How to Download and Reduce Asteroid Occultation DV Tapes

These instructions are for Windows machines with a Firewire connection. I have a Canon ZR45mc camcorder with miniDV tape

Scott Degenhardt's IOTA'08 ppt on this subject

Instructions for our 10" and gear, for getting video recording:
* For any scope, be sure that your IOTA VTI is up and running for 15 minutes before the event, so that leap seconds since manufacture can be auto updated and incorporated into the data.
* Target in eyepiece at ~3:30 o'clock when standing straight on to the eyepiece, and target 1/3 of the way from the center to the nearest edge. That will put the target in the middle of the chip. Swap out elbow and put on f/3.3+1.25" adapter on far end, shove in pc164cex2 all the way, with 1/4" hole facing up. Go 1/2 rev CCW and it will be in focus in the center of the LCD on the camcorder.


Run Windows MovieMaker (free with WinXP)
-- Start up Windows MovieMaker
-- Connect firewire - computer to camcorder
-- then turn on the camcorder to the play position (down position on my Canon ZR45mc). If not done in this order, WinXP and MovieMaker will not recognize the device
-- click file | capture video , and enter output filename and folder
-- choose Digital Device Format (DV-AVI) option, and answer the obvious questions that follow
-- click the forward arrow to begin playing the tape
-- Plan to capture at least 2 occultation durations before and after the drop, for good statistics and solution from Occular, later on.
-- click Start Capture when you're at the point you want, and Stop Capture, then finish and the file will be written to your hard drive
-- close MovieMaker
-- this avi file is compressed. LiMovie needs an uncompressed avi file, so you need now to uncompress it with VirtualDub - it'll be much bigger!

Run Virtual Dub (free software off the web). Goal is to make an .avi file which LiMovie can read. (maybe can skip this step if you use an S-video connection above) . Or use AVIsynth if your file is very long. Steve Preston's instructions for AVIsynth
-- file | open | and navigate to your file
-- drag the narrow little box on the frame number line to the spot you want to begin recording, and click the right half arrow. Then move the little box to the stop recording point and click the left half arrow.You should see your newly restricted range in light blue for your output file.
-- file | save as | AVI and give file name. I like to append a 'VD' to the end of the original file name root.
-- close Virtual Dub


(here's some dialog from Jan Manek on not dropping frames....)
when you are in Capture mode of VD, you have at the right side of the window information section. In the part "Video" are two lines listing inserted/dropped frames.

However my opinion is to set VD in such manner it will never insert/drop a frame. How to do it ?

You must do following settings in the 'Capture mode' :
1) Menu Capture -> item Timing (opens another window)
2) you must UNcheck the following two option there (they are in fact the first
two from top):
- Drop frames when captured frames are too close together
- Insert null frames when captured frames are too far apart
- UNcheck the option 'Correct video timing for fewer frame drops/inserts39;
If you apply also the second recommended setting, the resample value
will be always 1.00000

Then you can make a test recording.
On the right side of the window in Capture mode is a section 'Video39; where 'Frames dropped' and 'Frames inserted' must be zero all the time during recording.

I have also following setting - but this depends on your personal choice.
3) disable Audio capture (you will save some disk space & I don't need to record audio)

Run LiMovie (there's a lot of options, but for the basic use, here goes...)
-- file | AVI file open | and your filename. You'll see the first frame show
-- click on your target star and adjust the red circle (radius in number of pixels / radius box) until it encloses all of your star and as little sky as possible
-- adjust the blue annulus to be beyond the red circle and not include any other stars or bad pixels. Make sure your star can't slop over into this donut.
-- make sure Kiwi is checked (middle right edge of the screen) if you have Kiwi OSD, then LiMovie will read the time stamps

For my telescope, I find that the tracking isn't perfect. It's probablly a mixture of field rotation, gear slop, and not perfectly centered alignment star procedure. If your stars wander at all, you'll want to click on 'drift' in the tracking box for the target. Then pause just before LiMovie arrives at the D, and switch the tracking for the target to 'anchor'. This keeps the circles from moving very much while it's out and better enforces that the star will R inside the red circle. If drifting is real bad, you may have to track using the guide star. In that case, the circle for the target will dance strictly in synch with the guide star and because of seeing, they may not in fact dance in synch, so be careful and consider upping the size of your circles. Anyway, to do linked tracking...
-- with just your target star visible, then click off in the tracking box
-- if you have a second star in the field, then right-click your occulted star which brings up a window where you click add object
-- then click on your second star and a yellow circle will appear around that star. Make sure the Synch-APT (synchronize aperatures) is clicked. Now you're guiding on the second star which will be really helpful during the occultation when the target star is gone. Click Link under the Link Tracking box. Make sure your second star aperature is identical to that for the target, and it has drift clicked in the tracking box.

