98/99 Mars CMO Note (3)

1998/99 Mars CMO Note
- 03 -
from CMO #227

Early-morning white patch witnessed near at Baltia in late-April 1999

  WHEN we met at Fukui at the beginning of May 1999 on the occasion of the 7th CMO Planetary Meeting, MURAKAMI (Mk) asked us whether we had observed an extraordinary morning bright patch to the north of M Acidalium at the end of April 1999 as he checked. ISHADOH (Id) and IWASAKI (Iw) responded confirmatively, and MINAMI (Mn)'s drawings were not contradictory. As to the observations of Mk on 26 April, we reported as follows in CMO 217 (10 Apr 1999) at p2501: "MURAKAMI (Mk) noted on 26 Apr (130°Ls) at LCM=326°W ~ 355°W that the morning area of Baltia between M Acidalium and Hyperboreus L was thickly misted. Iaxartes was detected preceding the morning mist. Mk also checked it again on 27 Apr at LCM=312°W ~ 351°W."
  @ One evening in mid-May, NAKAJIMA (Nj) came up to the Observatory bringing with a Newspaper which showed a Martian surface with a strange cloud patch taken by the HST on 27 April. The photo was a blue-light one, and hence there was no appealing dark marking (or almost all were dark) and so the place was puzzling at first. But soon we noticed the position of Chasma Boreale, and came to know that the true position was near Baltia. And finally we gave a shout on the rooftop: it's just MU-RA-KA-MI! Later we were informed that Mk and HIGA (Hg) also readily pinned down the place. The record by the HST was partly cited in CMO 218 (25 May 1999) at p2524.

  @ We here begin with the results on 27 Apr (130°Ls): HST's WFPC2 worked from 17:55 GMT to 18:51 GMT: The surface ranged from LCM=017°W from LCM=030°W.
  Our observations on the day preceded them from 12:50 GMT to 16:10 GMT and are given as follows:

  Iw-047D     LCM=302°W  (at 12:50 GMT) 
  Id-054D     LCM=304°W  (at 13:00 GMT) 
  Iw-048D     LCM=312°W  (at 13:30 GMT) 
  Mk-113D     LCM=312°W  (at 13:30 GMT) 
  Iw-049D     LCM=322°W  (at 14:10 GMT) 
  Mk-114D     LCM=322°W  (at 14:10 GMT) 
  Mk-115D     LCM=332°W  (at 14:50 GMT) 
  Mo-   C     LCM=336°W  (at 15:10 GMT)
  Mk-116D     LCM=341°W  (at 15:30 GMT) 
  Mk-117D     LCM=351°W  (at 16:10 GMT) 
  Observation Iw-047D at LCM=302°W did not show any bright morning mist, and Id-054D at LCM=304°W a bit, while the observations by Iw and Mk at LCM=312°W (Iw-048D & Mk-113D) showed clearly a bright patch at the morning Baltia. At LCM=322°W, it became thicker (Iw-49D & Mk-114D). Mk continued to trace it until 16:10 GMT (at LCM=351°W) and watched how it came into the disk. The HST began to work about one hour and half later. The moment when Mk observed last, the Cyclone had already formed but such a resolution was not expected. If we regard the preceding part of the Cyclone was at areo-centric longitude=045°W, the local time of the place at LCM=322°W must have been at 6:30 am LMT, and the observation time by HST was about 9:00 am LMT. The morning mist must have been condensed soon after dawn, and rapidly developed into the Cyclone.

  @ We are in a position to stress that Mk started his observation in full readiness on 27 Apr because he had already observed similar singularity on the preceding day on 26 Apr. Conversely speaking, we may conclude that the same phenomenon on 27 Apr was also occurred on 26 Apr. As noted in CMO 217, Mk watched the morning bright patch to come into the disk on 26 Apr from LCM=326°W to LCM=355°W.
  @ On the day, Iw also made an important observation: He observed on 26 Apr at 13:30 GMT and produced a drawing at LCM=321°W which is comparable with the drawing at LCM=322°W above on 27 Apr at 14:10 GMT: Notable is that the bright patch at Baltia appears quite the same on both days. And thus from the observations by Iw and Mk, we can easily conclude that Cyclones occurred similarly on 26 and 27 April.

  @ Our observations on 26 Apr went as follows:

  Iw-044D     LCM=311°W  (at 12:50 GMT)
  Hg-426-1V   LCM=316°W  (at 13:13 GMT)      
  Iw-045D     LCM=321°W  (at 13:30 GMT)
  Id-053D     LCM=321°W  (at 13:30 GMT)
  Hg-426-2V   LCM=326°W  (at 13:52 GMT)
  Mk-109D     LCM=326°W  (at 13:50 GMT)
  Mk-110D     LCM=335°W  (at 14:30 GMT)
  Hg-426-3V   LCM=336°W  (at 14:32 GMT)
  Hg-426-4V   LCM=346°W  (at 15:13 GMT)
  Mk-111D     LCM=345°W  (at 15:10 GMT)
  Mo-   C     LCM=350°W  (at 15:30 GMT)
  Hg-426-5V   LCM=355°W  (at 15:53 GMT)
  Mk-112D     LCM=355°W  (at 15:50 GMT)
  Hg-426-6V   LCM=001°W  (at 16:18 GMT)

  The Video images by Hg further confirm our above conclusion: The images before 13:45 GMT (at LCM=324°W) show the morning mist to be weak, while it became vivid after. The morning patch looks brighter at LCM=336°W. Then it is quite definite at LCM=355°W. At LCM=001°W, it is very bright. The colour photo by MORITA (Mo) also shows the bright limb cloud.

