Thu, 10/19/2023 - 13:29
Is it worth reporting just Time series on EBs without determining ToM?
Hi
I’ve recently reported 5-6 time series observations of EBs, both from the legacy listing and from the Otero listing at Rolling Hills Observatory, mainly the later. Oddly, Vstar seems unequipped to do ToM determinations, and I haven’t yet gotten to download and learn to use Persano, so I’ve been limited to just analyzing and reporting the time series results. Is this of any benefit without an associated ToM determination? I enjoy the observation, analysis and report process but I don’t want to waste time if it brings no meaningful benefit to the research community. Appreciate hearing from folks in this Section
cheers,
Gary
Gary,
IMHO, of course it's worth submitting magnitude data to AID. Other researchers may study data for TOM.
In fact, why not share your raw mag data with Gerry Samolyk. He is the calculator and reporter of TOMs in the JAAVSO.
Ken
Does sharing with Gerry just mean emailing the AAVSO report or does he need images etc.
gary
Gary:
He likes a simple csv file with JD, Mag, Error. Make contact with him through his profile page. Tell him what you want to do.
Ken
"Oddly, Vstar seems unequipped to do ToM determinations."
I use VStar's polynomial fit to determine mid eclipse times of eclipsing binaries in data from TESS. The result is sensitive to the length of the light curve segment chosen for the analysis and the degree of the polynomial fit. There are methods to assist in deciding on the 'best' settings.
It is necessary to use VStar for TESS data with a 10 minute cadence because as far as I know Peranso downloads only those TESS datasets with a 2 minute cadence.
Unlike Peranso, VStar does not calculate an estimate of the error of the mid eclipse time. The RMS of the residuals is displayed instead. The numerical values of these two 'error' estimates differ substantially.
The last time I looked, the Peranso user manual did not reveal the method used to calculate the times of polynomial fit extrema. Tonny Vanmunster will, I believe, provide a description of the method if Peranso subscribers contact him directly (he did for me).
Roy
Hi Roy and thank you for your note.
I enrolled in a recent Choice Vstar course but withdrew after learning that Vstar did not perform time of minima analyses. Since then, I’ve come across a written statements to the same effect. That statement indicated that Vstar didn’t ‘currently’ determine ToMs so perhaps a future update will include that functionality.
When reviewing the features of Peranso, I thought I read that it did determine ToMs. I’ll have to recheck that in light of your information - thanks again.
regards
Gary
You should consider…
Gary,
You should consider getting Peranso. It is a great program, and there is so much you can do with times of minima or maxima.
Allen
Allen
I'd actually like to but the learning time is not in my time budget of it cannot determine ToMs sufficient for viable submissions to O-C diagramming. I seem to be getting mixed comments on whether Peranso can do ToM. From my reading of its features, it struck me it would do ToM determinations but I don't yet understand the nuances of what 'level' (?) of ToM determination is required to be suited for inclusion in the O-C histories. Thank you for chiming in on Peranso.
Gary
What do you actually…
Gary,
What do you actually mean when you say VStar does not perform time of minimum analysis? My perspective is that the statement is not correct.
I have both Peranso and VStar and in both of them have used polynomial fit to determine times of minimum for EBs and times of maximum for pulsating variable stars.
Roy
I'm just referring…
Hi Roy
I'm just referring to the quoted text below that appears in the EB Section pages under Software resources.
"The AAVSO program VStar is a platform-independent data analysis package for analyzing astronomical time-series data. It does not yet have a module for computing the time-of-minimum of an EB time-series."
Perhaps this is out of date, but that's what is says.
Thank you
Gary
Hi Gary,
Yes, I've seen the comment on the EB section web pages re VStar and times of minimum.
The comment may be technically correct in that there may not be something that could be called a 'module' for computing EB time series. However, in my opinion it is misleading, because it could easily be interpreted (as I think you have done) to mean there is no way of calculating EB times of minimum in VStar.
That is clearly incorrect.
Roy
I am not familiar…
Gary,
I am not familiar with VSTAR, but Peranso does a fine job of determining times of extrema (either maxima or minima) along with computed uncertainties. The program offers numerous options for use in this process. The ToM values are work quite well for PTD analysis.
Allen
Thanks very much Allen. Does "PTD" refer to Peranso's ability to feed into O-C data?
Gary
PTD is predicted time difference, sometimes called O-C. Take a look at Alton, K.B. and Gilchrist, W.A., 2022, JAAVSO, 50. The ToMx times were determined in Peranso.
Thank you Allen...found it and added to my W/E reading...
Gary