Transcript Multi-Station Reduction Techniques

Multi-Station Reduction Technique
IOTA ANNUAL MEETING
November 20th – 22nd, 2009
&
(234) Barbara occultation of Nov 21, 2009
Orlando, Florida
20090909 (449) Hamburga
(attempted) 20 station deployment
S. Degenhardt
20090909 (449) Hamburga
Pre-deployment setup
20081211 (134) Hertha Post-Deployment…. MESS!
20081211 (134) Hertha Post-Deployment…. MESS!
20090719 (790) Pretoria log sheet for tracking site location data.
It is essential to keep good records in order to organize the output data.
Video is transferred to computer via firewire, thus it is already in a DV AVI near lossless format
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
This DV control panel allows me to chose which part of the tape to upload to computer
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.
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
Using VirtualDub and ImageJ I was able to take every 100th frame and using a
median filter I created one dark frame.
Using an AVISynth script I took the dark frame and subtracted it from the entire
movie revealing the target star (circled).
The resulting lightcurve from this simple AVIsynth script process
showing the positive event.
AVISynth scripts speeds up the time from downloading video to resulting lightcurve
Time keeping method for multi-station deployments
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.
Upon retrieving each station after the occultation I record an ending time stamp
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.
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.
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.
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.
What you hope your results will look like!
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/