Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 12/07/2019 - 11:29
Dear friends,
I would like to focus in the future especially on the long-term analysis of very rarely observed LPV with data from DASCH and ASAS-SN. I think that there too many surprises await us and that many of the variables classified as L-star can be reclassified.
If the data are sufficiently tight in time, maximum time and brightness could be determined, analyzed and published. Is there any colleagues or projects in the AAVSO who are dealing with this topic and whom I could join?
Best regards from Thomas
Hi Thomas,
I have analyzed the period changes of miras with O-C technique. I have concentrated on to see how the period for known miras have changed over time and to see if there is any long-time trends. You can find my work at http://var.astronet.se/mirainfooc.php. I have built a database with maxima for miras that I have collected from various sources including ASAS-SN and DASCH. The database have data for 509 miras. These are among the brightest and most observed by AAVSO. I'm sure it should be possible to find surprises among the lesser observed stars.
Thomas Karlsson
Hello Thomas K.,
Is there any sort of tutorial on how this work is done? I have a student who would like to start digging into "L" stars, in hopes of discovering one or more periods, but I don't know how to get started. Are you using VStar to analyze light curves from these surveys?
Thank you kindly,
Brad
Hi Brad,
I wrote an article in JAAVSO, https://www.aavso.org/media/jaavso/2940.pdf, there I describe in more detail what I have done. I do not use VSTAR, but for using data from ASAS-SN or DASCH to find periods I think VSTAR would work fine.
I calculate periods from the time of maxima and have 3 different sources, published maxima from various old astronomical journals, maxima published by AAVSO and maxima calculated from observations using a program I have made. From the maxima number and the dates the period could be calculated by regression analysis (for example by using Excel).