Science Operations

LMS Troubleshooting tips

Problems loading images in SkyCat

You may see an error “Error: unknown preview data. Content type: text/html; charset=iso-8859-1” when trying to load catalog images in SkyCat.  Updating your SkyCat should resolve this issue.

OT Position Editor mask does not match that generated by LMS

  • Check that you are running the latest version of the OT.
  • If a FITS image was used to generate the mask, check that the WCS if that FITS image is correct.  SkyCat and LMS rely on the WCS header information while the OT does not.
  • Curved slits are not supported at this time by the OT, although should be included soon.  Check release notes if to see if this is available function or there are known bugs. Contact and we will investigate!

Wavelength limits shown do not match

The Instrument and telescope configuration should be set before setting any slits.  The wavelength solution will not update if this is updated after slits are updated.  If you need to, then this will need to be done manually in your lms file.

Placed slits disappeared

The slits defined are set for a particular  RA DEC and PA.  If you nudge the mask center at all the slits generated will disappear.  Save often!  Toggle off Move Pointing when you are satisfied with the mask position

Overlapping Slits

These can be subtle and tricky to track down. There is a hint about which slits are overlapping when you run verify slits that will list 2 slit numbers in the terminal. KNOWN BUG: These slit numbers do not take into account deleted slits so will increment incorrectly if you have deleted any.

Checking Distances and Separations

If you need to check separations between objects or slits in your mask you can use Skycat’s built in tools.  Right-click on your mouse and drag between two positions.  The vertices drawn (or line) will show in either arcseconds or arcminutes, depending on the distance.

Using Panstarrs images to make masks

Masks made with Panstarrs images have been found to cause problems.  The issue is that Panstarrs uses non-standard astrometric header keywords.  This can apeear as a mirror flip in X or slits appearing progressively offset from targets when masks are overlaid on other images (DSS, SDSS, 2MASS, etc) or on-sky when data are taken.  SOLUTIONS:  1) Recompute the Panstarrs astrometry using standard keyword headers (more info on Panstarrs header keyword issues can be found here; 2) Once the masks are finished and saved, restart MMS, load a DSS image and save the images again.  If using Panstarrs you may wish to contact before the deadline to discuss how to handle the situation.