Var Her 04 Disappearing Superhumps - Visual & CCD Observations Needed

Disappearing Superhumps!
Var Her 04 continues to be an interesting object. Around 06 UT on July 1 (2453187.75) superhumps disappeared from the light curve and have been replaced with a 27 minute hump with an amplitude (estimated visually) of around 0.2 magnitudes! BVR data from Arne Henden (USNO) and BV data from Donn Starkey illustrates the shift in this light curve:
http://www.aavso.org/news/varher04lc-9.png
Fourier plus CLEANEST analysis puts the new period at 0.0289 +/- 0.0006 days. Updates, light curves and additional information are all available at this web page:
http://www.aavso.org/news/her04.shtml

Visual Observers:
If this is indeed a UGWZ object (which is by no means certain), then a rebrightening phase will be expected this weekend. From Friday-Monday intensive visual monitoring of Var Her 04 is needed. Please observe it at the start and again at the end of your observing session. Right now it is faint (~15-16th V magnitude) but a rebrightening episode could reach 13.5 - 14th magnitude. If you detect such a rebrightening please report it to the AAVSO and to this discussion group as soon as you can (ie run inside!). It is important that we get good coverage during the rebrightening phase which will probably last only a portion of a day (perhaps 12 hours or less).

New charts with more comparison stars have been published here:

http://www.aavso.org/cgi-bin/searchcharts3.pl?name=var%20her%2004

CCD Observers:
BVR photometry is needed during the rebrightening phase to look for changes in color, temperature and test some modeling of the mechanism behind these echo outbursts. In addition, we need to look for evolution in these humps and for the possible reemergence of orbital humps or superhumps.

If you have BVR filters and a large enough aperture to get a SNR of 30 please get as much data as possible. Time resolution is not a priority so feel free to take long exposures and stack. Have your filters ready and monitor the aavso-discussion and aavso-photometry mailing lists for announcements of a rebrightening. It won't last long so get on quickly. If you are available, go ahead and observe it filtered while in quiescence. An extra bonus would be to get filtered observations of the object as it begins the outburst!

Observe unfiltered if you don't have filters or if your aperture doesn't support filtered observations of faint objects.

Reminders: 1. Make sure your computer's clock is sync'd. 2. Watch out for the companion to the east in your photometry. 3. if the Moon poses a significant problem see if R band photometry reduces interference. (Let us know if it helps.)

Clear skies,

Aaron Price, Technical Assistant
on behalf of Elizabeth Waagen, Interim Director