Superbird A + other high flashers
Kurt Jonckheere (kjonckheere@mail.unicall.be)
Mon, 5 Jan 1998 22:07:01 GMT
hello all,
last week we went to a darker place than Belgium (Southern France)
and I was able to observe some high sats with my 8 inch dobsonian.
Superbird A = 20040 = 89- 41 A
------------------------------
Rob Matson wrote two weeks ago :
>to predict when it is flashing right now is very much in question. Using
>the best extrapolation I can come up with (since October 7), Superbird
...
[for 24 December : ]
>Southern France, Italy, Greece 3:43 UT
>I have no idea how accurate these times might be -- I wouldn't be
>surprised if they're off by as much as 40 minutes either way. However,
>once you've found the time that it's flashing, you can find it on subsequent
>nights by adding approximately 2 minutes/night.
In the evening of 27 Dec at an altitude of 16 degrees, nothing was seen
with a limiting magnitude of 12.5 or so.
During another attempt in the evening of 28 Dec nothing was seen again.
Because the sky and seeing were very good, I went on observing and
tried again around 1h50mUT (29 Dec 1997), again nothing was seen...
Suddenly from 2h04m on, I started seeing flashes of about mag +12.5
with an interval of about 11.6 seconds.
At 2h16m the flashes were about mag +10,
2h19m mag +6
2h21m mag +3, easily seen naked eye
2h25m mag +6/+8
2h38m mag +12, some flashes not seen from then on
So the maximum brightness of the flashes occured
around 2h21m on 29 Dec 1997.
I did not observe during the proposed time interval of Rob (around 3h40),
so I'm not sure if I saw the primary flash session, or a secundary one
which has been suggested to occur about 1h15 earlier (or later) ?
I hope other people can use this to observe the bright flashes and
that Rob can adjust his predictions. From now on it is visible over
about complete Europe.
I could also deduce the asymmetric period of about 11.1 s + 12.1 seconds,
making a total of 23.24 seconds. This was seen by Jim Varney, Mike
McCants and others before.
89- 41 A 97-12-29 02:42:11.7 KJ 0.3 97 23.240 11.1+12.1s, max+3@2h21m
Just as Gorizont 23 (see below), it seems that Superbird is also
very slowly accelerating !? :
October 96 : 11.70 +- 0.01 (Jim VArney)
97-09-07 : 11.65 +- 0.01 (Jay Respler)
97-09-16 : 11.61 +- ? (RS)
97-12-29 : 11.62 +- 0.01 (KJ)
20040
1 20040U 89041A 97365.71933992 +.00000106 +00000-0 +10000-3 0 09774
2 20040 005.5698 058.4529 0006399 112.8632 247.1119 00.99741749030787
Gorizont 23 = 21533 = 91- 46 A
------------------------------
Is visible over America for the moment.
Ron Lee wrote :
91-046 A 97-12-27 02:46 RGL 2044.1 1.0 40 51.10 ssm 1/4 period
>> Using his obs of 16 Dec and mine from
>>27 Dec 97, the rate of change of the period (decrease)
>>is about double from earlier this year.
>>
>>Does this not imply some sort of outgassing from the
>>spacecraft?
Tony Beresford replied :
>For such small changes I wonder I solar radiation pressure
>can be adding angular momentum to the spin. the rate would
>be variable through seasonal changes in the direction
>of the Sun relative to rotation axis.
To check this we definately need more accurate observations !
Try to time more than e.g. 40 periods, so with an timing
accuracy of 0.4s, you can get an accuray of about 0.01 second
on the period.
Please report your timings.
Latest elements from OIG :
21533
1 21533U 91046A 98005.17718704 .00000017 00000-0 10000-3 0 310
2 21533 3.6498 66.9359 0008064 90.0320 269.8603 0.98905758 17964
Some other observations :
-------------------------
ATS 5 Rocket = 4069
69- 69 B 97-12-29 00:27 KJ 567.1 0.2 64 8.861 FF, mag+8->inv
Observed recently by Vince Gardiner with 8.87 seconds period.
Comstar 2 Rocket = 9329
Flashing with assymetric period
76- 73 B 97-12-27 23:16 KJ 461.5 1.0 11 42.0 =24.0+18.0 asymm, AA
76- 73 B 97-12-28 20:34:26.2 KJ 587.1 0.2 14 41.94 asymm half period
Last observed by Daniel Karcher in '91 with 19.8 seconds (half period),
so going up nicely
Intelsat 4A6 Rocket = 10779
Each second maximum is followed after about 1 second by a sharp flash.
So : F....Ff...F....Ff...
78- 35 B 97-12-28 23:21:32.8 KJ 870.1 0.2 194 4.485 each second max double
Last observed in '83 (!) by Ron Welch with 3.86 seconds period
Comstar 3 Rocket = 10976
78- 68 B 97-12-29 00:49 KJ 489.9 0.2 100 4.899 FF, mag +8.5->inv
Last observed in '83 by Pierre Neirinck with 4.45 seconds period
SL-12 R/B AUX
94- 38 E 97-12-28 23:57 KJ 12.0 0.4 12 1.00 mag11-12, diff max
Discovered by Jay Respler, is rapidly flashing, sometimes sharp maxima,
no big amplitude, difficult to measure.
Observations made at 43degr 55min 40sec N, 5degr 45min 50sec E, 400 m ASL
Greetings,
Kurt Jonckheere (kjonckheere@unicall.be)