96/97 report 007

1996/97 Mars Observation Reports -- #007 --

OAA MARS SECTION - Fortnight Report

Martian Surfaces in the First Half of February 1997

- - - by MINAMI, Director of the Mars Section of the OAA ---

The disk diameter went up from 10.6" to 12.0" during the period from 1 Feb to 15 Feb. The season proceeded from 072°Ls to 078°Ls. The phase angle decreased from 29° to 22°, and the disk became more roundish. The central latitude was nearly 23°N. The planet was stationary on 6 Feb, and henceforward the rise of Mars has been rapid, and it is now observable before midnight.

We received with thanks this time observations as follows:

ADACHI, Makoto (Ad)  Otsu, Japan 
   2 Drawings  (9 Feb) 360× 31cm speculum
AKUTSU, Tomio (Ak) Karasuyama, Tochigi, Japan 6 CCD Images (6, 8, 14 Feb) f/66, 32cm speculum, Lynxx PC
ASADA, Hideto (Aa) Kyoto, Japan 8 CCD Images (8, 9, 10 12, 13, 14 Feb) f/37, 31cm speculum, Mutoh CV-04
FALSARELLA, Nelson (NFl) Brasil 6 Drawings (5, 6, 7, 8, 9, 10 Feb) 260× 20cm speculum
HIKI, Toshiaki (Hk) Minowa, Nagano, Japan 11 Drawing (6, 7, 8, 8, 9, 13, 14 Feb) 340× 16cm speculum
ISHADOH, Hiroshi (Id) Naha, Japan 2 Drawings (9 Feb) 530× 31cm speculum
IWASAKI, Tohru (Iw) Morodomi, Saga, Japan 16 Drawings (2, 7, 8, 9, 13 Feb) 400× 21cm speculum
LEHMAN, David J (DLm) CA, USA 3 Drawings (8, 9 Nov; 15 Feb) 250,290,300× 25cm speculum
MINAMI, Masatsugu (Mn) Fukui, Japan 49 Drawings (5, 7, 8, 9, 10, 14 Feb) 400,480× 20cm refractor*
MURAKAMI, Masami (Mk) Fujisawa/Fukui+, Japan 28 Drawings (4, 8+, 9+, 13, 14 Feb) 370× 15cm speculum / 400,480× 20cm refractor*+
NAKAJIMA, Takashi (Nj) Fukui, Japan 22 Drawings (5, 7, 9, 10 14 Feb) 400× 20cm refractor*
NAKANO, Yuhkichi (Nn) Oh-ita, Japan 2 Drawings (8 Feb) 420× 20cm speculum
NARITA, Hiroshi (Nr) Kawasaki, Japan 14 Drawings (31 Jan; 4, 6, 8, 12, 13, 14 Feb) 400× 20cm refractor
NISHITA, Noriaki (Ns) Fukui, Japan 3 CCD Images (8, 9 Feb) 20cm refractor* , Mutoh CV-04
SCHMUDE, Richard W, Jr (RSc) GA, USA 2 Drawings (26 Jan; 1 Feb) 170, 300× 15cm speculum
SIEGEL, Elisabeth (ESg) Malling, Danmark 1 Drawing (1/2 Feb) 270× 20cm Schmidt-Cassegrain
TEICHERT, Gerard (GTc) Hattstatt, France 2 Drawings (6, 7, 8, 10 Feb) 170, 300× 15cm speculum
WARELL, Johan (JWr) Upsala, Sweden 6 Drawings (20 Dec; 3, 19, 24, 31 Jan; 1 Feb) 330,200× 16cm refr, 290× 45cm spec * Fukui City Observatory

As announced we coordinated the first OAA Mars Watch Days on 8, 9 and 10 February: Several joined and, as far as we received until now, a total of 101 drawings and CCD images were obtained including a few overseas observations. The 10th day was generally cloudy in Japan, and at Okinawa ISHADOH (Id) was just able to catch the planet twice on 9 Feb (according to him, the weather at Okinawa is generally bad in Feb) . HIKI (Hk) experienced minus 6° C at southern Nagano. At Fukui we enjoyed by chance clear skies on all three days: MURAKAMI (Mk) came down to Fukui and observed happily on 8 and 9 Feb there. NISHITA (Ns) also tried to take pictures by a CCD camera and was well successful. On 10 Feb NAKAJIMA (Nj) and Mn enjoyed better seeing.

