[Aavso-photometry] Which Photometry Filters to Begin With ?

[arne]

Stewart Yeung wrote:
> Hi,
> 
> I am going to use STL-6303E and LX200R 14" to do
> astrophotography + light-curve photometry. I control the
> sub-urban observatory remotely from my city dwelling.
> 
> For astrophotos, I have the options of
> LRGBC : 5 filters for colors
> Ha, OIII, SII : 3 filters for narrow-bands
> 
> For photometry, the options are
> UBVRI  : 5 filters
> Clear : 1 filter
> 
> I suppose the Clear filter is the same for both jobs.
> 
> The STL-8W filter wheel can only hold 8 filters and I can't
> replace filters remotely.
> 
> What other options, e.g. different filter wheel, are available ?
> Which photometry filters are essential for beginner ?
> Are V-R or B-V  o.k. ? Which color index pair is easier to begin with ?
> Are the U and I filters basically impractical for use with amateur 
> instruments ?
> 
Hi Stewart,
The luminance/clear filters are essentially the same for both
astrophotos and photometry; you only need one.  This is
especially true with the 6303, which has relatively poor red
response. The next question is whether you really want the
8 filters for astrophotos, in which case you don't have any
room for *any* photometry filters. :-)

Let's assume that you want to mix and match.  Then I'd recommend
the LRGB for color imaging, and BVRI for photometric measures.
With the 6303, (B-V) is your best color index.  U-band should
be your lowest priority; V-band should be your highest priority.
Ic is pretty easy with amateur cameras as long as you have
reasonable throughput at 850nm, and (V-Ic) is an alternative
color index to use.  So my suggestion is V first; B and V second;
B, V, Ic as your third choices.  Rc is ok but is a bit too close
to the V bandpass to give you as much scientific value compared
with either B or Ic.

Good luck!  Ask here if you have any additional questions.
Arne