Re: which filter set to get? ugriz or UBVRI?

From: Joe Patterson <*jop_at_astro.columbia.edu*> Date: Mon, 10 Nov 2008 08:58:12 -0500 · jop_at_astro.columbia.edu

Well, here's my take.  I'm not fully informed about the QEs and physical 
characteristics (fragility etc.) of these filters... so Arne and 
Michael, who keep much better abreast of such things, should weigh in too.

V is by far the best, because it joins to a century of data.  That's easy!

BVRI is likely to be the choice for the next few years, on grounds of
compatibility.  There's certainly a movement towards Sloan - enough of a 
movement to make Sloan the preferred choice for comparison to individual 
classes of stars.  But the advantages of Sloan are somewhat mitigated by

(1) using it for composite objects, like nearly all CVs; and
(2) the availability of pretty good transformation equations between the 
two systems.

And yet another criterion.  The collection of interesting CVs fainter 
than 17-18, known and unknown, is likely to be drawn mostly from the 
Sloan universe.  Brighter ones mostly from the BVRI universe.  For 
time-series studies with small telescopes, you're likely to have happier 
hunting in the latter.  Hence my vote for BVRI... though I'm by no means 
sure.

joe

Tom Krajci wrote:
> There are some changes in the filter product lineup at Astrodon:
> 
> <http://www.astrodon.com/products/filters/photometric_-_schuler/>  will 
> soon be discontinued, except for ye-olde V filter
> 
> <http://www.astrodon.com/products/filters/astrodon_photometrics_-_uvbric/>  
> are the new replacement UBVRI, higher transmission, etc.  (double the cost)
> 
> <http://www.astrodon.com/products/filters/astrodon_photometrics_-_sloan/> 
> are a new set of Sloan/ugriz filters.  Interesting.
> 
> I'm rebuilding my C11 and plan to get a 5-position filter wheel.  I 
> would like to get four filters and leave one filter wheel position 
> unfiltered/clear.
> 
> What should I get?  The old BVRI?  The new/improved BVRI?  Or perhaps 
> the griz filters?  (I presume I can not do much good work in the u band 
> with an SBIG ST-8XME...am I wrong?)
> 
> If I get the griz filter set...does that mean I'm 'out in the cold' 
> because so few other amateurs use them?  Is there an AAVSO and CBA 
> position on the use of Sloan/ugriz filters?
> 
> If anyone proposes I get a 10-position filter wheel and both UBVRI and 
> ugriz sets (probably only one u filter so that there is still one 
> clear/unfiltered position)...there need to be wonderful and great 
> scientific justifications for the extra cost, size, and weight.
> 
> Thanks in advance,
> Tom Krajci
> Cloudcroft, NM
> 