2001 Mars Observation Reports -- #15--

OAA MARS SECTION

CMO Mars Observations


in the Second Half of August and the First Half of September 2001
from 16 August 2001 (215Ls) to 15 September 2001 (234Ls)
based on the article published in CMO #251 (25 September 2001)

 


Masatsugu MINAMI, Director of the OAA Mars Section



W

HILE the dust-laden atmosphere is still persistent in covering the whole surface of the planet, the activity of the yellow cloud has become mild and the apparent angular diameter has been decreasing, and henceforth we publish the CMO once a month as scheduled though we have published fortnightly since #243 (10 May issue). This time we review the observations made during the one-month period from

 

16 August (215Ls) 2001 to 15 September (234Ls) 2001.

 

  The day 16 August corresponded to Day 54 since the onset of the major dust disturbance. The angular diameter went down from 15.1" to 12.0" during the period. The central latitude gradually moved from 5N to the opposite hemisphere and read 2S on 15 September. The season is drawing at hand for the centre of the south polar cap to deviate from the pole (see #240 p2925).

 

  The meridional altitude of Mars was lowest from the Northern Hemisphere around 25 ~ 26 August; the apparent declination pointing to -27 02'. On 15 September, it recovered to -26 41'.

 

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

 

 

 

BARNETT, John H (JBt) Richmond, VA, USA

1 Drawing (26 August 2001) 360x 18cm refractor $

 

BIVER, Nicolas (NBv) Noordwijk, Netherlands / Versailles, France#

4 Colour Drawings (16, 24, 25 August; 1# September 2001)

300x 20cm speculum / 330x 26cm speculum#

 

HIKI, Toshiaki (Hk) Minowa, Nagano, Japan

8 Drawings (16, 17, 18, 24, 25 August; 1 September 2001) 430, 400x 22cm speculum

 

ISHADOH, Hiroshi (Id) Naha, Okinawa, Japan

15 Drawings (29, 30 August; 2, 3, 6, 10, 15 September 2001) 340, 410x 31cm speculum

 

KUMAMORI, Teruaki (Km) Sakai, Osaka, Japan

5 CCD Colour Images (22, 23, 28 August; 4 September 2001)

20cm Dall-Kirkham with a Sony PC-5

 

MELILLO, Frank J (FMl) Holtsville, NY, USA

7 CCD Images (16, 22, 27 August; 4, 11, 13 September 2001)

20cm SCT with a Starlight Xpress MX5

 

MINAMI, Masatsugu (Mn) Fukui, Japan

53 Drawings (16, 17, 18, 23, 24, 25, 27, 28, 29, 31 August; 1, 4, 5 September 2001)

400, 600x 20cm refractor*

MOORE, David M (DMr) Phoenix, AZ, USA

5 Sets of CCD Images (17, 21, 24, 25 August 2001)

f/40 36cm Cass with an Astrovid 2000 video camera

 

MORITA, Yukio (Mo) Hatsuka-ichi, Hiroshima, Japan

28 Sets of CCD Images (19, 23, 27, 28, 29, 31 August; 1, 4, 9, 15 September 2001)

f/50 25cm speculum equipped with an ST-5C

 

MURAKAMI, Masami (Mk) Fujisawa, Kanagawa, Japan

10 Drawings (16, 17, 26 August 2001) 320x 20cm speculum

 

NAKAJIMA, Takashi (Nj) Fukui, Japan

27 Drawings (16, 17, 22, 24, 25, 29 August; 1, 5 September 2001) 400x 20cm refractor*

 

NARITA, Hiroshi (Nr) Kawasaki, Kanagawa, Japan

2 Drawings (12 September 2001) 400x 20cm refractor

 

PARKER, Donald C (DPk) Miami, FL, USA

9 Sets of CCD Images (19, 24, 29, 31 August; 3, 6 September 2001)

f/44 41cm Newtonian equipped with a Lynxx PC

 

SCHMUDE, Richard W, Jr (RSc) GA, USA

3 Drawings (17, 23, 24 August 2001) 230x 10cm refractor

 

TEICHERT, Grard (GTc) Hattstatt, France

2 Drawings (24, 25 August 2001) 330, 310x 28cm SCT

 

