1998/99 Mars Observation Reports -- #15--

OAA MARS SECTION

CMO Monthly Report
published in CMO #222 (25 August 1999)

Martian Surfaces in the Second Half of July 1999 and the First Half of August 1999

  We are thankful to the following observers who directly contributed this period to the CMO:

      AKUTSU, Tomio  (Ak)   Karasuyama, Tochigi, Japan
             8 Sets of CCD images (27, 28, 30, 31 July; 2, 3, 8 August 1999)
                 f/60 32cm spec equipped with a Teleris 2 

      HIKI, Toshiaki  (Hk)  Minowa, Nagano, Japan
             5 Drawings (25, 29 July; 4, 8, 11 August 1999)  400x 22cm speculum

      ISHADOH, Hiroshi  (Id)   Naha, Okinawa, Japan
            15 Drawings (16~20, 23 July; 6, 9 August 1999)  340,400x 31cm speculum

      IWASAKI, Tohru  (Iw)  Kitakyushu, Fukuoka, Japan
            11 Drawings (18, 19 July; 9, 11, 12, 14 August 1999)   400x 21cm speculum

      MINAMI, Masatsugu  (Mn)   Fukui, Japan
            30 Drawings (16, 21, 24, 25, 26, 31 July; 1, 2, 7 August 1999)  400x 20cm refractor* 

      MURAKAMI, Masami (Mk)   Fujisawa, Kanagawa, Japan
            15 Drawings (20, 26, 31 July; 1~4, 6, 7, 8, 11 August 1999)  425x 20cm speculum

      NAKAJIMA, Takashi  (Nj)  Fukui, Japan
            34 Drawings (16, 21, 22, 25, 26, 31 July; 1, 2, 3, 6, 7, 8, 12 August 1999) 
                                                            400x 20cm refractor*

      NARITA, Hiroshi  (Nr)  Kawasaki, Kanagawa, Japan
             8 Drawings  (26 July; 1, 2, 7, 8 August 1999)  400x 20cm refractor

      PARKER, Donald C  (DPk)  Miami, FL, USA
             5 Sets of CCD Images (21, 24, 27, 28 July 1999) f/55 41cm speculum + Lynxx PC

      TEICHERT, Gerard  (GTc)  Hattstatt, France
             2 Drawings  (24, 25 July 1999)  330,310,280x 28cm Schmidt-Cassegrain

      WASIUTA, Myron E  (MWs)  VA, USA
             1 Set of CCD Images (16 July 1999)  f/35  15cm AP refractor+ Lynxx 
             5 Drawings (4, 15, 27, 30 July 1999)  430x 15cm F7 AP refracor

     * Fukui City Observatory (The Fukui City Museum of Natural History)

     FALSARELLA, Nelson  (NFl)    Sao Jose do Rio Preto - SP, Brasil
         16 Drawings (19, 21, 22, 25, 28 May; 7, 9, 10, 11, 15, 16, 21, 22, 23, 27 June; 3 July 1999)
             260,325x 20cm speculum
         38 CCD Images (3, 9, 10, 11, 12, 19, 22 April; 1, 3, 8, 12, 13, 15, 18, 19 May; 21, 24 June 1999)
             20cm speculum + AVA ASTROVID 400 

