[vsnet-chat 4939] Re: (fwd) Finding the right focal lenght for Novae Search

[aah@nofs.navy.mil]

Cristovao Jacques wrote, regarding Nova searching:
>Increasing the focal length we gain in
>magnitude but we loose in field coverage, so what will be the best FL.
>Do you also recomend any kind of filter?
  I would worry a bit about source confusion at 10th magnitude
in the heart of the Milky Way with 70arcsec pixels.  You may not
be able to uniquely identify novae until they get quite a bit
brighter.  There is always a tradeoff between depth and field
coverage, and how you choose depends on how bright you think a
typical nova will be when you can detect it.  Perhaps some
research into the nova discoveries over the past decade would help.
  If you want to use a filter, I'd recommend R.  It matches the
peak response of the CCD and also includes Halpha, a very strong
emission line in most novae.  However, many telephoto lenses will
have to be refocussed once you get into the red.
Arne

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