TSUNEMACHI, Hitomi (Ts) Yokohama, Japan

10 Drawings (17+, 25+, 26 August 2001)

320x 20cm speculum+ chez MURAKAMI / 360x 12.5cm Fluorite refractor

 

VALIMBERTI, Maurice (MVl) Victoria, Australia

12 Sets of CCD Images (29, 30 August; 5 September 2001)

f/85 15cm refractor with a TC245 based camera

 

$ Richmond Astronomical Society Ragland Observatory

*Fukui City Observatory

 

 

The Yellow Cloud :

 

T

he major dust storm has longer lived than expected, and the surface is still covered by the yellow cloud without showing any of the well-known dark markings explicitly. Late in August, however, there appeared several comments that noted a decrease in dust opacity. For example, MOORE (DMr) noted 17 August (day 55) at LCM=352W as follows: " It appears the dust has cleared a bit on this hemisphere from last rotation" (17 August, p3117), and PARKER (DPk) also commented on 19 August (day 57) at LCM=295W, 301W: " The albedo features are somewhat more visible" (20 August, p3115). Both were concerned with the area of Syrtis Mj. MELILLO (FMl) aso stated simlarly on 24 August (p3116). The visual observer BARNETT (JBt) at Richmond, VA also noted 26 August (day 64) at LCM=235W as follows while he admitted that M Cimmerium and M Tyrrhenum were still covered by the cloud: " The dust storm seems to be less intense than a month ago." Similar observations were often made from our side, though some including ISHADOH (Id) and MURAKAMI (Mk) considered that the atmosphere should be said still thickly laden with dust. The present writer (Mn) is of the similar opinion, though, as we admit, the optical depth has lessened to the extent that the dark markings are visually appearing more contrasty to the level the IR light dug out in July. We should take also account of the large phase angle which implies the oblique incidence of the Sun rays.

 

Region including Solis L and Auror S :
  Notably, Solis L is long lost. From Japan its angle faced until around 24 August (day 62), but it did not show up in any sense. It was also difficult to identify the area around Auror S. There were still two light streaks from Thaumasia, one maybe to Auror S and the other preceding the Tharsis ridges: The observation by the present writer (Mn) on 23 August (day 61) at LCM=071W proved that the configuration was not so different than the one at LCM=074W made on 16 July (day 23) as far as the streaks were concerned. The following streak was brighter in July, but less bright this time, however. The area corresponding to the south of Solis L (maybe to the north of the south polar cap) was broadly darker than any other as shown by the images of KUMAMORI (Km) on 22 August (day 60) at LCM=084W and on 23 August (day 61) at LCM=060W.

 

Noachis, S Meridiani, S Sabus, . . . :
  Noachis is dusky in contrast with the brighter northern deserts on MOORE (
DMr)'s images made on 17 August (day 55) at LCM=352W. The western half of S Sabus does not look to have recovered. DMr's images on 21 Aug (day 59) at LCM=330W show similarly.

  Noachis came into sight to the Oceania and the Orient around from 29 August (day 67). VALIMBERTI (MVl) obtained nice images on the day (IR was at LCM=326W, 347W, 352W, 004W). At Fukui NAKAJIMA(Nj) & Mn watched from LCM=333W to LCM=022W. ISHADOH (Id) observed at LCM=000W, 012W. Noachis was rather shadowy while Depressiones Hellespontic had been weaker. At LCM=333W, the area of M Serpentis was darkest and detailed. The east part of S Sabus did not extend to the west while S Meridiani was suspected. MVl's IR images don't however show it. MORITA (Mo)'s R image at LCM=024W still proves that the area of S Meridiani is much weaker than the area of S Margaritifer, and so not so different from the description at p3095 in #249.

  MVl obtained a set of good images on 30 August (day 68) (RGB colours at LCM=312W, 323W, 332W, 358W). Id observed at LCM=015W, 024W on 30 August. On 31 August (day 69), Mn observed from LCM=313W to LCM=353W. Mo then shot at LCM=358W, 005W, 009W on the day: Syrtis Mj entered deep on the disk. The western part of S Sabus was invisible though the area of S Meridiani was a bit dusky. On 4 September (day 73), the M Serpentis area looked quite dark and detailed. The upper Noachis looked shadowy on Km's images at LCM=308W, 315W.

