Re: NOAA 15

Sue Worden (worden@fc.net)
Mon, 4 Oct 1999 21:00:57 -0500 (CDT)

	Don Gardner wrote:
	> The NOAAs, like the DMSPs will flare unpredictably from time to time

Speaking of DMSPs...

Ed Cannon, Mike McCants, and I observed a spectacular magnitude zero
flare from DMSP B5D1-3 (10820/78-42A) at about 1999-10-02 01:45 UTC,
just past culmination on a north-to-south pass high across the west.

Several seconds prior to the flare, I observed a very sharp specular
"glint" from this DMSP to approximately magnitude +2 through my 10x50
binoculars.

This DMSP was also flashing irregularly on both sides of these events.
My stopwatch data indicate that the period was about 6 seconds before
culmination, increasing to about 8 seconds after the flare.  However,
I observed NO triplet of semi-equally-spaced flashes throughout the
entire pass.  I.e., all of my "split times" flash period data points
are wildly different, though they appear to all be multiples of about
6 or about 8 seconds.

Note that the "glint" mentioned above was quite different in character
from the regular flashes.  It was definitely what I call a "glint" as
opposed to being a mere "flash".

But I would like to avoid another discussion on this list of "when is
a flash a flare or a glint"...  Below is what I use to subjectively
discriminate amongst them, and if you disagree, you can simply use
this table to translate my terminology into that of your own choosing:

        Duration in Time   Spatial Extent      d(brightness)/d(time)
Glint      very brief       very small           very "steep" slope
Flash        brief            small         "moderate" to "steep" slope
Flare      "extended"       "extended"              "flat" slope

Getting past those asides, later that same evening, we also observed a
flare from NOAA 15 (25338/98-30A) just past its culmination.

QuickSat output for both passes:

  30.310  97.881  920.   BCRC (Nike Site)         2000 15.0 15 F F T T T

***  1999 Oct   1  Fri evening  *** Times are PM CDT  ***  20 0  642

 H  M  S  Tim Al Azi C Dir  Mag Dys F  Hgt Shd  Rng  EW Phs  R A   Dec

10820 DMSP B5D1-3    78 42A   6.4 1.7     6.9 3.9 S 4.5
 8 43 14  0.0 52 336   316  5.3   3 1  492 315  604 1.5  92 1745  61.5
 8 43 46  0.0 61 315   297  5.1   3 1  493 318  555 1.6  94 1751  47.5
 8 44 18  0.0 64 282 C 267  5.1   3 1  493 320  540 1.6  96 1753  31.9
 8 44 50  0.0 59 250   238  5.2   3 1  493 323  562 1.6  97 1755  16.5
 8 45 22  0.0 51 232   222  5.4   3 1  493 327  616 1.5  98 1755   2.9

25338 NOAA 15        98 30A   6.0 2.0     24. 3.8 S 4.0
 9 11 35  0.0 40 230    68  5.4   3 2  508 232  734 1.2  99 1756  -5.7
 9 12  8  0.0 44 246    79  5.3   3 2  508 247  696 1.2 103 1736   5.1
 9 12 41  0.0 44 264 C  93  5.3   3 2  508 263  687 1.1 107 1712  16.5
 9 13 14  0.0 42 281   106  5.5   3 2  508 278  708 1.1 111 1645  27.3
 9 13 47  0.0 38 295   116  5.7   3 2  509 294  756 1.0 114 1614  36.7

--Sue Worden (worden@fc.net)