1996/97 Mars Observation Reports -- #010 --

OAA MARS SECTION - Fortnight Report published in CMO No 188 (10 April 1997)

Martian Surfaces in the Second Half of March 1997

The OAA All-Night Mars Watch was carried out four nights from 19 Mar to 22 Mar (GMT). The statistics shall be reported later. Almost all enjoyed a fine night on the 20th, though IWASAKI (Iw) was interrupted by clouding after two observations. MURAKAMI (Mk) observed seven times, and ISHADOH (Id) five times. Iw took 6 drawings on the 22nd. At Fukui NAKAJIMA (Nj) and MINAMI (Mn) observed fully three nights except the 21st, and for example obtained 21 drawings in all on the 19th (each observed every forty minutes). It was fine at Fukui also on the 17th and 18th of the opposition days. On the 18th, both tried to make the CMT timings of Olympus Mons (see below). Nj was at the eyepiece by chance when the red planet most approached the Earth at 11h GMT on the 20th. Seeing was moderate to good at least at Fukui during the period: Nj feels the night on the 27th was the best.

We received with thanks the following observations contributed to the CMO:

  AKUTSU, Tomio (Ak)   Karasuyama, Tochigi, Japan
     8 CCD Images  (16, 17, 20, 27 Mar)   f/66× 32cm speculum, Lynxx PC
     9 CCD Colour Composites  (12,31 Jan;23 Feb;3,4 Mar)  f/66× 32cm spec, Lynxx PC

  CAVE, Thomas R (TCv)  CA, USA
     7 Drawings  (12, 14, 19, 21,25 27, 30 Mar)    230, 400,660× 32cm speculum

  FALSARELLA, Nelson  (NFl)  Brasil
    12 Drawings  (4-8, 11-14, 17, 18 Mar)   260× 20cm spec
     7 CCD Images  (18, 20, 22, 23, 25 Mar)   20cm spec   ASTROVID 400

  GROSS, Horst  (HGr)   Hagen, Deutschland
     2 Drawings  (12, 31 Mar)     250× 25cm Schiefspiegler

  HIKI, Toshiaki  (Hk)   Minowa, Nagano, Japan
    10 Drawings  (20, 13, 24, 25, 27 Mar)  340× 16cm speculum
 
  ISHADOH, Hiroshi  (Id)  Naha, Japan
    11 Drawings  (20, 24, 27, 30 Mar)  530× 31cm speculum

  IWASAKI, Tohru  (Iw)  Morodomi, Saga, Japan
    19 Drawings  (17, 20, 22, 24, 29, 30 Mar)  400× 21cm speculum

  MELILLO, Frank J   (FMl)   NY, USA
     4 TP Photos (17, 23, 24, 28 Mar) 20cm Schmidt-Cassegrain AO-2 unit  Wr47 & Wr21

  MINAMI, Masatsugu  (Mn)  Fukui, Japan
   112 Drawings  (17-20, 22, 24, 25, 27, 28, 30, 31 Mar)  400, 480× 20cm refractor*

  MURAKAMI, Masami (Mk)  Fujisawa, Japan
    14 Drawings  (18, 20, 24, 27 Mar)    370× 15cm speculum

  NAKAJIMA, Takashi  (Nj)  Fukui, Japan
    68 Drawings  (17-20, 22, 24, 25, 27, 30, 31 Mar)  400, 480× 20cm refractor*

  NAKANO, Yuhkichi  (Nn)  Oh-ita, Japan
     3 Drawings  (16, 27 Mar)    420× 20cm speculum 

  NARITA, Hiroshi  (Nr)  Kawasaki, Japan
    15 Drawings  (18, 20, 24, 31 Mar)  400× 20cm refractor
     3 B&W Photos (8, 23 Feb; 4 Mar)  20cm refractor    TP?