 Surface features during the present period:
  On 16 July (171°Ls) WASIUTA (MWs) at Virginia took a set of CCD images at 01:44 GMT (LCM=128°W) where Propontis I was seen in R at the morning side, while on our side ISHADOH (Id) watched the morning Syrtis Mj at 10:50 GMT (LCM=262°W) under good seeing. At Fukui, NAKAJIMA (Nj) and the present writer (Mn) started slightly earlier on the day. The apparent diameter was 10.3" and it was still possible to grasp some details: Id, Nj and Mn noticed that Syrtis Mj was already dark, Cebrenia made a light belt, Hellas was rather light (intensity was at 3.0 by Id) and so on. N Alcyonius was visible. As to the north polar region (npr), Id just saw the north polar hood (nph), while Mn and Nj saw in addition a light area at the pole position at LCM=264°W and LCM=269°W respectively. Id enjoyed fine skies for five successive days until 20 July.
  On 17 July (172°Ls), Id observed at LCM=260°W, 272°W and 282°W, where he suspected a presence of the north polar cap (npc). An equatorial-band mist was weakly seen to the north of M Cimmerium. Hellas was light but not whitish but having a tint of brown.
  On 18 July (173°Ls), IWASAKI (Iw) watched at LCM=252°W & 262°W, where the nph looked irregular, and the south polar hood (sph) was dull. Id observed then at LCM=270°W that Hellas was less light and Utopia looked darker than the day before. Id felt the npc at LCM=282°W.
  On 19 July (173°Ls), Id saw at LCM=236°W that Eridania was whiter and lighter than the morning area of Hellas. Syrtis Mj was then not visible. Iw observed at LCM=243°W & 252°W: Iw judged the shape of the nph was different to that on the day before. Iw detected the morning Syrtis Mj quite near the terminator at LCM=252°W, but failed the day before at the same angle (though seeing was slightly better on the preceding day). Elysium was dull just like a usual desert.
  On 20 July (174°Ls), Mk observed the surface of LCM=216°W: The southern limb to the west was white though didn't shine. A weak mist was seen along the northern coast of M Cimmerium, being whiter at the morning area. Elysium was only lighter at the western part. The intensity of the nph was at 2.5, and slightly showed a bluish tinge. Id observed then at LCM=253°W & 263°W that the nph was indefinite, while the sph was down to the south of Hellas: Hellas itself was off-white.
  On 21 July (174°Ls), PARKER (DPk) produced good CCD images at 01:35 GMT (LCM=078°W). The R images show faintly but definitely the npc surrounded by the dark ring including Hyperboreus L where Chasma Boreale is also seen. In B (and colour), a large white mist is visible at the morning Baltia. Ophir is shot in B, and hence white in colour. The images are really good to the extent that Oxia P is seen quite near the preceding limb. Solis L dark, and the sph down to the south of it. Some of Tharsis Montes shown as dark spots near the morning terminator. At Fukui we started from 10:00 GMT (in the twilight) at LCM=202°W: The npr was whitish, and the sph looked large but dull light. The Ætheria dark patched was rather brownish. Elysium and Cebrenia made a Y-shaped light area. The preceding limb-side was light thru G (noted by Nj).
  On 22 July (175°Ls) at LCM=204°W, Nj saw a mist following Elysium near the terminator.
  On 23 July (175°Ls), Id observed at LCM=210°W and 224°W, where the sph or spc was light but still dull while the npc was definite and round.
  On 24 July (176°Ls), DPk took good images at LCM=039°W (00:51 GMT) and at LCM=051°W: The limb haze hides half of S Meridiani though the latter is completely seen in R. A morning mist is seen from Tempe to M Acidalium. Deuteronilus apparent. The Orestes extension explicitly dark visible. At Fukui, Mn started from 10:00 GMT at LCM=173°W. The nph was small in size but definite. The sph or spc appeared louder, and was in a good contrast with M Sirenum and M Cimmerium. TEICHERT (GTc) in France watched at 20:10 GMT (LCM=321°W) where Syrtis Mj was near the preceding limb.
  On 25 July (176°Ls), we started from 10:00 GMT (LCM=163°W): The sph or spc was obvious, and at LCM=173°W it frequently shined, and hence Mn judged that it was mainly made of the spc. Well light thru O56 at LCM=193°W. The nph was rather smaller but showed a core inside. HIKI (Hk) observed at LCM=188°W. GTc followed at LCM=302°W (19:55 GMT).
  On 26 July (177°Ls), we started from LCM=154°W, but seeing was not enough. MURAKAMI (Mk) observed at LCM=163°W: The south-western limb had intensity 3, while the nph was at 2.
  On 27 July (177°Ls), MWs took a drawing at 01:20 GMT (LCM=018°W): The nph was prominent, and was seen also the sph. The drawing shows the afternoon S Sabaeus and the morning M Acidalium et al, and they are shown more detailed in DPk's CCD images taken at LCM=018°W - 032°W. These show also a large morning mist to the south-west of M Acidalium. The sph is not so bright but quite large. In Japan, AKUTSU (Ak) took a set of CCD images on the day at LCM=142°W.
  On 28 July (178°Ls), DPk worked at 01:22 GMT (LCM=008°W; the apparent diameter should read 9.5"), where there is a large dull mist (off-white?) at the npr while the western tail of Utopia is visible and maybe also the npc. The R image at LCM=007°W seems to show the spc. Note the image at LCM=011°W still shows Syrtis Mj near the preceding limb. On our side, Ak worked at 10:04 GMT (LCM=136°W), where Tharsis is light near the limb.
  On 29 July (179°Ls), Hk made a drawing at LCM=144°W.
  On 30 July (179°Ls), MWs secured a drawing at LCM=344°W (01:00 GMT); Syrtis Mj occupied, and the nph was seen thru all filters but not the sph. Ak shot at LCM=116°W (10:02 GMT), where Solis L was at the afternoon side.
  On 31 July (180°Ls), we started at Fukui from 09:50 GMT at LCM=103°W; but this first one was the last drawing made under a favourable seeing; since then the sky condition at Fukui was broken down for more than half a month. Solis L was definitely seen, the spc was not so light but the contour was clear, and the nph was roundish white followed by a morning mist. Ak took a set of good images at LCM=105°W describing Solis L, Nilokeras, M Acidalium et al. Xanthe light. Both of the sph and nph are thick in B. Mk observed at LCM=108°W & 118°W; in the former Solis L was located near the preceding limb, but the local Martian time was 10:20 am since the phase angle was large up to 44°. The disk diameter was 9.4" on the day.

