[Aavso-photometry] At a crossroads and need some help RE BVRI.

[Walker, Gary]

Hello Tim

AAVSO right now has only 8 stars that require BVRI Transformed data.
They are on the web page.  Among them are S Per, U Ori, VX Gem, DH Dra,
VX UMa, W Leo, RU Vir, and RR Boo.  You can get to them by going to the
web page and clicking Observing, Observing Programs, CCD, CCD BVRI.

Optional transformed measurements are always welcome.

Let me know if you have any other questions.

Gary Walker
Chairperson
CCD Committee




-----Original Message-----
From: aavso-photometry-bounces at mira.aavso.org
[mailto:aavso-photometry-bounces at mira.aavso.org] On Behalf Of Tim
Crawford
Sent: Thursday, June 10, 2004 2:23 PM
To: aavso-photometry at mira.aavso.org
Subject: [Aavso-photometry] At a crossroads and need some help RE BVRI.

At a crossroads and need some help RE BVRI.

I now have my color wheel and have added the BRI
filters to go with my V filter.

I have created a listing of AAVSO Charts with extended
sequences.

I use AIP4WIN and I am comfortable with differential
reduction of V filtered fields.

I am, however, somewhat confused as to how to proceed
with the BRI filters using the AAVSO Charts with
extended sequences in that do I have to do
transformations first?  

The AAVSO CCD Observing manual does not address BVRI 
(Section 5.7 is missing).  I did locate some
information under observing programs "BVRI CCD
Photometry observing program,"
http://www.aavso.org/observing/programs/ccd/ccdobs.shtml,
(which very well may be the missing Section 5.7 from
the CCD manual); never the less, after studying this 2
page discussion I am still unable, with a field chart
for the example, to follow completely what is going on
and how this can be applied to differential reduction
using the existing charts with extended sequences. 

Are Transformations of my filtered images required
when using charts with extended sequences or are the
transformations just required for all-sky photometry?

Enduring my 18th continuous day of cloudy sky's ....
Guess I have lots of time to study responses  ;  ).

I am ever reminded that knowledge is very finite while
ignorance is infinite.


Thanks for the help folks.

Tim Crawford
Arch Cape Observatory
OR

Ps-will post on several lists


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