  NIKOLAI, Andre  (ANk)  Berlin, Deutschland
     1 Drawing  (17 Mar)   330× 10cm refractor

  OHBA, Yoshio  (Oh)  Yamagata, Japan
     3 Drawings  (19, 20, 26 Mar)   270, 320× 20cm speculum

  QUARRA SACCO, Giovanni A (GQr) & the SGPG (A LEO & others)  Firenze, Italia
     9 CCD  IR, G, B & Colour Images  (13, 15/16+ Mar) 
              f/24× 30cm Cass; f/32, 16× 42cm refr+, ISIS CCD800 with Kodak KAF0400

  SIEGEL, Elisabeth  (ESg)  Malling, Danmark
     3 Drawings  (17, 29, 31 Mar)  270× 20cm Schmidt-Cassegrain

  SUDWISCHER, Harry   (HSw)  NY, USA
     6 CCD Image  (16, 21, 25 Mar)    13cm refractor  VAV 505E Video Camera

  TEICHERT, Gerard  (GTc)  Hattstatt, France
     4 Drawings  (13, 17, 21, 22 Mar)    280, 310,330× 28cm Schmidt-Cassegrain

  TROIANI, Daniel M  (DTr)  IL, USA
     4 Drawings  (15, 16, 24 Mar)   580× 25cm spec, 520× 44cm spec
 
  WARELL, Johan  (JWr)  Uppsala, Sweden
     7 Drawings  (27/28 Feb; 4, 12, 16, 18, 23, 24 Mar)
        330, 200× 16cm refr, 290× 45cm spec, 430× 36cm refr

                                       * Fukui City Observatory
                                       + Pino Torinese Observatory, Torino

  ISHIBASHI, Tsutomu  (Is)  Sagamihara, Japan
   12 Colour Images on Provia 400  (23, 30 Dec; 11, Jan; 8, 12, 23 Feb; 4 Mar) 31cm spec

We also received

  ASADA, Hideto (Aa)  Kyoto, Japan
   9 CCD Images  (17,18,20,22,24,25,27,30,31 Mar)  f/37× 31cm spec, Mutoh CV-04

1) Olympus Mons, Evening: As reported in No 185 p2003, Olympus Mons looked Very Active in the sense of SMITH & SMITH when we observed in Feb at around 075°Ls: Its summit became really covered in the afternoon by a water-iced cloud, and looked very conspicuous as if it were a floating white cotton ball. Now chosen the case of 9 Feb (076°Ls), it began to be whitish apparent from ω =150°W, and at about ω =175°W it became striking like an isolated cotton ball, and finally at ω =200°W the bright ball came to the evening terminator. On 9 Feb, the phase angle was 25°.

Now, this turn, Olympus Mons appeared to be much weaker even in the afternoon.
IWASAKI (Iw) didn't see any of it on 20 Mar at ω =147°W, and just faintly recognised it at ω =156°W. On 22 Mar at ω =168°W, he saw it near the preceding limb, but it was never marked (and lost it at ω =178°W).
HIKI (Hk) observed it well on 20 Mar at ω =149°W, 161°W and 173°W in contrast with the whitish Tharsis cloud, but just described it to have a yellow tint.
MURAKAMI (Mk) observed Olympus Mons on 20 Mar at ω =176°W, but similarly saw it to be weak though slightly whitish.
ISHADOH (Id) observed it on 20 Mar every forty minutes from ω = 146°W, but just reports that it became slightly brighter with a whitish colour only at ω =185°W (more white at ω =195°W).
Similarly at Fukui, Olympus Mons was observed to be nearly caught through Int-light on 17 Mar (092°Ls) at opposition yet at ω =153°W (more evident by use of a Green filter or Y48), and at ω =173°W it was clearly seen but never white. The situation was the same on 18 Mar, 19 Mar, 20 Mar and 22 Mar (094°Ls).
[The present writer (Mn)'s observations at around ω = 175°W were carried out as follows: on 18 Mar at ω =176°W, 19 Mar at ω =170°W, on 20 Mar at ω =174°W and 22 Mar at ω =176°W (Nj observed twenty minutes - five °s - earlier and later): In any case Olympus Mons was faint and its colour was off-white.]

Olympus Mons at 092°Ls ~ 094°Ls was thus weak in appearance. It is however necessary to take account of the noon (N line) or the phase angle to compare the two cases.
[As was stated in No 098 p0842, the phase angle is a convenient substitute how far the noon line is located from the CM. To be precise, both are different, but roughly not so different: In the case of 9 Feb phase angle =25° while the N line was deviated from the CM by 27°.]

