I wanted to have another go at BinStar with my double star drift movie files that I had shot last August. My first attempt at processing was unsatisfactory, with Position Angle and Separation values different than what I was expecting. So, I settled in for some learnin'.
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The first step was finding where I had put everything. It had been a while. I couldn't remember where I had installed the BinStar application. Couldn't remember where I had saved the AVI movies of the double stars. If I had made notes, I didn't know where they were. Couldn't remember where Ed and I had left things, via an email conversation. So, I started searching for files and apps on John Smallberries, the Dell, John Littlejohn. Looked in Thunderbird and Evernote for notes and tips and reminders.
Oh! Found the software installed on Littlejohn, the netbook. The drift movies were there as well. OK.
Found some emails from Ed, answers to my questions at the time, in Thunderbird on Smallberries, in the astronomy folder.
But did not find any notes per se on what I had done during the first analyses run. In Evernote, I had a somewhat related entry. The focus here was on using a QuickCam for astroimaging. But I had made some notes on BinStar and some of its features and requirements. Like the maximum resolution of 640 x 480. And that the files to be analysed must be in AVI format.
The only notes per se were in the brief blog post from 23 Aug. It intimated that I tried to analyse the Cor Caroli video but didn't do well... I remembered experiencing some bugs, errors, or crashes. Too bad I did not note any details. So, it looked like I would have to start at ground zero. But I would follow the advice in the first attempt, to use the κ (kappa) Herculis video instead, with those stars being more widely separated than those in α (alpha) Canes Venaticorum.
Did not spot it at first but found a "results" text file for kappa, which I had made on Aug 24. It showed a separation value of 30.52" and position angle of 166.78° based on 106 frames. Forgot about this.
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Gathered data about the star itself, κ Her, aka Marfik.
From SkyTools 3 Pro:
| declination ° ' " | split data | magnitude | orbital period | |||
| 1 Aug 2011 | epoch 2000 | sep " | PA ° | A | B | |
| +17 01 35 | +17 02 49 | 27.40 | 13 | 5.0 | 6.4 | n/a |
From the double stars for small telescopes book:
| declination ° ' | split data | magnitude | orbital period | |||
| 1 Aug 2011 | epoch 2000 | sep " | PA ° | A | B | |
| n/a | +17 03 | 27.4 | 13 | 5.1 | 6.2 | n/a |
It looks kappa is not a binary system. Which was, if I remember correctly, the reason I selected it. The numbers shouldn't change. This pair can be used to verify my recording process and data analyse with Ed's software is correct.
On considering now the results.txt for κ, from August, the Sep. was not far off (a delta of 3") but the PA was totally wrong (Δ153°). Something about it though... The Dec. number I used looks to be apparent or current: 17 1 36. Not sure where that came from though. Probably SkyTools.
Loaded the AVI file into BinStar and reviewed the frames. Drifting started at about frame 300. The pair then drifted from the top-left corner all the way off the frame or screen, right edge, at the end of the video. The last good images seemed to be around 2900. Wow. 2600 usable frames.
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Re-read Ed's documentation on his web site. Read the help information.
Did a quick run in the BinStar software. After setting the starting and ending frames, after setting the primary and secondary boxes (to 4 pixels, I think), top and bottom stars, respectively, I let the software do it's thing. The automatic option chose the "best" frames. After a moment, it showed a Sep of 31.11 and PA of 164.21.
Hrm. Sep is close. But again, this goofy PA. Way off.
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Did another run with the same file. But I had a go at manually removing bad frames. And I also added some good ones. Just to make it a little better... But it takes a long time to go through 2500 frames! Wow. Now I got a Sep of 29.32 and PA of 167.99. Cool. In the right direction. The separation delta is only 2" now. But the PA. What's up with that... Something in my brain was going. Churning. It struck me as curious that the PA is about 13° from 180°. Coincidence?
I must have considered that before... I had asked Ed, via email, late August, if one got the primary and secondaries mixed up, if you could change add or subtract 180°. But even then, it didn't work out right. It was just weird that 13° was the target and the difference of the calculated value from 180...
I started build a "checklist" form to use, during future recordings, to ensure I'm doing all the necessary steps, not forgetting anything, keeping excellent records...
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Previously, I had thought the primary to be the top star. On my third attempt, I re-selected the primary and secondary stars, inverting them. Used a 6 pixel box. Auto mode. But the numbers were worse. Clearly wrong.
Reset things. Ran some quick trials. Did a short test with 800 frames. Got myself good and confused. Whoa whoa. Let's get back to reasonable numbers.
primary star: top; red line
secondary: bottom; yellow line
box size: 4 pixels
frames used: 800
frames selected: 54
orientation: correct or inverted (rotated 180)
separation: 32
position angle: 170
OK. Back to where we— Then... like the light at dawn, after a long night, things changing slowly, brightening... something occurred to me.
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180 minus 13...
I suddenly remembered that the MallinCam could do flipping. Both horizontal and vertical flipping of the image. Handy when you're doing public outreach and trying to mimic the view naked eye. Or eyepiece view.
And I suddenly wondered if the video had been recorded with flipping on... (Clearly I had not re-read my notes carefully. Neither on 24 Aug or now.) Every BinStar run had been performed using the "rotated" view. Which is how the Tele Vue would have presented the image, without the mirror diagonal installed, which is the way we normally set up the gear.
I fired up ST3, set to an SCT (with mirror diagonal), and found that the view in the eyepiece matched the camera display!
I knew west was the direction of drift.
And I saw 8 Herculis drift into view around frame 2000.
Damn it. Mystery solved.
I added an item to the new checklist form!
And again, ironically, I had noted it. I should have gone back and carefully re-read my observing notes...
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With a new piece of information in hand now, that I hadn't used before, I re-ran analysis of the κ Her movie.
primary star: top; red line
secondary: bottom; yellow line
box size: 4 pixels
start frame: 423
end frame: 2951
frames selected: 188
method: peak search
orientation: upright reverted
separation: 32.44
position angle: 10.21
Ah ha! Finally! I had a PA value very close to the known number of 13. And now it was all clear why the 167 was 13 from 180. Inversion. Damn...
Still not highly precise values but this was a major milestone. I had the BinStar yielding good numbers based on my video file. I could now take it to a higher level.
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If I had only reviewed my notes... Would have avoided a lot of confusion!
Certainly, I had not made any notes anywhere about the optical path and camera set-up with the video file. But I had brief notes blogged. Brief but good notes! But I did not carefully review these notes until later.
On reviewing the observing session notes from the evening of Aug 1 to 2, I found that I had had the MallinCam in the Celestron 14" SCT briefly, to view Saturn. So the configuration used for the κ Her video was:
telescope: Tele Vue 101
focal length: 540 mm
mirror/prism diagonal: no
focal reducer/extender: no
camera: MallinCam Hyper Color
ALC: 1/100
AGC: on, max 7
WB: ATW
zoom: 8
gamma: 0.45
h-rev: off
v-rev: on
Look at that. V-flipping... Right there! In my notes. Doh!
The video was recorded at 10:13 PM on 1 Aug 2011.
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