98/99 report #02

1998/99 Mars Observation Reports -- #02--

OAA MARS SECTION - Monthly Report published in CMO No 209 (25 November 1998)

Martian Sufaces Observed from 16 October to 15 November 1998

- - - by Masatsugu MINAMI, Director of the OAA Mars Section ---

 On 7 November (App.Diam. δ=4.7", 054°Ls), MURAKAMI (Mk) joined our routine observation from a new place in Yokohama. HIKI (Hk) was annoyed by the morning fog since his place faces to a well-known valley called Ina-dani in the central Japan. At Fukui we rather enjoyed warm weather for the season and we made progress especially with the statistics of the size of the north polar cap (npc).

We here treat the period from 16 October 1998 (044° Ls) to 15 November 1998 (057° Ls) and the observations recorded are as follows:

      HIKI, Toshiaki  (Hk)  Minowa, Nagano, Japan
            3 Drawings  (7, 15 November 1998)  360×  16cm speculum

      MINAMI, Masatsugu  (Mn)   Fukui, Japan
           64 Drawings  (21, 24, 25, 26, 28, 29, 31 October; 1, 3, 5, 12-15 November 1998) 
                            400×  20cm refractor *

      MURAKAMI, Masami (Mk) Yokohama, Japan
            4 Drawings  (7, 14, 15 November 1998)    370×  15cm speculum

      NAKAJIMA, Takashi  (Nj)   Fukui, Japan
           34 Drawings  (21, 24, 25, 26, 28, 29 October; 1, 3, 5, 10-14 November 1998) 
                            340, 400×  20cm refractor *

                                                                 * Fukui City Observatory

Andre NIKOLAI from Germany sent us his first CCD image this apparition, may be one of the earliest productions in this season:

      NIKOLAI, Andre (ANk) Berlin, Deutschland
            1 CCD Image  (1 September 1998)   15cm refraktor am WFS
ANk's Mars image is tiny (App.Diam.=3.9") but shows well the large npc which must have just emerged from the hood. The season was 023° Ls. The central latitude was17° N.

A NIKOLAI's CCD Image on 1 Sept 1998
by use of a 15cm Refr at WFS

  During the present period, the apparent diameter (δ) increased from 4.4" to 4.9", and the season proceeded from 044°Ls to 057°Ls, thus the npc was on the way of thawing. The central latitude rose from 24°N to 25°N, and the phase angle from 27° to 31°. Around 25 October, we had an experience that the telescope which had kept Saturn at Psc inside the eye-field easily introduced Mars no more than by ascending. Henceforward Mars is apparently to the south of Saturn, the latter now giving a good view. At present, the Sun rises at about 6:40 local time (21:40GMT), and the planet Mars is observable until 22:00GMT.

  Unfortunately we (NAKAJIMA (Nj) and Mn) missed Solis L since we failed to observe for ten days in mid-Oct, while M Acidalium passed the CM on 21 Oct (046°Ls) from our side: At 20:40GMT (in the twilight) it was dark and definite at ω =039°W. The npc was whitish bright in contrast. At the southern limb a white patch was visible, maybe Argyre.
  24 Oct (048°Ls) S Sabaeus came into sight: It was rather bluish while M Acidalium on the morning side looked brownish. At ω =000°W, S Meridiani was separated from Margaritifer S. Noachis dull, but the morning Chryse light.
  A bit of Syrtis Mj was seen on 25 Oct. Hellas rather light (at 048°Ls).
  28 Oct: the eastern part of S Sabaeus was darker. The dark band surrounding the npc was broad.
  29 Oct (050°Ls) we met good seeing under which Syrtis Mj passed the CM. M Tyrrhenum was dark as well as Utopia, and the dark fringe encircles the npc. At ω =309°W, Hellas was white and Syrtis Mj was definite. The npc was well bright but not glossy.
  31 Oct (051°Ls), the southern limb light but not identical with Hellas. We should say the npc have certainly shrunk than before.

  1 Nov (051°Ls) at ω =280°W, M Tyrrhenum dark and Syrtis Mj apparent.
  3 Nov (052°Ls): seeing was good in the twilight: Syrtis Mj appeared from the morning. At ω =260°W, the npc quite roundish and clearly seen with the dark band. M Cimmerium seen, and M Tyrrhenum dark. Hellas rather dull but whitish, while Aeria off-white in the morning.
  5 Nov (053°Ls), the npc evidently smaller than before, and roundish. Utopia dark together with the broad dark band. At ω =241°W, seeing being good, the morning Syrtis Mj was obscure, and its north near the limb misty. The southern dark markings were in general weaker than the northern dark band.
  On 7 Nov (054°Ls), HIKI (Hk) observed at ω =219°W & 227°W: The npc was clearly seen and white. Elysium was however undetected. Temperature read 4 °C. On the same 7 Nov (054°Ls), MURAKAMI (Mk) made his first observation at ω =224°W: The npc bright definite, and the evening side of the dark band was darker. Mars was near Rho Leo.
  On 10 & 11 Nov, Nj observed at Fukui alone under poor sky.
  12 Nov (056°Ls), Mn joined: the transparency was so good that Canopus was seen low in the southern sky while seeing was poor for Mars. Just a shadowy area near Propontis I at ω =180°W and so on.
  13 Nov (056°Ls) at ω =140°W, we tried to detect Alba but it was not so evident (this is the season when Mk et al detected a bright Alba in January 1995. Cf #179) because of the small disk diameter. Tharsis also duller. At ω =170°W, the area of Propontis I was the darkest and Cebrenia was hazed in the morning. The s limb of the disk light.
  14 Nov (057°Ls) at about ω =120°W, Alba gave a light image. Notable was that the dark band surrounding the npc was much broader at the morning side. The s-limb haze looked very complexed. At ω =141°W, the dark fringe of the npc was also darker in the morning side. At ω =160°W & 170°W, Propontis I was about to be separated. Elysium was off-white at the morning limb. Tharsis in the evening was not so conspicuous. On 14 Nov at ω =148°W, Mk observed the npc.
  15 Nov (057°Ls), the dark area surrounding the npc proved to be much broader from ω =130°W westward. The fringe of the npc was fine and quite dark. On the southern hemisphere M Sirenum was witnessed, and there was a white limb area to the south of the Mare (maybe the similar to the one seen one month before). On the night, Hk observed at ω =136°W, and Mk at ω =139°W & 148°W and secured the size of the npc. The season corresponded to the one we met in February 1995 or in December 1996, and the data obtained will prove interesting if compared with respect to the size of the npc and the southern limb hazes.

  The next issue shall review the observations during the period from 16 Oct to 15 Nov 1998.

Reports will be acknowledged if air-mailed to M MINAMI at Mikuni
(ask the mail-address through vzv03210@niftyserve.or.jp ) .

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