SPA variables

SPA VSS programme

Tony Markham

The primary function of the Variable Star Section of the Society for Popular Astronomy (SPA) is to introduce society members to variable star observing. A secondary aim is to collect and analyse observations. The programme consists of a mixture of naked-eye and binocular variables. Observations from non SPA members are always welcome - many of the variables (labelled *) are not on the program of the BAA VSS.

So why observe the variables on the SPA VSS programme ?

Here are some reasons :

Mira_Type_variables	T Cephei (), Omicron Ceti, Chi Cygni, U Orionis, R Serpentis, R Trianguli (), R Ursae Majoris (*)
	You can rely on these stars to vary all of the time! They may not be as fashionable as eruptive variables, but still need observing. These variables are bright enough to be visible in binoculars for several months at a time.

Eclipsing_variables RZ Cassiopeiae, u Herculis, Beta Lyrae, Beta Persei and Lambda Tauri.
Another group of variables which for some reason seem to be out of fashion with visual observers. Although the periods of these variables are often quoted to many decimal places, the eclipses don't always occur at the predicted times.
Cepheid_Variables Eta Aquilae(*), Delta Cephei(*), Zeta Geminorum(*)
They are predictable, but this means that you can use them to test the accuracy of your observations - are they really accurate to the tenth of a magnitude ? And how often is a supposed class 1 observation just plain wrong!
Semi_Regulars Mu Cephei, Eta Geminorum(*), Alpha Herculis(*), R Lyrae, Alpha Orionis(*), Beta Pegasi(*), Rho Persei(*)
How often have you read that Rho Persei varies between magnitudes 3.3 and 4.0 every 50 days ? Anyone who has observed Rho Persei knows that this isn't the case. Many of the periods quoted for semi regular variables are highly suspect and need re-investigating.

Eclipsing_variables	RZ Cassiopeiae, u Herculis, Beta Lyrae, Beta Persei and Lambda Tauri.
	Another group of variables which for some reason seem to be out of fashion with visual observers. Although the periods of these variables are often quoted to many decimal places, the eclipses don't always occur at the predicted times.
Cepheid_Variables	Eta Aquilae(), Delta Cephei(), Zeta Geminorum(*)
	They are predictable, but this means that you can use them to test the accuracy of your observations - are they really accurate to the tenth of a magnitude ? And how often is a supposed class 1 observation just plain wrong!
Semi_Regulars	Mu Cephei, Eta Geminorum(), Alpha Herculis(), R Lyrae, Alpha Orionis(), Beta Pegasi(), Rho Persei(*)
	How often have you read that Rho Persei varies between magnitudes 3.3 and 4.0 every 50 days ? Anyone who has observed Rho Persei knows that this isn't the case. Many of the periods quoted for semi regular variables are highly suspect and need re-investigating.

Gamma_Cassiopeiae Be ready to see its next outburst/fade.
R_Scuti You may have read that this shows fades to 8th magnitude alternated with shallower minima. Its not that predictable - some deep minima only reach 6th magnitude, and the pattern of alternating deep and shallow minima isn't always followed either!

Gamma_Cassiopeiae	Be ready to see its next outburst/fade.
R_Scuti	You may have read that this shows fades to 8th magnitude alternated with shallower minima. Its not that predictable - some deep minima only reach 6th magnitude, and the pattern of alternating deep and shallow minima isn't always followed either!

For further information on the SPA VSS e-mail Tony Markham
or see the SPA Variable Star section web page.