Three Craters

On the night of January 19^th, I decided to start the night by imaging the moon. Lunar or planetary imaging now is done by making a movie, actually an .avi file, of the target and then processing that movie in a program like Registax. What Registax does is, among other things, “decompose” the movie into individual frames and process the individual frames. In this case, there were 500 frames, which were taken in about 18 seconds. The resulting .avi file turns out to be almost a Gigabit in size. The reason for so many frames is that a large number of frames can be used to help sharpen the final image. How, you asked? As I understand it, the idea is to use a Gaussian distribution and work back to what the image, should be. A Gaussian distribution is known as a “bell shaped curve”. If you can get a lot of points around the center of the curve, the median, and you know that the distribution of the points is Gaussian, you have a pretty good idea what number the median is, even if you don't know for sure exactly what it is. The large number of frames hopefully gives us the Gaussian distribution, which allows us to determine what the image should look like. Hopefully, you get the idea, even though that's not a really great explanation. Anyway, what we have is a slightly blurry image, which the large number of frames helps to sharpen, the Registax allows to us further sharpen the image with the magic of wavelets. If the Gaussian distribution was difficult to explain, wavelets are even harder, especially because I have at best a rough idea of how they work. Suffice it to say, the image gets sharper.

Image that has been "stacked" in Registax

Same image sharpened with wavelet functions in Registax

And what is it that we are looking at? And how do I know that's what it is?

We are looking at an area around the crater Ptolemaeus. The easiest way of determining that is to compare my image to a map of the moon. An easy one to use is the program Virtual Moon Atlas.

Here is a screen shot showing my image on the left and Virtual Moon Atlas on the right, clearly showing the same area of the moon, but VMA has kindly labeled the craters for us.

Finally, where on the moon is Ptolemaeus?

Here is a screen shot of VMA showing the full moon with Ptolemaeus labeled.