September 19 Vandenberg Launch

What: Launch of a Falcon 9 rocket from Vandenberg AFB, CA, latitude 34.7° N, longitude 120.6 W
When: September 19, 2016, 21:49 PDT  (04:49 UT September 20)
Where: Use Google Earth to get the direction from your location  (as I did above)

You’ll need to be less than 500 km from Vandenberg to have a chance of seeing it. And whatever direction you have to look, it helps to have a clear view of that horizon with no obstructions. And of course, you’ll need the weather to cooperate with clear sky right down to the horizon. The graphic above shows the geography to scale. I’m at Heimhenge, near the maximum visibility distance.

If you’re fortunate enough to live in Southern California, within 100 km of Vandenberg, just look in the right direction at the right time and only thick clouds will prevent you from seeing it. Use the Google Earth ruler tool to find the distance and compass heading between you and the launch site.

This graphic shows a side view of the geometry involved in observing a launch from my location in Arizona, 780 km (485 miles) from Vandenberg. Let’s break down the important features, as the basics apply to observing a night launch from any location within a reasonable distance.

  • If the night launch is shortly after sunset, some of the exhaust trail can still be brightly illuminated by high-altitude sunlight.
  • The “top” of the atmosphere is nominally set at 50 km — the stratosphere/mesosphere division. Weather happens below this altitude.
  • Outer space, by definition, starts at 100 km — the altitude where aerodynamics no longer works.
  • Depending on the type of rocket fuel used, exhaust trails may be visible up to several 100 km altitude.
  • From Phoenix, a launch will not be visible until it hits an altitude of at least 60 km.
  • For the Sep 19 launch, the sunlight will be 1200 km above Vandenberg (unlike the 30 km shown in this graphic).

This launch will use a SpaceX Falcon 9 carrying 10 Iridium Next commercial communications satellites. The first and second stages burn liquid oxygen (LOX) and rocket grade kerosene (RP-1). This fuel doesn’t produce the thick trails characteristic of solid rocket boosters, but still provides a nice show. Enjoy these night launch images.

Vandenberg does around a dozen launches each year. You can always check the current Vandenberg launch schedule here to stay apprised of viewing opportunities. If you’re within driving range, directions to several viewing sites are provided. Most launches are toward the west, over the Pacific Ocean, just as a safety precaution. But if a military launch requires a different trajectory, Vandenberg will make it so.

You can see a time-lapse I shot of an Atlas rocket launch from Vandenberg here. Scroll down to video #5. Note that from my location, the maximum elevation of the visible rocket was a mere 5° — this is why having a clear view of the horizon is so important, especially at greater distances from Vandenberg.

If you just want to look at some pretty pictures, you can see a nice gallery of rocket launch trails here. Thanks to Fred Bruenjes for those images. He lives in Southern California and easily sees most launches. Your mileage may vary, so good luck and clear skies!

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