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18455+0530A STF2375A HR7048

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#1 StarDusty

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Posted 23 October 2012 - 10:29 PM

Attached is a capture summary plate for STF2375A. I measured the PA and Separation using REDUC using one drift and two separation avi files. Video files were recorded using a monochrome Imaging Source camera imaged through a home made 4" f/28.5 Schiefspiegler with no barlow.

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#2 Cotts

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Posted 24 October 2012 - 08:19 AM

Dusty, I am in the infancy stages of doing what you are doing. What image scale, in arcsec per pixel are you working at for your set-up? It is most impressive that you're getting good data for a pair so close (only 3x your Dawes limit).

I will be doing this with my 6" f/8 APO barlowed to f/16 (2400mm). I haven't obtained REDUC yet.

Dave

#3 WRAK

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Posted 24 October 2012 - 10:48 AM

Amazing - magnification this high without any hint of a diffraction pattern, not even of the first ring.
Wilfried

#4 PJ Anway

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Posted 24 October 2012 - 01:03 PM

Very nice!

Akira Inaka has this one on his site. If you have never been there, it's well worth visiting; though navigation takes a bit of practice.

Here is the link:
LINK

To find STF2375:

(1) Click on Constellations tab
(2) pink = Spring Constellations
green = Summer Constellations
orange = Fall Constellations
white = Winter Constellations
Click on the Summer Constellations (green)
(3) Click on Aquila
(4) Click on object #10 in the star field

#5 StarDusty

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Posted 25 October 2012 - 10:53 AM

Cotts,

My image scale is 0.39 arc-sec/pixel for my Schiefspeigler with no barlow.

Since I made this telescope, I am able to estimate its actual focal length fairly closely which in turn can be used to calculate the image scale.

I have verified image scale for this and my other telescopes by recording the drift of doubles and other stars with GEM tracking halted. I used LiMovie to estimate the frame by frame pixel position of the star as it drifts across the CCD chip. Using the time between frames and the number of frames, image scale can be determined. [You also need to know the Declination.] LiMovie has the ability to export x,y pixel positions for as many as three stars for each frame of the avi file. This is a comma delimited file that Excel will import.

#6 Ed Wiley

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Posted 31 October 2012 - 06:24 PM

Very nice, Dusty. You have an interesting way to determine plate scale. I use either calibration pairs or rectilinear pairs for plate scale and drift for camera orientation. do you plan on publishing your data?

I have just submitted a paper on the use of high-speed data capture and the REDUC interferometry routines to obtain data on close pairs. It is not true interferometry but what I am calling "pixel autocorrelation." It should work on scopes that are too small to capture speckles. It would be interesting to see how a 4" scope would perform and you have a very nice one at the right F-value.

Ed






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