  The Martian season reached the autumnal equinox 180°Ls on 31 July so that a glimpse of the largest spc could have already been caught. So the observations in August shall be reviewed individually especially with respect to the spr observations.
  At the beginning of August, AKUTSU (Ak) enjoyed better seeing under High, but the detection of the spc was difficult: On 2 Aug (181°Ls) at LCM=091°W, he produced Solis L. As well the spr is not so light in B on Ak's image on 3 Aug (181°Ls) at LCM=078°W where M Acidalium remains. The images on 8 Aug (184°Ls) at LCM=026°W & 039°W prove that the sph or spc was better seen, but the nph looked stronger. S Meridiani is separated. The apparent diameter was 8.9".
  HIKI (Hk) observed on 4 Aug (182°Ls) at LCM=077°W, where the npc was apparent and the spr was whitish. On 8 Aug (184°Ls) at LCM=031°W, the nph declined to the morning side, and Hk seems to have detected the spc at the opposite side. The nph looked to invade the morning northern part of M Acidalium on 11 Aug (186°Ls) at LCM=002°W.
  ISHADOH (Id) was annoyed by several tropical cyclones which stayed near Okinawa but could observe on 6 and 9 August: On 6 Aug (183°Ls) at LCM=068°W, the spc or sph was apparent on or to the south of Argyre. The preceding limb was well light. The nph was definite and round. Solis L was about to be dark. Nilokeras et al looked normal. On 9 Aug (185°Ls) at LCM=039°W & 058°W, Id saw a light area in the npr. The spc was rather light to the south of Argyre. The afternoon limb light. Maybe a mist at the morning Acidalium M.
  IWASAKI (Iw) observed on 9 Aug (185°Ls), 11 Aug, 12 Aug and on 14 Aug (188°Ls) from 10:50 GMT. He did not detect any tip of the spc, but detected usual dark markings. There was observed by Iw a faded part in S Margaritifer on 11 Aug (186°Ls) at LCM=022°W and so on. Just the season when E C SLIPHER detected a local dust over there on 10 July 1922 (187°Ls) which lasted for four days. Iw similarly observed on 12 Aug at LCM=012°W. Iw saw Hellas near the preceding limb on 14 Aug (188°Ls) at LCM=343°W to be whitish light, but much less so compared with the nph.
  MURAKAMI (Mk) saw a weak stream of mist at the equatorial band on 1 Aug (180°Ls) at LCM=106°W. Seeing slightly improved on 8 Aug (184°Ls) at LCM=031°W & 041°W, where M Acidalium showed a brownish tint. The nph declined to the east. No explicit observation of the spc.
  NAKAJIMA (Nj)'s observations turned out to be poor because of bad seeing condition at Fukui until 12 Aug (186°Ls) when he watched at LCM=353°W, 002°W & 012°W: There was a light area in the npr (even thru G). The spc was not particularly light. Syrtis Mj remained until LCM=002°W. Deuteronilus apparent. No comment on Iw's phenomenon.
  MINAMI (Mn) also met no preferable seeing, but just judged that the spc was present on the disk on 1 Aug (180°Ls) and 2 Aug (181°Ls).

