96/97 report 013

1996/97 Mars Observation Reports -- #013 --

OAA MARS SECTION - Fortnight Report published in CMO No 191(25 May 1997)

Martian Surfaces in the First Half of May 1997

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

The red planet is already high in the early evening, and the observable time much diminished. The apparent diameter was 11.5" on 1 May but decreased to 10.3" on 15 May. The image looks smaller even by use of 400× . The phase angle augmented to 30° to 35° during the period, the morning side becoming broader. The central latitude was about 25°N. The season proceeded from 112°Ls to 118°Ls

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

      AKUTSU, Tomio (Ak)  Karasuyama, Tochigi, Japan
            8 CCD Images  (1, 4, 6, 10 May)   f/66@32cm speculum, Lynxx PC

      CAVE, Thomas R (TCv) CA, USA
            2 Drawings  (9, 11 May)   400,550,660,780× 32cm speculum

      GROSS, Horst  (HGr)  Hagen, Deutschland
            4 Drawings  (23 Apr; 2, 12, 15 May)     250× 25cm Schiefspiegler

      ISHADOH, Hiroshi (Id) Naha, Japan
            8 Drawings  (8, 12, 14, 15 May)  530× 31cm speculum

      IWASAKI, Tohru (Iw) Kita-Kyushu, Japan
            9 Drawings  (4, 5, 9 May)  400× 21cm speculum

      MELILLO, Frank J  (FMl)  NY, USA
            3 B&W Photos (27, 30 Apr; 5 May) 20cm Schmi-Cass AO-2 TP Wr47 & Wr21 

      MINAMI, Masatsugu (Mn) Fukui / Otsu+, Japan
           37 Drawings  (1, 4, 5, 9, 10, 12+ May)  400,480× 20cm refra* / 400× 20cm spec+ 

      MURAKAMI, Masami (Mk)   Fujisawa, Japan
           10 Drawings  (1, 9, 11#, 15 May)  370× 15cm speculum / 400× 20cm refractor#

      NAKAJIMA, Takashi (Nj)  Fukui, Japan
           14 Drawings  (4, 5, 9, 11 May)    400, 480× 20cm refractor*

      NARITA, Hiroshi  (Nr)  Kawasaki, Japan
           35 Drawings  (1, 2, 4, 6, 9, 10, 11, 12 May)  400× 20cm refractor#

      NIKOLAI, Andre  (ANk)   Berlin, Deutschland
            4 Drawings   (23 Apr; 7, 13 May)   225,375× 15cm refractor at the WFS

      QUARRA SACCO, Giovanni A (GQr) & the SGPG (A LEO & others) Firenze, Italia
            1 CCD Image  (2 May)  f/24@30cm Cass, ISIS CCD800 with Kodak KAF0400

      TEICHERT, Gerard  (GTc) Hattstatt, France
            5 Drawings  (22, 23, 24 Apr; 1, 2 May) 280,310,330,390× 28cm Schmidt-Casse

      TROIANI, Daniel M  (DTr)  IL, USA
            3 Drawings  (4, 5, 7 May)  520× 44cm speculum 

                                              * Fukui City Observatory
                                              # Tama AstroObservatory
As the observations obtained earlier, we received with thanks the following:
      DIJON, Jean (JDj) Champagnier, France
            6 CCD Images (7, 9, 12, 13, 14, 16 Apr) 31cm spec with KAF400

      OHBA, Yoshio (Oh)  Yamagata, Japan
            1 Drawing  (16 Apr)  320× 20cm speculum

      WHITBY, Samuel R  (SWb)  VA, USA
           12 Drawings  (28$ Oct; 4$ Nov; 16 Feb; 5$, 29 Mar; 2, 5, 8, 17, 19, 30 Apr )
                   270,340,460× 18cm refractor$ (RAS Observatory),  310×  15cm speculum

0) From Japan
We were able to watch Solis L near the CM, M Acidalium, S Meridiani, S Sabaeus and Syrtis Mj at the evening side. The weather became rather poor because of the lingering of the fronts and the total number of observations reduced by half.

Solis L was observed on 1 May (112°Ls) and 5 May by Mn and Nj at Fukui: it remained the same as before and dark in an eggplant shape, and a dark curve went down to the dark Aurorae S. Melas L and the east side of Tithonius L were still particularly dark. From the west side of Tithonius L a border ran up surrounding Thaumasia which was followed by a shadowy region in the morning.

Chryse-Xanthe was bright at the preceding limb, and at the same time an area from Tharsis to Olympus Mons in the morning was covered by a diffused cloud (roundish large, maybe flowed out from Tharsis), and furthermore there was seen a dim morning haze near the morning terminator, as observed by Mn on 1 May at ω =094°W and 104°W etc. In a G light CCD by AKUTSU (Ak) on 4 May at ω =090°W, a contour is visible. The morning mist is difficult to catch because of the diffused boundary, but ISHADOH (Id) observed clearly the morning mist on 8 May at ω =062°W, and detected inside it a brighter spot at the north of Tharsis (a cloud floating around Ascraeus Mons?). The morning Chryse was light even further inside on 10 May at ω =021°W observed by Mn. (Since phase angle=33°, it was near at 8: 00am local time. - The CM line at 10:00am.) In Ak's CCD at ω =035°W on the same day, it was still light.