Now let us assume the position of Olympus Mons is at ω =135°W. Then, if phase angle=25°, the ω =175°W when we saw the white cotton ball- like bright spot implies the local time of Olympus Mons was about 04:30pm since 25+(175-135)=65°. On the other hand, at opposition the local time 04:30pm implies ω =200°W since 135+65=200°. Similarly ω = 175°W at the opposition day implies about 02:30pm at Olympus Mons since 175-135=40°. This in turn implies on 9 Feb at ω =135+15=150°W since 40-25=15°. We previously noted that at ω =150°W, Olympus Mons was not conspicuous even on 9 Feb.

So we should be concerned with the angle around ω =200°W at opposition: As suggested by Id's result aforementioned, Olympus Mons proved well active from these angles: It was quite near the evening limb from our eyes, but it was very whitish active. Chosen the present writer's observations on 17 Mar (092°Ls), Olympus Mons seen from ω =192°W was roundish still off-white separated from the preceding very whitish Tharsis cloud, and at ω =202°W it became more white while still roundish. At ω =212°W it shined well at the evening limb. At ω = 222°W it remained a bit, but at ω =231°W there was no trace of it diffused into the evening limb haze. On 18 Mar, Mn saw the white Olympus Mons near the evening limb ω =206°W and ω =215°W. Similarly on 19, 20, 22 Mar. On 20 Mar Nj saw it at ω =198°W and Mn at ω = 222°W (at 18:40GMT=03:40JST). Ak's B-light CCD image taken on 17 Mar at ω =196°W shows well the bright Mons near the evening limb. We thus conclude that contrary to the appearance, Olympus Mons was Very Active on the opposition days (near 095°Ls) on the same basis as in Feb at around 075°Ls.

The above analysis conversely tells us that the cotton ball-like Olympus Mons can only be seen well inside the disk when the phase angle is rather large, and February was once in a good chance. It should be remarked that we cannot necessarily consider Olympus Mons to be free from any atmospheric matter up until ω =170°W. It must be thinly covered already by some water-ice haze because it was watched better by use of a Green filter, and Frank MELILLO (FMl)'s blue photo on 8 Mar at ω =135°W (reported in the preceding issue) and also Ak's B light CCD image on 20 Mar at ω =144°W also faintly but clearly show the presence of Olympus Mons near the centre of the disk

2) Olympus Mons, CM Transit: It will be usually said that the planet was at opposition on 17 Mar at 08h GMT this apparition. It should however be noted that the three bodies, the Sun, the Earth and Mars, do seldom lie on a line, but on a plane making a triangle even if it is a big obtuse one. The opposition therefore should be classified by definition since we have a infinite numbers of such planes. The above opposition date is derived ecliptically. It is also possible to choose another plane by use of the right ascension of the planet. This opposition occurred on 18 Mar at 11h GMT.

On 17 Mar Nj and Mn noticed Olympus Mons to be slowly passing the imaginary CM derived by the presence of the bright npc, and hence they tried on 18 Mar the CM transit observations of Olympus Mons (just as a ceremony). They began from 11:00GMT ( ω =127°W), just the opposition time, and made alternately 20 times CMT timings up until 11:47GMT ( ω =139°W). As was reported Olympus Mons was faint near the noon, and so Nj and Mn frequently made use of a Green filter or Y48. The result was as follows: Olympus Mons was "before" the CM until 11:23GMT ( ω =133°W) and "after" the CM after 11:41GMT. It looked to stay or be passing the CM between 11:26GMT ( ω = 134°W) and 11:36GMT ( ω =136°W). Nj and Mn hence concluded that the centre of Olympus Mons was located at ω =135°W.
[According to the result by the US Geological Survey, the centre of the volcano is at ω = 133°W.]
This was just a ceremony, but we should say it is very rare for us to come across the case where Olympus Mons transits the CM in the presence of a bright small npc at opposition. As to a history of the measurements, see CMO #144 p1385.

