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Eclipsing Binary O-C FilesBob Nelson has developed over 2800 O-C (Observed - Computed) files of eclipsing binaries, all in Excel format that we are hosting on our site. The purpose is to provide information on period variation for selected eclipsing binaries (for astronomers interested in a particular star) and to determine the best elements for predicting future eclipses. These elements go into eclipse prediction software, like at Shawn Dvorak's site. (Bob and others help provide updated elements for Shawn.)For each star, they try to develop the best relationship possible; however ambiguities of course arrive, in these cases the most likely set of elements are displayed. The files are updated about once a year. Last Update: 2010-01-11. Most of the information used in creating these files came from the Crakow Atlas, Eclipsing Binaries Minima Database, IBVS, SIMBAD, and VSX. (Tom Krajci contributed about 30 of these files.) Note the grouping of GSC stars into their appropriate constellations. ('GSC' has been shortened to 'G' to save space.) Other designations such HD and SAO have been used where no GSC name was available. Many of the systems having newly discovered elements have only one point in the O-C file; however, it is to be hoped that the listed elements will be useful and that more data will follow soon. The 2009 upgrade includes some 754 new elements in EB_Elements.xls (see below) and 220 new files thanks to the work of J.M. Kreiner (website: http://www.as.up.krakow.pl/ephem/, ref: J.M. Kreiner, 2004, Acta Astronomica, vol. 54, pp 207-210). Note: If you don't know the constellation for a GSC, HD or SAO object, you can always use 'Edit > Find ...' -- available with most browsers. NEW: As the positions in the GCVS 4 are oft times inaccurate or confusing, an effort has been made to provide each star with cross-reference to the Guide Star Catalogue (GSC) or other nomenclature used in planetarium programs, like Guide 8. The code in the alias name is as follows: GSC 0xxxx-0xxxx . . . Designation has been clipboard-copied from SIMBAD (no mistakes!) GSC xxxx-xxxx . . . . Designation has been otherwise recognized (Guide 8, or by position) gsc xxxx-xxxx . . . . . A GSC star (of similar magnitude) lies within 10", DSS image agrees. gsc xxxx-xxxx? . . . . . A likely GSC star is nearby, but it is outside a 10" circle; it is a guess. na . . . . Alternate designation cannot be found; however any position in blue makes sense or has been verified. ?? . . . . No alternate designation is possible. Many more elements have been added in 2010 for stars in the southern hemisphere; however, they may still be under-represented. If you would like to help in establishing and maintaining that part of the database, please contact Bob Nelson. (Remove dashes from email address.) Also, an Excel worksheet (EB_elements.xls) with the essential data for over 5800 stars (some listed below, some not) is available here, and at Bob Nelson's website. The last site offers various pieces of software including EB_Min, Minima, Phases, ToMcat and WDwint plus useful Excel worksheets. Comments are welcome! Much effort has been expended to eliminate errors in filenames and links. However, errors will inevitably creep in. If you find an error or a bad link, please contact Bob Nelson at b-o-b.nelson@shaw.ca (remove dashes). Also, the listed periods will change as more data are accumulated. An effort will be made to compare periods with those in the Crakow Atlas, and resolve discrepancies where possible. Consult EB_elements.xls, as this file will be updated more frequently that the O-C files (which are updated on an yearly basis).
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