2003 Dust Storm Director's Notices #1
Letters to the Editor
from Konrad DENNERL

Date: Tue, 11 Nov 2003 18:11:02 +0100
From: Konrad Dennerl <kod@mpe.mpg.de>
To: Masatsugu MINAMI <VZV03210@nifty.ne.jp>

Dear Masatsugu,

first of all I would like to congratulate you to the CMO Gallery, which is currently one of my most favorite Web addresses. It is always a pleasure for me to have a look into this nice collection of stunning amateur images from all around the world.

I have now finally got time for observing Mars in X-rays. This time not with the US satellite Chandra, but with the European satellite XMM-Newton. Unfortunately, XMM-Newton can only observe objects which have a solar elongation between 70 and 110 degrees, and so it was not possible to observe Mars during its very close approach to Earth.

XMM-Newton will observe Mars soon after its solar elongation will have decreased to 110 degrees (this happens on Nov 16), during the following period: *** from Nov 20, 00:07 - Nov 21, 05:04 UT ***

This is a particularly long observation, which will cover more than a full Mars rotation. Compared to the previous observation of Mars with Chandra, the upcoming observation with XMM-Newton will collect more X-ray photons and will have better spectral resolution, but less spatial resolution. Mars will also be considerable smaller in angular diameter (12 arcsec compared to 20 arcsec before), so that its disk will probably not be well resolved. The scientific investigation will more concentrate on the X-ray halo which was indicated in the Chandra data.

Despite these limitations, it might nevertheless be good to have some simultaneous optical coverage. Although there is a good chance that such images will be taken anyway by amateurs around the world (according to the beautiful CMO Gallery, which contains practically for every day stunning amateur images), I think that it might be good to inform amateurs in advance that November 20-21 will be a particularly rewarding time for taking images of Mars.

I myself will also try to take optical images, although I have only a 112 mm Newton telescope at home (more than 30 years old). During several Mars oppositions in the past I had used it for taking images on photographic film. During this opposition I have used a WebCam for the first time, and I was impressed how easy this is to handle and how much detail this technique reveals, even when used with such a small telescope. I have attached one such example, which, however, cannot compete with the incredible quality which can be reached with larger amateur telescopes.

Coming back to the X-ray observations, we are now in a period of enhanced solar activity. This is, on the one hand, a very interesting situation for X-ray studies of Mars, but, on the other hand, also a real threat: last week practically all X-ray observations with XMM-Newton had to be cancelled because of the high radiation. I hope that this will not happen on November 20-21; I will keep you informed.

Best wishes,


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