default value for altitude, blue flash?, Iridial glints

Walter Nissen (dk058@cleveland.freenet.edu)
Mon, 3 Aug 1998 18:11:54 -0400 (EDT)

OBS: 
 
Ir 24 difficult to find, must have brightened quickly. 
      end of peak of long mag 2? glint, i.e., it 
      finally began declining   19980801  33239.24 
      down to mag 5?            19980801  33251.47 
 
Ir 47 located mag 4 or 5        19980801  34118.12 
      mag -3?      glint        19980801  34138.02 
      down to mag 5 or 6        19980801  34158.25 
 
Ir 48 located mag 5?            19980801  35031.25 
      mag 0?       glint        19980801  35051.00 
      lost mag 5 or 6           19980801  35111.25 
 
Ir 49 located mag 4 or 5        19980801  35938.11 
      mag 3?       glint        19980801  40003.96 
      quickly lost 
 
Ir 49 located late? mag 4?      19980802  32645?? 
      down to mag 5 or 6        19980802  32706.08 
 
Ir 26 located mag 6?            19980802  33510.12  then brightened steadily 
      mag 1?       glint        19980802  33538.02  very shallow dip, .5? mag 
      mag 1?       glint        19980802  33549.17 
      down to mag 5 or 6        19980802  33557.83  lost immediately 
 
Ir 69 located mag 6?            19980802  34429.25 
      mag -3?      glint        19980802  34449.77 
      down to mag 6?            19980802  34505.17 
 
Ir 22 located mag 6?            19980802  35328.46 
      mag -1?      glint        19980802  35355.99 
      down to mag 6?            19980802  35417.43 
 
Flat maxima, PPAS code: M, are quite difficult to judge. 
 
 
As you can see by looking at the details below, I've been following these 
glints to lower and lower altitudes.  I would like to question the default 
limit for altitude provided by glint prediction programs (IRIDFLAR, Randy 
John's program, GSOC, and any others).  1 or 2 degrees is probably 
reasonable.  Individual observers will want to adjust that upward as 
required by local conditions, but bright glints are visible at very low 
altitudes.  I would believe a fractional altitude, i.e., less than 1 
degree, is possible.  In DC, in the summer, the Sun sometimes disappears 
at 20 or even 30 degrees altitude.  Typical urban or even suburban 
environments can make observing at low altitude difficult.  We don't want 
to frustrate newbies, but observers with good horizons shouldn't be denied 
bright glints. 
 
 
Green flash?  Green glow?  Blue flash?  Well, how about a blue-green glow? 
I've seen dozens of variations on the green flash and green glow, many at 
Sunrise over the land horizon from my 8th-floor apartment.  I've seen 8 
green flashes at a single Sunset from the air over a distant cloud 
horizon.  I've seen green flashes "brighter than flashbulbs going off". 
But I haven't had much luck with blue.  Sunday morning, I saw the bluest 
event I've ever seen.  There was just a little orange haze on the Eastern 
horizon, brighter above the orient.  As the orange brightened, a bright 
blue-green glow appeared as not much more than a speck at the lowest, 
brightest point of the orange.  It brightened rapidly, rapidly yellowed, 
and overwhelmed.  If I reverse the time arrow for such an event, I can 
easily see why it is so difficult to see such events at Sunset.  You have 
to protect your eyes till the last second or two.  Maybe expose only one 
eye to the bright Sun. 
 
 
Cheers. 
 
Walter Nissen                   dk058@cleveland.freenet.edu 
-81.8637, 41.3735, 256m elevation 
 
--- 
 
Be sure to tell people that the best airliner seats are the aisle seats. 
They are very convenient, and provide the fastest escape route. 
 
--- 
 
Details: 
Latitude:  41.37350  Longitude:  -81.86370  Altitude:  256.0 m 
                      Iridium Coordinates  Range   Sat   Solar                Peak  Std    Maximum Flare 
Ir   Date      Time    Azm El   RA   Decl  (km)  N Ill Azm  Elev M FlrAng Mag  Mag  Mag Latitude Longitude 
24 98- 8- 1  3:32:15.0 260 12 13h44   0.6 2203.1 A Lit 328 -23.7 F  2.17  3.3 -6.0  1.1  40.8522  -79.8152 
24 98- 8- 1  3:32:31.6 263 12 13h38   3.2 2160.7 A Lit 328 -23.7 F  0.57 -0.5 -6.0 -2.7  41.4973  -80.5589 
24 98- 8- 1  3:32:46.5 266 13 13h32   5.6 2127.0 A Lit 328 -23.7 F  2.03  3.1 -6.0  0.9  42.0988  -81.0843 
 
47 98- 8- 1  3:41:15.0 261 09 13h42  -0.6 2410.5 A Lit 330 -24.5 F  2.17  3.5 -5.8  1.1  40.5685  -81.6106 
47 98- 8- 1  3:41:34.4 264 10 13h36   2.2 2359.9 A Lit 330 -24.5 F  0.27 -3.9 -5.8 -6.3  41.3065  -82.5870 
47 98- 8- 1  3:41:51.5 267 10 13h30   4.8 2320.6 A Lit 330 -24.6 F  2.00  3.3 -5.8  0.9  41.9901  -83.2315 
 
