Iridium observations and format

Leo Barhorst (leobarhorst@pi.net)
Sat, 20 Sep 1997 18:12:55 +0200

Missed those Iridium flare observations in Ron's list and added the observations
of last night.

The flare of 24838 (97030C) was quite spectacular. I don't know if my estimate
of mag -6 is correct but it was much brighter than I've ever seen Venus.
There were some faint aircraft contrails and I saw some sort of halo around
the sat.

  NORAD   date       time   Dir  aI eI  aM  eM  aS   eS Phs  Dur  Mag Obs
  xxxxx  dd-mm-yy  hh:mm:ss  x  xxx xx  xxx xx  xxx -xx xxx  tt  Sn.n  II

  24841  31-08-97  20:42:46  S   69 43   69 43  xxx -18 Unk      -3.5  LB
  24839  02-09-97  20:30:47  S   73 42   73 42  xxx -17 Unk      -2    LB
  24836  07-09-97  20:00:49  S   84 40   84 40  xxx -16 Unk       3    LB
  24841  07-09-97  20:09:54  S   79 48   79 48  xxx -17 Unk   7  -3    LB
  24842  19-09-97  19:01:20  S  136 24   90 43  xxx  -4 Unk  ~5  -3    LB
  24838  19-09-97  19:16:28  S  106 58   81 60  xxx -14 Unk  ~5  -6    LB
  24839  19-09-97  19:25:08  S  114 67  105 69  xxx -15 Unk       2    LB
  24836  19-09-97  20:04:14  S  199 26  291 60  xxx -21 Unk       5    LB

For the first 4 obs the flare occured at the max pass elevation; the next three
were before the max pass elevation and the last was when the sat was way down
to the south. I see the same behavior in Ron's list.

Furthermore on 97-09-19 I saw 24840 97030E at 19:55 steady, mag 5;
at 19:05 24930 97048F, a piece of the chinese dummy Iridum launch at a height
of about 187 km, steady mag 3.
On 97-09-20 I first saw 24905 97043C at 03:04, almost steady mag 8;
then in just over 4 minutes the whole train but one of the 97051 launch passed
just north of Beta Canis Minor; one after the other passed through the same
fov at almost steady mag 6; the last 97051D passed at a slightly higher elevation
and was mag 5.
In between the pass of E and D 86- 61 A Ajisai crossed the fov, flashing very fast.
Shortly after D MIR made an almost overhead pass at mag 2.

NORAD COSPAR    DATE   TIME    Time diff wrt previous sat
             yy-mm-dd hh:mm:ss mm:ss.ss  at pass Beta Cmi
24950 97051G 97-09-20 03:14:27 00:00.00
24945 97051B 97-09-20 03:16:08 01:41.17
24946 97051C 97-09-20 03:17:01 00:52.77
24944 97051A 97-09-20 03:17:40 00:38.71
24949 97051F 97-09-20 03:18:02 00:22.98
24948 97015E 97-09-20 03:18:30 00:27.77
24947 97051D 97-09-20 03:26    07:30

I propose to the group that we also collect these NOFLARE Iridium observations.
Perhaps in the same format as for the FLARE report with the magnitude reported 
S3 or S6 for steady mag 3 or 6.
In this way we can exclude parts of the sky where the flares do not occur.


Here's my contribution to the Iridium format

  NORAD  date      time  Dir aI eI aM  eM  aS  eS Phs Dur Mag  Obs COSPAR
  xxxxx yy-mm-dd hh:mm:ss x xxx xx xxx xx xxx -xx xxx  tt Sn.n III yynnnx
  24842 97-09-19 19:01:20 S 136 24  90 43 xxx  -4 Unk ~5  -3   LB  97030G
  24838 97-09-19 19:16:28 S 106 58  81 60 xxx -14 Unk ~5  -6   LB  97030C
  24839 97-09-19 19:25:08 S 114 67 105 69 xxx -15 Unk      2   LB  97030D
  24836 97-09-19 20:04:14 S 199 26 291 60 xxx -21 Unk      5   LB  97030A

As you can see I've condensed the proposed format  by using just one space
between columns; changed the date to yy-mm-dd; Obs is now 3 digits (for Kurt
and others observers that have 3 digit PPAS initials and added the COSPAR ID.
I use this format and 97-30A as we will need an extra digit when more than
99 launches occur in one year. Of course the cospar colomn can be put in front
or after the Norad colomn.

The line is no longer than Ron's and could even be 1 digit less when we only
give the maximum magnitude of the flare to the whole mag.
Both lines can be two digits shorter if the first two blank ones are dropped.

I think the list can be read quite well

Any comment are welcome

Greetings
-- 
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Leo Barhorst    Alkmaar   The Netherlands
52.65 North   4.77 East   3 m asl
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Every day I wonder about what I see in the sky