3) Ascraeus Mons, Evening: There was witnessed at Fukui a roundish Mons preceding Olympus Mons beyond a dark band on 17 Mar at ω =163°W: This must have been Ascraeus Mons ( ω =104°W), and on the way to be covered by the evening cloud from Candor. At ω =173°W, it became much whiter. On 18 Mar (092°Ls), Ascraeus Mons was seen separated from the Candor cloud at ω =147°W, and similar at ω =157°W, while at ω = 166°W it was brought into contact with the Candor cloud and at ω = 176°W, it was absorbed in the evening cloud. That is, the evening cloud crept up to Ascraeus Mons at that time while Olympus Mons was still separated by the dark band. At ω =196°W it shined brightly. On 19 Mar, Ascraeus Mons was witnessed from ω =141°W. On 20 Mar, it was visible from ω =134°W as well as Pavonis Mons. Ascraeus Mons precedes Olympus Mons by about three hours local time, and hence it became whiter earlier than Olympus Mons, but activity pattern seemed to be similar. Id watched Ascraeus Mons as well as Pavonis Mons on 20 Mar at ω =146°W. Id notes that this was his first experience. Id also noticed that Ascraeus Mons was absorbed in the evening cloud at ω =173°W.

4) Ascraeus Mons, Morning: Mn observed by chance Ascraeus Mons distinctly pinched by a dark fork near the morning terminator on 31 Mar at ω = 058°W. It looked as a larger patch at ω =078°W and much larger at ω =092°W. We considered that Ascraeus Mons was independently light, but soon the Tharsis ridges were covered by a large morning haze. From ω = 102°W, Olympus Mons followed very misted. We consider the morning haze might disappear as they reach the noon:
It was hard to see Ascraeus Mons pass the CM. Nj however saw it on 27 Mar at ω =098°W. Mn detected that the west side of Ascraeus Mons was slightly shadowy on 27 Mar at ω = 103°W.

5) Alba: It was already reported that the white cloud activity passed of Alba Patera ( ω =110 +/- 005°W), and this period we also could not fully detect the white Alba. On 17 Mar (092°Ls), Alba was seen slightly whitish at ω =163°W, while on 18 Mar at ω =176°W it was only visible through a G filter. Id observed Alba to be weak on 20 Mar at ω = 146°W. HIKI (Hk) saw its setting as an off-white spot on 20 Mar at ω = 173°W. Hk pursued well Alba: He described that it was ground sunlit on 24 Mar at ω =117°W and 126°W. Similarly on 25 Mar at ω =103°W. IWASAKI (Iw) also caught Alba on 24 Mar at ω =102°W and described that it was sunlit though weak. Note that Alba was thus observed in the morning side, and so different in nature to Olympus Mons. In fact at Fukui, on 27 Mar at ω =079°W (by Nj) and at ω =083°W (by Mn), and on 31 Mar at ω =078°W (by Mn) it was caught already through Int. Alba frequently seen together with Tempe, and on 20 Mar at ω =115°W, both appeared in a shape of a yellowish thumb running from the evening limb, and similar aspect was also observed by Mk on 27 Mar at ω =118°W. If Ceraunius was detected, Tempe and Alba lay together as adjacent two roundish light areas. The brightness of Alba depended on seeing, but if improved it appeared to be a sharp small light roundish area.

6) Densely Reddish Bands and Areas: It is well known that the Martian surface shows a reddish tint. We this time by use of the 20cm excellent refractor experienced often the chance to see the surface colour around ω = 100°W. We here pick out the case as a representative on 25 Mar at ω = 108°W, where Solis L through Propontis I were included. Note first several roundish areas of Mons are excluded from the reddish area, and so the reddish surface was to look as if holed by several off-white light spots.

Colour of the ground appeared to us to be rather coral reddish as shown in the colour images by Don PARKER at Coral Gable, and different than the strong colour of the HST images, but we here use the word "reddish" for simplicity sake. In addition to several Mons, the elliptic area of Thaumasia surrounding Solis L is not reddish in this sense. We note furthermore there are several "densely reddish" bands or areas: these bands or areas sometimes appear to be well dark. For example the dark band which runs from Nilokeras westward to the narrow area between Olympus Mons and Tharsis ridges (as frequently noticed by FALSARELLA (NFl) and known since 1982 by our members) is densely reddish. The area to the west of M Acidalium is vastly reddish including Tempe and Alba, just Tempe and Alba being light inside the reddish area (reddish or coral light). M Boreum is also reddish, and especially the area to the north of Propontis II is densely reddish. We also note that the area following to the west of Thaumasia is reddish in good contrast with Thaumasia and we can say now the area to be "densely" reddish (so dark in a sense). Otherwise, Deuteronilus is also densely reddish, and Cerberus-Styx as well as Azania are densely reddish.

