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

[Aaron Price]

 The team is very active and I'll send you a reply via private e-mail this
evening. Sorry I didn't respond sooner. You sent the e-mail at the
beginning of a 2-week trip and when I got back I must have deleted the
e-mail with all the spam. When I have the vacation autoresponder
turned on the spam filter is disabled and I had over 1000 e-mails in
the charts box when I returned. Next time I wil be much more careful with
the spam folder.

Aaron

On Mon, 28 Jun 2004, Pedro Pastor wrote:

> I would like to make use of the last comment from Arne to ask you a
> related question.
>
> I read there is a Database Working Group at the AAVSO. They are asking
> for volunteers for their task. I offered myself (my experience on
> computing) to charts at aavso.org in order to help on this project, but I
> got no answer.
>
> Does anybody know if this Working Group is active? Is there any paper,
> report available explaining the project development (objectives,
> planning, achievements, etc)? Do they need any help at all?
>
> Regards,
>
> Pedro
>
> On Mon, 2004-06-28 at 01:24, Arne Henden wrote:
> > Tim actually raises some questions that have been around for
> > a number of years.
> >    The normal method of submitting observations to the AAVSO is
> > a bit too general to handle the variety of observations that
> > amateurs are making these days.  My personal preference is
> > the following:
> >       CR   unfiltered (clear), but using comparison star R magnitudes
> >            for zeropointing
> >       CV   unfiltered (clear), but using comparison star V magnitudes
> >            for zeropointing
> >       U,B,V,R,I  properly transformed observations using proper comparison
> >                  star magnitudes/colors
> >       u,b,v,r,i  observations taken through a standard filter, along
> >                  with the proper comparison star filter/magnitude, but
> >                  untransformed
> >
> > Using a B filter and not transforming, you obtain the B magnitudes for
> > the comparison stars by Bcomp = Vcomp + (B-V)comp
> >
> > The errors on the comparison star magnitude are then the square root
> > of the Verr and the BVerr.  Yes, this implies a larger error than if
> > the comparison star table were given as BVRI (filtered magnitudes)
> > rather than V, (B-V), etc. (V plus colors).  You can't have everything;
> > when transforming, you need the color indices rather than individual
> > magnitudes and that is why most tables use the magnitude/color format.
> >
> > There is no problem reporting untransformed magnitudes obtained through
> > standard filters, except in somehow identifying that these are untransformed
> > by some kind of comment.  The real problem is that I think the current
> > database has everything mixed together and may be difficult to correct
> > at some later date.
> > Arne
> > -----------
> >
> > Tim Crawford wrote:
> > > 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
> > >
> > >
> > > _______________________________________________
> > > Aavso-photometry mailing list
> > > Aavso-photometry at mira.aavso.org
> > > http://www.aavso.org/mailman/listinfo/aavso-photometry
> > >
> > >
> >
> > _______________________________________________
> > Aavso-photometry mailing list
> > Aavso-photometry at mira.aavso.org
> > http://www.aavso.org/mailman/listinfo/aavso-photometry
>
> _______________________________________________
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> http://www.aavso.org/mailman/listinfo/aavso-photometry
>