98/99 report #01

1998/99 Mars Observation Reports -- #01--

OAA MARS SECTION - Monthly Report published in CMO No 208 (25 October 1998)

Martian Sufaces Observed from 16 September to 15 October 1998

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

  Our planet Mars has come back in the morning sky! The apparent diameter is not large enough, but its apparent declination is enough to make the planet shine high up in the eastern sky. We heard from Nicolas BIVER (NBv) at Hawaii that he had already started observing Mars on 20 September (see LtE). At Fukui NAKAJIMA (Nj) and the present writer (Mn) set about their routine work on 2 October: It was easy to find the planet since it was near Regulus, alfa Leo. In fact on 6 Oct at 16hGMT Mars passed 0.9°N of Regulus (the star is of magnitude 1.4, while Mars 1.7). At Fukui, Mars rises near after 2 o'clock am, and it is observable from 4:30JST, and around 5:00JST (20:00GMT) it may be the best time to observe at present. At 6:00JST the sun rises. Meanwhile we received a report from R SCHMUDE (RSc) who made his first observation on 27 September. HIKI (Hk) at Nagano produced his first observation on 9 October at 20:05GMT.

  In the present issue, we treat the observations made during the period from 16 September 1998 to 15 October 1998

  On 16 Sept, the apparent diameter (δ) was 4.0" while it only rose to 4.3" on 15 Oct. During the period the Martian season proceeded from 030°Ls to 043°Ls, the central latitude De (φ) from 20°N to 24°N, and the phase angle (ι) from 20° to 26°. The illumination of defect will increase gradually for the present. Notable was the fact that the apparent declination was +17° on 16 September, while it went down to +11° on 15 October. This is an annoying problem we encounter this apparition as stated in the preceding issue.

We received with thanks the following observations this time:

      HIKI, Toshiaki  (Hk)  Minowa, Nagano, Japan
            1 Drawing (9 October 1998)  360× 16cm speculum

      MINAMI, Masatsugu  (Mn)   Fukui, Japan
           20 Drawings  (2 - 5, 9, 10, 11 October 1998) 340, 400, 480× 20cm refractor * 

      NAKAJIMA, Takashi  (Nj)   Fukui, Japan
           17 Drawings  (2 - 5, 9, 10, 11 October 1998) 340, 400, 480× 20cm refractor *

      SCHMUDE, Richard W, Jr  (RSc)  GA, USA
            1 Drawing  (27 September 1998)  570× 51cm speculum

                                                                         * Fukui City Observatory

  From Fukui (136°E, 36°N) we were able to watch the surface from ω =210°W eastward to ω =100°W during the period. The dark markings were scarce but the north polar cap (npc) was large enough and clearly whitish bright from the outset. On 2 Oct the season was 041°Ls and φ=23°N. The npc was surrounded by quite a dark fringe, and beyond it a shadowy area in Vastitas Borealis was seen. 9 Oct at ω =124°W, the morning side looked darker. The southern dark markings ran always but unidentifiable. 5 Oct at ω =175°W, a tip of M Sirenum was visible. The southern limb was seen always covered by a whitish haze, especially its evening side being brighter. The Tharsis cloud was less conspicuous than the npc. Elysium was not detected. Propontis I was not separated (in 1994 Propontis I was first clearly detected when apparent diameter δ=7.4").
  HIKI (Hk) (at 138°E, 36°N) first observed on 9 Oct at ω =133°W where the npc looked large evident, while the Tharsis area slightly light. The season was 041°Ls, and the apparent diameter was 4.3".
  SCHMUDE (RSc) (at 85°W, 34°N) made his first observation at ω =105°W when 035°Ls. The npc was 0.5 in intensity while the dark fringe 7. No other particular dark markings though there were seen shadowy areas which were not identified. In red, no other brighter part than the npc was found: a lighter area was seen at the evening side adjacent to the dark fringe but not bright in Red. The apparent diameter δ=4.1". Seeing was 8.

  We have not received yet the drawings from N BIVER (NBv) by the editing time. We should say we cannot cover all the personal data from the Internet Web-Sites, and so in principle we make it a rule not to refer to the personal data in the Web-Sites in this column.

  The next issue shall review the observations during the period from 16 Oct to 15 Nov 1998. The mail address is found at the final page of each issue.

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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