Mars Sketch (12)

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

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

  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 (096degsLs) 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(096degsLs) at LCM=079degsW
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          LCM           Seeing     Remark 
  Mn-440D  LCM=044degsW   moderate to good 10:40GMT
  Nj-162D  LCM=049degsW     8-9/10
  Mn-441D  LCM=054degsW   moderate / good    (*)
  Id-099D  LCM=056degsW      4/10
  Nj-163D  LCM=059degsW     7-8/10
  Mn-442D  LCM=064degsW   moderate to poor
  Nj-164D  LCM=069degsW       6/10
  Id-100D  LCM=071degsW       6/10           (**)
  Mn-443D  LCM=074degsW   poor / moderate
  Nj-165D  LCM=079degsW     6-7/10           (***)
  Mn-444D  LCM=083degsW   poor / moderate
  Nj-166D  LCM=088degsW       7/10
  Mn-445D  LCM=093degsW   poor / moderate
  Nj-167D  LCM=098degsW       5/10
  Mn-446D  LCM=103degsW   moderate 
  Nj-168D  LCM=108degsW                    15:00GMT
  Mn-447D  LCM=115degsW   poor / moderate  15:30GMT
  Nj-169D  LCM=120degsW     
  Mn-448D  LCM=125degsW   poor
  Nj-170D  LCM=130degsW     
  Mn-449D  LCM=135degsW   poor
  Nj-169D  LCM=130degsW                    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 LCM=094degsW as cited in CMO #191 p2102. The LCM 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 LCM=094degsW 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)