2001 Mars Observation Reports -- #07--
OAA MARS SECTION
in the Second Half of April 2001
from 16 April 2001 (146°Ls) to 30 April 2001 (154°Ls)
based on the article published in CMO #243 (10 May 2001)
by Masatsugu MINAMI, Director of the OAA Mars Section
HE CMO shall be published twice a month for a while. This is the first of the series of the fortnight reports of this 2001 season.
We have hitherto written this report to stimulate the observers standing by to set out to observe, while we are now in a position to renew the style of presentation since the disk diameter is now over 15 arcsecs and the cloud phenomena will be main until 180°Ls or so.
On 16 Apr (146°Ls), the angular diameter was 12.1", but rapidly increased upto 14.1" on 30 Apr (154°Ls). The central latitude was 1°S to 2°S, so that the northern and the southern hemisphere are equally seen. The phase angle went down from 34° to 30°, and so the polarization of the Sun beam is still large for the white morning mist.
The members who contributed this time are as follows:
AKUTSU, Tomio (Ak)
5 Sets of CCD Images (16, 26 April 2001)
f/70 32cm spec equipped with a Teleris 2
CAVE, Thomas R (TCv)
2 Drawings (21?, 24 April 2001)
280, 430, 380, 525x 33cm speculum
HERNANDEZ, Carlos E (CHr)
1 Drawing (24 April 2001)
220x 20cm Schmidt-Cassegrain
HIGA, Yasunobu (Hg)
13 Video Images (18, 19, 22 April 2001)
25cm f/6.7 spec equipped with Sony VX-1000
HIKI, Toshiaki (Hk) Minowa,
3 Drawings (27 April 2001) 430x 22cm speculum
ISHADOH, Hiroshi (Id)
8 Drawings (17, 18, 19, 22 April 2001)
400, 530, 320x 31cm speculum
MELILLO, Frank J (FMl)
4 Sets of CCD Images (20, 29 April 2001)
20cm SCT equipped with a Starlight Xpress
MINAMI, Masatsugu (Mn)
49 Drawings (16, 17, 20, 22, 25, 26, 27, 30 April 2001)
400x 20cm refractor*
MORITA, Yukio (Mo) Hatsuka-ichi,
12 Sets of CCD Images (19, 21, 22, 25, 30 April 2001)
f/50 25cm speculum equipped with an ST-5C
MURAKAMI, Masami (Mk)
13 Drawings (22, 26, 27, 30 April 2001)
400, 425x 20cm speculum
NAKAJIMA, Takashi (Nj)
7 Drawings (27, 28 April 2001) 400x 20cm refractor*
NARITA, Hiroshi (Nr)
5 Drawings (16, 17, 20, 23, 27 April 2001)
400x 20cm refractor
Donald C (DPk)
6 Sets of CCD Images (24, 26 April 2001)
Richard W, Jr (RSc) GA,
5 Drawings (1, 7, 14, 29 April 2001)
230, 310x 10cm refractor
TSUNEMACHI, Hitomi (Ts)
9 Drawings (22, 27 April 2001)
360x 12.5cm Fluorite refractor
WASIUTA, Myron E (MWs)
13 Drawings (16, 17, 19 April 2001)
360x 32cm speculum/ 420x 16cm refractor
1 Set of CCD Images (23 April 2000)
16cm refractor equipped with a Lynxx PC
We here pick out the following:
1° Observations until 22 April:
On 6 May, the rainy season set in at the
From around 150°Ls, the afternoon cloud over Elysium Mons (215°W) is known to reduce its activity. The Elysium Mons cloud on Hg's images on 18, 19 Apr at LCM=234°W is considerably bright; since the phase angle is 33°, the LMT is still around 3:30 PM. Elysium itself was one-point lighter than the surroundings, maybe ground lit, from LCM=180°W. TSUNEMACHI (Ts) also detected it on 22 Apr (150°Ls) at LCM=206°W.
2° Movements inside the sph:
The season being at 150°Ls, the freezing fallout of the atmospheric CO2 has begun to decelerate, and the sph also might rush in the last stage. There is however observed a gay movement inside the sph. There was an apparent difference inside the sph on 25 April (151°Ls) and on the following day.