7) Evening Haze or Cloud: Independent of the area having a coral tint, the area covered by the evening haze was whitish. As the phase angle decreased, the evening cloud area became slim, but it crept up to Chryse, to Xanthe, to Candor and to Tharsis as before. If the evening cloud extended to Candor, Ganges was faintly visible: that is, the haze was rather thinner, and so each section could be seen through depending especifically on the altitudes around the regions. We feel therefore an objection to disposing this kind of haze behaviour simply just as an equatorial-band cloud activity.

8) Hernandez Effect: As reported, the elliptic area of Thaumasia Foelix surrounding Solis L showed a different tint to the following region. On this point we remember HERNANDEZ (CHr)'s remark on 29 Jan (071°Ls) at ω = 132°W when he noticed a dust cloud inside Thaumasia (e-mailed to us: cf No 184 p1995): The dust activity itself was denied, but we should admit that the area still needs attention. As observed at Fukui on 25 Mar at ω = 098°W, the evening Thaumasia Foelix was peculiar in the sense it was dull off-white, never white nor reddish. Same at ω =108°W and 118°W. The area to the south of Thaumasia near the limb was haunted by a thick white cloud or frost, but the elliptic area was independent of the white cloud activity in the evening. The nuance was different from day to day (weaker on 27 Mar), and behaves as usual at noon and in the morning.

9) Olympia: This time from our angle it was easier to catch the east end and/or main part of Olympia: Mk saw the east end come up on 20 Mar at ω = 152°W, but more clearly observed it on the right-hand side of the npc on 24 Mar at ω =142°W. Id also saw the eastern part of Olympia on 20 Mar at ω =146°W, and especially he described it to the south of the npc on 20 Mar at ω =185°W. At Fukui Nj and Mn frequently observed Olympia. Among them the finding of the appearance of Olympia from the morning limb was carried out by Mn on 27 Mar at ω =103°W, and by Nj on 31 Mar at ω =107°W (otherwise on 25 Mar at ω =108°W, and on 24 Mar, 31 Mar at ω =112°W by Mn). It was rather hard to discern the time when the east end went around to the south of the npc and passed the CM since the east end was not so definitely defined, but according to the observations on 22 Mar (094°Ls), we observed it transited between ω = 166°W and ω =176°W, and hence the position appeared to be around ω =170°W. Same result on 20 Mar. Especially at ω =183°W (resp at ω =188°W) on 20 Mar, Mn (resp Nj) observed the same aspect as revealed by Id on the day (see above); that is, the southern skirts of the fine dark fringe of the npc was covered by a thicker part of Olympia. We note again (as in the preceding issue) that, seen from ω =200°W, a part of Olympia still occupied the CM, and this was somewhat contradictory to the situation observed by DOLLFUS in 1950/52 as cited in CMO No 183 p1984 (Fig 1). The fragment denoted B by DOLLFUS was found to exist there as observed on 20 Mar at ω =134°W, on 25 Mar at ω =128°W and on 27 Mar at ω =135°W etc.

10) Miscellanea: As stated, during the period the planet was in a full- moon state so that the surface shined to prevent seeing any shadow: From the scenes we faced we may pick out the "washed-out" state of Cerberus-Styx as an example. Azania, which was rather shadowy previously, looked rather light this time. On the other hand Propontis I was different and appeared very dark and isolated, and observable quite early morning from around ω = 110°W. Elysium and Cebrenia were light, but Elysium Mons was undetectable in the morning, just seen on 17 Mar at ω =192°W at Fukui. We had no occasion to watch its evening. Syrtis Mj was caught on the morning limb on 17 Mar at ω =212°W by Mn, recorded in a light-blue tint. M Cimmerium was as usual and appeared composed of several (or three) blocks. M Sirenum was very distinct and dark. Solis L was dark evident in a shape of egg-plant and it curved down to Aurorae S. Interesting was the fact that the segment from Melas L to Tithonius L was deep dark prominent. These features were also caught by Id and Nj. Chryse was almost misted even near the CM and on 31 Mar at ω =019°W there was seen a lighter core at the area following Oxia P.

