.ETB ("Event table") format in Guide

With the 29 December 1999 version of Guide, there is a feature for displaying 'miscellaneous' lists of events. This feature resembles Guide's user-added dataset capability, in that you can add new lists of your own as ASCII files.

Each list is stored in a file with extension .ETB (either "Event TaBle" or "English-language TaBle"; click here for information about translating the files.) At present, the Guide update files contain eight such tables, giving lists of asteroid occultations visible in Japan, Europe, and North America in 2000; mutual planetary occultations; and more. These can serve as examples of how such lists of events work.

One list, constant.etb, just contains assorted physical constants. Its main use is a somewhat selfish one; for some reason, I can never remember certain useful numbers such as the mass of a proton, or Avogadro's number, and so forth. But it also shows that .ETB files can be used for more than just storing lists of events.

As you may see, each .ETB file begins with a ';e' line, followed by the name of event tables. That name is shown in the list box of event tables, given when you click on "Tables... Miscellaneous". Following this are comments (prefaced with ';'s), and the actual text of the list.

Keywords are surrounded in carets (^). Thus, for example, in JUP_MUT.ETB (table of mutual eclipses and occultations of the Galilean satellites), the names of the satellites and phrases such as "Dynamical Time" are enclosed in carets, so that Guide will know they are glossary terms.

Links to tell Guide to show a given event (the links that appear in light purple) are much harder to set up. These, too, are enclosed in carets. The text to be shown is followed by a '//' (double forward slash) plus a set of commands for Guide to interpret. Here, for example, is the first such 'command link' from JUP_MUT.ETB:

//td 4/ 6/1996 14:21:26;gp12

The 'td' tells Guide to set a (Dynamical) time, in this case, of 4 June 1996 at 14:21:26. The ';' is used as a separator between commands. Then, 'g' indicates 'go to', followed by 'p' to indicate a planet, plus a '12' to specify which planet (planet 12=Europa).

At present, there are not very many such commands available. That will probably change as lists are created demanding new commands... but for the moment, here's what's available:

d(url,filename);
   See 'add_mpc.hee' for an example of this function.  Clicking on the
   link causes Guide to download the specified file,  saving it to the
   given file name.
a(action_number);
a(action_number,text);
   See 'add_mpc.hee' for an example of this function.  Clicking on the
   link will cause Guide to execute the given 'action_number'.  The
   actions are listed in 'toolbar.dat'.  For example,  if your .etb or
   .hee contained text such as:
   ^Click here//a2006;a2357,Bowdoinham ME^
   ^Set time to midnight 1 Jan 2000 and zoom level 4//a2037,1/1/2000 0:00:00;a2383^
   then clicking on 'click here' would cause Guide to execute action 2006
   ("set current time"),  then action 2357 ("set location") to Bowdoinham,
   Maine.  Clicking on the second line would perform the actions mentioned.
j(number);
   Set a specific JD (Julian Day.)
t(date);
   Set a specific Universal Time (UT) date.
td(date);
   Set a specific Dynamical Time (TD) date.
gg(object name);
   Go to a generalized object;  anything of the sort that can be entered
   in 'Go To... Object Name' will work.  For example,  'ggHIP 31415' would
   cause Guide to recenter on the star HIP 31415,  and so on.  If you can,
   it's probably better to use one of the following more specific commands;
   it's apt to be faster and more reliable.
gp(number);
   Go to planet (number). 0=Sun, 1=Mercury, ...9=Pluto; 10=the Moon.
ga(number/designation);
   Go to asteroid (number/designation).
gs(name);
   Go to artificial satellite (name).
gr(ra,dec);
   Go to the given RA and declination.  These are given in decimal degrees.
gr(ra,dec,pm_ra,pm_dec)
   See 'nearby.hee' for an example of this use.  It's similar to the above
   example for a simple RA/dec,  except that proper motion in RA and dec
   is given,  in milliarcseconds/year.  The RA/dec is for J2000.  It's
   hard to see this as being useful for any but this limited case.
x(url)
   See the first line of 'add_mpc.hee' for an example of this function.
   Clicking on the link causes Guide to fire up your Web browser to
   examine the URL.

You'll see that not all of these are used in the current .ETB files. The rest are present because Guide uses them; for example, when you build a list of satellite phases, Guide creates a temporary file where the links set a given time and tell Guide to go to a certain satellite. (The temporary file is TEMPHELP.TXT, and is always built when you click for help, or 'more info', or build a table of any kind.)

Translation of event tables: Translation can be done in two ways: an 'easy' way where only the name of the dataset is translated, and a 'hard' way where you create a brand-new table.

For an example of the 'easy' way, look at the first two lines of ASTEUR00.ETB, the list of asteroid occultations in Europe for 2000. They read as follows:

;d KP Occn. Europe für 2000
;e Asteroid occn's Europe 2000

By default, the English ';e' text would be used in all languages. Adding the ';d' line means that, when Guide runs in German ('d'='Deutsch'), it will use that text instead when naming this table in a list box. An additional ';f' line for French could be added, and so on. That's the 'easy' way. It's quick, but unfortunately, only the dataset name is changed.

The 'hard' way would be to make a completely translated version of ASTEUR00.ETB, to be stored under the name ASTEUR00.DTB. The Italian version currently has many examples of translated event files, with extension .ITB; click here to download the Italian files, and you can see some excellent examples of how this works.