, i guess your much larger aperture probably helps!

must - get - bigger - scope

[lunator]

Seb

Very good sketch.

Mars was impressive last night

Although we are looking at the 'blander' side. There were still hints of darker patches visible in my 10" scope.

Cheers

Ian

[DarkerSky]

Thanks for the comments.

Chris - I checked out Pete's image. The similarities in what I saw with his image are amazing. Good to get that confirmation on the northeast limb brightening. I stayed with the red filter throughout the obs and that bright area just popped into view no more than 3 times. I should have popped a green or blue filter in to get a proper look really, but I didn't

The notches in the collar were challenging to pin down. Again, good to see them present on Pete's image.

[chrisrnuttall]

Thanks for the comments.

Chris - I checked out Pete's image. The similarities in what I saw with his image are amazing. Good to get that confirmation on the northeast limb brightening.

The notches in the collar were challenging to pin down. Again, good to see them present on Pete's image.

it's a great feeling when you match up the sketch with hi quality photos from the same night!

I intend to make a few more sketches of mars this season, hopefully seeing some details around that shrinking polar cap.

[Paul G. Abel]

Hi Darkersky,

I was observing Mars the same night- it seemed to me that the whole of the proc. limb was filled with bright white clouds which I took to be bright clouds over the Tharsis volcanoes. There also appearedd to be a cloud over Olympus Mons and in the deserts of Amazonis and Arcadia. The NPC has shrunk (as it is spring in the northern hemipshere) as so the cap sublimates away.