[Aavso-photometry] Determination and use of BVRItransformationcoefficients with Maxim DL

[Steven Orlando]

Lionel,

Either one!

The catalogs are there with their magnitudes, once the image is solved, and 
there is the option to load it in yourself.

If you choose to get the software, there is an excellent users guide in .pdf 
to explain this to you.

Steve
----- Original Message ----- 
From: "Lionel Catalan" <lcatalan at lakeheadu.ca>
To: <gc at nelsonbay.com>; <Aavso-photometry at mira.aavso.org>
Sent: Saturday, January 12, 2008 4:43 PM
Subject: Re: [Aavso-photometry] Determination and use of 
BVRItransformationcoefficients with Maxim DL


> Thanks for the tip about Canopus. I checked their website, and it
> seems ideed like an interesting software. One thing that was not clear
> is whether one can load charts from the AAVSO website into Canopus.
> Also, does one enter the data for comparison/check stars manually, or
> does the software read them (somehow) from the chart?
>
> Lionel
>
> On 1/12/08, Greg Crawford <gc at nelsonbay.com> wrote:
>> >I am using Excel to do the transformations. I don't think that Maxim
>> >can do these transformations. In fact, I don't know any software that
>> >can apply colour transformation coefficients. Do they exist for
>> >Windows?
>>
>> Yes, MPO Canopus will work out colour transformation coefficients and 
>> first
>> order extinction and nightly zero points internally. For example, with 
>> colour
>> transformation coefficients, one loads one's images and a star chart on 
>> which
>> the standard stars are marked. The magnitudes of the standard stars are 
>> stored
>> in the program and supplied to the chart. An "automatch" matches the 
>> stars in
>> your image to the stars on the chart. You select which stars on your 
>> image you
>> intend to measure, and measure them for the whole set. Then a single 
>> mouse-click
>> will give you colour transformation coefficients, along with a plot 
>> showing how
>> close to the line each star falls and the standard deviation, so you can 
>> get an
>> idea of the quality of your measurements. The first order extinction 
>> routine is
>> similar, but you require image sets from high and low altitude. There are 
>> also
>> routines for calculating the CIs of comparisons where those are not 
>> known.
>>
>> In a field where the comparison values are known, such as a typical AAVSO
>> target, the routine is even simpler. Having used the first routine above 
>> to
>> determine your colour transformation coefficients a few times a year, 
>> they are
>> stored in the program. You then use another routine to identify the stars 
>> in
>> your image (comparisons, check and target), and then run them through an
>> automated matching a measurement process. In this process, the known 
>> comparison
>> values are applied by the program. There is a check box to apply your 
>> stored
>> colour transformation coefficients in the processing. The end result is a 
>> table
>> of transformed measurements in the new AAVSO format.
>>
>>
>> Greg
>>
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