Monthly Report published in CMO #221 (25 July 1999)
Martian Surfaces from 16 June 1999 (155°Ls) to 15 July 1999 (171°Ls)
We are thankful to the following observers who directly contributed this period to the CMO:
AKUTSU, Tomio (Ak) Karasuyama, Tochigi, Japan
4 Sets of CCD Images (7, 9 July 1999) f/60 32cm spec equipped with a Teleris 2
HIGA, Yasunobu (Hg) Naha, Okinawa, Japan
18 Video Images (17, 23, 24, 25 June; 4 July 1999)
25cm spec with Sony DCR-TRV900
ISHADOH, Hiroshi (Id) Naha, Okinawa, Japan
38 Drawings (16, 17, 24~27, 29, 30 June; 1, 2, 4, 5, 12, 15 July 1999)
340, 400, 530x 31cm speculum
IWASAKI, Tohru (Iw) Kitakyushu, Fukuoka, Japan
12 Drawings (19, 20, 30 June; 5, 6, 8 July 1999) 400x 21cm speculum
MELILLO, Frank J (FMl) NY, USA
3 CCD Images (24 June; 6 July 1999) 20cm SC Starlight Xpress MX-5
MINAMI, Masatsugu (Mn) Fukui, Japan
63 Drawings (20, 21, 22 June; 1, 6~10, 15 July 1999) 400, 480x 20cm refractor*
MURAKAMI, Masami (Mk) Fujisawa, Kanagawa, Japan
16 Drawings (21, 30 June; 1, 4+, 7, 8, 9, 15 July 1999)
425x 20cm Saheki speculum, 400x 20cm refractor+ at Nr's
NAKAJIMA, Takashi (Nj) Fukui, Japan
25 Drawings (20, 21, 22 June; 1, 9, 15 July 1999) 400x 20cm refractor*
NARITA, Hiroshi (Nr) Kawasaki, Kanagawa, Japan
24 Drawings (21, 30 June; 1, 4, 6~9, 15 July 1999) 400x 20cm refractor
OHBA, Yoshio (Oh) Yamagata, Japan
1 Drawing (6 July 1999) 320x 20cm speculum
PARKER, Donald C (DPk) Miami, FL, USA
6 Sets of CCD Images (4 June; 5, 6, 7 July 1999) f/55 41cm speculum + Lynxx PC
SIEGEL, Elisabeth (ESg) Malling, Danmark
2 Drawings (18, 19 June 1999) 270x 20cm Schmidt-Cassegrain
TEICHERT, Gérard (GTc) Hattstatt, France
7 Drawings (17, 19, 22~25, 28 June 1999) 310, 330x 28cm Schmidt-Cassegrain
WASIUTA, Myron E (MWs) VA, USA
5 Drawings (19, 21, 29, 31 May; 27 June 1999) 360, 550x 15cm AP refractor
* Fukui City Observatory
We further received the observations made earlier as follows :
ISHIBASHI, Tsutomu (Is) Sagamihara, Kanagawa, Japan
6 B&W Photos (15, 20, 30 April; 17, 21 May 1999) 31cm speculum (R58, B390, Non)
2 Colour Photos (21 May; 1, 11 June 1999) 31cm spec on Fujichrome Provia
JOYCE, Daniel P (DJc) IL, USA
6 Drawings (5 Jan; 24 Feb; 4, 12, 15, 20 March 1999) 450x 45cm spec, 410x 60cm spec
TROIANI, Daniel M (DTr) IL, USA
15 Drawings (16, 27 March; 13, 24, 26, 27, 29 April;
1, 2, 12, 13, 15, 22 May; 8, 15 June 1999) 480?x 44cm spec, 500x 25cm spec
WARELL, Johan (JWr) Uppsala, Sweden
7 Drawings (18,19, 20, 27, 30 May; 7 June 1999) 330x 16cm refractor at UU
North Polar Region:
It is well known that the north polar region (npr) enters a new stage at around 160°Ls (see for example Fig 1 in #109 p944). This year the season was expected to come at the end of June, and so we kept watch for the npr. Unfortunately we were at the height of the rainy season in late-June at the main islands here. We therefore asked especially ISHADOH (Id) at Okinawa to be on the watch: On 23 June the rainy season turned out to be over at Okinawa, earlier by a month than here, and Id made precious observations. From 6 July to 11 July a tropical cyclone stayed near Okinawa, but the weather at Fukui et al happened to be fine complementarily from 6 July to 10 July, and thus we were able to trace eventually the npr without any serious blank from 155°Ls to 171°Ls.
