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  1. #1
    Join Date
    Nov 2005
    Location
    Virgil, NY
    Posts
    4,854

    Thumbs up A look at some eclipsing binaries

    I've been coming along with some research observation programs of eclipsing binaries. I've started by thinking I'd look at timing the minima - a lifetime job considering the thousands of cataloged eclipsers, but capturing the whole light curve seemed to come along pretty easily, too. Some of the nights I've been observing have been less than "perfect," but reduction of CCD image data using ensemble photometry techniques in MaxIm removes a lot of the dispersion in the observations.

    Here's a link to by website where I've posted some of these data. The results are all still pretty preliminary. Results will make their way into the AAVSO archives.

    http://www.brightskies.us/short.html

    Using ACP has made all this straightforward and effortless. And Mike Dodd's Planalyzer has enabled me to tweak the observing schedules so that I can begin a run with adequate lead time heading into an eclipse.
    Dick
    www.VirgilObservatory.us
    Pier-mounted Meade 12-inch SCT "classic"
    w. focal reducer to f/5.3 ~ FL 1630mm
    Optec TCF-S focuser
    SBIG CFW-8A and ST7-XME
    FOV ~ 15' x 10'
    H-alpha, BVRI, RGB & Clear filters
    MaxIm and, of course, ACP!
    AAVSO Code: BRIC

  2. #2
    Join Date
    Feb 2008
    Location
    Goian, Northern Spain
    Posts
    76

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    Very interesting work and the website is perfectly laid out and an enjoyable read.
    You have made me want to try this now!

    Neil C

  3. #3
    Join Date
    Nov 2005
    Location
    Virgil, NY
    Posts
    4,854

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    Hi Neil,

    It's so interesting. Every one of these hummers is different. And there are literally thousands of eclipsing binaries, and many recently discovered fainter ones that have essentially no detailed study.

    What I've put on my website up to now are just a few pairs that are really well-known (well, relatively anyway). I'll keep doing these, and adding others, but I'm going to also add alternating V and R band observing, doing V-R-V-R-V-R... for a couple/three hours for these. Then I'm going to go after some of these fainter, new objects. As long as the sky's not too bad, I can usually get three-hour runs on three objects (in Winter).

    Then I really need to worry about transforming these data values to "outside atmosphere" and then to a "standard" system, because that's the only way data from multiple observers can really be accurately combined.

    Good luck. Keep in touch if you have questions or information to share.
    Dick
    www.VirgilObservatory.us
    Pier-mounted Meade 12-inch SCT "classic"
    w. focal reducer to f/5.3 ~ FL 1630mm
    Optec TCF-S focuser
    SBIG CFW-8A and ST7-XME
    FOV ~ 15' x 10'
    H-alpha, BVRI, RGB & Clear filters
    MaxIm and, of course, ACP!
    AAVSO Code: BRIC

  4. #4
    Join Date
    Sep 2006
    Location
    I live in Massachusettes; Observatory in New Mexico
    Posts
    448

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    Hi Dick

    Your plots and lovely web site inspired me to give a try to plot some eclipsing binary light curves. So for a couple of nights I did some long runs on AH Gem. I'm using Canopus by Brian Warner - a great piece of software, by the way. I have a question - what did you do about your observing aperture and the star just to the NNE of AH Gem - did you try to eliminate it with a tight aperture or assume its not variable and include it? I couldnt quite determine from the Maxim screen shots.

    Thanks for the inspiration and help!

    ..george

  5. #5
    Join Date
    Nov 2005
    Location
    Virgil, NY
    Posts
    4,854

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    Hi George,

    Good for you trying this out, and thanks for your compliments.

    I've attached a better (I think!) version of the graphic from Dec 30. You'll see that I've included the star immediately to the north of AH Gem inside the inner aperture - it would be awfully hard to exclude it with a smaller aperture unless the seeing were perfect. It was pretty good this evening.

    I then tried specifically to exclude the next-adjacent star to the south in the null zone between the inner aperture and outer annulus. I could have made the dead zone a little wider, probably by shrinking the inner aperture by one unit. For this night it was okay as it was a pretty steady night. One thing I've found is that it is helpful to keep the same aperture dimension settings for each object and reusing them for measuring separate nights on the same object.

    I've also used Canopus - I like it very much, but I need more practice and experience with it. I've owned it for a long time. I've never gotten fluent with it, or used it frequently enough, so that every time I use it again, it's like learning it all over. It has the ability to generate transform coefficients, which is necessary for the correct reduction of photometric data. Right now, I'm just using MaxIm for previewing the photometry, and an Excel (Office 2007) spreadsheet I ginned up to do the combined plots and generate the HJDs of the mid-eclipse.

    If you haven't already, you might try using the predictor spreadsheet I included in the "User contributed apps and scripts" page of the Ref. Guide, although for these very close binaries, observations are useful to collect at any phase.

    Good luck. Let me know how you're doing. If you latch on to a particularly interesting object, I'd love to cooperatively collect data, and try to get data in V,B,R or I filters.
    Attached Images Attached Images
    Dick
    www.VirgilObservatory.us
    Pier-mounted Meade 12-inch SCT "classic"
    w. focal reducer to f/5.3 ~ FL 1630mm
    Optec TCF-S focuser
    SBIG CFW-8A and ST7-XME
    FOV ~ 15' x 10'
    H-alpha, BVRI, RGB & Clear filters
    MaxIm and, of course, ACP!
    AAVSO Code: BRIC

  6. #6
    Join Date
    Sep 2006
    Location
    I live in Massachusettes; Observatory in New Mexico
    Posts
    448

    Default

    Hi Dick

    Night before last I spent a good part of the night imaging AH Gem in V,B,R,I. 90 images thru each filter. I've attached 4 screen shots showing the curve thru each filter. Couple of notes: Some clouds floated by about 2/3 of the way thru the run and that fuzzed up the data. All the exposures were 60 seconds and I knew the SBIG ST8 was not sensitive enough at that end, but gavee it a shot. U'll notice that the error was about 0.1m on the B filter.

    The run was from about air mass 2 in the east to about the same in the west. Even after two years I'm still amazed at how easy ACP makes these things! Bravo Bob!

    About Canopus - Ur correct a big leaning curve there. When I'm using it I ALWAYS have the manual open on my desk. I originally bought it for PhotoRed to make transformation coefficient calculations easier.

    I'm all for trying to do some cooperative data collection. I'm just starting down this road, but if u have a target in mind, I'd love to give it a shot!

    Thanks,

    George
    Attached Images Attached Images

  7. #7
    Join Date
    Sep 2006
    Location
    I live in Massachusettes; Observatory in New Mexico
    Posts
    448

    Default

    Hi Dick

    Here is the V filter without the windows blocking the left portion. Sorry.

    ..g
    Attached Images Attached Images

 

 

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