 30 June Revisited:
  Images of dust cloud occurrence found by the MGS on 30 June (163°Ls) was published on 10 August at the following Web-Site:
    http://mpfwww.jpl.nasa.gov/mgs/msss/camera/images/8_10_99_releases/moc2_172/index.html

  The images were taken at 06:52, 08:50, 10:47 and 12:45 GMT: the dust stream curled looks to have ejected from the npc (near from Chasma Boreale) and conceals Hyperboreus L. The stream appears new because its branch is wavy. The motion is slow macroscopically. The npc is visible, a part of which is covered by a thin haze. In Japan the sky was still bright at 09:00 GMT on the day, but it was possible in principle to observe from 10:00 GMT if we disregard its small dimension.
  From the documents on the very day 30 June (163°Ls) we can pick out the observations by ISHADOH (Id), IWASAKI (Iw) and MURAKAMI (Mk) at 10:40 GMT (LCM=054°W, Mk), 11:30 GMT (LCM=063°W, Iw), 12:10 GMT (LCM=073°W, Iw), 12:30 GMT (LCM=078°W, Mk), 12:50 GMT (LCM=083°W, Iw), 13:10 GMT (LCM=088°W, Id), and 14:00 GMT (LCM=100°W, Id). Unfortunately any of the observations gave no notice of the dust projection. ISHADOH (Id), who used the largest speculum among them, started late and the dust must have then been quite near the preceding limb. He just commented that the nph was large and faint, and didn't see any singular brightness inside it. The dust cloud can be considered to stay or rise again on the following days:
  We have the following observations on 1 July (163°Ls) at 10:10 GMT (LCM=034°W, Mn), 11:30 GMT (LCM=054°W, Mn), 12:00 GMT (LCM=061°W, Id), 12:10 GMT (LCM=064°W, Mn) and 12:40 GMT (LCM=071°W, Id). Anyone tried to detect Hyperboreus L but failed, and this must have been because of a veiling of Hyperboreus L by the dust expanded.
  The shape of the nph observed by Id on 2 July was also singular as was reported in #221 p2569. Furthermore, it is highly possible that the large patch observed by Id and HIGA (Hg) on 4 July (165°Ls) was one developed from the dust cloud. We can also speculate that the morning cyclone (possible) observed by Id on the preceding day on 29 June (162°Ls) pulled the trigger at the phenomenon on 30 June. We hope to be able to return to this point again later.

 Now 180°Ls:
  Here are some results of the early aspect of the south polar cap (spc) in 1986 and 1988: The spc was apparent from around 170°Ls, and the present writer (Mn) at Taipei by the use of a 25 cm refractor noticed a shadowy band and brighter spots inside the spc already on 24 May 1986 (176°Ls). After 1 June 1986 (180°Ls), the top of the spc always looked shadowy. The shade inside was rather easily seen because it was occurredwhen the central latitude was 10°S, and in 1988 there was observed clearly a rift inside the spc at 208°Ls (on 3 June 1988) when the central latitude=23°S. The largest snow-line lies between 50°S and 60°S, and it must have been possible to detect the perimeter of the spc this year on 1 Aug 1999 (180°Ls) as is easily seen from the Figure of the grids presented in #216 p2494. The Viking in 1977 began to take the images of the spc from 176°Ls: The image obtained at 176.4°Ls shows the spc whose perimeter is beyond 55°S and a small dust at the border at about 060°W. The image at 183°Ls was copied in CMO #007 p0047, as well as the references therein.
  This year the MGS took the image of the border of spc to the south of Arsia Mons at around the same season which was presented in the Web-Site:
    http://mpfwww.jpl.nasa.gov/mgs/msss/camera/images/8_2_99_spring/index.html

 We-Further-Received:
  FALSARELLA (NFl)'s drawings that produce static images and are not so different from one another without observing notes. The CCD images are good for a 20 cm telescope, but sometimes fails to make the npc and suffer from several ghosts. The image before opposition on 12 Apr (123°Ls) at LCM=246°W shows Hellas in the morning. The evening Hellas is seen on 13 May (138°Ls) at LCM=348°W (0:56 GMT), but scarcely at LCM=356°W. The former image on 13 May is said to shoot a bright spot to the south of the dull npc near the CM, but we will need several images to be composed to exclude any light ghost (four hours later PARKER obtained good images on the day but no such thing is found near the evening preceding limb). NFl is located at (48° 23'W, 20° 49'S) with altitude 468m.
  WASIUTA (MWs) made drawings on 4 July (164°Ls) at LCM=246°W & 265°W: The sph was more prominent than the nph.