Fortunately, there's a handy web site to determine the correct dates and times-of-day based on your location's latitude and longitude. Here's how to use it ....
1. Surf to http://gjullien.fr/satellite.htm (you'll need Java enabled on your PC for this page to work)
2. Find your latitude and longitude (Google makes it easy). Enter your latitude/longitude on the web page where indicated. For example, for my location in Seattle I enter Longitude = 122ºW, Latitude = 48ºN
3. Enter the desired satellite. For DirecTV's 5-LNB dish (Ka/Ku AT9 or SlimLine AU9), you'll need to perform this step five times, once for each satellite location. For the newer 3-LNB Slimline, you only need to worry about the first three locations. Those satellite locations are:
99.2ºW (new Ka-band satellite beaming many national HD channels and HD Locals to certain cities)
101.0ºW (SatA: main DirecTV satellite)
102.8ºW (new Ka-band satellite beaming national HD channels and HD Locals to certain cities)
109.8ºW (SatC: some MPEG2 HDTV channels, but now mirrored from the 99.2ºW satellite. Not needed with SlimLine3 dish.)
119.0ºW (SatB: international Spanish channels, local channels for some cities. Not needed with SlimLine3 dish.)
This is a bit easier as the new SlimLine3 3-LNB HD dish because you only need to worry about receiving the 99º, 101º, and 103º satellites.
In addition, for DirecTV's International Channel Package you also need:
95.0ºW (international channels)
If you're not sure which satellites beam channels you require, check out this web site
Just realize that DirecTV often moves channels between satellites (especially HiDef channels), so ideally you'll want a clear view of ALL FIVE of the main satellites.
4. Press "Calculate first date". The table below will update with dates and times when the sun (or moon) will appear at that location in the sky. It will also provide the azimuth and elevation for the exact satellite location. For example, for my location in Seattle when I enter "101 W" and press "Calculate first date", I see the following ....
Satellite position is: 152.68ºAZ, 31.23ºEL
Wed, Oct 10, 11:22:03 PDT 2007 Sun Position is 152.61ºAZ, 31.62ºEL
Thur, Oct 11, 11:21:34 PDT 2007 Sun Position is 152.68ºAZ, 31.24ºEL
These mean that on either of October 10 or 11 at 11:22AM local Pacific Time, the sun will be at nearly the exact location where DirecTV's SatA 101-deg W satellite "beams" its signal from the sky. Any spots on my house NOT covered by shadows can "see" that satellite.
5. Repeat step 4 for each of the desired satellites.
6. On the specified dates and times, go outside with your camera. Hopefully the sun is shining! Simply take pictures at the correct times. Study them to find spots on your house without shadows. Those will make good dish mounting locations.
By the way, these times and dates actually don't change much for a few days before and after the "exact" times/dates. So you have a bit of leeway if the weather doesn't cooperate on the exact days, or you can't be home from work.
You'll also see that there are dates/times each month when the moon can be used for this. It's a bit trickier since the moon doesn't cast much shadow, but you can look straight at the moon without killing your eyes. So just walk around your house at night at the correct time/date and you can eyeball where the satellites would be located if you could see them.
NOTE: With the changes in Daylight Savings Time dates, be sure to use the GMT time to verify the local times shown.
Hope you find this information useful.
Edited by litzdog911, 04 March 2009 - 06:48 PM.
Updated for March 2009 to reflect new satellite information.