The object of this section is to point the novice ASTERIX user to the various pieces of documentation (online and offline) that will get them started on using ASTERIX and to guide them through a few example commands.
The first thing you should do if you haven't already done so is get a copy of the User Guide (SUN98). You should read this before you start trying to do anything else with ASTERIX, so that you are familiar with ASTERIX terminology - 'event dataset', 'binned dataset' etc.
Next you will need to get hold of some test data. Three files of test data were provided with this ASTERIX release. You should ascertain the location of these from your system manager and copy them to your own work directory. There is one event dataset ( event_data.sdf) and two binned datasets ( time_series.sdf and image.sdf). You can give your own copies different names, but the .sdf extension must be retained.
Before you start doing things with these datasets it would be worth reading through the help sections, Shortform commands and Macro commands to make sure you are totally familiar with the different sorts of ASTERIX command. You should also read the section on 'Using_ASTHELP', so that you know, for example, how to get a hardcopy of the help. You may find it more convenient to get a hardcopy of this section.
The simplest commands are probably the general HDS ones. If you are not already in ICL then type icl at the shell prompt to load it and once loaded, type asterix to load ASTERIX command definitions (unless this is done automatically at your site). Now try this command:
There will be a slight delay as this section of ASTERIX is loaded and then you will be presented with a 'directory' listing of the top level of the dataset. In this case you gave HDIR the parameter it wanted on the command line. At this point it would be worth looking in the help section 'User_interface ADAM_parameters' to familiarise yourself with the other ways parameters may be handled. Having done that try giving the HDIR command without any parameters. First you should notice that you get much quicker response because that part of ASTERIX is already active. Second, you will see that you are now being prompted for a parameter and that a value is being suggested - the same value you gave last time. PressICL> hdir time_series
<RETURN> and it will take that value by default.
Now give the command:
You will see that this time it doesn't prompt, but instead takes the default directly. Now try:ICL> hdir \
It will prompt for the object name. Give it a different one this time - event_data. Now you'll find it's asking for another parameter. This parameter gives you the option of sending the output somewhere else - for now just take the default value. This parameter is normally hidden and just takes its default. The only way to make these parameters visible is to use the PROMPT keyword. Give the HDIR command again by itself. This time when it prompts, press theICL> hdir prompt
<TAB> key. You will see
that the default it offers you is transfered to the input buffer and
that you are able to edit it. Just add '.X_RAW' onto the end to have
a look at one of the event lists. Finally, before we give HDIR a rest,
invoke it again without parameters and give !! in response to the
prompt. The command will abort.
You have been guided through the use of just one command so far. It would be appropriate now to explore some other commands and also become familiar with the help given on commands. Have a look at the help on HDIR ( ICL> asthelp hdir) and see how the way it's presented fits with what you now know about the command. Explore and try some of the other commands in the same group.
The general HDS commands that you have been exploring have no knowledge about the datasets they are dealing with and make no assumptions about components they find there. ASTERIX does have other display commands, though, which do know about the standard structures. Try the following:
These commands will require a different part of ASTERIX to be loaded so there will be a slight delay before the first one responds. This first command will display the contents of the standard header and tell you the origin of the data. The second will actually list a part of the data in tabular form and the final one will give you its processing history.ICL> header time_series ICL> binlist time_series slice=1:20 ICL> hist time_series
The next thing you will probably want to do is plot out the data. First type:
to get a list of available graphics device names known to your system. Again this is a new part of ASTERIX, so there will be a slight delay. Having selected the appropriate device, type:ICL> dlist
This will give you a default plot of this dataset. The graphics sub-system is quite large and comprehensive and has its own extensive help section which you should explore separately.ICL> gdraw time_series device-name
The time series plot probably took some time to draw because it is quite large. It also has some duff data at the end where the instrument slewed off-target. You could use GRAFIX to cut down the size of the graph window, but GDRAW would still spend time invisibly plotting the points outside this window. Instead it would be better to subset out the section of data you want to look at. Type:
it will prompt for an output dataset, for which you can supply a name. Then it will ask for the range of axis values you want to keep, and will give you as a default the full range. PressICL> binsubset time_series
<TAB> and then edit
the second number to something much smaller. You can then try drawing
this smaller dataset.
There are several commands in ASTERIX where a range or a list of values are required to be input. Such ranges and lists are input as a character string which is parsed to extract the numeric values. This allows a more comprehensive syntax to be used. You have seen an example in the BINSUBSET command.
You should by now be getting a feel for ASTERIX and the ADAM parameter system that it uses. By looking at the list of commands in the help topic 'Command_summary' or in the Appendix to the user guide, you should select some groups of commands that you are likely to want to use, explore the help on them and try them out with the test data.
After hacking the test data about some more you are probably ready to take some real data right through the system. The list of documents includes reference guides for the instruments supported by ASTERIX. You should consult these.