(cba:news) (cba:chat) DQ Her

Joe Patterson jop at astro.columbia.edu
Tue May 31 04:37:34 EDT 2016


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 at astro.columbia.edu
> <mailto:jop at astro.columbia.edu>> 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
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>
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>
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