Hello, all:

THIS IS A LONG POST ABOUT MY QUEST TO RESURRECT SOME OLD PASS DATA. PLEASE EXCUSE IT IF IT IS NOT OF INTEREST TO YOU.

Long story, but I have some interesting results and a theory:

1. My MP3 file is timestamped UTC as created at January 29, 2015 at 05:19. Here is some indication of that:

ls -la *

-rwxrwxrwx@ 1 bag staff 14289701 Jan 29 05:19 20150130T0519Z KL7CN_W6 CM98fn AO-73.mp3

2. My notes indicate that the pass occurred from 21:18 - 21:31 LOCAL time for me on January 28. This corresponds with the MP3 file timestamp, since at that time my local time was 8 hours behind UTC.

3. I have this file that I received from AMSAT by e-mail on January 23, 2015. I stripped it down to the satellite of interest:

cat AMSAT-20150123.tle

AO-73 1 39445U 13066AF 15030.17519879 .00004024 00000-0 52953-3 0 3695 2 39445 097.7494 097.9267 0060013 224.4600 135.1787 14.79459520 62573

4. I have this QTH file defined:

cat KL7CN_W6-CM98fn.qth

KL7CN/W6 38.573201 121.529596 7

5. With all that in mind, here is what I ran:

predict -t AMSAT-20150123.tle -q KL7CN_W6-CM98fn.qth -p AO-73 `date -u +"%s" --date="2015-01-29 05:00:00"`

6. Here is what I get. I call this FINDING OF INTEREST #1:

1422509554 Thu 29Jan15 05:32:34 0 168 104 14 116 2987 6243 1422509643 Thu 29Jan15 05:34:03 6 168 108 19 117 2376 6243 1422509732 Thu 29Jan15 05:35:32 15 169 112 25 119 1777 6243 1422509819 Thu 29Jan15 05:36:59 29 170 116 30 120 1224 6243 1422509898 Thu 29Jan15 05:38:18 54 175 119 35 121 815 6243 1422509952 Thu 29Jan15 05:39:12 82 211 121 38 122 683 6243 1422509966 Thu 29Jan15 05:39:26 84 288 122 39 122 682 6243 1422509977 Thu 29Jan15 05:39:37 79 320 122 39 122 690 6243 1422509996 Thu 29Jan15 05:39:56 68 334 123 41 123 726 6243 1422510031 Thu 29Jan15 05:40:31 51 341 125 43 123 847 6243 1422510088 Thu 29Jan15 05:41:28 32 344 127 46 125 1143 6243 1422510165 Thu 29Jan15 05:42:45 18 346 131 51 126 1620 6243 1422510251 Thu 29Jan15 05:44:11 9 347 134 56 129 2192 6243 1422510341 Thu 29Jan15 05:45:41 2 347 138 61 132 2799 6243 1422510374 Thu 29Jan15 05:46:14 0 348 140 63 133 3029 6243

NOTE: predict indicates that the AOS is 05:32.

I went with predict because it is old and very well know. I get very similar results with Orbitron and Nova for Windows, with a start time of 05:32. I get these results even when I set the PC internal clock back to January 29.

7. Here is FINDING OF INTEREST #2:

Using GoSatWatch (my go-to prediction software in the field) and using the Keps from TODAY, I get an AOS of 05:16. (It is understandably a bit off due to the Keps being a little off.) This agrees with my extemporaneous notes and the timestamp of the MP3 file.

8. Here is FINDING OF INTEREST #3:

David G0MRF very kindly provided this information using Keps from mid-March and Nova. It CONFIRMS my notes and MP3 file timestamp. I am not able to reproduce it.

Here is a link to an annotated screen capture: http://screencast.com/t/76mfu9HLi

9. These results are inconclusive. I would LOVE to get predict to work properly with my observations.

10. My best theory: Daylight savings time confuses most satellite prediction software. GoSatWatch knows how to handle it. I wish I knew how to reproduce David's results with Nova. And I wish I could just get predict to work properly.

Any thoughts? Thanks in advance and 73!

-- bag

Bryan KL7CN/W6