Mid-eclipse time!

How the time flies.  Seems like yesterday (actually 2005) when the first observing proposals* for monitoring epsilon Aurigae were being submitted - and suddenly we have arrived at predicted mid-eclipse.  According to Jeff Hopkins, who has made a study of the light curves, he expected mid-eclipse to occur August 4th, 2010 = JD 2,455,413.

The light curve shows no strong evidence for "mid-eclipse brightening" thus far.  Now that epsilon Aurigae is getting well separated from the sun, airmass corrections are less a problem, so more accurate photometry is possible.  From Mt.Evans this week, we had an exceptional morning for J& H band work, very good signal to noise, but found the brightness was close to that reported during spring 2010 - well into totality.

Spectroscopically, observers like Robin Leadbeater have noted the symmetry in the neutral potassium line, signalling mid-eclipse as well.  Reports on H-alpha and other lines are eagerly awaited.  More about the implications of all this in future blogs.

With the return of Aurigae to the morning dark sky, more observing is expected to commence.  During August, a new round of interferometric imaging at CHARA is scheduled, along with the first near infrared spectra (SpeX at IRTF) since solar conjunction.  Also scheduled during September is a look into the ultraviolet with the COS instrument on Hubble.  Stay tuned & hope to see you at Cal Academy for the Citizen Sky II workshop in early September.

p.s. *This includes Spitzer cycle 2 IRS & MIPS, and MIMIR spectroscopy accomplished during winter 2005/2006.  Predating those were mid-infrared observations with Denver's "TNTCAM" during 1995 - 1997, seeking evidence for secondary eclipse heated disk.
Mid Eclipse: JD= 2,455,413
Wednesday. 04 August 2010