-- click Start and watch the video and make sure the red circle encloses all of the star especially as it reappears.
-- Adjust red circle if necessary. Before clicking Start again, you'll have to delete the .csv data just created by clicking DataRemove and repositioning to the beginning by clicking on the double left arrow
-- It'll run through the video creating a .csv output. Save it by clicking save to CSVfile
-- click GRAPH to see the light curve
-- shift+PrtScr and then open Photoshop and file | new and then CNTRL-V to paste in the screen shot, and trim to include just the light curve so you can make a .jpg for it for your scrapbook!

Run Occular V4.0 - Will Statistically Analyze Your .csv File To Find the Best Timings Possible
-- select file and get your file. It'll show the .csv files
-- click on the gray box left of the header line with No. next to it, immediately above the first data line. This should highlight the entire top row. Make sure the entire row is highlighted. This tells Occular the headers titles
-- find the Object1 Result Measurement column and click on the first data entry to highlight it.
-- use the vertical positioner to go all the way to the last data entry in this column and Shift left-click on it, to highlight the entire column
-- click Analyze Data and it'll warn you you need a time stamp, click yes and you then navigate to the row 1 column 1 entry (which is frame number 0.0) and double-click on it to bring up a box for you to work with. It should show a complete date time in a text box; click and then OK. If that doesn't work, then...
-- follow the format they suggest and enter the month/day/year/hr/min/sec in the white space provided, and click OK. It will populate the individual boxes for date, hr etc. More likely, if you click on a valid record, it'll fill in the proper format along the text line in the bottom, and when you ask it to take the time from the text, it'll fill in the boxes correctly.
-- click Analyze Data. You may find it fails the data integrity check. Occular verifies that your captured VTI times are spaced .033 or .034 sec apart. If there are any frame spacings which are different than this, it'll fail the integrity check. For me, I find that LiMovie reads my KIWI time stamps sometimes confusing "6", "8" and "9". It'll flag them and they're pretty easy to see what the digits should have been read as, from the records on either side. Click on write 'error marked' csv file and use a different name so you don't lose the original.. This 'error marked' file will have added a new column 1 which has "red" in any row you modified. This added column will foil being able to use this same file for reduction. So, you open Excel and open both the original file and the error marked file and use the error marked file to locate the records needing to be fixed on the original. Fix the original and save it.
--Again click Analyze Data. It should bring up a box which includes your light curve and parameter boxes. I like to prt-screen this over to Photoshop as it's a bigger light curve plot than is done by LiMovie. You can click drag a box around the part of the light curve you want displayed. Occular will search through a range of occultation time lengths to search for a range which includes an obvious occultation.
-- for Event Bottom it wants the duration, in frames, of the occultation. For minimum and maximum enter the shortest and longest durations it could be. No need to go overboard, if you can see the obvious occultation by eye, then just go comfortably above that and below that.
-- for Wing Length choose a number of frames as long as possible but less than the un-occulted time length before the D and after the R.
-- click on Star Magnitude and fill in the available magnitudes of the star, using Steve Preston's "detailed information" link on the event.
-- click Use Mr as Star Magnitude and it'll bring up a new box for you to enter the asteroid magnitude, red magnitude being more relevant for most videocam's.
-- and click Use Mr as Asteroid Magnitude, which is the red magnitude
-- click Calculate MaxFOM to calculate the best figure of merit from the possible occultation parameters you've entered. It'll take a bit of time to generate the 100 trials. Click on show noise histogram and you'll see the distribution of errors to the model, and it should look single-peaked and roughly Gaussian. Do PrtScr and CNTRL V to cut/paste to Photoshop for the graphs you want.

-- click final report to generate, and ignore the warning about the magnitude drop, unless it's obvious you made a mistake. I like to shift-PrtScr and CNTRL-V in Photoshop so you can save the final report as part of my webpages on these events.

Reporting Observations to IOTA

Use OccultWatcher to populate the spaces in the report form with the right numbers, but you must first have claimed a station, and that must be done BEFORE the event happens!

Or, go to Brad's page here.

Using Tangra 1.4 (Light Curve Instructions by Hristo)

* Capture video in Windows MovieMaker as above and save file
* No need to uncompress. Open Tangra 1.4
* file | Open Video and select file


Issues with Tangra:
* Can only specify OSD blue border before targeting stars, not after
* Once you specify OSD at the beginning, it won't let you target stars! It seems to be one or the other, not both
* The OSD display is blurred in the fractions of second, even before selecting integrating frames
* You can produce and load a dark frame, but after the dark frame loads the video is very dark, and even the brightest stars are mostly gone, as is the OSD.