Magnetic Declination

[rjc3895]

Ok. I am just about ready to put the 10' BUD up. The pole has been installed. I'm getting ready to adjust the Janeil 180 H to H motor for my elevation.

My coordinates are 39.510886 latitude and 76.18054 longitude. My dish elevation would be set at 44.3 degrees. SBS6 is the closest satellite to my true south.

However, none of this takes magnetic declination into account. According to http://www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcDeclination
I need to add 11.45 degrees for magnetic declination. So would this make my true south 191.45 and a satellite located at 83 degrees as my true south satellite?

Basically I need to know if I should consider at SBS6 or AMC9 as my "true south" satellite. Neither will really help me with c-band since both are ku band only, but I want to make sure that I am setting the proper elevation on the motor before I put the dish on it. Thanks.

 

[voomvoom]

Your true south is your longitude, which would be 76.2w. That puts SBS 6 (74w) as the closest with AMC 5 (79w) a close 2nd. With a polar mount it don't matter so much, just line it up with the poles. The elevation is the fun part. If you use an analog C-band channel to find the arc with, you should have plenty of room to play around. It's not nearly as hard as ku-band.
If you use a compass for magnetic declination, you would add the 11.45 degrees and it should get you your true south. Bottom line is the polar mount should point true south one way and true north the other way. If you know where south is, point it that way. If the elevation is correct, you shouldn't have any problems. When you get your dish mounted, put the analog receiver on 20 or 22 and head from straight up toward the west and you should hit one of these 2 channels (if your polarity is correct). If the elevation is right, you don't half to mount the dish pointed at mid-day (true south), you can mount it pointed anywhere.

Al

 

[rjc3895]

Ok. I think I understand. If I were to locate SBS6 without a motor, I need to point the compass to 188 degrees rather than 176.6 degrees to compensate for magnetic declination. This is where (from my location) SBS6 would be located in the sky.

Would the elevation be based on my magnetic declination coordinates or the actual latitude and longitude coordinates? The difference is less than 1 degree, so it probably won't make much of a difference.

 

[voomvoom]

That all sounds right. The elevation should be based on your actual location. If you know where a BUD dish is located in the area, you can check it's elevation to see what is right.

Al