48 98- 8- 1  3:50:20.0 263 07 13h39  -1.0 2608.5 A Lit 333 -25.3 F  1.99  3.4 -5.7  0.8  40.4379  -83.7165 
48 98- 8- 1  3:50:38.1 266 07 13h34   1.4 2560.9 A Lit 333 -25.4 F  0.85  1.2 -5.6 -1.5  41.1180  -84.6901 
48 98- 8- 1  3:50:55.5 268 08 13h29   3.8 2519.9 A Lit 333 -25.4 F  1.98  3.4 -5.6  0.8  41.8068  -85.3910 
 
49 98- 8- 1  3:59:25.0 265 05 13h38  -1.1 2798.4 A Lit 335 -26.1 F  1.84  3.4 -5.5  0.6  40.3831  -85.8781 
49 98- 8- 1  3:59:40.5 267 05 13h34   0.8 2757.5 A Lit 335 -26.1 F  1.21  2.3 -5.5 -0.5  40.9588  -86.7524 
49 98- 8- 1  3:59:56.0 269 05 13h29   2.7 2719.9 A Lit 335 -26.1 F  1.88  3.5 -5.5  0.7  41.5639  -87.4265 
 
49 98- 8- 2  3:26:25.0 263 13 13h38   3.0 2150.2 A Lit 327 -23.3 F  1.91  2.9 -6.0  0.7  41.2138  -77.8061 
49 98- 8- 2  3:26:35.0 265 13 13h34   4.6 2126.9 A Lit 327 -23.3 F  1.39  2.1 -6.0 -0.1  41.6085  -78.3837 
49 98- 8- 2  3:26:45.5 267 13 13h30   6.4 2104.4 A Lit 327 -23.3 F  2.01  3.1 -6.0  0.9  42.0332  -78.8877 
 
26 98- 8- 2  3:35:25.0 263 10 13h36   1.4 2361.1 A Lit 329 -24.2 F  1.87  3.1 -5.8  0.7  40.8480  -79.5199 
26 98- 8- 2  3:35:40.6 266 10 13h31   3.7 2323.4 A Lit 329 -24.2 F  0.43 -1.3 -5.8 -3.8  41.4535  -80.5409 
26 98- 8- 2  3:35:57.0 269 11 13h25   6.2 2288.3 A Lit 329 -24.3 F  2.02  3.3 -5.8  0.9  42.1165  -81.3346 
 
69 98- 8- 2  3:44:30.0 265 07 13h34   0.8 2559.7 A Lit 331 -25.1 F  1.65  3.0 -5.7  0.4  40.7286  -81.3962 
69 98- 8- 2  3:44:45.8 267 08 13h29   3.0 2521.2 A Lit 331 -25.1 F  0.19 -5.5 -5.7 -8.1  41.3344  -82.5350 
69 98- 8- 2  3:45:04.5 270 08 13h23   5.6 2480.6 A Lit 331 -25.1 F  2.01  3.5 -5.6  0.9  42.0857  -83.4929 
 
22 98- 8- 2  3:53:35.0 266 05 13h32   0.5 2758.6 A Lit 333 -25.9 F  1.63  3.1 -5.5  0.3  40.6251  -83.4660 
22 98- 8- 2  3:53:51.2 269 05 13h28   2.5 2718.9 A Lit 333 -25.9 F  0.62  0.3 -5.5 -2.4  41.2423  -84.7043 
22 98- 8- 2  3:54:09.5 271 06 13h22   4.9 2678.5 A Lit 333 -25.9 F  1.87  3.5 -5.5  0.7  41.9746  -85.6849 
 
reformatted to conform to my one-line QuickSat output: 
       H  M  S  TIM AL AZI C   U  MAG SHD  RNG  R A   DEC 
       3 32 15   ?  12 260     A  3.3     2203 1344   0.6  Iridium 24 -23 
24905  3 32 31   ?  12 263     A - .5     2160 1338   3.2  Iridium 24 -23  ! 
       3 32 46   ?  13 266     A  3.1     2127 1332   5.6  Iridium 24 -23 
       3 41 15   ?   9 261     A  3.5     2410 1342  -0.6  Iridium 47 -24 
25106  3 41 34   ?  10 264     A -3.9     2359 1336   2.2  Iridium 47 -24  !!! 
       3 41 51   ?  10 267     A  3.3     2320 1330   4.8  Iridium 47 -24 
       3 50 20   ?   7 263     A  3.4     2608 1339  -1.0  Iridium 48 -25 
25107  3 50 38   ?   7 266     A  1.2     2560 1334   1.4  Iridium 48 -25  R 
       3 50 55   ?   8 268     A  3.4     2519 1329   3.8  Iridium 48 -25 
       3 59 25   ?   5 265     A  3.4     2798 1338  -1.1  Iridium 49 -26 
25108  3 59 40   ?   5 267     A  2.3     2757 1334   0.8  Iridium 49 -26  r 
       3 59 56   ?   5 269     A  3.5     2719 1329   2.7  Iridium 49 -26 
 