Taking account also the overseas timely observations, we consider we obtained the following:
1) Up until 18 June (156°Ls), the north polar cap (npc) was definitely seen together with the dark base,
2) then until 27 June (161°Ls), the dark base (for example Rima Borealis) was still faintly visible, while
3) since then the dark floor was not detected perhaps due to a thickening of the white canopy over the npc. However
4) when M Acidalium greeted the morning, the ingredient making the canopy moved to the lowlands to make a thick morning mist, and the npc looked uncovered as observed by Id on 29 June (162°Ls), by Id and HIGA (Hg) on 4 July (165°Ls) and also by Mn on 8 July (167°Ls). The presence of the morning mist over the area seemed to occur frequently at this season, and hence we may suppose that
5) the appearance of the npc was almost diurnal at the dawn time of the area to the extent that the items 1), 2), and 3) held when M Acidalium (or possibly other lowlands) was in the afternoon or at the rear side.
This apparition provided the rare opportunity to watch the moment we had after these 15 years since 1984. The results 1), 2), and 3) were almost identical to those obtained in 1984. We will meet 160°Ls again in mid-May 2001 with apparent diameter of 16 arcsecs, but the the sub-Earth point will be casted on the southern hemisphere.
We should recall that to observe the npr we need good seeing condition: If not, the npc must look always blurred. We therefore pick out only preferable observations in the following:
We reported in the preceding issue that the npc was definite until 15 June (155°Ls).
16 June (155°Ls), Id was endowed with a good seeing at LCM=233°W (14:10 GMT) and at 246°W, and detected the npc together with a faint Olympia.
17 June (156°Ls), Id observed a presence of Rima Borealis at LCM=193°W (12:00 GMT), LCM=209°W and LCM=231°W(14:40 GMT) during which Olympia moved from the centre to the left-hand side. The Video images by Hg at LCM=191°W ~ 220°W also show the bright npc.
18 June (156°Ls), SIEGEL (ESg) in Denmark observed clearly a very bright, roundish npc at LCM=314°W (21:00 GMT).
19 June (157°Ls), IWASAKI (Iw) observed at LCM=176°W (12:10 GMT) that the npc looked indefinite and the whitish npr was slightly larger. ESg then observed at LCM=302°W (21:50 GMT) that the npc was bright but was not very bright, and that the npc has grown a bit since the beginning of June. We might consider that some mist started to cover the npc.
20 June (157°Ls), NAKAJIMA (Nj) and Mn detected the npc (at LCM=138°W(Mn) and at LCM=142°W(Nj)) while could not do Rima Borealis, though at LCM=162°W, Nj saw partially Rima Borealis. Iw observed at LCM=157°W and 167°W and detected the npc (contrarily to the preceding night) without any mist (with seeing 7~8/10). Mn also saw the npc at LCM=167°W, and faintly detected Rima Borealis.
21 June (158°Ls) we clearly saw the npc and Rima Borealis at LCM=128°W(Mn), 133°W(Nj) and 138°W(Mn). Seeing became then poorer, but the whiteness remained until LCM=177°W.
22 June (159°Ls), we observed that the npr was without haze at LCM=121°W(Nj) and LCM=126°W(Mn), but the npc was not bright. At LCM=155°W(Mn) and LCM=141°W(Nj) the npc looked like a core under good transparency but it was never glossy.
23 June (159°Ls), Hg's Video produced the npc at LCM=134°W and 154°W; and there seems to exist another white spot preceding the npc (not identified). It proved rainy from this day on at Fukui.
24 June (160°Ls),
MELILLO (FMl) took CCDs at LCM=338°W (01:49 GMT) and at 359°W: the former image conveys the npc (thru Wr25). Id now obtained his first observation after the rainy and cloudy days at LCM=142°W (13:00GMT). He also observed at LCM=151°W: He judged that the npr was slightly hazed, but Rima Borealis was still detectable faintly and the second observation detected Olympia. Observed up until LCM=176°W.
25 June (160°Ls), Id observed at LCM=135°W that the npc part was bright but not so definite in contour, while Olympia was seen in the morning. At LCM=152°W, the npc looked blurred and might be hazed. TEICHERT (GTc) observed at LCM=237°W (20:10 GMT) that the npc (npr) was white.
