List of the stars in the database sorted by constellation
List of the RR Lyraes in database sorted by GCVS number
List of the RR Lyraes extracted from GCVS (2003)
statistics on RR Lyr maxima
List of observers
Bibliography

The present database is intended to help observations and studies on RR Lyr stars by amateur astronomers. 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. Delta Sct/SX Phe stars (former 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 ...

The data are collected in the literature or are submitted by the observers themselves.

These 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 thirty 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 study with the data of the database.

expected accuracy:
The typical uncertainty on visual observation 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.

Description:
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 RR database team:

The web site of the GEOS RR Lyrae stars database is maintained by Jean-François Le Borgne (email: leborgne at ast.obs-mip.fr).
The work of collecting data and sorting them is mainly done by Anton Paschke (email: Anton at Paschke.com ) and Massimiliano Martignoni (email: maxmartignoni at inwind.it ). Scanning and digitalizing old publications to recover precious data is done by Francesco Acerbi (email: acerbifr at tin.it ).
Recent data from GEOS observers are collected by Jacqueline Vanderbroere (email: j.vandenbroere at skynet.be ) (GEOS RR Lyrae stars coordinator)

Publication policy:

The GEOS RR Lyr database is not a publication. If you use it for a publication, please quote the original papers. In case of ambiguous reference please contact the database manager or the source of the data (GEOS or BAV, mainly) in case of "unpublished" data. The acknowledgment of the GEOS RR Lyr database would be appreciated in your publications, if you find the present database useful for your work.

List of the stars in the database sorted by constellation
List of the RR Lyraes in database sorted by GCVS number
List of the RR Lyraes extracted from GCVS (2003)
statistics on RR Lyr maxima
List of observers
Bibliography