Schematic description of the south polar region
extracted from MINAMI's drawings on 25 April (151°Ls) ~ 27 April (152°Ls)
(observed from the same angles every 40 minutes)
showing an apparent movement of the cloud matter inside the sph
(the brighter parts being encircled by dotted lines).
On 25 Apr (151°Ls), the present writer (Mn)
started from LCM=132°W (at 15:40 GMT), and noticed a conspicuous bright patch
on the f side, and chased it until LCM=201°W (at 20:10 GMT).
At LCM=142°W, this patch was near the CM to the south of M Sirenum
that was very dark. At LCM=162°W, it moved to the evening side. At LCM=171°W,
another bright area appeared from the f limb,
and so the sph looked composed of two
bright patches, and the second one was coming and looked downward to Eridania
and Ausonia at LCM=181°W. Difference occurred next day:
On 26 Apr (152°Ls), Mn started from
LCM=123°W, but even at LCM=143°W, the bright patch observed the day before did
not show up. At LCM=152°W, the second bright patch came out, but even at
LCM=162°W the preceding part stayed dull and gray. MURAKAMI (Mk) who was observing at LCM=150°W also noticed the brighter
part on the f side. The part was still before the CM at LCM=171°W
while it was brighter than the preceding day.
On 27 Apr (152°Ls) (Mn started from LCM=114°W), the part remained dull at LCM=143°W, though the southern limb was bright. At LCM=153°W, a brighter part came out from the f limb. At LCM=172°W, the contrast was evident through O56. HIKI (Hk) noticed this brighter part at LCM=176°W on the day. It is difficult at present to tell what the bright part found on 25 April to the south of M Sirenum is, but it is quite evident that a movement of the cloud matter exists.
waited then until 30 Apr (154°Ls) but it was unfortunately clouded at 17:30 GMT
( LCM=113°W) at
WASIUTA (MWs)'s Wr47(+Murnighan IR rejection) image on 24 Apr (150°Ls) at LCM=043°W shows a brighter segment at Argyre. DPk's images show a faint mist over Chryse, and a white cloud at
3° Evening Olympus
The rise and fall of the summit cloud at Olympus Mons has a pattern (as delineated in CMO #134 p1251), and classically its activity attains its peak at 100°Ls ~ 110°Ls, and begins to cease from 140°Ls and becomes very faint at 180°Ls (while Tharsis may be active till 200 ~ 210°Ls). So at present it should be weaker. Mn's observations on 25 Apr (151°Ls) were as follows: At LCM=142°W, the large area of Olympus Mons (133°W) including its skirts appeared ground lit bounded by a roundish faint shadowy band, but did not show any white tint even at LCM=152°W. At LCM=162°W, a roundish small area was outlined clearly and was evident through a Green filter but the brightness was weak. At LCM=172°W it became white; its LMT being 4 o'clock (the phase angle is 31°). It appears like a cotton ball through G, but never strong as before. As the disk diameter increases, the presence of Olympus Mons without cloud will be easily checked. The disparity of the activities of Olympus Mons and Tharsis Montes are interesting (#077 p0636).
As to the morning Chryse and Tharsis, we should recall that the white cloud/mist appears in an off-white tint thicker than dust, especially when the phase angle is around 30° (cf CMO #161 p1639).
We are happy to hear Tom CAVE (TCv) has very recovered and watched Mars this season also: He tests his eyes and seeing by trying to detect Juventæ Fons every apparition and this April he succeeded at LCM=089°W. We hope he will welcome as well the 2003 apparition in good health.
For a while, the CMO shall be published twice a month. The next issue shall review the observations made during a fortnight period from 1 May (154°Ls) to 15 May 2001 (162°Ls). Our CMO Internet Web-Site has a Gallery Page where some new Mars images are flashed before our reviewing. We hope every CCD image is emailed in a jpg file with a file name beginning with the observer's name to firstname.lastname@example.org as well as to email@example.com. Drawings are preferred to be sent in an A4 sized format with just one drawing on one sheet.
will be acknowledged if air-mailed to M MINAMI at Mikuni
(ask the mail-address through firstname.lastname@example.org ) .