On 14 Mar, 12:46, "Jerry" wrote:
On Mar 13, 2:35 am, "George Dishman" wrote:
On 12 Mar, 22:11, HW@....(Henri Wilson) wrote:
Actually the data is from 1908

http://articles.adsabs.harvard.edu/c..._query?1908Lic...

If the above link is truncated, you can search for the paper:
"The orbits of the Cepheid variables Y Sagittarii and RT Aurigae :
with a discussion of the possible causes of this type of stellar
variation", by John Charles Duncan, 1908

A real bit of history then.

This is a more recent curve from an amateur:

http://www.student.oulu.fi/~ktikkane/AST/RTAUR.html

There is far more detail in that which shows how far
the capabilities have come, and I suspect you'll get
even better data if you do some serious searching.
Note the amount of detail in the variations.

Yes, instrumentation has advanced a wee bit in the last century...

Here is a 1969 publication by Bappu et al.http://adsabs.harvard.edu/abs/1969MNRAS.142..295B

Excellent, thanks. Given the importance of Cepheids,
I'm a surprised there aren't more recent studies, or
is that just the latest you know of?

Thanks for the data Jerry, it will be intersting to
see what numbers Henry can come up with to fit those,
though it is already clear he will get a poor fit at
best.

George