24

th Report:

The CMO/OAA Observations made during a fortnight period

from

16 February 2004 (351Ls)

to

15 March 2004 (005Ls)

 


An OAA Mars Section article to be published in CMO #289 (25 March 2004 issue)


Masatsugu MINAMI, Director of the OAA Mars Section


Japanese version here


T

his time we deal with the period from 16 February 2004 (λ=351Ls) to 15 March 2004 (λ=365Ls).

On 5 March (ecliptic longitude=345 when in the oriental area the day is thought that insects come out from the ground. In 2004 the planet Jupiter was at opposition), the planet Mars welcomed the spring equinox λ=360Ls: End of one cycle. In the 2005 apparition it will occur on 20 Jan 2006, and in the case of 2007/2008 apparition, it does on 9 Dec 2007: Since in 2007 the planet will be closest to the Earth on 19 Dec 2007, and hence the 2007 apparition is for the northern seasons.

 This period above, the apparent diameter decreased from δ=6.1" to 5.3". The central latitude was from φ=26S to 13S. So gradually the northern hemisphere became easy to see. The phase angle was from ι=38 to 34.

 

This time we received precious observations from the following members:

 

AKUTSU, Tomio (Ak) Karasuyama, Tochigi, Japan

2 Sets of (IR)RGB Images (20, 22 February 2004)

f/3332cm spec with a Bitran BJ-41L

IWASAKI, Tohru (Iw) KitaKyushu, Fukuoka, Japan

    9 Drawings (16, 17, 29 February; 13, 14 March 2004)

40021cm speculum

KUMAMORI, Teruaki (Km) Sakai, Osaka, Japan 

18 CCD Images (18, 20, 25, 27, 28 February; 5, 6, 9 March 2004)

f/4060cm Cass# with a ToUcam

#Sakai City Observatory, Sakai, Osaka

MELILLO, Frank J (FMl) Holtsville, NY, USA

3 Red CCD Images (16, 28 February; 12 March 2004)

20cm SCT with a Starlight Xpress MX5

MINAMI, Masatsugu (Mn) Fukui, Fukui, Japan

30 Drawings (18, 19, 20 February; 10 13, 15 March 2004)

400, 480, 60020cm F/12 ED Goto refractor*

*Fukui City Observatory, Fukui

MORITA, Yukio (Mo) Hatsuka-ichi, Hiroshima, Japan

19 Sets of (IR)RGB Images (20, 21, 29 February; 4, 9, 13, ~15 March 2004)

25cm spec equipped with an ST-5C

MURAKAMI, Masami (Mk) Yokohama, Kanagawa, Japan

    5 Drawings (16, 20+, 27, 28 February 2004)

32020cm speculum, 32015cm refractor+

+ Kudan High-School Observatory, Tokyo

NAKAJIMA, Takashi (Nj) Fukui, Fukui, Japan

8 Drawings (13 February 2004)

480, 60020cm F/12 ED Goto refractor*

*Fukui City Observatory, Fukui

PARKER, Donald C (DPk) Miami, FL, USA

1 Set of RRGB Images (23 February 2004)

f/5941cm F/6 spec equipped with an ST-9XE

SIEGEL, Elisabeth (ESg) Malling, Danmark

6 Drawings (18, 19, 23, 29 February; 3, 7 March 2004)

27020cm F/10 SCT

  

TEICHERT, Grard (GTc) Hattstatt, France

2 Drawings (16, 20 February 2004) 33028cm SCT

WARELL, Johan (JWr) Tcuson, AZ, USA

    4 Sets of CCD Images (18, 23 February; 1, 9 March 2004)

f/2425cm SCT with a ToUcam

 

The NPH or NPC: That is a question which occurs if the season arrives at λ=350Ls: that is, we wonder if the white matter located at the northern limb is the north polar hood (nph) or the north polar cap (npc). It is generally believed the npc is brighter than the nph, but it is not necessarily the case. The npc should not be usually clear if we do not quite pass the vernal equinox. This time there are a lot of observations which show the white and bright northern limb matter. For example, on 18 Feb (λ=352Ls) Teru KUMAMORI (Km) showed the nph clearly at ω=238W~251W. On 23 Feb (λ=354Ls) Don PARKER (DPk) claimed that a bit of the npc was seen (in a lull ?) on the R image at ω=076W, though the following nph is brighter. The B image largely shows a thick nph. Yuki MORITA (Mo) also produced a set of images at the same angle at ω=077W on 9 Mar (λ=002Ls), and its IR image shoed similar bright white matter near the northern limb. His B also shows it thickly. According to Masami MURAKAMI (private communication), however, this cannot be considered to be the npc, but still the nph since Mos IR image from the set of images on 13 Mar (λ=004Ls) shows it from a different angle (by50W) at ω=025W, and apparently it is not perpendicular to the NS line (fortunately Mo always associate w← on the files and on the day exactly w← declines by 37). On 9 Mar, φ read 14S with δ=5.4".