To the north of Tharsis, the densely reddish dark patch still prevailed from Ascraeus L to Mareotis L. MURAKAMI (Mk) judged that it passed the CM when he observed at ω =104°W on 1 May. The same result by Mn on the day. As repeatedly reported, there existed a dark band which started from Nilokeras, and passed the dark patch and went up to Memnonia to make a shadowy patch. The dark band however is not uniform in intensity: Nilokeras is dark but Lunae L is normal or fainter (made of a few curved scratches), and there is a gap between Lunae L and the dark patch. As also be reported, the area to the west of M Acidalium was largely reddish shadowy, as observed by IWASAKI (Iw) on 4 May at ω =076°W etc. Among the region Alba and Tempe looked lighter. On 1 May, as observed by Mn, Alba appeared less light than Tempe from ω =075°W to ω =094°W, but after ω =124°W, Alba became lighter, perhaps by a reflection of the level surface (see the preceding issue). On the R-light CCD by Ak, Alba and Tempe were both light on 1 May at ω =126°W, and also Alba is seen through G at ω =140°W. As well as Alba, Tempe is not atmospheric: NAKAJIMA (Nj) saw Tempe surface- like dull light on 4 May at ω =064°W and so on. Ak shows that Tempe is more shadowy through B light than R light on 4 May at ω =090°W. Iw didn't feel Tempe on 5 May at ω =058°W. The morning Tempe, however, looked to be covered by a hazy core; as checked on 10 May at ω =002°W and 011°W by Mn, and on 11 May at ω =004°W by Nj etc. It can also be said to be seen on the B-light CCD by Ak on 10 May at ω =022°W.

Mare Acidalium also looked to remain unchanged. The northern part was darker as well, and separated from the much darker Hyperboreus L. ISHADOH (Id) observed again that the bottom of M Acidalium was connected by two cannals with Hyperboreus L on 12 May at ω =034°W; This was also checked earlier by him on 30 Mar at ω =069°W and so on. The preceding one must be Iaxartes. As observed by GROSS (HGr) and QUARRA (GQr) in a previous case (when 101°Ls: see #189 p2070) the slit was spotted by a limb bright patch, but this time it was not conspicuous (on 1 May and 5 May). To the south of Tanais there was witnessed another dark segment by Mn on 1 May at ω = 075°W and on 5 May at ω =062°W/082°W. Deuteronilus was also apparent this time as observed by Mn on 10 May at ω =002°W and by Id on 14 May at ω =351°W.

Due to the declined phase angle, S Sabaeus and S Meridiani were evident dark quite in the afternoon. AKUTSU (Ak) took S Sabaeus clearly by R light on 10 May at ω =021°W. MURAKAMI (Mk) felt even Syrtis Mj very near the preceding limb on 11 May at ω =355°W, and ISHADOH (Id) saw the thin Syrtis Mj on 15 May at ω =359°W: He however noticed that an evening mist already covered from Libya to Aeria weakening Syrtis Mj at ω =347°W. Mn saw a tip of Syrtis Mj under mist on 12 May at ω =000°W. The limb light area was less broad. The evening limb from Deucalionis R to Noachis was dull hazed. Id observed it on 8 May at ω =062°W, Mn did on 9 May at ω = 028°W and on 10 May at ω =041°W, and also Nj did on 9 May at ω = 052°W etc. Argyre was not conspicuous while dull whitish eg on 5 May at ω =072°W; perhaps because of the high fai (central latitude).

At the end of period the evening Hellas began to face to us: It was very brilliant as observed by NARITA (Nr) on 11 May at ω =340°W, by Mk 11 May at ω =345°W and on 15 May at ω =315°W: Mk considered that Hellas was whiter than the npc. Id observed the brilliant Hellas on 14 May at ω = 351°W, and at the same time, he noticed Libya to Aeria misted as on 15 May.

The npc looked stationary, and very clearly bounded if Hyperboreus was visible. Olympia was seen frequently, and Mn caught its brightest part to the west-southward of the npc on 1 May at ω =143°W. Id saw a shadowy area inside the npc on the morning side, and considered it was caused by a presence of Chasma Boreale on 12 May at ω =034°W.

Overseas Observations

From America:

CAVE (TCv) made observations on 9 May (115°Ls) at ω =271°W and on 11 May at ω =247°W: In the former the southern end of Casius was carefully caught as well as Utopia. The northern end of Syrtis Mj was flat (as observed by SAHEKI in 1935). N Alcyonius was obvious, but the Aetheria was not. Cebrenia light. In the latter, under nearly perfect seeing, a thick morning mist concealed Syrtis Mj. Elysium dull even near the CM.

