1996/97 Mars Sketch (12)
from CMO #209 (25 November 1998)

-- T NAKAJIMA Detected the Morning Olympus Mons as a Dark Spot on 27 Mar 1997?--

Japanese here

  Takashi NAKAJIMA (Nj) and the present writer (Mn) set out from this summer to write a Japanese report on the 1996/97 Mars Observation performed at the Fukui City Observatory to be submitted to the Bulletin of the Fukui City Museum of Natural History (not yet completed). We first checked a bulk of 1012 drawings made by us during the apparition, and on the way we became aware of an interesting drawing by Nj. The drawing was obtained on 27 Mar (096°Ls) at 13:00 GMT by the use of the 20cm refractor at the Fukui City Observatory and we became of the opinion that it implied the presence of the morning Olympus Mons as a dark spot.


T NAKAJIMA (Nj)'s drawing on 27 Mar 1997(096°Ls) at ω=079°W
showing some dark stains at the morning side

  This shows the night was really interesting because the day was the very day when ISHADOH (Id) and Mn also saw Ascraeus Mons as treated in CMO #201 Mars Sketch (3).

  So we here list up some data of all drawings made by Id, Nj and Mn on 27 March 1997:

    Code      ω           Seeing       Remark

  Mn-440D  ω=044°W   moderate to good 10:40GMT

  Nj-162D    ω=049°W     8-9/10

  Mn-441D  ω=054°W   moderate / good    (*)

  Id-099D    ω=056°W      4/10

  Nj-163D    ω=059°W     7-8/10

  Mn-442D  ω=064°W   moderate to poor

  Nj-164D    ω=069°W       6/10

  Id-100D    ω=071°W       6/10           (**)

  Mn-443D  ω=074°W   poor / moderate

  Nj-165D    ω=079°W     6-7/10           (***)

  Mn-444D  ω=083°W   poor / moderate

  Nj-166D    ω=088°W       7/10

  Mn-445D  ω=093°W   poor / moderate

  Nj-167D    ω=098°W       5/10

  Mn-446D  ω=103°W   moderate

  Nj-168D    ω=108°W                    15:00GMT

  Mn-447D  ω=115°W   poor / moderate  15:30GMT

  Nj-169D    ω=120°W    

  Mn-448D  ω=125°W   poor

  Nj-170D    ω=130°W    

  Mn-449D  ω=135°W   poor

  Nj-169D    ω=130°W                    17:10GMT

 

where (*) corresponds to the drawing cited in #201 p2245, (**) does to the Id's drawing in #201 p2243, and (***) is the observation by Nj in question. We note Id-099D does not show any morning dark spot.

  It may not be easy to identify Nj's spot (rightmost) with Olympus Mons. In the case of Id-100D, the characteristic shadowy area of Arsia Mons helped us to identify Ascraeus Mons. Nj-165D was obtained at the session not so far from Id-100D, and so Nj's spot might possibly be Ascraeus Mons.
  As an explicit example which shows the morning Olympus Mons we can refer to an HST image taken on 30 Mar 1997 at ω=094°W as cited in CMO #191 p2102. The ω implies a time difference of one hour from Nj's to compare.　 NAKAJIMA hesitated to write about these spots in his Observing Notes, but he remembers well that he saw several times the dark stains during his session: He was then uneasy about these because he wondered whether these were just noises or true signals. He wanted they were some blurred dark areas, but they remained like dark spots. He experienced these things for the first time and did not come to be well confident of their positions. The latter fact on the contrary rather suggests us that the spot at the right-hand side was most possibly Olympus Mons.

  MINAMI (Mn) sat at the same eye-piece twenty minutes before (Mn-443D) and later (Mn-444D), but was not endowed with seeing enough to notice the stains. Thetime of drawing Mn-445D at ω=094°W was the most possible opportunity because it caught the shadowy area of Arsia Mons, but the seeing scale at that time proved poorer.

  The case of Nj proves that if we are endowed with an improved seeing, we will be able to catch Tharsis Montes as well as Olympus Mons as they are deep inside even by use of a 20cm telescope if the apparent diameter is above 14 arcsecs. So it may be also possible to find the moment Montes will begin to be covered by the orographic clouds.
  NAKAJIMA failed to see the stains again on the next occasion at Nj-166D, and he henceforward remained silent about this phenomenon.

 

Weather Map near Japan on 27 Mar 1997 at 9:00GMT

  N.B.: T NAKAJIMA (Nj) was born in 1939, and a Mars observer since 1954 (as Mn) at the Fukui City Observatory. In 1956 and 1973 he observed an early stage of the great dust storms. In 1990 /91, he obtained a total of 498 drawings which may be his record number for one apparition. In the preceding 1996/97 apparition he secured 282 drawings. He has been an acquaintance of MINAMI since Junior High. He is one of Editors of the CMO and a secretary of the OAA Mars Section. He teaches English in a High School at Fukui.

(Mn : Masatsugu MINAMI)

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