Two-Color Photometry?

[BPVietje]

I'm so impressed with how much AstroImageJ CAN do, and how well supported it is here and elsewhere that I'm hesitant to ask for anything new!

Has anyone figured out how to do time-series photometry with two photometric filters -- say a multi-band time series on an eclipsing binary or RR Lyrae star?

I used to be able to do this with MaxIm DL, but multi-band photometry is no longer working for me.  I find that this is useful for demonstrating the difference between exoplanet transits and eclipsing variables, and for prompting students to think about the brightness and color changes happening in short-period pulsators.  I'll attach a B & V time series of an RR Lyrae star from AAVSO I did a few years ago as an example.

I can run a pseudo multi-band time series by opening an image sequence in two filters, but when I enter the comp star magnitudes, they are in one band or the other, so not entirely accurate, and the plot doesn't differentiate between the two series except by their Y-axis offset.

If anyone has tackled this, I'd be delighted to learn how to do it in AIJ.

Thank you,

Brad Vietje
Newbury, VT
www.nkaf.org

[karenacollins]

Hi Brad,

You will need to process each filter separately in AIJ, save the individual measurements tables, and then merge the two tables so that you can plot them together using Multi-plot_Main->File->"Append table from file as new columns..." to append the new table to an already open table. When asked what to append to the column names for each table, I'd recommend using the corresponding filter names. Then use the "X-data" settings on the Multi-plot_Y-data panel to select different time data column for the different filter bands in the "Y-data" column.

Karen

[BPVietje]

Thank you Karen -- I appreciate any time you can give to such a trivial question!

I'll give it a shot.  I can do this in other software, but we use AIJ with students to remove any price barrier to participation.

Clear skies and happy exoplanets.

Brad Vietje
Newbury, VT
www.nkaf.org