26 June (161°Ls), Id saw faintly the border of the npc at LCM=108°W, but then seeing turned poorer.
27 June (161°Ls), WASIUTA (MWs) drew the surface at LCM=307°W (01:40 GMT) without definite npc. Id observed at LCM=096°W(11:50 GMT) with seeing 7/10: The dark filament encircling the npc was faintly seen but Id thought that the npr was largely covered by a thin canopy. Similarly at LCM=106°W. Olympia appeared at LCM=118°W. Observed up to LCM=143°W.
28 June (162°Ls), to GTc, the npc (or the canopy) looked faded at LCM=208°W (similar expressions since 22 June).
29 June (162°Ls), Id started from LCM=066°W (at 11:00 GMT) where the npc was not bright nor glossy, but isolated, and there can be seen a patch of morning mist at Baltia. Similarly at LCM=075°W. At LCM=085°W the morning white patch was more inside, and the dim npc was separated. On 30 June (163°Ls), Iw watched at LCM=063°W, but was not able to catch the size of the npc nor the brightness. Might be sure about the size at LCM=073°W. MURAKAMI (Mk) saw the npr was pale at LCM=078°W. Id observed at LCM=088°W but the npc was indefinite. At LCM=100°W, he saw a brightness but the shape was obscure.
1 July (163°Ls) when apparent diameter=11.5", Mn observed at LCM=034°W (10:10 GMT), but could not detect the possible presence of Hyperboreus L though saw a canopy in the npr. It was seen a core at LCM=064°W. Id observed at LCM=061°W where the npc was not visible but some light shape was seen (seeing 7/10).
2 July (164°Ls), Id saw the npr was largely whitish made of two white patches at LCM=040°W; the northern one must have been a remnant of the npc.
4 July (165°Ls), Id observed at LCM=021°W et al. There was observed a white morning mist patch to the north of M Acidalium (see below, and also shot clearly by Hg), and also another white core which might be the npc remnant.
5 July (165°Ls),
PARKER (DPk)
obtained good CCD images at LCM=228°W (01:25 GMT) where the npr showed a haze canopy in B while the npr looked bald in R. It is considered that the canopy is too thick to send the image of the ground even in R. Iw watched at LCM=016°W (11:30 GMT) where the npr is just light. Id did at LCM=019°W when he detected a white patch to the north of M Acidalium, and seemed to see the npc (?) to the further north of it. Doubled white patches also at LCM=033°W.
6 July (166°Ls), FMl obtained CCD images at LCM=217°W (01:19 GMT) without any canopy even thru Wr47.
DPk produced good CCD images at LCM=228°W (02:03 GMT) where no npc nor Rima Borealis was found in R. Mn watched at LCM=345°W (10:00 GMT) where the npr was just light and at LCM=014°W where a core was seen, maybe a canopy. OHBA (Oh) observed at LCM=357°W where a morning white patch was seen. Iw observed at LCM=026°W and 036°W that the npr was largely whitish (seeing poor 2~3/10).
7 July (166°Ls), DPk obtained good CCD images at LCM=212°W (01:38 GMT) where the npc is not visible, but a part of Rima Borealis seems to be present in R. Mn observed from LCM=335°W (10:00 GMT): the npr was light and at LCM=012°W a core or the canopy was seen. AKUTSU (Ak) shot at LCM=355°W where the npr is light without any core.
8 July (167°Ls), Mn started at LCM=323°W: a white morning mist occupying the northern part of M Acidalium was seen from LCM=333°W and chased to LCM=024°W: AtLCM=012°W, it was well inside, and the situation was different to the one at the same angle on the preceding day. Notable was that the presence of the morning patch caused a disclosure of the npc remnant.
9 July (168°Ls), at Fukui we observed from LCM=316°W(Mn) and LCM=321°W(Nj): the npr was just light, but from LCM=326°W we felt a core. Seeing was poorer the night. Ak obtained CCDs at LCM=328°W and 348°W: the npr was white, but nothing thru R and IR.
10 July (168°Ls), Mn was from LCM=307°W up to LCM=346: The day the core was rather apparent, and might be the uncovered npc.
12 July (169°Ls), Id observed at LCM=319°W et al: The npr looked covered by the np canopy.
15 July (171°Ls, The apparent diameter=10.4"), we observed from LCM=257°W(09:50 GMT, Mn) and LCM=261°W(Nj): The npr was light, and Nj saw frequently a core. Id observed at LCM=281°W (11:30 GMT), 291°W, 301°W and 308°W: the core was not so light.
