Configure and Locking Allocations

Please note: in the discussion that follows, it is assumed that you are trying to lock the allocation to the same 2dF field plate for which it was originally configured, and that you are observing at a similar Hour Angle. Trying to lock the fibres to the same targets on different field plates or for at very different HA may fail at Configure time due to fibre collisions. Check your Allocation.

It can often be useful to lock a number of fibres (any number of them between 1 and 399) onto certain targets while still allowing Configure to freely allocate the rest of the fibres. The classic example might be that perhaps one has observed a field for 2hours on one night and it has returned redshift for half of the targets (the brighter targets or the emission line objects one would assume) but the remaining targets need to be observed for a second 2 hours, as per the original telescope proposal, while adding in additional targets for the remaining fibres.

While in principle one could just trust to luck that the same objects would be re-observed in a new configuration, it is often better to force the allocation of some fibres on to previously observed targets, and then reconfigure the remaining objects.

The procedure for creating and using an import file

Load your .fld file as normal, and configure as normal.
Save the .sds file.
Save a .lis file using the File->List.. menu option.
Edit the list file to create a new file, by default Configure is expecting a .imp file. The nature of the Edit is discussed below.
Reopen your .fld file (NOT your .sds file).
Turn on Configures Expert mode (in the Options menu, select the Expert flag).
From the Commands menu, select Import Allocations... and select your .imp file. This will allocate the fibres as specified in the .imp file.
Now select Lock Allocations.
You can now proceed with the normal configuration, as you did in step 1 above, but the locked fibres will stay in place.

Editing your .imp file

The file saved by the File->List.. option in configure, a .lis file by default, is a plane text file which shows which fibres are allocated to which targets. The format is close to that of a .fld file, but with an additional column of * (to prevent .lis file being poorly parsed as .fld file by the software) and a column of Fibre numbers between the * and the object names. For some programs it may be possible to edit the .lis/.imp file by hand in a text editor. For most programs, you will probably wish to write a simple script to remove or re-prioritize allocations based on the results of an initial examination of the spectra from a first observations.

.imp file format

The .imp file format should is almost identical to that of a standard .fld file, but with the addition of an extra column of fibre numbers. This column should be the very first column, i.e. it goes before the Objects Name column, of a standard .fld file.

To convert the File->List.. file into a .imp file (although clearly you will normally want to modify the contents of this file as well, or else all 400 fibres will stay locked which is of little value), simply delete the first column of * characters that have been added.