Combining data recipes
With the availability of data from a number of surveys in addition to the AAVSO International Database, VStar's wealth of observation source plug-ins provide a way to load light curves for a variable from many sources at once. The recipes in this section show how to combine data for analysis.
In order to refine the period for a variable it helps to have data over a wide time span, but often this mean multiple sources and filters. In some cases the lightcurve is given in flux and VStar converts it to magnitude with an arbitrary zero point. This lightcurve shows observations for ASAS J112550-5935.6 with ASAS-3 data in V band starting in 2000 and TESS data for sectors 10 and 11 in 2019.
Looking at the mean magnitudes (Tool-Descriptive Statistics by Series) we see the the V band series has a mean of 9.064. We want to shift the magnitude of the TESS observations so they, too have a mean of 9.064. The two TESS sectors have to be shifted separately since they have different means.
For each TESS sector, load the observations separately (Add to current? not checked). Find the mean. For example 2.833 for sector 10. Use Tool->Magnitude Baseline Shifter to bring this in line with 9.064 - shift by 6.231. Switch to the Observations tab and save the shifted TESS sector 10 to a file. Repeat for sector 11.
Now the observations for ASAS-3 and the two TESS sectors can be combined using the New Star from File Add to Current? option. For the TESS observations just saved, specify Download or Simple as the source.
Using Analysis->AoV with Period Range to look for a period based on the TESS series generates this phase plot:
There is the shape characteristic of an EA, but we have not combined the long baseline for the 19 years. We just need a filter that selects observations from both TESS and ASAS-3. You can do this in the plot pane by selecting all the points and then View->Filter from Plot. Also, you can do this in the Observations pane with Select All and Create Selection Filter. With the new filter the AoV analysis pane shows Filtered as an option to base the analysis on. Using those results and adjusting the epoch to put the primary minimum at phase zero gives the following:
