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Fwd: [AAVSO-DIS] Re: photo archives
The following is from the AAVSO list:
It says "It turned out that significantly more than 50 percent of the stars
have to be regarded as variable."
This from a plate survey with 0.1 mag accuracy. It looks like there may be
lots of things to find with tass.
Of course all stars are variable. It just depends on the time scale used.
Tom Droege
>Date: Wed, 27 Mar 2002 08:58:33 +0000 (GMT)
>From: Michael Rupen <mrupen@astro.ox.ac.uk>
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>To: aavso-discussion@informer2.cis.McMaster.CA
>Cc: mrupen@nrao.edu
>Subject: [AAVSO-DIS] Re: photo archives
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>
>Dear colleagues,
>
> thumbing through the ADS the other day, I came across some interesting
>work by P. Kroll et al., who are in the process of digitizing the
>Sonneberg Plate Archive (some 270,000 plates!). I don't think this
>has been published yet, but I append one of their abstracts below, to
>give a feel for what they're finding. Note also the work of
>Tsvetkov & collaborators, with the Wide-Field Plate Database (1997;
>contains descriptive information on some 330,000 observations from 57
>plate archives, though no actual scanned images;
>http://www.skyarchive.org) and the Sofia Sky Archive Data Center, which
>is aimed at helping scan & analyze plates for countries in south- and
>east europe (Russia, Romania, Yugoslavia, etc.). My apologies
>if this work has already been referenced in this forum; I've read many of
>the messages, but probably not all...
>
> Cheers,
>
> Michael Rupen
> NRAO/Socorro
>
>===============================================================================
>
> Title: New Phenomena and Statistics of Stellar Long-term Variability
> Authors: Kroll, P.; Vogt, N.; Braeuer, H.-J.; Splittgerber, E.
> Affiliation: AA(Sonneberg), AB(Santiago de Chile / Heidelberg),
> AC(Sonneberg), AD(Sonneberg)
> Journal: Astronomische Gesellschaft Abstract Series, Vol. 17.
> Abstracts of Contributed Talks and Posters presented at the
> Annual
> Scientific Meeting of the Astronomische Gesellschaft at
> Bremen, September 18-23, 2000.
> Publication Date: 00/2000
>
> Abstract
>
> Plate archives contain hundreds of thousands of individual images,
> taken from the beginning of last century up to thepresent. The Sonneberg
> Plate Archive, a collection of some 270,000 plates, is in the process of
> being digitized. First investigations on the basis of selected fields
> in the Orion/Taurus/Auriga region have been conducted. 300 more or less
> randomly chosen stars were examined for variability on about 500
> plates taken between 1960 and 1996. Although the intrinsic photometric
> accuracy of individual data points is only in the order of 0.1 mag, the
> findings were a surprise: 1. Among the stars investigated, new types
> of variability have been detected. We found irregular stars, objects
> with
> cyclic variations with peroids of some thousand days and several tens
> of mag amplitude, and stars of slowly increasing and decreasing
> brightness of a few hundredths of magnitude over decades. 2. It
> turned out
> that significantly more than 50 percent of the stars have to be
> regarded as variable. A lot of HIPPARCOS-constant stars reveal
> variability
> on long time scales. The talk gives a brief overview about the
> potential of digitized plate archives from the aspect of detecting and
> investigating long-term variability and shows first results.
>
>===============================================================================
>
>
>
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