From the AMERICAS:
CAVE (TCv) saw Alba on 12 Mar at ω =098°W, but he comments that Olympus Mons was lighter in the morning. On 14 Mar at ω =102°W, he more distinctly saw the morning Olympus Mons so far this apparition. Hyperboreus L was described. Also made on 19 Mar at ω =042°W and on 21 Mar at ω =018°W. On 25 Mar at ω = 348°W, S Sabaeus very evident. On 27 Mar at ω =300°W, Libya light. On 30 Mar at ω =275°W, Utopia proved made of several dark patches

FALSARELLA (NFl) saw a thick Xanthe evening cloud through G on 5 & 6 Mar (at ω =090°W), and detected a light patch inside Cydonia on 17 Mar at ω =010°W and 18 Mar at ω =0??°W. The CCD images don't tell us much, while the one taken on 25 Mar at ω =280°W shows the bright Elysium Mons. We hope his REA form of drawings as well as the CCD images is filled with the ephemeris data.

MELILLO (FMl)'s Blue photos by Wr47 are interesting: The morning side including Tharsis and Candor is very bright on 17 Mar at ω =037°W. Chryse slightly hazed. On 23 Mar at ω =010°W, the morning side (Xanthe) is weaker through orange (Wr21) than the evening limb, while thru Wr47, the morning side is much brighter, and the evening haze looks compact. On 24 Mar at ω =320°W, Hellas and Libya-Neith are bright. Same on 28 Mar at ω =315°W. Hellas is brighter than the npc thru Wr47 indicating that the npc is never misted.

CCD images by SUDWISCHER (HSw) show several markings but look all unstable. On 16 Mar at ω =053°W, the image seems to catch Alba, and Solis L is dark nearly on the limb. The npc is unknown. On 21 Mar at ω =002°W, eg S Meridiani is taken but slightly ghosted as before (as in Feb). The images on 26 show the areas from Syrtis Mj to the morning M Acidalium.

TROIANI (DTr)'s drawings: given on 15 Mar at ω =037°W, 16 Mar at ω =006°W (seeing 10/10), ω =039°W and 24 Mar at ω =301°W (the noon Hellas bright).

From EUROPE:
GROSS (HGr) observed on 12 Mar at ω =318°W and on 31 Mar at ω =153°W. In the former the evening Hellas bright. In the latter, Propontis I was evident while Cebrenia to the north of it is not clear cut.

The RYB set of drawing by NIKOLAI (ANk) was made on 17 Mar at ω = 325°W(R). Is the filter B+W081 well thick?

QUARRA (GQr) sent us again excellent series of CCD images taken on 13 and 15/16 Mar. The colour composite CCD on 13 Mar at ω =340°W shows the blue Syrtis Mj covered by an evening haze. The morning mist or frost at the limb is thick through B, but the whole of M Acidalium is nearly outside of it. In IR, Rima Borealis is darker and broader. The colour image on 15 Mar was taken at ω =323°W: The evening haze and Hellas are bright. The morning mist is divided to two at the deep Nilokeras. Already Oxia P is evident. The IR images were taken up until 16 Mar at 02:55GMT ( ω = 026°W). The image at ω =008°W is excellent, and Hyperboreus L proves divided into two parts by a fainter canal extended from something like Iaxartes. Images are all good, recommended to be appreciated through the Internet. Mars Watch 1996-1997, Image of Mars - March 1997

SIEGEL (ESg) saw Syrtis Mj through Wr47 on 17 Mar at ω =290°W. She saw the slit of Cebrenia between Propondices, but didn't detected the isolated Propontis I. Elysium bright at the morning limb side on 29 Mar at ω =183°W. Nearly the same on 31 Mar at ω =158°W.

TEICHERT (GTc)'s drawings were on 13 Mar at ω =343°W, 17 Mar at ω = 309°W (Hellas bright), 21 Mar at ω =238°W, 22 Mar at ω = 282°W (Hellas bright). His npc is all too small for the diameter of the drawing disk (too larger?).

WARELL (JWr) made observations on 16 Mar at ω =302°W, on 18 Mar at ω =271°W, on 23 Mar at ω =244°W (Elysium Mons bright - the npc divided), on 24 Mar at ω =246°W: both show Syrtis Mj and Utopia in details.

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