SOME VARIABLES

Eclipsing Binary U Sge - Action near the Coathanger

U Sge

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.

A.A.V.S.O. charts for this star.

Some convenient forthcoming minima occur on the following dates (UT): 2008 Aug 30 21.6h; Sep 10 1.0h; Sep 26 22.7h ; Oct 13 20.5h; Oct 30 18.2h.

Eclipsing Binary RZ Cas

One of the best eclipsing variable stars in the sky is RZ Cas. From the latitude of Ireland it is circumpolar. It usually shines brightly at magnitude 6.2 but every 1.2 days a less bright companion passes in front of it reducing the magnitude at minimum to near 8.

Some convenient forthcoming minima occur on the following dates (UT): Aug 8 22.6h; Aug 14 22.1h; Aug 20 21.5h ; Aug 26 20.9h 2000.

Use this A.A.V.S.O. chart to estimate the magnitude. As the light curve is 'V' shaped this should be done at least every quarter of a hour and ten minutes near minimum.

Long Period Variable T Cep

Light Curve (5K)
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.

V.S.O.G. members Mary Glennon (red) and John O'Neill (green) contributed data for this light-curve (raw data). Each point is an observation. The x-axis is labeled with truncated Julian Day Number. Use these A.A.V.S.O. charts to estimate the magnitude.

Active Galatic Nucleus Markarian 421

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.

Top | VSOG Home | IAS Home