       3 26 25   ?  13 263     A  2.9     2150 1338   3.0  Iridium 49 -23 
25108  3 26 35   ?  13 265     A  2.1     2126 1334   4.6  Iridium 49 -23  r 
       3 26 45   ?  13 267     A  3.1     2104 1330   6.4  Iridium 49 -23 
       3 35 25   ?  10 263     A  3.1     2361 1336   1.4  Iridium 26 -24 
24903  3 35 40   ?  10 266     A -1.3     2323 1331   3.7  Iridium 26 -24  !! 
       3 35 57   ?  11 269     A  3.3     2288 1325   6.2  Iridium 26 -24 
       3 44 30   ?   7 265     A  3.0     2559 1334   0.8  Iridium 69 -25 
25319  3 44 45   ?   8 267     A -5.5     2521 1329   3.0  Iridium 69 -25 !!!! 
       3 45 04   ?   8 270     A  3.5     2480 1323   5.6  Iridium 69 -25 
       3 53 35   ?   5 266     A  3.1     2758 1332   0.5  Iridium 22 -25 
24907  3 53 51   ?   5 269     A   .3     2718 1328   2.5  Iridium 22 -25  r 
       3 54 09   ?   6 271     A  3.5     2678 1322   4.9  Iridium 22 -25 
 
For predictions, from molczan.tle: 
Iridium 26 
1 24903U 97043A   98211.21223524 -.00000305  00000-0 -11585-3 0  2270 
2 24903  86.3983 257.3731 0003099  69.8662 290.2865 14.34215001 49302 
Iridium 24 
1 24905U 97043C   98211.18686785 -.00000058 +00000-0 -27635-4 0 02099 
2 24905 086.3974 257.3434 0002208 063.2878 296.8545 14.34216353049276 
Iridium 22 
1 24907U 97043E   98211.15515320 -.00000015 +00000-0 -12405-4 0 01725 
2 24907 086.3983 257.3469 0002226 046.6045 313.5323 14.34216946049276 
Iridium 47 
1 25106U 97082C   98211.19320762 -.00000025 +00000-0 -15994-4 0 01130 
2 25106 086.4000 257.3461 0001289 018.5789 341.5451 14.34216359031814 
Iridium 48 
1 25107U 97082D   98211.19955776 +.00000398 +00000-0 +13500-3 0 01850 
2 25107 086.3979 257.3344 0001991 089.2579 270.8838 14.34219345031845 
Iridium 49 
1 25108U 97082E   98211.13611737 +.00000085 +00000-0 +23407-4 0 01267 
2 25108 086.3964 257.4144 0001600 068.9930 291.1417 14.34218872031811 
Iridium 69 
1 25319U 98026A   98211.14882060 +.00000227 +00000-0 +74126-4 0 00823 
2 25319 086.3983 257.3875 0002121 013.1166 347.0082 14.34217252012749 
 
Later elsets, from OIG: 
IRIDIUM 26 
1 24903U 97043A   98214.14251637 -.00000202 +00000-0 -79176-4 0 02560 
2 24903 086.3991 256.1506 0003233 065.6769 294.4764 14.34214412049725 
IRIDIUM 24 
1 24905U 97043C   98213.21015419  .00000022  00000-0  68182-6 0  1929 
2 24905  86.3916 256.4898 0002293  59.0734 301.0687 14.34217079 49568 
IRIDIUM 22 
1 24907U 97043E   98214.15519978 +.00000014 +00000-0 -22350-5 0 01999 
2 24907 086.3989 256.0955 0002189 049.1837 310.9541 14.34217073049706 
IRIDIUM 47 
1 25106U 97082C   98213.07695814  .00000009  00000-0 -39843-5 0  1043 
2 25106  86.3970 256.5579 0000883  60.3874 299.7429 14.34216749 32081 
IRIDIUM 48 
1 25107U 97082D   98213.15307609 +.00000279 +00000-0 +92472-4 0 02039 
2 25107 086.3983 256.5192 0002142 089.9689 270.1737 14.34219413032129 
IRIDIUM 49 
1 25108U 97082E   98214.13616562 -.00000056 +00000-0 -27058-4 0 01201 
2 25108 086.3967 256.1610 0001649 070.7153 289.4205 14.34217375032249 
IRIDIUM 49 
1 25108U 97082E   98213.15940562 -.00000013 +00000-0 -11608-4 0 01412 
2 25108 086.3962 256.5683 0001615 067.5865 292.5490 14.34217912032108 
IRIDIUM 69 
1 25319U 98026A   98214.14886494 +.00000224 +00000-0 +73049-4 0 00764
2 25319 086.3979 256.1335 0001672 017.7085 342.4159 14.34218569013176