iridium, mir, moon
richard.keen@kingsmarket.com
Thu, 19 Feb 98 12:47:29
With the help on Ron Lee's pre-launch elements, which were, as always,
right on, I observed a high pass of the new Iridium satellites this
morning. But first, the abbreviated Quicksat and Iridflar predictions:
Quicksat:
Coal Creek Canyon, CO 2000 15.0 10 F F F T F
H M S Tim Al AziC Dir Mag Dys F Hgt Shd Rng R A Dec Name
1998 Feb 19 ThuUT129 13 1
12 41 39 .0 72 84C 87 5.9 1 7 399 311 417 1711 39.2 Iridium 98
Iridflar:
Ir Date Time Az El Range Flare Vis Peak Std Max Flare
UT km Angle Mag Mag Mag Lat Long
98 98-2-19 12:41:25 160 33 1036 8.85 5.1 -7.6 4.5 39.0405 -103.5473
With 7x50 binoculars, I saw five magnitude 5.5 objects at the location
in the Quicksat prediction. I counted off seconds after the first
object passed a star of opportunity, and the spacing was: 0, 5, 8, 13,
15 seconds. As with the Iridium (Iridia?) 45-49 launch in December,
the separation between the 4th and 5th objects was less than between
the other objects.
As the train of object headed south, they rose to about 4th magnitude,
and then, one by one, flared briefly to magnitude +2. That magnitude
implies a flare angle more like 4 degrees than the 8.85 degrees in the
Iridflar output, which further implies that the ground track of the Max
Flare was perhaps a degree west of the predicted longitude. That would
put it near Ron Lee's house - did the clouds clear out soon enough for
you, Ron?
Next, I observed (through broken clouds and light snow) a pass of Mir
and Progress last night:
1998 Feb 19 ThuUT129 13 1
H M S Tim Al AziC Dir Mag Dys F Hgt Shd Rng R A Dec
1 25 58 .1 73 218C 268 -2.2 7 3 240 196 251 333 25.2 Mir
1 31 23 .2 63 219C 268 .1 7 2 240 190 268 316 17.1 Pr M-37
Mir peaked at magnitude -2, as predicted, while the Progress only
reached mangitude +3. Perhaps I need to change my Quicksat standard
magnitude of 1.0.
Finally, and I'll find a way to keep this on topic, our natural moon
is presenting a rare opportunity to observe Mare Orientale, that huge,
1000-km impact basin on the moon's eastern edge. Due to libration -
the moon's attempt to tumble like a Cosmos rocket (there!!), the dark
floor of Mare Orientale is visible. I saw it this morning for the
first time in my life. For an overhead view, check out the Lunar
Orbiter photo in "Exploring Space with a Camera", page 110, and
elsewhere. The libration will be favorable the next two mornings,
February 20 and 21.
Cheers, Rich Keen
Coal Creek Canyon, Colorado, USA (39.877 N, 105.391 W, elevation
2728m)