[vsnet-chat 2490] ST6 - IR Blocking Filter

["William S G Walker" <astroman@voyager.co.nz>]

Greetings, All,

When using BVRI filters with the ST6 I notice that the I images show a halo
which would probably be a gradual brightening to the edges of the field if
there were no vignetting. Since I'm only doing BVR photometry this is not a
problem as all of the filters are adequately blocked.

But I wonder if this has any effect on unfiltered photometry. Has anyone
tried this with and without the IR blocking filter supplied by SBIG? Are
there significant differences? I'm not even sure what is causing the halo -
but I imagine that it's some radiation from the filter unit itself which is
not much cooler than ambient, which is usually about 8C to 20C at night.

Regards,
Stan

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp