VPhot update includes transformation for ensembles!

American Association of Variable Star Observers (AAVSO)
Mon, 03/13/2023 - 22:17

With the past addition of Transform Applier (TA) to Vphot, we provided a
tool that offered a convenient way to transform your observations,
including a time series with multiple filters. However, one feature it
lacked was the capability to apply transformation to ensemble observations.
The difficulty was that the AAVSO Report (AEFF record) that is the input to
TA could not provide any details for the comparison star ensemble, so only
a single comparison star photometric analysis could be transformed.

Now the VPhot/TA tool has this new feature!

This update to VPhot now records the ensemble's necessary observation
record summary information into the AAVSO Report. This additional
information is packed into the Notes section of the observation record.
This information includes:
        - the average of the ensemble comp star instrumental magnitudes, CMAGINS,

        - the average of the ensemble comp star reference magnitudes, CREFMAG, and

        - the target star instrumental magnitude, VMAGINS.

Note that the average is not restricted to arithmetic average, but can be
any protocol you use to create your ensemble. For example, if you weight by
flux, that is fine as long as it is applied to both instrumental and
reference magnitudes. The rule that must be complied with is that these
comp averages must be applied to standardize the VMAG value of the record.


The format VPhot follows to provide this information into Notes uses
'pipes' |key=value|key=value.... to separate the individual magnitudes as follows:

             - <NOTES>|CREFMAG=x.xxx|CMAGINS=x.xxx|VMAGINS=x.xxx


If you do not use VPhot to prepare your AEFF report for webobs submission
you will need to manually add this information to the record, until your
software provides them automatically.

If you have questions, please ask them in this forum.