Forthcoming 2007/2008 Mars
(10)

Vanishing NPH and the Perimeter of the NPC. II

CMO #334 (25 July 2007)

Masatsugu MINAMI & Masami MURAKAMI


 

Japanese here


A

S described in CMO #329, Forthcoming (5), it is interesting to watch the vanishing north polar hood (nph): Sometimes some markings or the perimeter of the north polar cap (npc) can be witnessed seen through the weakened nph. Here as a sequel of the article in #329, we exemplify two cases which can probably be seen at the end of this year.

 

One is to aim watching the Dawes slit at the same season as DAWES himself detected it in 1864. The season was between λ=330Ls and 340Ls, and so the period from 15 October to 31 October 2007 must be appropriate. The central latitude is from φ=6N to 7N, and so not so bad. We here show a figure with grids: It is expected the boundary of the nph will be around 45N (according to the BAUM- DOLLFUS diagram cited in CMO #109 (25 Sept 1991) p0944). Table I gives the date and time when the centre of M Acidalium passes the CM.

 

The second case is to watch the thin nph and the perimeter of the npc from the angle at around ω=180W at the northern spring equinox. Here Panchaia must be covered by the npc, while the perimeter (maybe Gyndes) can be seen through as a segment inside the vanishing nph. Table II also gives the time table when the area is to face us. The boundary of the npc is supposed here at 57~58N (according to the diagram of P B JAMES (see CMO #130-25 Feb 1993: Baum's diagram points to slightly smaller at 54N) so that the perimeter of the dark region of Vastitas Borealis is expected to be visible..

 

 

 

 

 Table I. The transit time at the CM of Ω=030W (M Acidalium): In Asia, 02 h JST corresponds to 17 h GMT and so the M Acidalium faces to them in mid Oct. At the end of October, the European observers catch the face at the end of October at the meridian. In the US, the observers at the region where GMT-6h is standard will be able to check M Acidalium at 02 hrs Local Time at 08h GMT and hence at the beginning of November. The season DAWES saw the slit was between λ=330Ls and 340Ls


 

GMT

15 Oct at 16:57 (λ=331Ls)

16 Oct at 17:32

17 Oct at 18:10

18 Oct at 18:49

19 Oct at 19:28 (λ=333Ls)

20 Oct at 20:06

21 Oct at 20:44

22 Oct at 21:23

23 Oct at 22:01 (λ=335Ls)

24 Oct at 22:40

25 Oct at 23:18

 

GMT

26 Oct at 23:56

27 Oct at - - - - (λ=337Ls)

28 Oct at 00:35

29 Oct at 01:13

30 Oct at 01:52

31 Oct at 02:29 (λ=339Ls)

01 Nov at 03:07

02 Nov at 03:45

03 Nov at 04:23

04 Nov at 05:01 (λ=342Ls)

05 Nov at 05:39

 

GMT

06 Nov at 06:17

07 Nov at 06:55

08 Nov at 07:33 (λ=344Ls)

09 Nov at 08:11

10 Nov at 08:48

11 Nov at 09:26

12 Nov at 10:04 (λ=346Ls)

13 Nov at 10:41

14 Nov at 11:19

15 Nov at 11:56

16 Nov at 12:34 (λ=348Ls)


 

Table II. The transit time at the CM of Ω=180W (Gyndes segment): In Asia, 00 h JST corresponds to 15 h GMT and so the perimeter of the npc at Gyndes faces to them in mid December. The European observers catch the area in midnight at the end of December at meridian. In the US, the observers at the region where GMT-6h is standard will be able to check the region at midnight at the beginning of December or just before.


 

GMT

01 Dec at 07:27

02 Dec at 08:03 (λ=356Ls)

03 Dec at 08:40

04 Dec at 09:16

05 Dec at 09:53

06 Dec at 10:28 (λ=358Ls)

07 Dec at 11:05

08 Dec at 11:41

09 Dec at 12:18

10 Dec at 12:54 (λ=000Ls)

 

GMT

11 Dec at 13:30

12 Dec at 14:06

13 Dec at 14:42

14 Dec at 15:18 (λ=002Ls)

15 Dec at 15:54

16 Dec at 16:30

17 Dec at 17:06

18 Dec at 17:42 (λ=004Ls)

19 Dec at 18:18

20 Dec at 18:54

 

GMT

21 Dec at 19:30

22 Dec at 20:06 (λ=006Ls)

23 Dec at 20:42

24 Dec at 21:18

25 Dec at 21:54

26 Dec at 22:30 (λ=008Ls)

27 Dec at 23:06

28 Dec at 23:42

29 Dec at - - - -

30 Dec at 00:18 (λ=010Ls)

 


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