Contents
Slits are milled using an endmill with a diameter of
0.015 inches. We mill slits in two passes: a first rought
cut, and a second cleanup cut that removes a section 10% the width
of the tool. Hence, the minimum slit width is 0.018 inches
on the mask; at the LRIS and DEIMOS telescope focal plane plate
scales of 0.727 mm/arcsec, this corresponds to a projected
slit width of 0.63 arcsec if the slit is not tilted (i.e.,
the position angle of the slit project onto the sky matches the
postion angle of the mask).
The answer depends on your slit width, according to the formula
pa_max = acos(0.63/w)*180./pi
where pa_max is the maximum PA of the slit (relative to
the mask), and w is the slit width in arcsec. For a
slit width of 1.0 arcsec, the slit may be tilted by up to
50° relative to the mask position angle. For a slit width of
0.7 arcsec, the maximum tilt is 26°.
The deadlines for submitting your slitmask designs are the same:
four weeks for normal LRIS and DEIMOS slitmasks, and eight weeks
for masks with more than 200 slits. Exceptions to the deadline
may be granted for valid scientific reasons if a request is made
by contacting the director of Science
(jomeara@nullkeck.hawaii.edu),
before the deadline.
The masks are no longer deleted from the database, however, they
can be marked as ARCHIVED.
- Login to the slitmask
database.
- Click the Show Me My Mask
Inventory button to get a list of your masks.
- For each mask you want to delete, hover over the entry and select ARCHIVE button. This will bring you to a new page
where you can mark the mask as ARCHIVED.
Use the ARCHIVE function to archive the old
masks in the database, then submit revised mask files.
Any newly submitted mask which has a “guiname” that
matches an existing mask's guiname will be renamed with
a letter or number appended to the end. This is required in order to
prevent conflicting masknames, which can cause software issues.
Unfortunately, no. Once the slitmask information has been
ingested, the name is used as a unique identifier of the mask.
What you can do is to ARCHIVE the masks you
submitted, change the mask names in your input files, and submit
revised mask files.
Only registered users of the slitmask database system are
permitted to submit slitmask design files. You can either have
the other user register, or you can use the fv program
as described above to edit the observer
email. Then you should be able to submit the file successfully.
The mask is checked for formatting and completeness on submission.
If the mask is ingested, the mask has the correct format.
If you have an error, the mask can be checked
using the following: (see sanity-check
your slitmasks)
If the mask has the status = ARCHIVED then the best practice is to
send the mask to be REMILLED. The use-date can be updated on the re-mill
page, and that will let Keck staff know to mill the discarded mask again.
By default, slitmasks are retained for 6 months past their "Use
Date". This is the date you specified in DSIMULATOR when you
designed your DEIMOS mask, or the date you entered on the web
page when you submitted your LRIS mask. If in doubt, check the
LRIS/DEIMOS
Slitmask Database and view the record for your mask. If it
shows the status = ARCHIVED, the mask will need to be REMILLED.
If you plan to re-use a mask you probably
want to extend the Use Date past the date of your upcoming run
to ensure that it is not discarded; please see the next entry.
- Login to the slitmask
database.
- Click the Show Me My Mask
Inventory button to get a list of your masks.
- For each mask you want to remill, click the Remill button.
- You should receive email notification when the mask has
been remilled.
By default, the slitmask droplists on the LRIS/DEIMOS run
configuration form list all of the slitmasks which have "use
dates" that occur during your run. If you wish to use a mask
which has a use date outside of this range, simply do the
following:
- Log in to the LRIS/DEIMOS
Slitmask Database
- Click on the Show Me My Mask Inventory button.
- Locate the mask to be extended.
- Hover over the line and the table and select Edit Use Date option.
- Select the number of days/weeks/month/years to extend by
(max 1 year).
- Click the Extend Mask button.
- Return to mask inventory page and reload; verify that the Use
Date has changed.
We set a mask status to ARCHIVED and discard the mask
itself when it is over 6 months past its Use Date as
recorded in the database.
An email is sent to the mask owner two weeks prior to the date
of deletion notifying him or her of the pending mask removal.
To ensure that the mask is retained beyind the standard 6-month
retention period, the mask owner must complete the following
steps to extend the use date:
- Log in to the LRIS/DEIMOS
Slitmask Database
- Click on the Show Me My Mask Inventory button.
- Locate the mask to be extended.
- Hover over the line and the table and select Edit Use Date option.
- Select the number of days/weeks/month/years to extend by
(max 1 year).
- Click the Extend Mask button.
- Return to mask inventory page and reload; verify that Use
Date has changed.