Near the Coathanger asterism in Vulpecula lies U Sagittae. It is an eclipsing variable with a remarkably large range from magnitude 6.5 to 9.3. Eclipses occur every 3.3806 days, with the total part lasting 1 hour 40 min. In binoculars it is easy when out of eclipse and all but disappears when totally eclipsed. See finder chart above (from Guide 8).
A smaller hot star is periodically totally eclipsed by a larger, but fainter and cooler star.
Some convenient forthcoming minima (from Ireland) occur on the following dates (UT rounded to nearest hour): 2009 Aug 31 0h; Sep 16 22h; Oct 30 21h.
Practice on this large amplitude eclipser (i.e. of 2.8 magnitudes) before doing Epsilion Aurigae for IYA2009.
One of the best eclipsing variable stars in the sky is RZ Cas. From the latitude of Ireland it is circumpolar (i.e. always above the horizon). It usually shines brightly at magnitude 6.2 but every 1.2 days a less bright companion passes in front of it reducing the brightness at minimum to near mag 8.
As the light curve is 'V' shaped this should be done at least every quarter of a hour and ten minutes near minimum.
High in northern sky T Cephei is easily followed with binoculars or a small telescope. It is a typical Long Period Variable (or Mira type). The average period is 388 days and it's mean range is magnitude 6.0 to 10.3.
See a light curve by members. Use these AAVSO Variable Star Plotter for a comparison chart.
Estimated to be some 400 million light-years away Markarian 421 is an Active Galactic Nucleus that varies, in a irregular fashion, from about magnitude 11 to 16. More usually it will be found to be magnitude 13 or so.
Although the object can be quite faint the field itself is easily found. Look 5.1° south of Psi UMa for the 6th magnitude star 51 UMa. Markarian 421 is just S.W. of this star.