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GEOS RR-Lyr database | |
The GEOS RR Lyr database is intended to help observations and studies on RR Lyr
stars. It contains times of light maximum of RR Lyr stars obtained either visually or with
electronic devices or photographically. The stars concerned are field RRab and RRc. The
observations are collected in the litterature or submitted by observers. It presently contents
some 60000 maxima on more than 3500 stars.
Delta Sct/SX Phe stars (formerly RRs) are not included in the database since they do not have
the same evolutionary status. RR Lyraes in globular clusters would not be neglected, but it is
another job ...
Access to data:
| Date of last updates
77490 maximums on 15475 stars | |||||||||||||||||||
The data, dating back to the end of century XIX when the first RR Lyraes were
discovered, can
display the period changes. The reason of these period changes of RR Lyr pulsators is still
unknown. It is then important to monitor the period variations of RR Lyraes to make a catalogue
of their behavior to help understanding the phenomenon as V.P. Tsesevich ("RR Lyrae stars",
1969, Israel program for scientific translation, for the english translation) made in a first
attempt some forty years ago. Apart from the secular period variations, RR Lyraes exhibit
another not fully explained phenomenon: the so-called Blazkho effect, named after the russian
astronomer who discovered it in his observations of RW Dra in 1907. This periodic modulation of
the RR Lyr pulsations (periods from 20 to 200 days) may be also studied with the data of the
database.
The typical uncertainty on visual observations of RRab times of maximum is about 30mn rms. As an example: the rms of the 18 times of maximum of RR Lyr observed in 1996 by 2 GEOS observers is 0.016 day (23MN); the O-C variations due to the secular period variations may reach hours over 10 years. Of course, observations made with electronic devices allow better accuracy of a couple of miniutes. However this accuracy depends on the general shape of the lightcurve at maximum. The accuracy of the time of a well sampled, sharp, maximum of a 10 hours period RRab obtained with an electronic device will be between 1 and 2 minutes, while a 15 hours period RRab observed in the same circonstancies will give an accuracy on the time of its wider maximum of the order of 6 minutes. For the same reasons, though the period of RRc is about 8 hours, the accuracy of maximum time determination is not better than 5 minutes due to the sinusoidal shape of the lightcurve. In all cases, the accuracy of the time of maximum depends on the dispersion of the measurements. For a given instrument, the accuracy will then also depends on the magnitude of the star at maximum.
To make the things easy to update, the web pages are automatically generated by a program which
runs under linux: the program read a file containing an updated ascii database of the times of
maximum and a database of elements. Then it computes the o-c for each times of maximum and for
each elements and draws the time variation of the o-c for each stars (postscript files). Finally,
it writes the html files ready to use with all the data. At a second step a unix script makes a
jpeg copy of the postscript files.
Stars are classified by constellation to retrieve them easily. For each star the user finds:
- the list of the available elements and O-C curves (postscipt and jpeg). a warning about the O-C
curves: since O-Cs are automatically computed, they necessarily range between -P/2 and P/2. Now,
absolute values of O-C variations are often bigger than |P/2|. The result is that the O-C curves
appear folded in y when the O-C crosses the P/2 value. When the elements are very wrong, it
becomes a mess! this is something to correct. Often, simply using elements describing better the
long term variations of the period than GCVS or hipparcos elements would help.
- the list of the available maxima
- a comment area which contains the data from GCVS (and supplement lists), data from hipparcos
when available, including the light curve. Any contribution from any user may be added here, at
least as a link.
- the user has the possibilty too download a text file with the list of maxima.
The web site of the GEOS RR Lyrae stars database is maintained by Jean-Francois Le Borgne (email: jleborgne at irap.omp.eu). The work of collecting data and sorting them was mainly done by Anton Paschke (email: Anton at Paschke.com ) and Massimiliano Martignoni (email: maxmartignoni at inwind.it ) between 2000 and 2005. During the same period, scanning and digitalizing old publications to recover precious data was done by Francesco Acerbi (email: acerbifr at tin.it ). Recent data from GEOS observers are collected by Jacqueline Vandenbroere (email: j.vandenbroere at skynet.be ). Presently, the main feeding of the databse comes from GEOS RR Lyr Survey robotic telescopes, and observers from GEOS, BAV and AAVSO using CCD cameras.
The GEOS RR Lyr database is not a publication. If you use it for a publication, please quote
the original papers. in case of "unpublished" data or "private communication" reference,
please contact database manager or the source of the data and do not publish these data
without observer agreement.
In case of ambiguous reference please contact the database manager. The acknowledgment of the
GEOS RR Lyr database would be appreciated in your publications, if you find the present
database useful for your work. The reference to quote is:
Le Borgne et al., 2007, Astronomy and Astrophysics 476, 307
The RR database team is particularly grateful to Professor Andronov, Odessa State University, who sent many times of maxima to Anton Paschke years ago and which constitute part of the historical found of the present database.
The GEOS RR Lyr database make an intesive use of the electronic version of the General Catalogue
of Variable Stars made available by the GCVS group at the Sternberg Astronomical Institute and
Institute of Astronomy (Russian Academy of Science), Moscow,
http://www.sai.msu.su/gcvs/gcvs/ :
Samus N.N., Durlevich O.V., Kazarovets E V., Kireeva N.N., Pastukhova E.N., Zharova A.V., et al.
General Catalog of Variable Stars (GCVS database, Version 2011Jan),
Also available at CDS
jleborgne at irap.omp.eu
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| Today is Mon May 20 13:45:05 CEST 2013 |
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License.
