Mars Section Circular No. 2

 

1998 November 16–December 15

 

 

 

General

 

Mars remains distant, so that many Section members have yet to begin work. This Circular summarises the period 1998 November 16–December 15 (Ls = 58–70 deg., D = 4.9–5.6 arcsec., lat. of centre of disk 25–24 deg. N), though some observations a little later and earlier have been added for comparison. Since publishing Circular No. 1 I have received two more of the OAA’s bulletins (Nos. 209, 210) which cover the periods Oct 16–Nov 15 and Nov 16–Dec 15 respectively. I have received nice CCD images from Don Parker and Frank Melillo; David Gray remains the most prolific visual contributor. Jim Bell emailed that HST coverage is unlikely to be extensive in 1999, which makes our efforts all the more worthwhile.

      Please note that all the following data have been obtained on a disk below 6 arcseconds diameter: congratulations to all concerned!

      The next Circular will cover the period 1998 December 16 to 1999 January 31, and I intend to compile it by February 15. Therefore please send any relevant work to cover that period in time for it to be included. I have sent e-mail or paper copies of Circulars 1 and 2 to all active Section members from 1997, and to others who might find it of interest. Inactive Section members may not receive further copies, please note!

 

North Polar Region

 

The cap remains bright and conspicuous (with dark surroundings) though somewhat reduced in size. Selected measures indicate normal recession. During the period reviewed no internal details were reported in the cap.

 

Atmospheric activity

 

No dust storm activity has been reported, but there is some white cloud activity, reported in no special order below:

      Hellas: Whitish or slightly so at the morning limb, dull thereafter. Patrick Moore (Nov 17, CML 256–271 deg.) drew it fairly dull. Combined data show that it began to brighten after CML 280 to 300 deg., becoming very bright by martian evening (CML about 330 deg.). Gray on Nov 10, just before the period reviewed, found Hellas very bright at the evening terminator under CML 339 deg., but it had gone off the visible disk by 345 deg.

      Chryse–Xanthe: Whitish to the OAA observers from about CML 50 deg. in the afternoon. Also seen light at the a.m. limb, but no brighter than other equatorial deserts at local noon.

      Libya: The OAA recorded ‘morning mist following Libya’ under CML 265 deg. on Dec 9. Gray must have had a similar experience on Dec 23 when he found the Syrtis Major apparently slightly veiled when rising, under CML 233 deg. It was not seen to be light near the CM.

      Elysium: Light at the evening terminator, the a.m. terminator and lightish in the afternoon, but never really bright.

      Tharsis; Nix Olympica; Alba: On Dec 2 under CML 149 deg. Gray sketched a mass of extensive bright cloud over the evening (p.) terminator, from which Nix Olympica (the orographic cloud over the slopes of Olympus Mons) was but imperfectly resolved. Alba was light but not easy to the same observer at the terminator on the same date.

      Aeria: Some indications of both morning and evening cloud.

      Tempe: No reports of cloud activity here as yet. Noachis: Masatsugu Minami, Nov 25, 28, found it whitish on the evening terminator (20-cm OG).

      S. polar hood: A constant feature, but variable both diurnally and with longitude. Thus: Minami and Takashi Nakajima (OAA), Nov 23, S. limb hazy and light, especially on the morning side (CML about 50 deg.); Gray Nov 6 (CML 27 deg.) p. side of hood brighter than the following in W58 green.

 

Dark markings

 

The following comments by Martin Gaskell (20-cm refl., Dec 8, CML = 175 deg.) should encourage other Section members to start their observations: ‘The northern maria around the NPC (Scandia–Panchaia) were the darkest features visible. The diffuse dark markings in the Diacria–Propontis–Phlegra region were surprisingly dark in white light given that the disk was only 5.4 arcseconds across.’ No changes in the markings from 1997 have yet been detected, but increasingly fine surface details are being recognised. Thus David Gray did well to make out the little N–S elongated ‘oasis’ of Nodus Alcyonius Np. the Syrtis Major. On Nov 23 Minami, with Nakajima, was even able to detect colourations with a 20-cm OG. M.Acidalium was slightly dark brownish and the Aurorae Sinus region dark bluish.

      On this last point of colour, the Director wonders if the difference in colour between such markings at aphelic apparitions can be ascribed to the presence of the bluish-white equatorial cloud bands? Such bands would tend to make the Aurorae Sinus, Syrtis Major, etc., more bluish than far northern areas such as Utopia and Mare Acidalium, even though the bands are rarely visible through direct observation near the CM with small telescopes. If this explanation is correct (rather than there being real differences in the hues of the dark markings themselves), then we can deduce that the ECB were present in many past apparitions even if they were not reported as such (e.g., 1935, 1952, and through to the present time). It will be easy to search the literature for earlier examples, though these are the earliest I can think of offhand where there were significant tonal differences in the manner described.

 

From the bookshelf

 

Patrick Moore on Mars is the title of a popular new Mars book by Patrick, his first for two decades. It is published by Cassell (1998), and it is recommended to members as an excellent guide to the Red Planet. Patrick is unique in having contributed observations to the Mars Section at every apparition from 1948 to the present.

      Iakovos Stellas writes from Athens that he has completed the draft of a translation of E.M.Antoniadi’s book The Planet Mars from English into Greek. He hopes to have discussions with publishers about the chance of printing an edition in Antoniadi’s native language, which would be very nice. In the 1970s Patrick Moore translated the original French edition of 1930 into English. I am often asked if this English edition is still available, and always have to say that it has been out of print for some years. If any member comes across secondhand editions of this, or any other classic Mars books, and does not want them for him or herself, please let me know as I may be able to match people with books. For myself I would like to find the French edition of Schroeter’s Mars book: I have it in German but cannot easily read it! I would also be interested in getting copies of the Annals of the Lowell Observatory – the formal reports on Mars by Lowell and his assistants covering the years 1894–1903 (volumes 1–3).

 

Reporting data to the Section

 

Send mail to Cherry Tree Cottage, 16 Upper Main Street, Upper Benefield, Peterborough PE8 5AN, Great Britain; home telephone 01832 205387; home e-mail Rmckim5374@aol.com. (Do not use the former email address for my place of work (mckim@oundle.northants.sch.uk).)

 

 

Richard McKim, Director

 

1999 January 7