Re: GSC 540-84

[Doug Welch <welch@physics.mcmaster.ca>]

Most likely, you are seeing the effects what is known as the spectral 
window. It is due to the pattern of times at which observations are
taken, and typically will have power at small integer fractions of
a day or multiples of a day. This pattern (due to gaps of sunlight,
cloud, moon, work, etc) gets convolved with the true underlying
power spectrum.

Cheers,
Doug Welch

On Sat, 4 Oct 2003, Michael Koppelman wrote:

> I don't know if there is anything valid here but check this out:
> 
> http://www.lolife.com/astronomy/gsc540-84/540_power.jpg
> 
> This is using Bob Koff's B data and my R data. The main period is 
> obvious. The biggest other period in both data sets is at about 6.25 
> days (0.16 cycle/day). I don't know if there would be a reason that the 
> 0.16 cycle per day would be in both mine and Bob's data.
> 
> Thoughts?
> 
> Michael Koppelman
> 
> 
> 
> On Saturday, October 4, 2003, at 10:20 AM, Michael Koppelman wrote:
> 
> > I'm going to see if I can get a rough idea of the period of the effect 
> > on this star using Fourier.