Reading your data from disk into AIPS

           

You may have decided to first load your data onto disk outside of AIPS\ and now you want to convert it into AIPS format. You may have done this because you wish to experiment with the many options in ATLOD and it will be faster to read from disk than tape. This is the section for you. You can load the data from disk into AIPS with either the Convex or a workstation depending upon where you have your disk booking (it could be the Convex) and what your needs are. Generally, you will be doing this with a workstation. We encourage you to restrict your use of the Convex to large computational jobs.

1. If you wish to be able to read into AIPS all the disk RPFITS files that you have created with one application of ATLOD, then you may find it convenient to concatenate all the files into one with a Unix command such as

   cat 91-04-23_* > BIGFILE

   where your files are all prefixed by 91-04-23_, say, and suffixed by the the UT (wild-carded with the *). It will save you some trouble later on in AIPS if the concatenated file is in time order. The current file naming convention should ensure this (i.e., the files list in time order when you examine a directory of them with, say, the UNIX command ls), but data from the first half of 1990 may not. If not, then put them all in time order on the command line in the cat operation. For example,

   cat 31jun90_2301 01jul90_0044 01jul90_0413 > BIGFILE

   Note that you must make the name of the concatenated file in upper case (here I have called it `BIGFILE') because of the disinterest AIPS shows in lower case. Remember to delete the multiple files, leaving only the concatenated file. Do this with a command such as

   rm 31jun90* 01jul90*

   If there was insufficient space to concatenate the files, then just rename them to upper case with the command

   RENAM .

   The `.' signifies that RENAM should do its work in the current directory. You will do the concatenation within AIPS with the task ATLOD in this case.
2. Before you start AIPS, you must set an upper-case environment variable to point at the location where you have stored your RPFITS files. Do this with a command such as

   setenv MYAREA `PWD`

   Note that this is not the standard Unix lower case command pwd but an ATNF specific upper case one which does not get confused by the automounters. Note also the backwards quotes; you must type these as shown. You can examine the value of `MYAREA' with

   printenv MYAREA

3. Start AIPS on whatever machine you choose to use, with the lower case command

   aips

   and enter your AIPS user number when prompted.

4. You can now load the data into AIPS with ATLOD. All of the inputs to ATLOD are described in § 4.4. Note here that you must set the adverb infile to point to the file you wish to read from disk. For example, set infile='myarea:bigfile' (you must include the forwards quotes; all strings in AIPS are quoted). If you do not include the environment variable, ATLOD will look, by default, in the /DATA/FITS area for your file.