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 (215°Ls) to 15 September 2001 (234°Ls)
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 (215°Ls) 2001 to 15 September (234°Ls)
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 5°N to the opposite hemisphere and
read 2°S 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)
1 Drawing (26 August 2001) 360x 18cm refractor $
BIVER, Nicolas (NBv)
4 Colour Drawings (16, 24, 25
August; 1# September 2001)
300x 20cm speculum / 330x 26cm speculum#
HIKI, Toshiaki (Hk) Minowa,
8 Drawings (16, 17, 18, 24, 25
August; 1 September 2001) 430, 400x 22cm speculum
ISHADOH, Hiroshi (Id)
15 Drawings (29, 30 August; 2, 3, 6,
10, 15 September 2001) 340, 410x 31cm speculum
KUMAMORI, Teruaki (Km)
5 CCD Colour Images (22, 23, 28
August; 4 September 2001)
20cm Dall-Kirkham with a Sony PC-5
MELILLO, Frank J (FMl)
7 CCD Images (16, 22, 27 August;
4, 11, 13 September 2001)
20cm
SCT with a Starlight Xpress MX5
MINAMI, Masatsugu (Mn)
53 Drawings (16, 17, 18, 23, 24, 25,
27, 28, 29, 31 August; 1, 4, 5 September 2001)
400, 600x 20cm refractor*
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,
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)
10 Drawings (16, 17, 26 August
2001) 320x 20cm speculum
NAKAJIMA, Takashi (Nj)
27 Drawings (16, 17, 22, 24, 25, 29
August; 1, 5 September 2001) 400x 20cm refractor*
NARITA, Hiroshi (Nr)
2 Drawings (12 September 2001) 400x 20cm refractor
PARKER, Donald C (DPk)
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,
3 Drawings (17, 23, 24 August
2001) 230x 10cm refractor
TEICHERT, Gérard (GTc)
2 Drawings (24, 25 August
2001) 330, 310x 28cm SCT
TSUNEMACHI, Hitomi (Ts)
10 Drawings (17+, 25+, 26 August
2001)
320x 20cm speculum+ chez
MURAKAMI / 360x 12.5cm Fluorite refractor
VALIMBERTI, Maurice (MVl) Victoria,
12 Sets of CCD Images (29, 30
August; 5 September 2001)
f/85 15cm refractor with a TC245 based camera
$
*
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=352°W 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=295°W, 301°W: " 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=235°W 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 Auroræ S :
Notably, Solis L is long lost. From
Noachis, S Meridiani,
Noachis is dusky in contrast with the brighter
northern deserts on MOORE (DMr)'s images made on 17
August (day 55) at LCM=352°W. The western half of
Noachis came into sight to the
MVl obtained a set of good images on 30
August (day 68) (RGB colours at LCM=312°W, 323°W,
332°W, 358°W). Id observed at LCM=015°W, 024°W on 30 August. On 31
August (day 69), Mn observed from
LCM=313°W to LCM=353°W. Mo then shot at
LCM=358°W, 005°W, 009°W on the day: Syrtis Mj entered
deep on the disk. The western part of S Sabæus was
invisible though the area of
Vicinity of Syrtis Mj :
The images of PARKER (DPk) secured on 19
August (217°Ls, day 57) at LCM=295°W, 301°W show Syrtis Mj at the centre
and M Tyrrhenum and S Sabæus at the left and right
wings. These are shown also on DMr's
images on 21
August (day 59) at LCM=313°W, on 24
August (day 62) at LCM=286°W, and on 25
August (day 63) at LCM=304°W as well as on the one by MVl on 30
August (day 68) at LCM=312°W. In
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=207°W, and it does not differ much from the images by
the present writer obtained previously on 10 August (day 48) at LCM=203°W and
on 11 August (day 49) at LCM=204°W where Electris was
light. One round later, Mo obtained images on 15
September (day 84) at LCM=203°W, 207°W, 213°W ( in
addition to LCM=190°W, 195°W). The one at LCM= 213°W 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=270°W.
M Sirenum :
As
to the aspect of M Sirenum, DPk's images on 3 September
(day 72) at LCM=169°W show vividly two points if we compare them with DPk's images on 24 June at LCM=167°W (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 160°W. 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=168°W is not so good but seems to suggest the same
aspect.
Elysium and Its Environs :
PARKER (DPk) commented 29
August (day 67) at LCM=207°W, the central latitude=2°N that Elysium and environs
(Tri Charontis, Phlegra,
Propontis I) were not visible. On 31
August (day 69) at around LCM=198°W, his images showed Propontis I vaguely.
From our side, Id tried to discriminate the dark patch at Ætheria and
others on 15 September (day 84) at around LCM=215°W, 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
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 (228°Ls, day 75) seem to show another kind of dark spots at the
northern part of Claritas Fossæ
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 (211°Ls) 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
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 (221°Ls) at
LCM=016°W, the central latitude=3°N, Ts
described the spc discriminated from the northern dark area. Mn made explicit description of the spc on the southern limb on 28 August (223°Ls) at LCM=017°W,
29 August (223°Ls) at LCM=333°W ~ 352°W. On the images of MVl made on 29
August at LCM=326°W the spr is
white, while Id saw visually the spc very
weak at LCM=360°W. The spr on
the images by MVl on 30
August is light at LCM=324°W but gradually it becomes weak to LCM=360°W. On
31
August (224°Ls, the central latitude=2°N), DPk's
images at around LCM=190°W seems to show the spc
bounded by a fine dark fringe. On the same day the spc was
explicit from
As September came in, the spc became more evident. Hk distinguished the spc from
|
W |
E further received
from:
ISHIBASHI, Tsutomu (Is)
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 (234°Ls) to
15 October 2001 (253°Ls). 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 )
.
Back
to CMO#251 Home Page / Back
to Façade/ Back to the CMO Home Page