Sun, 05/08/2016 - 18:28
Hello all
I spent the last many hours updating my spreadsheet for the EB recent ToM's and I have a question.
I noted that there were a number of EB listed with multiple ToMs with their own Epochs. My question is what is the period for these.
It is assumed (yes I know) that unless noted in the article or on http://www.as.up.krakow.pl/ephem that the secondary and following reoccurances
have the same period but just different start times?
I would like to try for some of these but not having the periods would make it difficult to time them.
Thanks
John R
Hello John
Have you looked in VSX for periods?
Gary
Gary
Yes, I checked a few of them but did not see multiple periods listed.
I also looked at http://www.as.up.krakow.pl/ephem without any luck. There were secondary ones list but none of them that I checked were referenced in the article.
John R
Hi John, is the article you are referring to, Gerry Samolyk's "193 times of minima...", or something similar? In that case, the article lists actual observed minima. They should fit one formula of the form T=T0+n*P, where T0 is the JD of one eclipse, n is the number of cycles since then, and P is the period. Of course they won't fit exactly, but if T0 and P are up to date, they should be a pretty good predictor. At any point in time, there is only one period that is suitable for predictions. As Gary W suggested you can go to VSX for each star to get T0 and a period, and use it to predict future minima. Or the Cracow site, which will give you times for minima in the next week or so, but also lists recently updated T0 and P. Does this help? Am I understanding your question?
Gary Billings
Gary
Yes it is Gerry Samolyk's article in the new release of JAAVSO.
I understand the equation, however my question was regarding multiple listing for the same EB with different T0's. I have a Excel spreadsheet that calc's each of my 217 EBs in the listing based on the current date and the hour I wish to observe a series run. I would like to add secondary eclipses to this file if in fact they are secondary events.
Where the multiple listings the primary eclipse or secondary or multiple ToM's?
Maybe they were the same primary eclipse but reported by multiple observers?
Just trying to figure out the repeated data for the same EB system.
Maybe only Gerry Samolyk can shed some light on my question.
Thanks
John R
John, the times in Gerry's paper are actual observed eclipse times. So, for one star, he lists as many Times of Minima (ToMs) as he received. You can see that they usually correspond to a different cycle.
When the cycle number is a whole number, the ToM is for a primary eclipse. When it ends in .5, it is a ToM for a secondary eclipse.
You can use these ToMs in several different ways. You could use them like Epoch in the equation for predicting future eclipses (in which case they correspond to cycle 0, or 0.5 in your new system. In this case, use the same period Gerry used, i.e. you'll have to go to the sources that Gerry mentions in the text of his paper to get the elements ("elements" refers to epoch and period, but if you are using a ToM from his paper to define a new Epoch, then you'll just get the period from the source that he quotes.)
Or, you could use the ToMs he published, in conjunction with other published data to compute your own period and epoch, i.e. develop a wholly new set of elements for making your own predictions.
Gary Billings
Thanks Gary
I forgot to look in detatil at the cycle number whether it was whole of some fraction.
I will look at them again but most may simple be the same EB stted by different observers.
Thanks for the key hint about the cycle number
My spreadsheet uses the current JD then determines the difference from the ToM listed by Gerry (or others) to compute the number of cycles and using the estimated duration of the ToM (from earlier AAVSO database) it then dertermine if the eclipse will happen during my schedule observing time. It has been very good for the last few months.
John R