[Aavso-photometry] Software for combining time series data taken with different filters to calculate transformed magnitudes

[Lionel Catalan]

The change in observing sequence will certainly help in having observation
pairs for all filters centered on the same time. Thanks. However, the
following issues will remain:
1. Since collect hundreds of images every night, I would still need a means
of automatically parsing the data to group the sets of 6 observations
centered on the same time from 3 lists of observations corresponding to b,v,
and I data (since I reduce all the v images for a night together as a group,
ten all the b images, etc). How can I do that in a time effective manner? 
2. Some of the sets of ivbbvi data would not be complete due to the fact
that some images need to be rejected due to wind, etc. 

Note that my variables change on time scales much longer than my observing
cadence and varying extinction is not an issue because I do differential
photometry.

Lionel CTE

-----Original Message-----
From: aavso-photometry-bounces at mira.aavso.org
[mailto:aavso-photometry-bounces at mira.aavso.org] On Behalf Of Dirk Terrell
Sent: Friday, September 05, 2008 4:17 PM
To: aavso-photometry at mira.aavso.org
Subject: Re: [Aavso-photometry] Software for combining time series data
taken with different filters to calculate transformed magnitudes

On 9/5/2008 Lionel Catalan wrote:
> I think that I need a program (or perhaps an excel macro) that can 
> interpolate instrumental magnitudes for each filter to common times so 
> that consistent values of b-v and v-i can be calculated.  I would 
> appreciate any suggestion.

I agree with Michael's comments about timescales. If the variable changes on
timescales similar to your observing cadence, you'll get misleading results
by interpolation. In the future, I would alter your observing sequence to be
ivbbvi and then average the pairs in each filter. When you do that, you will
have observation pairs for all filters centered on the same time. By putting
the longer wavelength filters on the ends of the observing sequence, you
minimize problems with varying extinction since the variation is slower at
longer wavelengths.

Dirk

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