multi-station reduction technique iota annual meeting november 20 th – 22 nd, 2009 & (234)...
TRANSCRIPT
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Multi-Station Reduction Technique
IOTA ANNUAL MEETING November 20th – 22nd, 2009
&
(234) Barbara occultation of Nov 21, 2009Orlando, Florida
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20090909 (449) Hamburga(attempted) 20 station deployment
S. Degenhardt
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20090909 (449) HamburgaPre-deployment setup
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20081211 (134) Hertha Post-Deployment…. MESS!
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20081211 (134) Hertha Post-Deployment…. MESS!
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20090719 (790) Pretoria log sheet for tracking site location data.It is essential to keep good records in order to organize the output data.
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Video is transferred to computer via firewire, thus it is already in a DV AVI near lossless format
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When the firewire is connected to an active ZR camcorder this window pops up.For data traceability I have adopted a filename format of:
YYYYMMDD (asteroid #) Asteroid name Station ID
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This DV control panel allows me to chose which part of the tape to upload to computer
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My generic AVISythn script. I simply remove the # symbol from in front of the line I want to use.
I can perform running averages and other processing “on the fly” with this.
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What do you get when you cover an objective lens with a ¼” of dew while staring at a part of the sky where the full moon is only 12 degrees away….?
An occultation reduction nightmare!!!
20080618 (19) Fortuna raw video from D. Dunham’s 4th station
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Using VirtualDub and ImageJ I was able to take every 100th frame and using a median filter I created one dark frame.
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Using an AVISynth script I took the dark frame and subtracted it from the entire movie revealing the target star (circled).
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The resulting lightcurve from this simple AVIsynth script process showing the positive event.
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AVISynth scripts speeds up the time from downloading video to resulting lightcurve
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Time keeping method for multi-station deployments
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Using AVISynth you can access the embedded frame counter and internal clock of the miniDV recorder. First, I record an initial KIWI time stamp on all my Canon ZR recorders before my deployment.
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Upon retrieving each station after the occultation I record an ending time stamp
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Using this spread sheet I enter the initial and ending KIWI time stamps and their associated internal clock reading. Column R is the calculated PPM error for that Canon ZR during the time period of the occultation.
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I then copy that PPM error and paste it in the Q13 window which applies that PPM correction to Rows 6-10. I can then enter the Internal Clock value for any frame in Columns J-M and Columns F-I give me the PPM error corrected UT time for that frame.
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This is a table of random frame clock times of a 1 hour recording to test this method. The standard deviation of any derived time = 0.013 seconds.
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The plot of this data shows that the encoded Internal Clock has an error of up to 1 NTSC video field. This would likely be because the encoded time is applied to an entire frame and not the field where a time transition from 0.999 to 1.000 of each second occurs.
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What you hope your results will look like!
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For more information on AVIsynth ideas, Steve Preston’s tutorial:http://www.netstevepr.com/Avisynth-LiMovie.htm
Scotty’s multi-station efforts and techniques:http://scottysmightymini.com/