Times of Minima of "Legacy" Eclipsing Binaries
Human lifespan, and human history, is short compared to the lifetime of stars, but you have to start sometime! Algol's O-C diagram goes back to 1775: for most other variables the observational timespan is shorter. The AAVSO's Eclipsing Binary Section (formerly called a 'Committee') has a list of about 200 stars, many of which have been observed pretty heavily since the 1960s. These are among the best-observed EBs in the sky, and it is important that observations of these stars be continued indefinitely. Yearly, Gerry Samolyk prepares an ephemeris suitable for North American observers to plan observations of these and other stars (available for download from this page, below). In fact, those stars are being observed to the point that the ones that are easily observed are probably over-observed! How can that be? Well, even if a star is undergoing period change, any more than a couple of good observations of time-of-minimum per year will not generally provide information that will be significant in an analysis. The effects of even comparatively large period changes need to build up over many many orbits.
There is no single real-time clearing house to inform observers of what has been observed recently. EB observers belong to many organizations, and submit their data to different places around the world. However, there are a few resources to help assess the need for observations:
- you can assess the general level of observing intensity for specific stars by looking at their O-C diagrams at one of the online time-of-minimum database websites. Those sites will be most complete for observations taken up to 1 - 2 years ago. .
Below are links to current ephemerides. We also have a spreadsheet containing catalogue information about these stars. The spreadsheet is a work-in-progress, and is a partial collection of information about the 200 stars on the list.
For other stars to observe see the "Otero+" EBs.