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Sun, 14 May 2017 - Beta Lyrae becoming better placed in the evening sky

Are you looking for a simple observing project to follow over the next few months?

If so, then Beta Lyrae is a good, easy to locate, object to follow.

The short nights of late spring and early summer do make it unfeasible to follow the shorter period eclipsing binaries all the way through an eclipse.

However ...

These short nights make no difference to the observation of longer period eclipsers. For these stars, the simplest policy is always to make one brightness estimate during each clear night.

The easiest of these slower eclipsers to follow is Beta Lyrae, which can be monitored using the naked eye or using smaller binoculars.

Beta Lyrae is quite easy to locate, being one of the brighter stars in the constellation of Lyra and located not far from the bright star Vega.

Although the brightness variations of beta Lyrae were discovered (by John Goodricke) back in the 1780s, the star is still interesting to both amateur and professional astronomers because its orbital period is lengthening and hence eclipse predictions made using orbital elements from more than a decade earlier prove inaccurate.

This light curve for beta Lyrae is based on SPA VSS observations made during 2016 and uses orbital elements from a few years ago to calculate the phase (the fraction of the orbit completed).

The deeper primary eclipse can be seen near phase 0.0 (and 1.0), with the shallower secondary eclipse near phase 0.5.

However, each of these is shifted slightly to the right (i.e. later) of these values. This is a consequence of the orbital period continuing to lengthen over these few years.

Plotting your own light curve (like the one shown here) for Beta Lyrae is a bit trickier than for many other types of variable star. The chances are that you won't have 13 consecutive nights of observations. Instead, you may well have many observations, but spread over several months ... and so to combine all of these into a light curve you will need to work out the phase at the time of each observation ... potentially a rather off-putting task.

Fortunately ... you can key in your observations into  this spreadsheet  and it will work out the phases for you ... and it will also plot the light curve for you.

And do let us have a copy of your results.  You can email them to

More information about beta Lyrae, including a finder chart and comparison stars, can be found in  this guide


Added by: Tracie Heywood