[Aavso-photometry] IL Aqr: Campaign Update 041012

[Aaron Price]

  Special thanks to Robert James (JM) and Mike Koppelman (KMP) for
their observations of IL Aqr during the last week. It seems to have
been pretty stable. Below is their light curve URL:

http://www.aavso.org/cgi-bin/superstar2.pl?objectname=IL+AQR&lastdays=7&ccdv=on&ccdr=on

 We need more people observing it during the baseline portion of the
campaign! One reason is because precision is paramount for this
campaign to succeed. This is a very red object with all sorts of
photometric challenges so please begin observing and practicing now!
Another reason is because there are lots of interesting variable
phenomenon for which to be on the lookout.
  In 1994, E.W. Weis published a period analysis of IL Aqr/GJ 876
based on about a decade of sparce photometry from Kitt Peak. He
detected a period of 2.9 years with an amplitude of V=0.04 (quoted
precision of 0.009 mag). He suspected additional periods at 28.7d and
20.2d.
  IL Aqr is a good candidate for the BY Dra class of M dwarfs. These
stars are young red dwarfs with active magnetic fields yielding
starspot and flaring activity.
  The ASAS-3 light curve (URL below) displays a half magnitude
brightening for a few days beginning August 2, 2003. The amplitude is
about right for a flare but individual flares don't last that long. It
could be a period of flaring activity, but we simply don't know.
http://www.aavso.org/cgi-bin/superstar2.pl?objectname=IL+AQR&lastdays=&date1=2452810&date2=2452900&ccdv=on

   So what does this mean for our intrepid observers? It means we need
lots more observations of this object. Please observe it:

     * Every night possible. Use these filters, in order of preference
(multiuple if possible): BVRIc
        Do this for the next 2 months. 
     * Every few nights get at least 4 hours of time series
observations in a single filter, preferably B
        or  V.
     * Observe it during the entire transit observing window Oct 21 - 23.
     
   Make your observations as precise as possible due to the low
amplitude nature of this star. Use careful flats, darks and transform
your data if you can to mitigate some of the effects of its red color.
Use the 119 comp star since it comes closest to matching IL Aqr in
color and will provide the best photometry. Note the 119 comp star's
photometry does not include its faint companion. If you can exclude
the companion from your annulus, please do so. If not, then make sure
to include the entire companion within your annulus. And be
consistent!

    What we are looking for:

     * Rebrightening episodes similar to August 3rd's event. If you
detect this notify AAVSO HQ and
        this discussion group ASAP and begin time series coverage as
long as the event lasts. I have
         added this object to the SNOBS MyNewsFlash watch list with a
trigger threshold of 10.05.
     * The reported 28.7d and 20.2d periods (the nightly observations
over a couple of months
        should help address this)
      * Any short term flaring that may occur over a few minutes (the
time series observations help
        here)
      * Of course, there is a tiny matter of a transit window on Oct 21-23. :)

   Send in your observations and I'll continue to analyse them, post
summaries here and update the IL Aqr campaign web page. Good luck!!

Aaron P.

More info:
IL Aqr Campaign Web Page:
http://www.aavso.org/news/ilaqr.shtml
Weis 1994: http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1994AJ....107.1135W&db_key=AST&high=413f2099f220492
UV Cet flare stars:
http://www.aavso.org/vstar/vsots/fall03.shtml

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