[Aavso-photometry] photometry of 27 virginis

[Wolfgang Renz]

Hi Trupti

Take a look at the TOPS Delta Sct Network of the University of Vienna,
Austria:
http://www.univie.ac.at/tops/
http://www.univie.ac.at/tops/dsn/intro.html

There you will find the free and powerful program Period04 to resolve
multiple periodicies:
http://www.univie.ac.at/tops/software.html
http://www.univie.ac.at/tops/Period04/index.html

There you will also find a description of the Three-Star Technique
they use to observe delta Sct stars:
http://www.univie.ac.at/tops/dsn/texts/photometry.html
http://www.univie.ac.at/tops/dsn/texts/obstechnik.html

Best for multi-periodic short periodic variables would be of course
a coordinated multi-site, multi-latitude campaign at get rid of the gaps in the
observations that make it difficult to derive more than the most basic
periods:
http://www.univie.ac.at/tops/dsn/texts/observation.html
http://www.univie.ac.at/tops/dsn/texts/multisite.html
http://www.univie.ac.at/tops/dsn/texts/img66.gif

Clear skies
 Wolfgang

-- 
Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO



----- Original Message ----- 
From: "trupti ranka" <trupti_ranka at yahoo.com>
To: <aavso-photometry at aavso.org>
Sent: Thursday, May 31, 2007 11:04 PM
Subject: [Aavso-photometry] photometry of 27 virginis


> hello everybody,
>  A month ago I started with photometry of a variable star named
> 27 virginis. i was using a 14" celestron telescope and SSP3-A
> photometer. Sky map pro software said that the star magnitude
> varies from 6.19 to 6.33 which we thought was good enough to
> be observed by 14" telescope. but after initial data reduction we
> found that star magnitude varies only by 0.05 magnitude. we
> checked some IBVS papers which confirmed are data. The
> papers (1975,1977,1980)reported a magnitude differences of
> about 0.02 to 0.03.
>  Now the problem is that since we were using a 14" telescope
> for such a small amplitide variation the data accuracy is poor.
> also the star is multi periodic delta scuti star. Its period varies
> fro 0.5 hrs to 3 Hrs (according to IBVS papers). I would like to
> know if there is a better and more relaible way to calculate error
> other that 1/SNR or some special data reductoin tricks to improve
> accuracy. also i would like to know if there is a specific software
> for calcualting periods of short duration multi periodic stars(i
> heard there is a FORTRAN based software but can't find it) .
> this has turned into a tricky star for data reduction but i would
> like have some help as i have spend lots of nights observing
> it and don't want the data to go waste.
>   
>  looking foward for you replies,
>  regards,
>  Trupti