Skip to main content

RR CET Ripple Evaluation - Please Check My Plan

1 post / 0 new
msheald
RR CET Ripple Evaluation - Please Check My Plan

Hello! I just uploaded another imaging run for RR CET. I still have the low amplitude "ripples" in the light curve data that seem to have a period of 60 to 90 minutes.

    I would appreciate suggestions on how to track down the source for this and comments about my below plan.

    1) Focus change during the run: I have MPO Connections perform an autofocus every 60 minutes. To evaluate this:

        A) Plot FWHM vs magnitude. If this shows the ripples, then that suggests focus change is the cause

        B) Change autofocus frequency. If this changes the ripples, then that would suggest that focus change is the cause.

    2) Comp Variability: Plot each comp vs. the other comps to see if there is a variation in each comps brightness, which would suggest it is a variable.

    3) Dither the images so that pixel sensitivity effect is minimized. In a way, I do this already. My equipment varies the star location aby up to 20 pixels. As a result, when I stack pairs of images, I can get through 4 to 6 pairs (30 to 45 minutes of run time - my best is 15 pairs) before MPO Canopus needs to have the reference image reset.

    Wouldn't flat fields minimize pixel sensitivity variation effect?

    Are there other areas that might cause these low amplitude ripples that I can evaluate?

 

    Thank you in advance for everyone's guidance and suggestions. Best regards.

 

Mike

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484