This document summarizes what DEIMOS observers should do to
prepare for their observing run.
Summary
If you plan to use custom slitmasks during your DEIMOS run, plan
to begin the process early. For standard masks (<200 slits),
slitmask design files are required
at least 4
weeks prior to your run. For mega-masks (>200 slits),
slitmask design files are required
at least 8 weeks
prior to your run. First, you'll need to install the official
DEIMOS slitmask design package
DSIMULATOR; both the
software and the documentation are available from
Drew
Phillips's DEIMOS slitmask design page at UCSC.
An important difference between observing with DEIMOS and
observing with LRIS is that LRIS observers typically must
perform a coarse slitmask alignment step in order to get the
alignment stars into their corresponding boxes on the
slitmask, then proceed to the fine alignment step. DEIMOS
observers typically use the DSIMULATOR package to provide
predicted coordinates for a star on the guider; by placing the
star at these coordinates, coarse alignment is achieved in
seconds.
DEIMOS observers must consider two characteristics when
selecting guide stars:
- Placement. The DEIMOS guider field of view
consists of two parts, one viewing the pickoff mirror and one
the reflected sky off the slitmask. The pickoff mirror, which
covers about 1/3 of the field of view, is the preferred place
to position your coarse alignment star. Stars can also be
placed on the slitmask region, but it is only about 30%
reflective and so stars seen there will be somewhat dimmed.
If possible, avoid choosing a star near the break between
the mirror and slitmask. And if you can select more than
one coarse alignment star, it's wise to do so.
- Brightness. The Keck guider displays are
notoriously bad at displaying images, and seeing faint stars
is hard. If you are forced to spend significant time
identifying your field, this defeats the purpose of using the
guider to complete the coarse alignment. Ideally, your coarse
alignment stars should be in the R=15-17 magnitude range.
Fainter stars become increasingly more difficult to identify,
but can be used if needed.
Once your slitmask designs are completed, you can submit them
for milling by using the
DEIMOS
Slitmask Database Access page at UCSC via these steps:
- Access to this page is restricted to known sites, so if
you find you can't access it, please contact the web page
administrator (
) to add your site.
- Once you reach the site, please register to create your
account for submitting masks if you haven't already got one.
The system will email you a password which you should retain
for future reference.
- Enter your name, email address, and password to log in.
- Click on the Submit a Mask Design
File button to access the page for sending in your masks.
Masks are now milled at the Keck summit, but in order to keep
the backlog of masks manageable we do require observers to
submit most masks 4 weeks in advance of the observing run;
please see the
Slitmask Incentives
Protocol for details.
We now have a
web
form for submitting your choice of DEIMOS gratings, filters,
and slitmasks. Please submit this information as soon as your
masks are milled.
If you plan to observe in Hawaii and stay at either the Visiting
Scientists Quarters in Waimea or at Hale Pohaku on Mauna Kea,
please use the
WMKO Lodging Reservation
Request form to make your arrangements. The VSQ in Waimea
sometimes fills up, so to avoid being sent off to Waimea Country
Lodge purgatory, make your reservation several weeks before your
run.
Certain things will make your life much easier during your
DEIMOS observing run. Please remember to generate and bring the
following:
Go to:
DEIMOS Home Page -
Instruments Home Page -
Keck Home Page
Last modified: Tue Sep 26 16:29:47 HST 2006