 So we may first employ W BAUMs plateau (see CMO #109 25 Sept 1991 p0944), then the snow line should be 64S at λ=010Ls. However BAUMs guessed plot shows 55S on λ=000Ls (spring equinox). On the other hand, JAMES and others obtained 60S at the equinox from the Viking data in 1977/1978 (JGR 84 (1979) 8332, Icarus 52 (1982) 565). Otherwise they also pinned down 58S from the Viking results during the elongated period in 1979/1980 (Icarus 52 (1982) 565)(they claimed in this case there was not occurred the Baum plateau because of a presence of the dust disturbance see reviews in CMO #130 25 Feb 1993 p1199). So here we employ the largest case of the snow line at 55S on λ=360Ls, then the half angle of the npc must be ψ=35, and since φ=14S, we can calculate the depth d of the npc by the formula d/r=1 cos(ψ φ) where r is a radius. This formula was first given by A DOLLFUS in Icarus 18 (1973) 142, and its derivation was given in CMO #003 p0017, and also cited in CMO #255 10 Jan 2002 and in CMO-Web: See the Appendix in

http://www.kwasan.kyoto-u.ac.jp/~cmo/cmomn0/01Note01/index.htm

Since ψ φ=21 , the above formula gives d=r0.066. If we employ a disc of 5 cm diameter, the depth at the CM is no larger than 1.7 mm. When φ is too south, the ambiguity increases: If we employ the JAMES and others case (58S instead 55S) d is down to 1.0 mm. Even if we are given 2mm/50mm, d should be said too small. And so we should say the npc must have still been buried inside the nph this period. It looks the seeing condition on 9 Mar was better than on 13 Mar, but even then the nph prevailed on Mos images on 9 Mar. We would like here to express our respect to MORITAs work which is always accompanied by the record of w← on the file which otherwise bothers him. The work on 13 Mar proved thus very precious with the attachment of w←. The B image is also helpful.

Before Mo, the visual observer Elisabeth SIEGEL (ESg) did not record the northern limb to be bright by the use of W25 on 3 Mar (λ=359Ls) at ω=239W, but on 7 Mar (λ=001Ls) at ω=203W the W25 observation gave her a bright northern limb, but not in the form of the npc.

The Km-images on 18 Feb (λ=352Ls) at ω=238W~251W does not naturally show any dark band around the nph, while Johan WARELL (JWr)s images on the day at ω=155W looks to show a perimeter. On the other hand, Kms image on 28 Feb (λ=357Ls) at ω=151W does never show it. The true description of any dark band is difficult at this time, even Utopia, though visible in G of Mos images on 20 Feb (λ=353Ls) at ω=258W, is vague on Mos images on 21 Feb (λ=353Ls) at ω=218W~240W. On the other hand JWrs images on 1 Mar (λ=358Ls) at ω=045W clearly show the dark M Acidalium to the south of the nph.

The present writer was unable to observe from 21 Feb to 9 Mar because of the dismal weather, but on 10 Mar (λ=002Ls), the sky recovered and he could look for the npc: the limb looked to suggest it, but not bright and uncertain. On 13 Mar (λ=004Ls), the situation was the same: Takashi NAKAJIMA (Nj) also tried to search, but he was also not sure: Just later at ω=028W, 038W Nj suspected the presence of the npc. Tohru IWASAKI (Iw) on the same 13 Mar recorded a whitish fine light piece along the northern limb, but noted it was not bright. The germinant npc was not necessarily bright when seen near the limb, and so it is possible for Iw to have seen the 2mm npc on 50mm disc. Iw gave similar results on 14 Mar (λ=004Ls) at ω=021W. Mk tried to check the npc but in vain during this period.

 

 The SPH: Kms images on 20 Feb (λ=353Ls, δ=6.0") at ω=224W~238W are excellent: M Cimmerium is evident and Valhalla is clearly seen (ι=37), and the sph is also apparent to the south of M chromium. On the day Grard TEICHERT (GTc) visually noted the sph from the angle ω=356W. Kms images on 25 Feb (λ=355Ls) at ω=177W, 187W also show the sph, while DPks excellent images on 23 Feb (λ=354Ls) from the angle ω=076W do not show it thickly. Visually, the present writer (Mn) saw the sph on 19 Feb (λ=352Ls), and detected a core at ω=240W. On 13 Mar (λ=004Ls) at around ω=033W, the spr was hazy with a clear boundary.

 

 Hellas Atmosphere: This time the ccd observations of Hellas are not enough. Iw visually detected a small whitish patch inside the morning Hellas on 16 Feb (λ=351Ls) at ω=279W, and subsequently pointed out a brightness at the WN part of Hellas. Mn observed the morning Hellas at the latter times of 18 Feb (λ=352Ls), 19 Feb and 20 Feb: it was not so light but looked hazy, and saw on 20 Feb (λ=353Ls) at ω=230W~260W that the northern part is brighter. ESg detected a bright patch at the northern part of Hellas thru Wr47 on 29 Feb (λ=357Ls) at ω=265W. On the drawing of Iw made on 14 Mar (λ=004Ls) at ω=021W, Hellas was light near the evening limb (following Aks observations on 10 Feb (λ=348Ls) at ω=355W).

 

 Markings: DPks excellent images on 23 Feb (λ=354Ls) at ω=076W show Argyre without any cloud, and clearly resolved such markings as Solis L, Tithonius L, Nilokeras and so on. On 5 Mar (λ=360Ls) at ω=075W~091W and on 6 Mar (λ=000Ls) at ω=077W, Km shot the area but Solis L was not separated. However on 9 Mar (λ=002Ls), Km was endowed with a good seeing and at ω=040W~056W resolved Sinus Meridiani, Aurorae S and M Acidalium, but no longer Solis L. The nph was very white.

Others: ESgs observation on 3 Mar (λ=359Ls) at ω=239W showed a bright patch near the evening limb around Phaethontis through Wr47. Mn noted on 10 Mar (λ=002Ls) at ω=035W that the central deserts are especially reddish. Still evening, and inside the dome 14C.

 


T

he next issue shall treat the observations made during the one-month period from 16 March 2004 (λ=005Ls) to 15 April 2004 (λ=020Ls, δ=4.6").


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