Transforms : submit Transf images with one filter and ensemble photometry

Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 05/25/2022 - 23:15

Dear all,

Well there is something I do not understand.

I would like to upload a time series of a variable in V only with ensemble comp stars with Tbv, Tv-bv, Tb-bv calculated before with TG

If I choose 'two color transform' I  must use two filters and if I choose 'transform applier' I must have a non ensemble comp report

So can I do this kind of observation ?

Thanks

Jean

Affiliation
American Association of Variable Star Observers (AAVSO)
Not normally done!

Jean:

1. Transforming single filter images in a time series is not normally done because in most cases the pulsating or eclipsing star (or other) you are following changes color over its phase. Since you have no other filter images to determine that color change over time, the two transform methods in VPhot do not allow that to be done.

2. Ideally, you would collect two filter (+) images during the run (e.g., BVBVBV...), then you could use Transform Applier. However, note that you are correct that TA only works with a single comp sequence. This is only due to the fact that the full ensemble information cannot currently be included in the report.

3. IF you want to assume that the color of your target does not change (I do not recommend this) it is possible to enter an assumed color for this target when setting up your sequence. Then a time series can be transformed for this one filter run.

4. My recommendation is that you submit your single filter time series as non-transformed magnitudes using an ensemble.

Ken

Affiliation
American Association of Variable Star Observers (AAVSO)
Dear Ken,

 

Many thanks, I…

Dear Ken,

 

Many thanks, I learned something important

I understand there is a difference in measuring a magnitude with a single image and a time series ?

For time series :

1) Submit your single filter time series as non-transformed magnitudes using an ensemble

(this requires an electric filter wheel or two nights each with one filter so it is a different process)

2) Submit two filter as transformed using non ensemble

if I well understood

So with a non-time series (one measure in a night for example) can we use the transform coef with a single filter ?

 

Best regards

Jean