LtE in CMO #269

From Konrad DENNERL

. . . . . . . . . . Dear Masatsugu,


please find enclosed some offprints of the paper on the discovery of X-rays from Mars (containing the image of Yukio MORITA in Fig 16c), and a 2003 calendar from the Institute where I am working.

I hope that you are satisfied with the reproduction of the image, and that I have got the citation right. Please forward my greetings and thanks also to Yukio MORITA.

His image demonstrates very well the impact of the dust storm on the optical appearance of this hemisphere, while the region which was visible at the end of the X-rays observation was much affected (as Fig 16a shows, which was taken by an experienced German amateur astronomer under observing conditions which were, at least on the Earth, very unfavourable). Nevertheless, no change was observed in the X-ray signal. This implies that the storm did not blow a sufficient number of very tiny dust particles into the upper atmosphere to influence the X-ray flux by additional scattering of solar X-rays on such dust grains.

Unfortunately, despite the upcoming extremely favourable Mars opposition, it is unlikely that additional X-ray observations of Mars will be performed. This is mainly due to the very high demand on observing time with the Chandra X-ray satellite. Compared to ground based astronomy, this satellite was extremely expensive, costing about 1.5 billion US$ (about 15 times the cost of one 10 m KECK telescope). In this context, I was very happy that I had got observing time for Mars.

Thank you very much for your support.

(18 December 2002)


. . . . . . . . . .Date: Mon, 17 Feb 2003 12:01:19 +0100

From: Konrad Dennerl <>

Subject: Re: Thank you


Dear Masatsugu,

thank you very much for your kind letter. I am sorry that my mail arrived so late. If I had known that then I would have sent it explicitly by air mail. This is an occasion where I appreciate the benefits of e-mail for communicating over large distances.


 In your letter you mentioned the idea that there might be a connection between solar activity and atmospheric disturbances on Mars. This is very interesting: while it is well known that the upper atmosphere of Mars (and that of Venus and Earth) responds to solar activity, I am not aware how changes in the upper atmosphere are expected to propagate into the lower atmosphere and may be related to storm activity. I think that your observations of Mars are very important in this context, and I am sure that you will continue to monitor Mars so well, in particular during the coming opposition. If something unusual should be found to happen on Mars and/or the Sun, then this might help to trigger another observation of Mars in X-rays.


Thank you for your remarks about the Calendar. I am impressed by your knowledge of the German language. In Germany it would be very hard to find someone who is able to read Japanese.

Best wishes,


(Garching bei Mnchen, Deutchland)

Max-Planck-Institut fr Extraterrestrische Physik,

(Note) The article received is entitled "Discovery of X-rays from Mars with Chandra" published in Astronomy & Astrophysics 394 (2002) 1119-1128. The offprints were sent out by snail mail, and so it took about two months from Germany to Japan. Dr DENNERL analyses the first X-ray image of Mars obtained on 4 July 2001 by the ACIS-1 detector onboard the Chandra satellite, and so the terrestrial images by GARRADD, MORITA & FLACHWILKEN on 4 July 2001 (respectively at LCM=172W, 212W & 311W) as well as an image by TAN Wei Leong on 1 July are cited. NASA's Chandra was launched by Space Shuttle Columbia on 23 July 1999, and is designed to observe X-rays from high-energy regions of the Universe. This X-ray Observatory was named after in honour of the late Indian-American Nobel laureate Subrahmanyan CHANDRASEKHAR.


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