LtE in CMO #274

FromChristophe PELLIER

. . . . . . Date: Thu, 26 June 2003 18:03:52 -0000

From: "Christophe Pellier" <>

To: <>

Subject: thank you !


Dear Masatsugu:

I have received today the printed CMO you have sent me. Many thanks! I wasn't expecting to see so much issues, and even less expecting to have some old CMO issues (such as those of 1991 or 1992). All this work is of great value to my eyes and I'll preciously keep them in my astronomical library.

Kind regards


. . . . . . Date: Fri, 27 June 2003 18:56:55 -0000

Subject: RE:thank you !


Dear Masatsugu and everyone:

Yes the CMO 272 arrived today. I will have a very fine time reading all of this! I totally agree with your thoughts about the best means to make a realistic color image of Mars. For me the right way is to make an RGB composite with R, G, B images (on my images of june 24 however, it appeared to me that the ToUcam used in color mode (with the UV/IR blocking filter) gave images close to what I saw in visual). I think that a false G image won't give a correct image. For example in my last images there is a brown-reddish tint around Hellas (like in Mare Hadriacum). This tint may be lost without a true G image, as in the RG610 red image Mare Hadriacum is almost white (with some dark markings); and it will be lost if we make a RRGB composite. And, as you said it right, the white clouds of Mars suppose also an RGB processing to be shown correctly. So my plan is to make RGB images with the complete Astronomik filter set - but the R and G filters haven't arrived yet. Nonetheless, the black and white ToUcam Paolo made for me arrived yesterday, and I will use it with the blue and red filter next time I can observe. On my two last mornings on Mars (june 21-24), the dark markings were visible on the blue images but I can't tell whether this is because of a false/true blue clearing or because of another problem in the spectral answer of the color chip. I also have closely followed Eric Ng and Tan Wei Leong's work with the Magenta filter, but it seems that on some their blue images obtained by this mean, the shape of the dark markings (the shape and not the markings themselves) was visible in the B images. Maybe because the red and blue components of the magenta image were not correctly split? Anyway a B/W sensor and a good blue filter will solve completely the problem for me.


Best wishes and thanks again; I just hope to send you very soon new images. Conditions are now nearly to the best, and the images will be quite good providing atmosphere is stable enough.


. . . . . .Date: Sat, 28 June 2003 16:30:25 -0000

Subject: Mars June 28 2003


Hello observers, these images are my first try with the B&W modified ToUcam made for me by Paolo Lazzarotti. Even if the seeing was poorer than on my previous observing mornings, I find the results very conclusive, as this chip gather much more light than the original color one and possibly has a better definition (?). I have even been able to make a selection of the raws obtained with the blue filter !

This webcam also solves for me the problem of the spectral response of the color ToUcam...




. . . . . . Date: Thu, 3 July 2003 19:08:21 -0000

Subject: Mars on July 3 2003


Hello Mars observers :


This morning I had a brief window of clear sky between two rainy days with thunderstorms, and surprisingly the seeing was quite good.


With the B&W ToUcam I have been able to use a set of R, G, B filters from Astronomik and I find that the RGB images obtained match almost exactly the visual aspect of the planet (to my eyes of course), colors and contrasts. I think this is a good way to go! The images made with the color ToUcam this same morning aren't satisfactory.


I see no dust activity at these longitudes, unlike the Hellas longitude, as seen on the beautiful observations made by the American observers. A white cloud is just barely seen over Tharsis.


Best wishes,


. . . . . . Date: Sat, 5 July 2003 16:53:46 +0200

Subject: Mars, july 5 2003


Hi all,

A few Mars images from this morning. I have observed shortly after sunrise because the dust cloud visible over Mare Cimmerium was just coming into view. The blue images seem to show that the dust may be accompanied by water vapor ?


We also see an orographic cloud forming over Arsia Mons I think, in the martian afternoon / evening.




. . . . . . Date: Sun, 6 July 2003 20:24:26 -0000

Subject: Mars july 6 2003 under excellent seeing


Hi all, this morning I had wonderful seeing conditions on Mars, unbelievable at an altitude of 20-29! There is still no dust in the important site of Solis Planum/Thaumasia.


Again a cloud is seen forming above Arsia Mons.


. . . . . .Date: Tue, 8 July 2003 21:12:20 -0000

Subject: Mars on july 8 2003


Hi everyone: I've observed Mars this morning under fairly good seeing but fair transparency. No dust !

The image is also at



Christophe PELLIER (Bruz, Ille-et-Vilaine, France)

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