It is difficult to predict when a new snow will overlie the npr, but we are sure the so-called the north polar hood (nph) has not yet been developed though the canopy may be transformed to the nph soon.
Hellas:
Hellas is also at the critical season. AKUTSU (Ak)'s colour CCD on 9 July (168°Ls) at LCM=329°W shows that Hellas looks slightly yellowish while the south polar hood (sph) is very white. This is because Hellas is light in R rather than in B. MELILLO (FMl)'s R image on 24 June (159°Ls) at LCM=338°W also bright Hellas in R. ISHADOH (Id) observed on 12 July (169°Ls) at LCM=332°W that the limb area from Hellas to the sph was considerably bright (at intensity 2~ 2.5). Mn watched the area from the similar angle from 7 July (166°Ls) to 10 July (168°Ls) (respectively at LCM=335°W, LCM=333°W, LCM=336°W and LCM=336°W): Before the angle, the sph appeared weaker than Hellas but after the angle, the sph became comparative with Hellas. At LCM=343°W, the sph was brighter and dominant. The haze over Hellas was not so thick, but could be traced up until LCM=352°W (even at LCM=002°W an afterimage of Hellas was seen).
In the previous occasion in 1984, Hellas was still seen at LCM=343°W but was not at LCM=014°W on 20 June 1984 when the season was 167°Ls and app diam=15.3", and so the situation seemed to have been repeated. If we compare the result with the recent observations for example on 30 May 1999 (147°Ls) and on 29 Apr 1999 (131°Ls), the situation was not so different since Hellas was caught near the afternoon limb until about LCM=355°W: At the stage of 131°Ls, the south of Hellas was darker at the limb than this time and the sph was isolated, and hence the sph was rather different. Earlier in season, Hellas observed at LCM=349°W on 20 Mar 1995 (075°Ls, phase angle=25°) was much whiter and brighter and seen also at LCM=358°W.
On 15 July (171°Ls) Hellas passed the CM. Hellas looked still misted and Id judged that the brightness remained the same as before at LCM=301°W. At Fukui we observed from LCM=257°W to LCM=300°W to see that Hellas hazy light and could not yet be separated from the sph. Note however even at LCM=286°W, Hellas' LMT was near 08:15 AM (phase angle=42°).
The South Polar Hood:
The south polar hood (sph) also is receiving a critical stage since the south polar cap must be apparent near at 170°Ls as observed in 1986. However the aspects of the sp region drawn by ISHADOH (Id) (38 times during the present period) are diverse, not fixed nor definite yet, and so the sph has been dominant. The Video images by HIGA (Hg) on 17 June (156°Ls) at LCM=190°W~200°W show a large and thick sph, while those on 24 June (160°Ls) at LCM=140°W~160°W do the sph to be thin and poor. The sph to the south and west of Solis L taken by Hg on 25 June (160°Ls) at LCM=112°W is complexed and interesting. Mn saw a brighter part inside the sph on 22 June (159°Ls), but it was not axis-symmetric. Furthermore, as above-mentioned, the sph became broader and thicker as Hellas went to the preceding limb, and Noachis came to the CM, that implied the sph itself was not symmetrical. The excellent images by PARKER (DPk) on
7 July
(166°Ls) show the sp region to be bright and thick only in B, but not necessarily in R.
Tharsis, Alba:
ISHADOH (Id) detected Arsia Mons and Ascraus Mons separated as dark spots on 27 June (161°Ls) at LCM=096°W and 106°W (seeing 7/10, phase angle=38°). On the other hand, MURAKAMI (Mk) saw white spots near Olympus Mons and Alba on 21 June (158°Ls) at LCM=138°W (Olympus Mons was at 10h AM LMT). NAKAJIMA (Nj) also chased similar light spots on 20 June (157°Ls) at LCM=142°W~172°W. He also made a similar observation on 21 June (158°Ls) at LCM=153°W. Mn also saw the light arm from Tempe to Alba, Olympus Mons on 20, 21, and 22 June. The Video images by Hg on 24 June (160°Ls) at LCM=138°W also show the arm to be light. At LCM=148°W, Tharsis became brighter near the limb. Hg's images on 25 June (160°Ls) at LCM=131°W, 141°W prove Tempe to be white near the limb.
