How to do temporal binning

[chrismlt]

Hello Karen,
Hello All,

Some recent surveys of bright stars let me with quite a few hundreds/thousands of images with 10 sec or so exposure time over the night.
A convenient way to handle those data would be to do some temporal binning so as to reduce the star scintillation, in order to get a smoother LC.

Is there any way to do this in AIJ ?

Thanks in advance,
Christophe

By the way, I use AIJ since it's debut ... what a software ! ;-)

[karenacollins]

Hi Christophe,

Unfortunately AIJ does not currently support temporal image binning when opening a stack. Temporal data binning can be done within Multi-plot after running all of the images. While this should give the same quality lightcurve, the stack image processing time might be very long.

We've looked at implementing temporal image binning before and didn't find a trivial way to implement it that supports all AIJ stack modes. But, I've taken a note and we will take another look in the next few weeks.

For now, you'd have to temporally bin the images outside AIJ somehow, or just be patient to run all of the short exposure images through Multi-Aperture, and then use the Multi-Plot "Out Binning" to achieve the result you are seeking.

Karen

[chrismlt]

Thanks Karen, for this quick reply.

I understand your way ; binning images is not a necessity, if temporal binning can be done in the multi-plot. This would be exactly the same result.

>"then use the Multi-Plot "Out Binning" to achieve the result you are seeking. "

Can you be nice to point out were I can find this marvelous option in the multi-plot ? I had a look, but did not found it.
Maybe lurking somewhere I forgot to look ...


My current AIJ version is 5.3.4.0
Many thanks
Christophe

[karenacollins]

Open the multi-plot Y-data panel. Over toward the right hand side, look for the "Out Bin" heading (at the top). Select it and set the number of minutes you want to bin in "BinSize (min)". That's it.

If you only want to see the binned symbols (and don't want to see the individual points in light symbols), then click the checkbox a second time.

Clicking the checkbox a third time turns binning back off.

Karen

[chrismlt]

Ahhhh ...
It was in front of my eyes since the biginning ... but I've never seen that little box ! Hahaha !
Thanks ! It works great.

Is there a way to create some new column with the binned data and errors in the measurement table, and to save it ?
Sorry to ask this one more time.

Definitely no need to bin the images before extracting the photometry.

Cheers,
Christophe

[karenacollins]

Hi Christophe,

Actually, there is no way to save the binned data at this point. it is on our development to-do list.

There is however an approximation to binning that you can use for now to save a data-averaged set of data points to the measurements table. Instead of using the Out Bin feature, use the "Input Average" feature on Multi-plot Y-data. It is just to the right of the Symbol shape selection. This option combines N number of samples rather than binning over a certain time bucket. For example, if you have 2 sec exposures and want to combine 10 data points to simulate a 20 sec exposure, set the "Input Average" value to 10.

Once you have the lightcurve plotted the way you want it to save, use the "New Col" icon on the left hand side to create the new columns in the measurements table. Then save the measurements table.

You can also output a reduced set of specific columns from the measurements table into a simplified data file using Multi-plot Main > File > Save data subset to file.

Karen

[chrismlt]

Oh ! I see.
That's perfect.
I think the sample binning is even a better solution, at this point.

Thank you Karen to have taken some times to point this out and explained it to me.

Clear skies,
Christophe