(right)   HIGA's colour image on 26 April at LCM=001°W      

  @ We here also check the situation on 25 Apr (129°Ls): On the day Hg and Id observed thickly as follows:

   Hg-425-1V  LCM=322°W  (at 13:00 GMT)   
   Id-048D    LCM=327°W  (at 13:20 GMT)  
   Hg-425-2V  LCM=332°W  (at 13:40 GMT)   
   Id-049D    LCM=337°W  (at 14:00 GMT)  
   Hg-425-3V  LCM=341°W  (at 14:20 GMT)   
   Id-050D    LCM=349°W  (at 14:50 GMT)  
   Hg-425-4V  LCM=351°W  (at 15:00 GMT)   
   Id-051D    LCM=359°W  (at 15:30 GMT)  
   Hg-425-5V  LCM=001°W  (at 15:42 GMT)   
   Id-052D    LCM=008°W  (at 16:10 GMT)  
   Hg-425-6V  LCM=010°W  (at 16:20 GMT)   
   Hg-425-7V  LCM=020°W  (at 17:00 GMT)   
   Hg-425-8V  LCM=030°W  (at 17:42 GMT)   
   Hg-425-9V  LCM=039°W  (at 18:15 GMT)

  The first LCM=322°W was the one standard on 26 and 27 Apr. The image by Hg at LCM=322°W does not show so clearly the mist, while Id's drawing at LCM=327°W shows the morning light mist. The image by Hg at LCM=351°W shows Hyperboreus L dark and to its south a morning mist. At LCM=010°W by Hg, the morning mist is bright, though Id drew it weaker at Id-052D. Hg's image at LCM=020°W shows it to be round and still thick but the cloud looks to remain near the terminator. At LCM=030°W, the morning patch seems to have retarded from the area of Baltia, and even at LCM=039°W, it is not so inside the disk. If we compare it with the one in HST's images on 27 Apr at LCM=017°W ~ 030°W, we can say the cyclone, if exists, looks very weak or not to have been produced on 25 Apr.

  @ On 24 Apr (129°Ls), in addition to observations by Id, Nj, Mn and others, Hg made three images as follows:

  Hg-424-1V  LCM=335°W  (at 13:16 GMT)
  Hg-424-2V  LCM=343°W  (at 13:52 GMT)
  Hg-424-3V  LCM=356°W  (at 14:44 GMT)
  The first two don't particularly show any thick morning mist to the north of M Acidalium though to the naked eyes some misty matter was seen there. Notable is the fact that the Baltia area was free of any thick mist at LCM=010°W (15:40 GMT, by Mn) where Iaxartes and the following canal were visible (Mn observed on the day at LCM=338°W, 348°W, 358°W and at LCM=010°W). This implies that the morning mist patch which became thicker and stronger from around LCM=010°W must have been rather absent on 24 Apr and caused apparent from 25 Apr or 26 Apr.

  @ We should therefore see the opposite days after 27 Apr, but no more we were able to watch the deeper angles.
  @ On 28 Apr we have

  Iw-052D     LCM=313°W  (at 14:10 GMT).
  This shows a similar bright patch near the terminator at the same angle as before, and so it is possible for a similar phenomenon to have occurred, but no further observations.
  @ On 29 Apr (131°Ls), we have several observations. However even the last observation by Mk was at LCM=314°W, and so further angles were already beyond his scope. Mn watched ten times on the day, and saw the morning mist from LCM=299°W, and the mist became thicker at LCM=329°W along the terminator upto the further south, but it did not much come into the disk even at LCM=358°W. We may consider therefore that, compared with the results by Mk and others on 27 Apr, the mist must have not developed so much on 29 Apr. Seeing condition was not good at LCM=008°W, the planet being already quite lower.

  @ We thus conclude that at the season 130°Ls this apparition the morning mist thickly broke out and developed into a cyclone every day from 25 April to 28 April. Our observations were concerned with the early-morning state. The equality of the disturbances on 26 and 27 April is more reliable because Mk and Iw made their observations by comparison. It was also certain that the disturbance was nearly absent on 24 April though the morning mist existed. After 28 April we don't have enough observations: The observations in Europe need to be taken into account.
  @ We should also note that from Japan it was impossible to chase the Cyclone much inside the disk. The Cyclone on 27 April was again shot by the HST-WFPC2 six hours later on 28 Apr from 00:22 GMT to 01:17 GMT showing the surfaces at LCM=111°W ~ 124°W: The Cyclone was located about 5 o'clock pm LMT and proved to be much weaker. We thus consider that the Cyclone was formed rapidly near dawn and then brought to noon and then gradually weakened in the afternoon. The cloud air must have been nearly dispersed in the evening and cooled at night. Again the mist must have been formed at dawn. The air must have contained much more ingredient of water-vapour than the morning cloud observed later in July (treated in the preceding issue).

  @ We finally list the locations and the instruments of the observers contributed:
Y. HIGA (Hg) at Okinawa located at 128°E took video images by the use of Sony DCR-TRV900 attached to a Newtonian with a 25 cm speculum,
H. ISHADOH (Id) at Okinawa located 128°E made visual observations by 400, 530x 31cm reflector,
T. IWASAKI (Iw) at Fukuoka located 131°E is a visual observer since 1984 and this time used 400x 21cm reflector, and
M. MURAKAMI (Mk) at Kanagawa located 139.5°E is also a visual observer by 320, 425x 20cm reflector.

  @ Reference figure :
  MURAKAMI's observation from 26 to 30 April
  IWASAKI's observation from 26 to 30 April