Monday, February 06, 2012

suspended animation

I peppered Ed with more questions after the much-improved run with BinStar.

He was pleased to hear I was making progress...

I asked if there was a way to manually re-centre the secondary marker bullet. I told him that I had some clearly excellent frames but the markers were all crazy. Alternatively, could I change the location of the primary? I could detect the centre in a number of cases better than the computer. But I couldn't adjust these frames; I could only drop them. Ed said that the peak search might get confused with equal brightness, particularly if the seeing was sketchy. If the secondary peak was brighter in one frame it would be selected instead.

I asked he if had any idea why there was a slight tendency for the software to choose the centre of the secondary one to two pixels too far away. He wondered if I had tried playing with the box size. He also wondered if the frame rate was slow and if the stars were trailed. Then the calculated centroid might not match the visual peak. I didn't think it was an fps issue; I thought my movie was at 30. And I had tried playing with the box size. A little anyway...

I asked if he was planning any updates from version 1.0. He shared that he had always hoped to make an update, including some of the features I had mentioned (like being able to change colours or filter for the good frames). But Delphi has changed hands a few times. The version he has doesn't work in Win7, and they no longer offer and educational discount. The latest version is a grand. This meant he'd either have to develop in XP or switch to another programming language.

He also commented on my total number of frames. He said that 2500 frames was a lot for drifting across the FOV. He had built it around 5-30 fps at a 2000-4000 mm focal length. I needed to check my notes to figure out what 'scope I had used. If it had been the Tele Vue 101 without a Barlow then the fl would have been 540. Even with the 2x, it would have been low.

Then Ed said something rather interesting... He knew of a Java program called tracker by Douglas Brown. It is piece of video analysis freeware for physics that might be useful to get the raw tracking data. But then one would need to build a spreadsheet to analyze the traces and produce the P.A. and sep. values.


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