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Re: (cba:news) (cba:chat) DQ Her (Joe Patterson) [2016-05-31T08:37:43Z]

Yes, some CBAers might be able to resolve that signal, though you'd need a cycle time of less than 25 s to do so. That would be tough for most people... so the main idea here is to explore for signals at or near the *orbital* frequency. Like for UX UMa.
An aspect of this that is also somewhat demanding, but interesting, is the shape of the deep eclipse. We know that it is slightly asymmetric, but have never understood exactly why. (Of course there's a story - "the hot spot" - but it'd be nice to improve on that.) Since it's a deep eclipse (to 17th mag), you need longish integrations to explore this. A study of the variations of brightness AT MID_ECLIPSE could be fascinating, and has never been done for this famous star.
Finally, there's a contaminating star about 4 arcsec away. Have a night of really good seeing? Know when the eclipses occur? Then take quite long images near mid-eclipse, and measure the contribution of the contaminant. Filtering isn't necessary or desirable; the key question is, how much of the flux detected by *your system* is from the contaminating star? 

I wrote a paper on this star way back when:

http://articles.adsabs.harvard.edu/full/1979PASP...91..487P

Wrote it in longhand, too.  I think I wrote everything longhand then.

joe p




On 5/30/2016 6:26 PM, Lew Cook wrote:

A reminder on DQ Her: It is pretty bright, and also has deep eclipses -
but -- there are circumstances which 15 - 20 sec image times will show
the rotation of the WD - 71 sec. I suppose you could vary the CCD
sampling times to coincide with the brightness of the system to get both
periods well.

Lew


On Mon, May 30, 2016 at 9:14 PM, Joe Patterson <jop@xxxxxxxxxxxxxxxxxx
<mailto:jop@xxxxxxxxxxxxxxxxxx>> wrote:

    I think LX Ser and V380 Oph are the prime evening+ northern stars -
    both admittedly "fishing expeditions", but that's about half of what
    we do. DQ Her also - far from a fishing expedition.  We'd like to
    get coverage on it similar to what we got on UX UMa.

    Lots of really good morning targets, and prime season for the south
    with all those Sgr-Sco novae finally coming into view.

    joe



    On 5/30/2016 4:11 PM, Michael J. Cook, Newcastle Observatory wrote:

        Any priority of the May/June stars on the target list?

        --

        Michael J. Cook

        AAVSO: CMJA
        CBA: Ontario
        MPC: H61

        *Web Site:* http://www.newcastleobservatory.ca
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