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VIMOS User Manual
VLT-MAN-ESO-14610-3509
• Curved slits: you picked the object and are now clicking madly in the ’Curved Slit’ window to determine
the fancy curved slit, but no little dots appear. We have not found out why this happens every now and
then, but we know that even if you do not see them, they are there (spooky). Try defining a few (virtual)
points and click ’View/Fit’ that should work.
• There are occasions in which the subroutine/algorithm used to optimize the slit positioning, SPOC, does
not converge. In such cases you will see a core dump message. One of the possible reasons is that the
number of compulsory (”C”) targets is too large. Try to solve this problem by reducing the number of
(”C”) targets changing the flag from ”C” to ”S” for a subset of them. If you still have problems please
contact ESO’s User Support at [email protected] for a possible workaround.
6.3.3
Problems with checksum in ADP files
• When attaching the ADP file, created with VMMPS, to an OB in P2PP I get the message that the file
is corrupt. What does it mean? Answer: The P2PP reports that the file is corrupt due to inconsistent
CHECKSUM value. This may happen due to opening the file with some editors which add some
invisible characters (e.g. end of line character), or sometimes by transferring files between windows and
linux computers (depending on the protocol and encoding used for the transfer). Additionally, recently
a bug was identified in the step where VMMPS writes the final ADP file. If the button ”Make 1 final
ADP” is selected, the pop-up window is displayed asking whether to overwrite and save the resulting
file .adp. The users should answer ”yes” to this question in order to have the correct CHECKSUM
written in the ADP file. However, at this point it is not possible to make any more modifications to
the mask design. If the button ”Make 1 final ADP file” is selected again and the file saved again the
resulting .adp file will have incorrect CHECKSUM saved, even if no modifications are made.
• The ADP file created with VMMPS has empty CHECKSUM, which then results in an error when I try
to submit the OBs. Answer: Make an ADP file by following the usual procedure and at the end when
your reach the step where the button ”Make 1 final ADP” has to be selected, a window is popped-up
saying that the file .adp exists and asking whether you want to overwrite it. If you say NO, the adp file
will still be there (because it was created before the question was issued) but it has empty checksum
value. ADP files with empty checksum are not accepted when submitting OBs. Please make sure that
when you create ADP files, you answer YES to the question whether to overwrite the file. However,
never do this step twice, because this will write an incorrect CHECKSUM.
6.3.4
ADP files and FITS headers
• The coordinates of MOS targets in the FITS headers make no sense. They are different from those
in the VMMPS ADP files. Answer: If, after the automatic slit adjustments, a slit is modified interactively (manually), then the coordinates written in the ADP file are in format: hh:mm:ss.ddd for RA
and dd:mm:ss.ddd for DEC. Instead for all slits automatically assigned the coordinates are written in
decimal degrees. Then when the FITS header is written the coordinate keywords: HIERARCH ESO
INS SLIT7 OBJ RA HIERARCH ESO INS SLIT7 OBJ DEC get truncated just before the first ”:”
and therefore have incorrect values. This may create problems for some data reduction pipelines (e.g.
VIPGI).
6.3.5
Other problems
• There are reports of a possible bug: the image is displayed but a pop-up message appears stating ”ERROR: Fits file VIMOS image”, after which one can not proceed with the cross-correlation. If that
happens the user can try to load the image again using the Open sub-menu of the File menu in the
skycat main window. If that does not work, please contact ESO’s User Support at [email protected].