Re: GSC 540-84

[Michael Koppelman <lolife@bitstream.net>]

On Tuesday, September 9, 2003, at 10:28 AM, Arne Henden wrote:

> My comments regarding eclipses were based on the phase 1.15 points,
> which look like just photometric error to me.  Your statement that
> the light curve is displaced a bit every so often did not say
> anything about minimum, so I assumed you were talking about just
> portions along the light curve such as on 08/22 around phase 1.10.
> Certainly, the larger, global deviations such as exhibited for
> 07/29 are due to Blazhko effects.  Look at Smith's RR Lyr book
> for more details, or look at Doug Welch/MACHO papers on their RR Lyrs.
> Doug has a great time series example of an RR Lyr undergoing Blazhko
> modulation on his web site.

Sweet, thanks. In regards to my "wild speculation" of it being an 
eclipsing RR Lyr system, the only thing I was thinking is that, since 
Doug Welch stated that we have never seen one, I'm not sure we would 
know what it would or would not do. John Greaves stated it would be 
virtually impossible that an eclipsing system would be in synch with 
the pulsation, but I wonder if this is true. There is no evidence that 
this is eclipsing, but the fact that those two weird points jump up and 
exactly match the brighter night of data at 1.15 made me wonder what 
could cause such a thing (assuming for a second that those points are 
not in error).

> Note that the displacement you are talking about is not "rough", but
> is a general displacement towards brighter values when the star is
> at minimum, and towards fainter values when the star is at maximum;
> that is, an amplitude decrease.  I don't see any roughness.  If
> it existed, it would not imply high-order Fourier terms unless there
> was obvious sinusoidal variation.

Roughness was probably the wrong word. I agree with you that there 
seems to be an amplitude change during some cycles. It seems to be 
repeating, which is why I'm wondering if it is an overtone of some sort.

Thanks!
Michael