[vsnet-chat 588] Re: Cloudy Weather

[Fraser Farrell <fraserf@dove.net.au>]

G'day Peter,

   >Over here in Melbourne I've only had one or two nights worth
   >setting up. We might be having a drought but that doesn't mean less
   >cloud.

(Note to non-Australian readers: Melbourne usually has only three types of
weather - wet, cold and wet, or 4-seasons-per-day    :)


   >I've been playing with an ST6 CCD of late (Melbourne
   >weather permitting) and looking for a small project to get me up to
   >speed. It seems to me that a series of filtered CCD images taken at
   >intervals through this period might allow you to extract these
   >sutble variations {if they occur}

That may work.  I think you would need to view the entire Homunculus, or
at least the same part, for each image.  Working from Melbourne metro would
also cause noticeable variations in seeing and sky background from night to
night; so your image would also need to include a couple of other stars as
brightness references.

Each image could then be corrected to these stars; thereby cancelling out
the effects of weather, air pollution, and those stupid searchlights aimed
upwards from some of Melbourne's bigger buildings.

Stan Walker (astroman@voyager.co.nz) has been doing Eta Car photometry from
Auckland for many years.  Peter Nelson (pnelson@dcscomp.com.au) has been
doing some variable star CCD work from near Warragul, and could help you
out with some "projects".  Suggest that you contact them for advice.

One "project" that still needs finishing is to measure comparison star
sequences around many southern variables.  The new Tycho Catalogue will be
some help, but it stops at 12th mag.




cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/   email: fraserf@dove.net.au
traditional: PO Box 332, Christies Beach, SA  5165, Australia

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