Elysium:
ISHADOH (Id) observed that Elysium still made a Y-shaped light area together with the Cebrenia band on 17 June (156°Ls) at LCM=209°W: The HIGA (Hg) Video images also show on the day the aspect was most apparent at LCM=220°W. Elysium was not so much white as Cebrenia (see below). Notable is a morning white cloud which is seen on Hg's images on 17 June (156°Ls) at LCM=191°W to the south-east of Elysium and near the morning terminator. The morning mist of this kind was thickly observed at Fukui on 21 June (158°Ls) at LCM=187°W, but could be checked from about LCM=150°W on 20, 21, and 22 June.
Cebrenia:
The Cebrenia band was observed by ISHADOH (Id) to be whitish lighter misted on 16 June (155°Ls) at LCM=233°W and 246°W, and further on 17 June (156°Ls) at LCM=209°W and 231°W. This conspicuous phenomenon was proved clearly by HIGA (Hg)'s Video on 17 June (156°Ls) especially on the B images. The coming-in misty band at Cebrenia was observed at Fukui from 20 June (157°Ls) at LCM=138°W. Id also noted again from 24 June (160°Ls) from LCM=142°W.
Phlegra:
ISHADOH (Id) observed on 16 and 17 June (156°Ls) that the area from Cerberus to Phlegra was quite dark and broadly curved. Don PARKER (DPk) on
6 July
(166°Ls) at LCM=228°W and also on 7 July (166°Ls) at LCM=212°W showed that the area in Phlegra was strangely dark, thick and broad along Styx in R as well as in G.
Morning Mists (Cyclones?):
As noted, ISHADOH (Id) chased a bright morning mist patch at Baltia on 29 June (162°Ls) at LCM=066°W, 075°W, 085°W and 095°W (less bright was thenpc in contrast). Id also found a white mist patch to the north of the morning M Acidalium on 4 July (165°Ls) at LCM=021°W and 033°W. This white mist can well be seen on HIGA (Hg)'s Video images on the day: Hg consecutively chased as at LCM=021°W, 031°W, 041°W, 051°W and 061°W: The round patch goes inside gradually. It appears that the mist invaded slightly the northern pat of M Acidalium. The images from LCM=041°W also show a less bright morning haze at Tempe that is separated from the patch in question. Id also saw a similar morning mist on 5 July. Mn observed on 8 July (167°Ls) at LCM=333°W that the northern part of M Acidalium was thickly covered by a morning mist and chased it as at LCM=342°W, 352°W, 002°W, 012°W and 024°W: From LCM=002°W the white patch was well inside the disk, and covered largely the northern M Acidalium. This had not been seen on the preceding day on 7 July at LCM=012°W. Seeing was however too poorer on 9 July to chase the area.
We-Further-Received:
We received with thanks further documents made earlier, but we don't necessarily review them, since we don't review all of the observations made during the present period.
ISHIBASHI (Is) obtained several B&W photos near the opposition, out of which his B photos by the use of B390 filter look good and useful. The ones on 15 Apr (124°Ls) at LCM=054°W and on 20 Apr (127°Ls) at LCM=029°W seem to show an equatorial band mist. The one on 30 Apr (132°Ls) at LCM=278°W shows Hellas light, and thenpc and Elysium apparent. The B one on 17 May (140°Ls)at LCM=130°W is interesting and shows the light arm from Tempe to Olympus Mons (cf Fig 1 at p2534 in #219). The colour photo on 1 June (148°Ls) at LCM=338°W shows thenpc clearly but does not well the sph. The dark markings on the colour emulsion are not well thick.
In the preceding issue we carelessly failed to list up the CCD images made by PARKER (DPk) on June (149°Ls) at LCM=186°W: These were excellent showing clearly Propontis I near the CM: Phlegra appeared to be broadly dark. Rima Borealis was very evident thru R, though the npc was not glossy in R. The sph was made of two patches; the one at Phæthontis to the south of M Sirenum being brighter in B and also a bit light in R.
WASIUTA (MWs) detected clearly the evening Olympia on 21 May (142°Ls) at LCM=282°W. Hellas was bright as well as the evening Elysium.
WARELL (JWr)'s drawings submitted this time range from 141°Ls to 151°Ls: The npc were quite evident in all. The one on 30 May (147°Ls) at LCM=121°W shows Olympia at the morning side.