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Molniya flasher identified !

In July and August 1991 some members of the BWGS observed a very slowly moving flasher with a flash period of 2.29 seconds. It was not identified though it was dubbed the 'Molniya-flasher' at the time, because it was suspected a Molniya was responsible for the flashes.

In March 1995 an observation of Molniya 3-3 (75-105A, 8425) was reported to SeeSat-L. It was flashing with a period of 11 seconds. Bart asked me to check wether 75-105A fits the observations of 1991. When I looked up the observations in PPAS, I realized that the dates of the observations were interchanged with that given in Flash 48 (September 1991). Kurt Jonckheere, who was one of the observers in 1991, looked at the 'paper'- archive of the working group and found out that the PPAS is right, and the dates in Flash Sep 91 were wrong.

I couldn't find elsets of 75-105A from 1991 and asked Pierre Neirinck to search through his printed elsets. He sent several elsets for July/August 1991, which showed that 75-105A was not identical with the Molniya-flasher. Pierre remembered that he had seen a similar flasher and scanned through his 1990-1992 observations, but didn't found the wanted one.

In April 1995 I derived a new orbit for the Molniya-flasher with the correct order of the observations:

    1 
   43.917    -5.917      2600.    Oraison (Quasar) 
Molnya-Flasher 
1 99999U          91221.79465633  .00000000  00000-0  00000+0 0    05 
2 99999  67.3323 171.5293 6193323 262.5192 196.0656  2.01598381    03 
  1 91  8  6 21 33  0.0  20 18.0  65.00 1950 
  1 91  8  6 21 48  0.0  20 42.0  63.50 1950 
  1 91  8  6 21 54 30.0  20 52.0  62.00 1950 
  1 91  8  6 22  1  0.0  20 55.0  60.80 1950 
  1 91  8  9 20 24  0.0  19 24.0  69.20 1950 0.1 uncertain 
  1 91  8  9 20 33  0.0  19 46.0  67.80 1950 
  1 91  8  9 20 41  0.0  19 59.0  67.20 1950 
  0  0 
  
 1 218 21 33   .0   8.7 20 19.5 65.26  20 18.0 65.00  -.17  -.26   .31 106 
 1 218 21 48   .0  27.0 20 39.9 63.18  20 42.0 63.50   .26   .32   .41 109 
 1 218 21 54 30.0 -67.2 20 51.1 61.86  20 52.0 62.00   .12   .14   .18 111 
 1 218 22  1   .0  34.2 20 56.8 61.06  20 55.0 60.80  -.23  -.26   .35 112 
 1 221 20 24   .0 234.8 19 23.3 69.04  19 24.0 69.20   .07   .16   .18  99 
 1 221 20 33   .0  -9.6 19 46.3 67.87  19 46.0 67.80  -.03  -.07   .08 101 
 1 221 20 41   .0   5.8 19 58.5 67.10  19 59.0 67.20   .06   .10   .12 103
This orbit has a period of 714.3 minutes and is approx. 3700 x 36500 km.

Then I searched through the Satellite Situation Report from September 30, 1991 for periods of 709.3 to 719.3 minutes and inclinations of 66.3 to 68.3 degrees. Between 1972 and 1987 I found 30 satellites of the Oko early warning series matching these parameters. Because the RAAN of these objects moves rather slowly, it was possible to estimate which of them had a RAAN of about 171.5 deg in August 1991 from current elements. After that only two possible candidates remained:

  
1981 058A  Cosmos 1278  12547   717.8  67.2  3823 x 36534 km 
1983 038A  Cosmos 1456  14034   716.6  67.0  3214 x 37080 km
I asked Pierre once again to search for old elsets. He found that due to luni-solar perturbations both RAAN's didn't match the derived orbit (81-58A was at 167 deg and 83-38A at 154 deg). Cosmos 1278 was a near miss though the period was 3.5 minutes off.

Pierre decided to search again for his similar object, which he had observed years ago. He spent three hours scanning 1987-1989 and found it! On 1988 July 09 he had observed Cosmos 1518 (83-126A, 14587) with sharp flashes +4/+5 to invisible with a flash period of 2.24 seconds. His elsets showed a RAAN of about 172.9 deg (epoch 91221.8) and period of 714.1 minutes.

When I looked into the Satellite Situation Report again, I found:

  
1983-126A  Cosmos 1518  14587   714.1  67.0  3289 x 36883 km. 
                                -----
I had overlooked this one.

There is no doubt that Pierre has found the correct identity of the Molniya- flasher:

  
    1 
   43.917    -5.917      2600.    Oraison (Quasar) 
Cosmos 1518    
1 14587U 83126  A 91215.10632874  .00001009  
2 14587  66.9861 173.4109 6332158 260.1881  27.7908  2.01643448 
  1 91  8  6 21 33  0.0  20 18.0  65.00 1950 
  1 91  8  6 21 48  0.0  20 42.0  63.50 1950 
  1 91  8  6 21 54 30.0  20 52.0  62.00 1950 
  1 91  8  6 22  1  0.0  20 55.0  60.80 1950 
  1 91  8  9 20 24  0.0  19 24.0  69.20 1950 0.1 uncertain 
  1 91  8  9 20 33  0.0  19 46.0  67.80 1950 
  1 91  8  9 20 41  0.0  19 59.0  67.20 1950 
  0  0 
  
 1 218 21 33   .0 -35.4 20 20.0 65.38  20 18.0 65.00  -.24  -.38   .45 106 
 1 218 21 48   .0   6.4 20 41.2 63.37  20 42.0 63.50   .10   .13   .17 109 
 1 218 21 54 30.0 -66.8 20 52.6 62.09  20 52.0 62.00  -.08  -.09   .12 110 
 1 218 22  1   .0  48.4 20 58.4 61.32  20 55.0 60.80  -.45  -.52   .69 111 
 1 221 20 24   .0 206.9 19 23.0 68.94  19 24.0 69.20   .10   .26   .28  99 
 1 221 20 33   .0 -21.5 19 46.2 67.85  19 46.0 67.80  -.02  -.05   .05 101 
 1 221 20 41   .0   3.0 19 58.6 67.12  19 59.0 67.20   .04   .08   .09 102
As Pierre noted, "it would be interesting to get a modern photometric period ... however it is not visible from here at the moment". We don't have to wait very long, Cosmos 1518 will be visible at the end of May and in early June. Observation at Oraison were made with phase angles of 78 to 87 deg, others in 1991 were 85 deg (Aug 08) and 95 deg (Jul 13). Possibly a phase angle of about 90 deg is favourable to see flashes from Cosmos 1518.

Latest Oko early warning satellite is Cosmos 2286 (94-48A, 23194). Description in Worldwide Satellite Launches is: Mass 1900 kg?, Satellite has a drum- shaped body, approx. 2 metres diameter and 2 metres long plus two vanes of solar panels and a telescopic cylindrical shroud. In Spaceflight April, 1995 there is a photograph of an Oko-satellite from Moscow television of poor quality.

Rainer Kracht



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Next: CCD-image of M104 Up: Flash 93 Previous: Cloud around Spot



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