Readme.txt for EBMin23.exe This program reads a data file for eclipsing binary stars and, based on the date and your location, prints out a list of stars undergoing minima for the coming days with other data. The default data file (EBStars.dat) requires some kind of text for the first two lines. Note that the text may be anything -- it just needs to be two lines of characters (max 255) separated by a carriage return. See the sample file for guidance. Then, data occupies one line for each star. Needed are the following (separated by commas): Starname (surrounded by quotes), [You don't actually need the quotes.] Right Ascension (2000.0) in the form HH.MMSSs, Declination (2000.0) in the form ąDD.MMSSs, Epoch (Julian Date of a past minimum) in the form XXXXX.xxxx (i.e., ditch the leading 24), and Period (days) in the form X.xxxxxxxx (as many digits as you have). Check that there is not a blank line at the end as this will produce an error. [I don't think it matters.] Now for the good part. You may create the data file using MicroSoft Excel. Just use one line for each star, enter the data into five columns (don't type the quotes around the star name). Insert two lines of text at the start. Anything your heart desires will do as long as it's 255 characters maximum. It may be one cell or many. When you are satisfied, save the file in the CSV (comma delimited) format. All is taken care of for you. For convenience, you can change the suffix to ".dat" afterwards if you wish. The following data is entered at the keyboard (and saved in the file EBSTARS.INI): Longitude, in degrees WEST of Greenwich (- to east) and in the format DDD.MMSS. For example, 122d 50' 51.5" W becomes 122.50515 (for ease of entering). Latitude, in degrees NORTH of the equator (- to south) and in the format DD.MMSS Time zone, in hours WEST of Greenwich. Use negative values east of Greenwich. For example, EST = CDT = 5; CST = MDT = 6; MST = PDT = 7; PST = 8 Maximum Sun elevation (or altitude), in decimal degrees. Note that this is negative since you want the Sun below the horizon! How high can the Sun be? It depends on your star brightness and what detection method you are using. Minimum star elevation, in decimal degrees. Note that this should be positive for stars above the horizon! How low can the star be? It depends on the type of detector you have. Visual work can tolerate stars quite low (10 deg?) while photometers may require 50 or 60 deg. Star data file. Any legal name. Note that when you enter the name from the keyboard, you may omit the .dat suffix which will be added if there is no period in the name you type. The following data is requested after time zone but is not saved: Year, in 4-digit format, Month, in 2-digit format, and Day, in 2-digit format. The system clock is used for default values. Now for an explanation of the output data, sent to the printer: We start with the six parameters read from the keyboard (or the .ini file). The predicted eclipses are sorted by Julian date and grouped by starting night (carrying over to the "wee hours" the following morning). I regret that the days of the week may not quite be correct for observers east of Greenwich (I had to do some simplifications!). If this is a problem, please contact me at the address below and I'll try to make a fix -- no guarantees. On each data line is listed: Julian Date, starname, LOCAL date, LOCAL time, Azimuthal angle, Altitude, and type of eclipse. Azimuthal angle is in the horizon coordinates for your location and is measured in degrees from the north point starting in an easterly direction. Note that due east is 90 deg, south is 180 deg, etc. Altitude (a.k.a. elevation) is measured in degrees up from the horizon. Type of minimum is I = primary, II = secondary. The program precesses the star coordinates to the epoch of date (this will become increasingly important for dates after 2010 or so). It does not allow for refraction, aberration, or nutation nor does it correct for times at the centre of the Sun (the heliocentric times) but should be accurate enough for most purposes. Remember that the epochs and periods that you get from, say the General Catalogue of Variable Stars (GCVS), may be so out of date that the errors or changes in the period may make these predicted times pretty well useless, so regard the output predicted times AS A GUIDE ONLY. We determine times of minima (ToM) because there are changes that happen, so the predicted times are expected to be inaccurate. As a word of advice, always start your run well before the predicted ToM as there is nothing so frustrating as getting a beautiful ascending branch but a highly truncated or absent descending branch preventing any useful result or at the very least, degrading the accuracy you can get. That's it. Enjoy! Please send any comments or reports of bugs to the following address: Bob Nelson bob.nelson@shaw.ca