Subject: New DIS Medium Resolution Gratings

From: elt@astro.Princeton.EDU

Submitted: Wed, 4 Mar 1998 16:01:16 -0500 (EST)

Message number: 43 (previous: 42, next: 44 up: Index)

Please note that the new medium dispersion gratings for DIS are available
*now*.  It is not necessary to wait until 2Q1998 to use them.  Since the
scheduling request forms for the current quarter do not include grating
requests, please notify the APO staff at least 24 hours in advance if you
want to use the new gratings.  To be on the safe side, it wouldn't hurt to
notify them of your grating preferences, whatever they are.  Note that you
may have to lose observing time (all charged to your program, not shared
with an adjacent DIS program) if your use of the new gratings requires a
grating change during the night this quarter.  We hope to avoid such middle
of the night changes in subsequent quarters (be sure to use the new template,
see apo35-general #254 for 2Q1998 and beyond).

I reproduce below the info on DIS gratings given in apo35-general #237.

Ed Turner

+++

New medium dispersion gratings for DIS have arrived and
will be tested in the next few months. Here's a summary
of what will be available (these are approximate numbers
only):

Low resolution          Blue        Red
      Dispersion          6.2 A/pix   7.0 A/pix
      Wave range          3175 A      5600 A

Medium resolution (new)   Blue        Red
      Dispersion          3.1 A/pix   3.5 A/pix
      Wave range          1590 A      2800 A

High resolution           Blue        Red
      Dispersion          1.6 A/pix   1.1 A/pix
      Wave range          820 A       880 A

The crossover wavelength is 5350 A.

Note that the addition of the medium dispersion gratings
is an enhancement, not a replacement, of current functions
(some people have the incorrect impression that the low
dispersion mode will not be available).  While DIS handles
only two pairs of gratings at once, it should be possible
to specify the setup needed at the beginning of the night
and have the proper gratings installed.
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