 

Vicinity of Syrtis Mj :
  The images of PARKER (
DPk) secured on 19 August (217Ls, day 57) at LCM=295W, 301W show Syrtis Mj at the centre and M Tyrrhenum and S Sabus at the left and right wings. These are shown also on DMr's images on 21 August (day 59) at LCM=313W, on 24 August (day 62) at LCM=286W, and on 25 August (day 63) at LCM=304W as well as on the one by MVl on 30 August (day 68) at LCM=312W. In Japan, the surface of LCM=295W was observed on 4 September (day 73) at 10:40 GMT (19:40 JST), and 5 September (day 74) at 11:20 GMT (20:20 JST). Mo took the images on 4 September at LCM=295W, 309W, 312W, 320W, and 331W. Deltoton S looked a bit recovered (since long time ago). On 5 September (day 74), MVl obtained good images at LCM=280W ~ 320W.

 

M Cimmerium:
  In #250 p3109, we stated that M Cimmerium had begun to recover its original relief around from 9 August (day 47) perhaps because the palling cloud started to be levelled. DPk produced an image of M Cimmerium on 29 August (day 67) at LCM=207W, and it does not differ much from the images by the present writer obtained previously on 10 August (day 48) at LCM=203W and on 11 August (day 49) at LCM=204W where Electris was light. One round later, Mo obtained images on 15 September (day 84) at LCM=203W, 207W, 213W ( in addition to LCM=190W, 195W). The one at LCM= 213W was to supplement the images put on p3071 in #248 (shot on 1 July ~ 4 July). The west end of M Cimmerium was caught by MVl on 5 September (day 74) at LCM=270W.

 

M Sirenum :
 As to the aspect of M Sirenum, DPk's images on 3 September (day 72) at LCM=169W show vividly two points if we compare them with DPk's images on 24 June at LCM=167W (the very dust-triggering day but yet far from the cloud disturbance): M Sirenum on 24 June was of the same form as we knew from 1986. The shape differs from M Sirenum in the ANTONIADI - EBISAWA map in the sense that the west end of M Sirenum has been retreated to the east up to 160W. The images on 3 September shows that 1) the faded part has recovered dark while 2) the eastern part of M Sirenum is still invisible and rather a tail is seen down to the north at the east end of Valhalla. A foregoing R image by Mo on 14 August (day 52) at LCM=168W is not so good but seems to suggest the same aspect.

 

Elysium and Its Environs :
  PARKER (DPk) commented 29 August (day 67) at LCM=207W, the central latitude=2N that Elysium and environs (Tri Charontis, Phlegra, Propontis I) were not visible. On 31 August (day 69) at around LCM=198W, his images showed Propontis I vaguely. From our side, Id tried to discriminate the dark patch at theria and others on 15 September (day 84) at around LCM=215W, but in vain.

 

Olympus Mons :
  In 1971 and 1977, the global dust storms were recorded by the Mariner 9 and Viking spacecrafts respectively to disturb the upper atmosphere in excess of 40 ~ 50 km, while the present yellow cloud should be said to have spread below the level of 20 ~ 30 km because the summits of Olympus and Tharsis Montes have been visible. From our side, the summit of Olympus Mons continued to show up (from 9 August) until 18 August (day 56): On 16 August (day 54) it was checked at LCM=118W ~ 147W (by Mn). HIKI (Hk) caught it at LCM=120W, and Nj at LCM=142W and so on. On 17 August (day 55) MURAKAMI (Mk) and TSUNEMACHI (Ts) detected it by the use of the same 20cm speculum: Ts did at LCM=135W and Nj at Fukui at LCM=138W. It was clearer on the much afternoon side than near the CM or in the morning. Arsia Mons appeared as a brownish spot. DPk's images on 3 September as well as on 6 September (day 75) at LCM=127W ~ 135W show clearly Olympus Mons in every ingredient of R, G, B. Tharsis Montes are also definitely caught. Finally ISHADOH (Id) detected clearly the evening Olympus Mons on 15 September (day 84) at LCM=178W and 188W.

