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

[Michael Newberry]

Lionel, The scripting language will allow you to do some things using just 
the language itself (the "programming" part) and other things by leveraging 
the more complex tools that are actually implemented by the host software 
(so you don't have to re-invent the wheel very often). Some of these tools 
are really quite complex, so it is really good that some other expert 
already has done the work for you! Choose a software platform and scripting 
language that has most of what you need already available and which is 
relatively easy to learn and implement. There are a number of options out 
there.

Michael Newberry

----- Original Message ----- 
From: "Lionel Catalan" <lcatalan at lakeheadu.ca>
To: "'Michael Newberry'" <mnewberry at mirametrics.com>
Sent: Friday, September 05, 2008 1:59 PM
Subject: RE: [Aavso-photometry] Software for combining time series data 
takenwith different filters to calculate transformed magnitudes


> I'm starting to be convinced too...Would you suggest a particular 
> language?
>
>
> Lionel
>
> -----Original Message-----
> From: Michael Newberry [mailto:mnewberry at mirametrics.com]
> Sent: Friday, September 05, 2008 4:55 PM
> To: Lionel Catalan; aavso-photometry at mira.aavso.org
> Subject: Re: [Aavso-photometry] Software for combining time series data
> takenwith different filters to calculate transformed magnitudes
>
> Lionel, Your situation is not that unusual. At some point many people
> involved in research will reach a roadblock where no "canned" software 
> will
> do exactly what they need. In that situation, it is good to learn a high
> level computing language or a scripting language that leverages as many
> existing (and relevant) software tools as possible. I thnk you are at that
> point. For example, you mentioned wanting to take into account images that
> had a large PSF because the seeing flared, or those having high errors, or
> whatever. That adds complexity, but it certainly is possible to do.
>
> Michael
>
> ----- Original Message -----
> From: "Lionel Catalan" <lcatalan at lakeheadu.ca>
> To: "'Michael Newberry'" <mnewberry at mirametrics.com>
> Sent: Friday, September 05, 2008 1:45 PM
> Subject: RE: [Aavso-photometry] Software for combining time series data
> takenwith different filters to calculate transformed magnitudes
>
>
>> Of course, you are right that it would help me to learn a bit of
>> programming. The issue has always been the availability of time to do so.
>> But in this case there may not be any other way around it...
>>
>>
>> Lionel
>>
>> -----Original Message-----
>> From: Michael Newberry [mailto:mnewberry at mirametrics.com]
>> Sent: Friday, September 05, 2008 4:38 PM
>> To: Lionel Catalan; aavso-photometry at mira.aavso.org
>> Subject: Re: [Aavso-photometry] Software for combining time series
>> data takenwith different filters to calculate transformed magnitudes
>>
>> There are various ways to do what you want and some parts of it may be
>> specific to the kind of project you are doing. I'm not sure I would
>> mess with Excel, but that's my way of doing things. In my opinion, the
>> best path would be to write a simple script, "customized" to your
>> particular project's needs, that pulls the reduced photometry from a
>> table (or tables) and interpolates it to a new time basis. In the end,
>> I think a little light programming would be worthwhile to learn.
>>
>> Michael Newberry
>>
>> ----- Original Message -----
>> From: "Lionel Catalan" <lcatalan at lakeheadu.ca>
>> To: "'Michael Newberry'" <mnewberry at mirametrics.com>
>> Sent: Friday, September 05, 2008 1:17 PM
>> Subject: RE: [Aavso-photometry] Software for combining time series
>> data takenwith different filters to calculate transformed magnitudes
>>
>>
>>> Hi Michael,
>>>
>>> I'm studying high mass X-ray binaries, and the time scale of changes
>>> is greater than a few hours, whereas my images are taken every minute
>>> or less.
>>> I would think that I could start by linear interpolation, since it
>>> would be the simplest. My problem is that I am not a programmer, and
>>> I don't see how I can easily implement an effective interpolation
>>> scheme in excel. I have hundreds of data points every night, and I
>>> obviously cannot manually interpolate between each couple of
>>> successive observations for each filter.
>>>
>>> Lionel
>>>
>>>
>>> -----Original Message-----
>>> From: Michael Newberry [mailto:mnewberry at mirametrics.com]
>>> Sent: Friday, September 05, 2008 4:05 PM
>>> To: Lionel Catalan; aavso-photometry at mira.aavso.org
>>> Subject: Re: [Aavso-photometry] Software for combining time series
>>> data takenwith different filters to calculate transformed magnitudes
>>>
>>> Be careful about interpolation according to the kind of science you
>>> are trying to do. There's no patent answer for this.
>>>
>>> First of all, a general rule would be to interpolate only if the
>>> timescale of what you are studying does not vary significantly on the
>>> timescale of your observations. You want the data points to conincide
>>> with what is happening on the star. For example, if doing RR Lyr, UV
>>> Ceti flare stars asteroid rotation, etc., then I would use the actual
>>> observation times and not interpolated ones (but see item 2, below).
>>> OTOH, if you are doing Mira variables, etc., having a very slow rate
>>> of change, then I don't think anyone would care about interpolating
>>> near
>> the time of observation.
>>>
>>> Second, what kind of interpolation would you use? Would you thread
>>> the points, do a piece-wide linear interpolation, cubic spline, etc.?
>>> Each will give you a different magnitude value at whatever
>>> interpolated time you choose. Be sure you understand the effects of
>>> the method you use so that you get numbers that are scientifically
> defendable.
>>>
>>> Michael Newberry
>>>
>>> ----- Original Message -----
>>> From: "Lionel Catalan" <lcatalan at lakeheadu.ca>
>>> To: <aavso-photometry at mira.aavso.org>
>>> Sent: Friday, September 05, 2008 12:49 PM
>>> Subject: [Aavso-photometry] Software for combining time series data
>>> takenwith different filters to calculate transformed magnitudes
>>>
>>>
>>>>I have times series data for B,V, and I filters that I would like to
>>>>combine  to calculate transformed magnitudes using transformation
>>>>equations. I use  a  filter wheel to change filters between images,
>>>>so I have sequences of  images  such as bvibvibvibvi etc.  Some
>>>>images have to be rejected from time to  time  due to wind or clouds,
>>>>so the sequences are not exactly regular. I already  have determined
>>>>the transformation coefficients for my system.
>>>> Essentially,
>>>> 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.
>>>>
>>>> Lionel CTE
>>>> _______________________________________________
>>>>
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>>>>
>>>>
>>>
>>>
>>>
>>
>>
>>
>
>
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