0) During this fortnight, the neighbourhood of Elysium was watched from Japan from the morning Syrtis Mj to the evening Tharsis.

1) The Elysium area was observed near the CM by several observers: Elysium and Cebrenia were more lit than before. At Fukui Elysium was caught on 5 Feb (074°Ls) at the CM, and its western part was zonally light (by Mn at ω =213°W) . Cebrenia was also zonally long light in the E-W direction. We judged however that the activity of the white haze was low, and not yet Very Active (VA) in the sense of SMITH and SMITH (cf CMO #134 p1251) . IWASAKI (Iw) also observed that Elysium is normally light on 8 Feb at ω = 208°W. The area remains to show the same shape as observed in the 1980s, and the Elysium and Cebrenia are the two branches of a shape of heart. This aspect was checked by Mk on 8 Feb (076°Ls) at ω =237°W and on 9 Feb at ω =223°W. Cebrenia also extend to the eastern slit between Propontices I and II: Mk observed it on 8 Feb at ω =169°W (also on 13 Feb at ω = 167°W) .

2) Mk also described Propontis I as a dark spot on 9 Feb at ω =169°W, but this time Phlegra and Azania were shadowy enough to make it not marked nor isolated. The area of Phlegra was nicely seen on 9 Feb (076°Ls) at ω =174°W under better seeing at Fukui (by Mn) : Phlegra was dark broad to extend to the Elysium area to the west of Propontis I, and Azania was well shadowy up to Cerberus; the latter being never washed out and also well evident.

3) Alba looked to be nearly out of season, but Olympus Mons was high in season and VA. Mk identified it on 8 Feb (076°Ls) at ω =159°W, 169°W separated from the evening Tharsis. On 9 Feb Mk and Mn more enjoyed Olympus Mons: it was like a very whitish cotton ball as if floating. On 10 Feb (076°Ls) , seeing becoming better, it was already caught when we began observing at midnight (15:10GMT) from ω =145°W, and NAKAJIMA (Ns) and Mn alternatively watched the distinguished white ball until it disappeared from the terminator: We judged that it came to the terminator at ω =204°W (when the phase angle was 25°) . Precedently the Tharsis cloud was also conspicuous bounded by a shadowy band from Olympus Mons. Iw also observed Olympus Mons clearly on 13 Feb at ω =153°W and 163°W, and it must have been more impressive to him than the evening cloud over Tharsis. Alba was clearly seen roundish on 10 Feb (076°Ls) at ω =165°W et al but it showed rather a pinkish tint and did not so stood out. By CCD, as taken by ASADA (Aa) on 13 Feb (078°Ls) at ω =157°W, Olympus Mons and Alba were evident even through R light. On 14 Feb AKUTSU (Ak) produced a series of CCD images of the region and the Int image at ω =115°W clearly show Tharsis, Olympus Mons and Alba separately. Olympus Mons is already seen on Ak's B light ω =119°W image. The aspect is similar to the classical one cited at p1253 of CMO No34. Don PARKER (DPk) ' Internet image on 1 Feb also produce the same aspect.

4) As aforementioned, the seeing condition on 10 Feb was favourable at Fukui: We therefore came to feel something extraordinary about the north polar cap (npc) at around ω =194°W, and then at ω =204°W, Mn clearly witnessed the fact that a fourth of the npc at the morning (following) side was less bright in a tint of yellow ocher. Not however detected any rift. The shadowy part was checked by Nj 20 minutes later by the same telescope. Mn once experienced a similar phenomenon concerning the south polar cap in 1986 and 1988 that a part of the spc became less bright in yellow ocher colour: In those cases it implied that the part more rapidly thawed away than the rest. This time, we were not able to judge what was happening, and must wait: So Mk (E-mail/Fax Secretary of the OAA Mars Section) first faxed an alert to Okinawa (however the weather was unfavourable there though Id and HIGA stood by) and then e-mailed on 16 Feb to the European observers to ask them to watch the angle around ω =200°W because the angle became to face towards them. We expect it will be concluded until the next turn whether it implies a melting or a kind of dust or a detachment. We looked later for the CCD images by Ak and Aa, and found that the R images by Ak on 8 Feb at ω =191°W and by Aa at ω =200°W show the less brightness of the morning (following) part of the npc.

