[daip] AIPS, Dat and VLA data

[Eric Greisen]

Melinda Taylor writes:
 > 
 > A user has some VLA data on dat tape that he wants to reduce in AIPS.
 > He runs AIPS on his linux system and the DAT drive is on a solaris box.
 > 
 > The task he wishes to use is FILLM.
 > 
 > Now as far as I can tell from what Ir ead the only way I can share a 
 > tape drive within aips is if the machine which houses the tape drive 
 > also has AIPS installed - is this correct?
 > 
 > For a number of reason this machine does not and cannot have AIPS 
 > installed on it. However I have setup passwordless access (using ssh and 
 > passphrase authentication) to the tape drive on the solaris machine 
 > (called bat) from the linux machine running AIPS.
 > 
 > So on the machine running linux he can type
 > 
 > linux machine% ssh bat mt -f /dev/rmt/0l status
 > /dev/rmt/0l: no tape loaded or drive offline
 > 
 > and it returns the appropriate result without asking for a passwd.
 > 
 > So my first question is:
 > 
 > 1) is there anyway to use this tape drive within AIPS if the machine 
 > housing the tape dirve does not have aips installed taking into 
 > consideration the tape drive can be accessed from the AIPS machine?
 > 
 > 
 > If not, I can do a raw read of the VLA tape using the dd command and get 
 > each data file off. The files I extract are identified as "raw G3 data, 
 > byte-padded" when I apply the 'file' command in linux.
 > 
 > Is there anyway the FILLM task can be modified to read these files from 
 > the disk and then convert them to fits. As far as I can tell it requires 
 > these files to be on the tape drive?
 > 

Does the Linux box have an Exabyte drive and could you copy the tape
from DAT to Exabyte with the Solaris box?

Is the user certain that this is raw VLA data requiring the use of
FILLM?  The format of that data is such tat it can be read from tape
only, not disk files.

If the answers are NO/YES, then I recommend that the user ask the VLA
analysts at nrao.edu to load his experiment onto a disk here.  Then those
data may be written to FITS files and those files may be read from
disk or tape and may even be copied over the internet.

Eric Greisen