MELILLO (FMl)'s TP photographies were taken on 27 Apr at ω =043°W by use of Wr47 (where Candor-Tharsis is largely light at the morning side), on 30 Apr at ω =356°W by Wr47 (where the npc is apparent, and Aeria light) and on 5 May at ω =287°W by Wr21 where Syrtis Mj is definite, but Hellas is not obvious (the Wr47 image is out of focus, but no trace of Syrtis Mj). NB: We are sorry in the preceding issue we missed to cite and review FMl's Wr47 photo taken on 14 Apr at ω =140°W. Fortunately in a recent MarsWatch Web site the very photo was uploaded with the comment "Olympus Mons was located at CM local noon time", but the original comment further adds that "no cloud yet", and this is more important. The situation is not so different from that reviewed about the 11 Apr photos (p2085). Note also that the noon line was not at the CM because phase angle=21° at that time.

TROIANI (DTr)'s drawings were obtained on 4 May at ω =328°W (Libya light), on 5 May at ω =286°W (Hellas bright), and on 7 May at ω = 272°W. Used Wr25, Wr47 and Wr80A filters. On 5 May Syrtis Mj was seen through Wr47.

From Europe:

GROSS (HGr) from Germany observed on 23 Apr at ω =279°W (where Hellas and the npc showed Intensity 1), on 2 May at ω =212°W (where Elysium was not so evident), on 12 May at ω =120°W (Mareotis L?) and on 15 May at ω =092°W.

NIKOLAI (ANk)'s imagesobtained at the WFS on 24 Apr at ω =338°W shows S Sabaeus lying on the centre. Made also on 7 May at ω =197°W and on 13 May at ω =124°W/131°W; the latter shows The bright Tharsis at the preceding limb.

QUARRA (GQr) and LEO (ALe) from Italy produced an IR (820nm) image on 2 May at ω =230°W, where the band of Cerberus-Styx is very evident to make the classical Elysium clear. Propontis I, the dark patch at Aetheria and N Alcyonius make a set of three similar dots.

TEICHERT (GTc) from France produced drawings on 22 Apr at ω =311°W, 23 Apr at ω =299°W, 24 May at ω =294°W (Hellas is brighter than the npc, while the latter too tiny), 1 May at ω =240°W and 2 May at ω =222°W (Elysium dull). The evening observations in Europe is behind us by about 10 hours, and hence the ω increases about by 150°W compared with ours.

We further received (results obtained earlier)

DIJON (JDj) sent us several CCD images without such physical data as ω , but all show the area of M Acidalium. The one taken on 14 Apr at 20:50GMT looks best: it shows Deuteronilus, and the slit between it and M Acidalium is light. Hyperboreus L is very dark and well separated from the bottom of M Acidalium. The image on 13 Apr at 22:00GMT shows a particularly bright preceding limb.

OHBA (Oh) made a drawing on 16 Apr at ω =255°W.

WHITBY (SWb) sent us several selected drawings obtained this apparition up until April which are all interesting: The drawings on 28 Oct and 4 Nov remind us of the dear big npc (season was respectively at 030°Ls and 033°Ls): At the same time we are to be aware that the ALPO format misses the description of the important data such as the apparent diameter and the phase angle. The drawing on 16 Feb (079°Ls) at ω =030°W proves that the bottom of M Acidalium was separated from the the dark fringe of the npc, may be Hyperboreus L: SWb describes the slit between them as "a strip of ochre of the intensity of the usual Martian desert". On 5 Mar (086°Ls) at ω =131°W, Tharsis at the evening terminator was as bright as the npc (Intensity 0), and apparent also through B-light. Alba was also caught (Intensity 2). The morning limb bright (Intensity 1). M Sirenum was visible far near the southen morning limb (Intensity 7). On 2 Apr at ω =220°W, the dark Cerberus-Styx and the Aetheria dark patch pinched classical Elysium. Observed up to ω =236°W. SWb observed Propontis I on 5 Mar (100°Ls) at ω =185°W where Elysium was inside the morning mist covering also the dark patch at Aetheria. He detected Olympia very clearly as a detachment to the south-west of the npc on 8 Apr (101°Ls) at ω =161°W. On 17 Apr (105°Ls) at ω =095°W, Tempe was light and the dark Ascraeus L- Mareotis L apparent (Intensity 5). On 19 Apr at ω =059°W, Hyperboreus L was separated. On 30 Apr (111°Ls) at ω =321°W, the evening Hellas brilliant. M Serpentis dark and S Meridiani well inside the disk. In the northern desert, Deuteronilus and its eastern extension was seen. SWb considers that the surrounding of the npc looked lighter through B-light on 5, 8 and 17 Apr (105°Ls).


1) Tohru IWASAKI (Iw) started his routine observations of Mars in 1984 from 113°Ls, and he at last synodically met 113°Ls on 4 May this year. He obtained more than 1900 drawings during the period. True recurrence will however occur next opposition.

2) The Okinawa district is now in a rainy season (officially from the beginning of May, but substantially from the end of April), and we are afraid ISHADOH and his colleagues feel difficult to catch the planet. We must also endure the rainy season from mid-June. 3) We heard that a big tornado whipped Miami very close to downtown on 12 May, but we are relieved to hear from Don PARKER that his Observatory was fortunately never damaged.

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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