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Alert Notice 401: Monitoring of EX Hya and DQ Her

August 13, 2009

Kunegunda Belle, Don Hoard and Steve Howell are observing two cataclysmic variables with Spitzer during the next couple of weeks.  They request ground-based light curves spanning the observation intervals so that they can identify the state each variable is in during the Spitzer visits.

1. EX HYA (12:52:24.20, -29:14:56.0, AUID 000-BBT-323)

The observations for EX Hya are scheduled for:

2009-08-18  19:25:01.1 UT 3.6micron single exposure
2009-08-18  19:26:52.9 UT 4.5micron light curve

EX Hya is an eclipsing system with 98-minute period and normally resides about V=13.  The eclipses are only a magnitude or so in depth.

2. DQ HER (18:07:30.20, +45:51:32.0, AUID 000-BCB-341)

The observations for DQ Her are scheduled for:

2009-08-23  03:25:13.8 UT 3.6micron single exposure
2009-08-23  03:27:36.5 UT 4.5micron light curve

DQ Her normally sits at V=14.5, but remember that this is a deeply eclipsing system (280 minute period) and during eclipse it will dip below V=18.

The researchers request that you obtain a time series light curve, preferably in V-band, starting at least one day prior to and continuing one day after the Spitzer visit to the appropriate field.  Expose long enough to get signal/noise = 30 in each individual frame.

Charts may be created using VSP.

This AAVSO Alert Notice was prepared by A. Henden.



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