Well this has been a busy week, most of which I had hoped to do some more spectroscopic analysis of the star images taken last week. But other things came up. First was the UCI physics colloquium where Marina Brozovic, Caltech/JPL, spoke on radar imaging of asteroids, and radar images are displayed, not in terms, of y vs. x plane locations, but in terms of radar range (distance) vs. Doppler shift. It's going to take some more time to think through how to make sense of that, but the more important thing right now is preparing and practicing for the trip to KSC to experience the launch of the SpaceX Falcon Heavy at Kennedy Space Center.
The launch is currently scheduled for Tuesday, February 6. What is the amateur astroimager to do to prepare for their first observing session of this first launch of this heavy lift vehicle? Well, I thought I might want to go out and try to track aircraft that were overhead and see what is involved in trying to track and shot an object that is moving. This is going to be a bit different than taking photos of the deep sky where things mostly stay in the same position while you can stop and scratch your head and ponder what to do next.
So, the image below is one of the first aircraft I saw in the sky and in this case the contrails provided a good way to track where the aircraft was and to slew the camera in that direction. The telephoto lens was set to 300mm and the exposure setting was at 1/2000 seconds. No, that is not the sound barrier or a cosmic string in the image; it is just some darn hair that keeps showing up on my camera sensor.
|Practicing for Falcon Heavy launch by tracking a plane (Source: Palmia Observatory)|
I started out with the 300mm lens because of the size of the Falcon Heavy and our distance from the launch pad. The Falcon Heavy is about 230 meet tall and we will be located about 7.5 miles from the launch pad. As we discussed in a previous post, we did not sign up in time to get the closest available tickets, as identified by OCA Tom Munnecke, and the closer sites were all sold out when we finally decided to go. We will definitely hear the rocket roar and while we are twice as far away as the location that Tom alerted us about, which is advertised as the place to "fell the burn", we still might be able to experience a little bit of that too!
At this distance, the angular size of the Falcon Heavy will be about 60 * arctan (230 / (7.5 * 5280 ) = 20 arc minutes, or about 2/3 the size of the full moon. This small size calls out for a longer focal length lens, but I don't want to pack the 600mm for the airplane ride, so, its the 300mm lens this time. Besides, its kind of like viewing your first eclipse where you often hear you should just concentrate on the experience rather than spend time trying to take photographs, too. Anyway, at our first total solar eclipse in Casper WY, we successfully did a little photography and experienced the eclipse at the same time.
Photographing a rocket launch is going to be a little more demanding though because you don't have too many second chances to adjust the camera or whatever because the rocket will be out of normal view within just a couple of minutes.
I also practiced on a high flying aircraft without visible contrails. I could hear the aircraft approaching and after finally seeing it, I slewed the camera and tracked the aircraft and tried to center it in the field of view. The image below was taken with the 300mm lens and 1/2000 second exposure.
|More practice for Falcon Heavy launch, this time using red dot finder (Source: Palmia Observatory)|
For this image, I also used a red dot finder, that I normally would use at night, but it worked fine in the daytime too. The red dot finder is very low power and should not pose a safety issue to the aircraft. But, it sure helped me in tracking the plane across the sky.
So, the setup that I plan on taking to Florida, the tripod, the camera, with Liveview screen visible, with 300mm telephoto and red dot finder, is shown in the image below.
|For photographing the Falcon Heavy launch, this DSLR, Tripod, 300mm lens and red dot finder is my choice (Source: Palmia Observatory)|
This represents my toolkit so far. I'm not sure what other folks do when they fly away to photograph rocket launches, but this is my approach so far. I already developed some lessons learned during this practices session:
Lesson Learned #1. Be sure to pre-focus the camera. Events are going to be happening pretty fast, so don't worry about having to focus too. I have just pre-focused on some available distant trees, but maybe that wasn't quite far enough. The moon was still up here, and that would have made a convenient focus target, but the moon is probably not up at the launch time. You might want your exposure set where you want it too. Also, the DSLR has many automatic options that might be useful in these kinds of situations, but I haven't read the manual yet.
Lesson Learned #2. Use some sort of red dot finder so you can easily turn pointing knobs to keep tracking the object. I found this tool very useful and I could track and lead the target and know that it was going to be in the field of view, without stopping, and taking my eyes off the target, to look at the Liveview screen.
Lesson Learned #3. Keep the shutter release where you can push it when you are ready. While tracking one aircraft and getting the aim just right, I had to fumble around and find the shutter release, at which time the plane moved out of the field of view and I had to reacquire the target.
There are probably more rules and lessons to be learned but this is my starting position. I wonder too if I might want to get some other shots showing more the rocket plume, for example. We are constrained a bit in our viewing location in that we do not have a clear view of the launch pad and we have to wait for the rocket to clear the tower before we can see anything. Anybody else have any experience or rules of thumb for photographing rocket launches? Ok, ok, for one, get in line for ticket sales to the best viewing locations as soon as you can! If I had been braver and had bought the tickets as soon as Tom alerted us about the upcoming launch, then we could have cut the distance to the launch tower in half. But, at that time there was no official confirmation of when the launch was scheduled to go and it is a bit risky to plan to fly across the country at some future date that might conflict with some of our other already scheduled calendar events.
|And for all you football fans, we are ready to toast the winners, losers, runners up, .... (Source: Palmia Observatory)|
Until next time,
Resident Astronomer George