Introduction

C-Band and Ku-Band Solar Transits

When a large dish, a space-borne satellite, and the sun are in conjunction, the sun spews enormous streams of incoherent microwaves, called noise, into the dish. The satellite's weak coherent microwave streams become swamped in the rising and falling tides of noise from the sun. It's called either a Solar Transit or a Solar Outage, because it interferes with, or severely degrades, satellite TV viewing.

Transits only occur between sunrise and sunset around the times of semiannual equinoxes. Interference persists for just a few minutes on the first and last day, lasting for more than a few minutes on the worst day.

All of the broadcasting satellites can't be interfered with simultaneously because the sun's spewing disc is too small. However, satellites that are co-located on orbit, will be interfered with at the same times.

Transits do not cause interference on uplinks, only on downlinks, so neither your subscription TV service provider nor uplinker can exterminate these fast, harmless pests.

SOLAR TRANSIT DAY LINES
FALL 2001	SPRING 2001

KEY	WORST DAY	KEY	WORST DAY
1. OCT. 6 - 16	OCT. 11	10. FEB. 25 - MAR. 7	MAR. 2
2. OCT. 5 - 15	OCT. 10	11. FEB. 26 - MAR. 8	MAR. 3
3. OCT. 4 - 14	OCT. 8 & 9	12. FEB. 28 - MAR. 9	MAR. 4 & 5
4. OCT. 3 - 12	OCT. 7	13. MAR. 1 - 10	MAR. 6
5. OCT. 2 - 11	OCT. 6	14. MAR. 2 - 11	MAR. 7
6. OCT. 1 - 10	OCT. 5	15. MAR. 4 - 12	MAR. 8
7. SEPT. 30 - OCT. 8	OCT. 4	16. MAR. 5 - 13	MAR. 9
8. OCT. 8 - 18	OCT. 13	17. FEB. 23 - MAR. 4	FEB. 28
9. SEPT. 29 - OCT. 3	OCT. 1	18. MAR. 10 - 13	MAR. 12

USING THE TIME ZONE MAP AND TIME ZONE TABLE

According to the spring dates on the time zone map, C-band and Ku-band households in the vicinities of Seattle, Great Falls (MT), Duluth (MN), and Quebec City, Canada, will see short interference periods beginning February 25 and lasting for perhaps 10 days, until March 7. The worst day will most probably be March 2 for these places. This also applies to other places on or near the map's February 25?March 7 Transit Day Line.

All are in the northern regions of their time zones; so, the onset of degradation via Galaxy 10 is expected to be seen every Transit day a few minutes earlier than the times shown in the time zone table of local-time predictions for the worst day. About six minutes earlier, to be more exact.

So, on March 2, the worst day, TV pictures from the co-located pair will probably start degrading in Seattle and environs at 12:54 p.m. Pacific (1:00 p.m. from the table, minus six minutes); around Great Falls at 2:01 p.m. Mountain (2:07 minus 6 minutes); urban and suburban Duluth at 3:07 p.m. Central (3:13 minus six minutes); and, near Quebec City at 4:13 p.m. Eastern (4:19 miix minutes).

Salt Lake City (near the map's February 28?March 9 Transit Day Line) is almost due south of Great Falls, so it will have the same time-of-day experiences as did Great Falls; however, they will begin and end two days later, and the worst day will be two days after the worst day in Great Falls. Predicted onsets are much closer to the times in the table, because Salt Lake City is closer to the north-south middle of the Mountain time zone. For Phoenix and vicinity, south of Salt Lake City, interference will begin, end, and be at its worst two days later than Salt Lake City's. And, since this region is far south in the Mountain time zone, the expected times will be some minutes later than the times in the table.

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