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Fri, 02/26/2016 - 11:51
Hi. I just want to ask, is there a way to know the amplitude and period of a semi-regular variable star? and i am somewhat confuse on what i am going to use, whether DC DFT or WWZ.
I hope someone can help me. I just using VStar weeks ago and still trying to learn from it.
thank you in advance :)
Hello vggarrido
I only took the Vstar class last year, so I am not an expert. BTW the class for Vstar is starting again soon, and I would reccommend it to anyone who is trying to learn this program--it will give you a jump start.
As I understand it, the DC DFT is an algorithm that is insensitive to data with gaps--which we find often in astronomy. A standard DFT will produce strong alias' when gaps are present and when the spacing between data points is irregular The DC DFT is designed to handle that. It does expect a periodic signal that does not change with time.
The WWZ transform is an algorithm that is used when the periodic nature of the signal changes. It displays this change in period with time.
Depending upon the nature of your semi regular variable, I would try the WWZ first. Let us know how this works out.
Gary
WGR
Thanks Gary for your helpful reply to vggarrido.
BTW, even with DCDFT, you'll still pick up annual no-obs type signals and aliases can still happen.
As an alternative, it's is also worth trying the AoV period analysis plugin, available in the VStar plug-in manager from the Tool menu.
See https://www.aavso.org/vstar-plugin-library#aov for details and doco.
Also, vggarrido: if you have a dataset you want to analyse and you want some help using VStar or other tools, feel free to post here or perhaps in the data analysis forum with a JD range in the AAVSO database or a text file or some other data source and we can compare notes re: analysis.
David