 

West of Tharsis :
  The summits of Montes are semi-diurnally visible because they are less bright than the surrounding cloud sea. However the excellent ccd images by DPk made on 6 September (228Ls, day 75) seem to show another kind of dark spots at the northern part of Claritas Foss and inside Tithonius L. We may suppose that these must correspond to the normal dark stains observable through IR in usual more transparent times, and the transcendentally dark places that are naked or have shadows for example behind cliffs, inside trenches, and so on (because the phase angle is 45) . If so, though the dust is still too intense to figure out usual surface dark markings but the optical depth for the longer waves has been thinner to produce the dark stains clearer in the lower and hollow areas.

 

  The South Polar Cap :

T

he morning cloud or ground fog that was seen thick previously following the south polar cap (spc) became thinner around from 9 August (211Ls) as noted on pp3110 ~ 3111, but the peripheral area of the spc was not so completely clear. The morning area did not look free from a faint misty matter (from 15 August) up until the end of August (the surfaces faced to us in Japan from LCM=170W eastward to LCM=330W). The explicit perimeter of the spc did not show up for a while: The spc thus looked beyond the horizon. TSUNEMACHI (Ts) explicitly noted on 17 August (216Ls) at LCM=116W, the central latitude=5N that the spc was not definitely seen. Mn dared to detect a faint spc on 18 August (216Ls, the central latitude=5N) at LCM=110W ~ 120W. At LCM=300W DPk's images show the slight spc on 19 August (217Ls).
  We now try to describe the aspect of the
spc since the size of the spc turns now to be important with respect to the longitude angles. On 26 August (221Ls) at LCM=016W, the central latitude=3N, Ts described the spc discriminated from the northern dark area. Mn made explicit description of the spc on the southern limb on 28 August (223Ls) at LCM=017W, 29 August (223Ls) at LCM=333W ~ 352W. On the images of MVl made on 29 August at LCM=326W the spr is white, while Id saw visually the spc very weak at LCM=360W. The spr on the images by MVl on 30 August is light at LCM=324W but gradually it becomes weak to LCM=360W. On 31 August (224Ls, the central latitude=2N), DPk's images at around LCM=190W seems to show the spc bounded by a fine dark fringe. On the same day the spc was explicit from Japan at around LCM=330W (by Mn).
  As September came in, the
spc became more evident. Hk distinguished the spc from Hellas on 1 September (225Ls, the central latitude=2N) at LCM=328W. Id weakly caught it on 2 September (226Ls) at LCM=317W, but on 3 September (226Ls, the central latitude=1N) at LCM=303W he noticed a fine dark fringe, and at LCM=329W, 339W he was convinced that the spc was very evident. On 4 September (227Ls, the central latitude=1N), Mn observed that the spc was rather thick in depth at LCM=300W. No morning ground fog. On 5 September (227Ls) the spc was quite explicit at LCM=276W ~ 315W, though on the images of MVl the spc on the day is obscure. The spc is visible on DPk's images on 6 September (228Ls) at around LCM=130W. Id did not catch any glimpse of the spc on 6 and 10 September because of poor seeing, but on 15 September (234Ls, the central latitude=2S) at LCM=178W ~ 215W, the spc was quite definite together with the dark fringe. Now the centre of the spc will move out from the south pole, if the season is normal, and so the observations of the size or depth of the spc including the detection of Novus Mons are henceforward important (cf #240 p2925).


W

E further received from:

ISHIBASHI, Tsutomu (Is) Sagamihara, Kanagawa, Japan

5 B&W Images (1, 3, 10, 16, 23 July 2001) 31cm f/6.4 spec; HIE, NP400P, TP

 


T

he next issue (#252) shall review the observations during a one-month period from 16 September (234Ls) to 15 October 2001 (253Ls). CMO #253 shall be regularly published on 25 November 2001.
  We hope every set of CCD images is emailed in a
jpg file with a file name beginning with the observer's name to vzv03210@nifty.com as well as to cmo@mars.dti.ne.jp. Drawings are preferred to be sent in an A4 sized format with just one drawing on one sheet.


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


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