5) A plan of the Mars Watch Nights in a sense implies a competition, and so the members are expected to make a challenge on several check-points, although this time our members did not necessarily attempt. We should say the moment when Syrtis Mj just appears from the morning limb is an interesting and important observation milestone. Mk succeeded to find it on 8 Feb at ω =227°W and on 9 Feb at ω =223°W (Mn near at ω =222°W on 5 Feb, 7 Feb, 8 Feb and 10 Feb) . Cf No.128 p1165 for a 1982 case. We can put forward several other challenging cases even when the markings are scarcely visible like the present time: For example the moment when the Aetheria dark patch or N Alcyonius or the apex of Utopia appears on the morning side. As to the latter, the apex was caught on 9 Feb at ω =174°W. We expect these mileposts challenge our members' attention next time.

FALSARELLA (NFl) observes an upside-down disk from our view point because he lives in the southern hemisphere. On 5 Feb (074°Ls) at about ω =070°W, he describes the evening Chryse light. On 10 Feb at about ω =000°W, he detected a thin line inside the npc running in the E-W direction. Seeing was 7.5/10. Truly and interestingly NFl observes the rear side of Mars from us.
LEHMAN (DLm) 's observation on 15 Feb was at about ω =040°W, and observed a morning bright part, but Chryse inside at mid-day was not light. He commented the npc was smaller. His first observations in Nov caught Syrtis Mj.
SCHMUDE (RSc) observed on 1 Feb at about ω =180°W: The npc was dull white, and asymmetrical in brightness.
SIEGEL (ESg) made her first drawing for this apparition on 1/2 Feb at ω = 006°W: M Acidalium was dark evident. The evening mist was blue whitish, while the morning one was off-white and hence she considers that the morning -side area was a ground sunlit.
WARELL (JWr) depicted a thick morning haze on 1 Feb at ω =071°W as well as on 31 Jan at ω =056°W through Int, but commented that Thaumasia was seen bright through Wr25, and hence he considered that the area was dust clouded as noticed by HERNANDEZ on 29 Jan. The IR image by QUARRA (see No184) however did not produce any trace of the dust cloud as mentioned there. See also below.

R McKIM e-mailed the 4th and 5th BAA Mars Section Reports on 11 Feb and on 17 Feb respectively: The former treats the period 1~31 Jan and the latter 1~ 15 Feb. The 4th refers to CMO#183 about ISHADOH (Id) 's observation of the npc which appeared to him slightly mixed with a brownish tinge. McKIM writes "The Japanese account fails to mention any particular CM longitude (or CML range) , which may be important." He may be right in general, but at present the npc has been totally inside the disk and Id did not particularly discern the brownish part. The HST images taken on 29 Nov, 30 Dec and 4 Jan clearly show the npc speckled largely with orange (or the orange npc spotted by several white areas) . Even for the HST images it is difficult to describe precisely the location of the orange areas. In the 5th report, McKIM kindly replies to our inquiry in CMO No184 about the source of his statement in the 2nd Report that PARKER imaged the 18 Sept dust storm. What the present writer implied in #184 was that, if this was the case, no one could "understand" that the dust storm associated with the npc on 18 Sept revealed by PARKER, with help from HERNANDEZ, was the same dust that the HST took on the day because of a large difference of angles. Otherwise, in the 5th, McKIM clearly denied the possible existence of the dust storm over Thaumasia on 29 Jan (communicated by HERNANDEZ, cf LtE in No184) . We agree with his conclusion, though the area then had nothing to do with the Japanese area. It is always no good to discuss the dust storm only at the limb sides.

Next issue (No186) will be published on 10 Mar in which we will treat the observations from 16 Feb to 28 Feb (dead line 5 Mar) . The observations from 1 Mar to 15 Mar will be dealt with in No187 (dead line 20 Mar, published 25 Mar) . Reports will be acknowledged if air-mailed to M MINAMI at Mikuni (ask the mail-address through vzv03210@niftyserve.or.jp) .


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