Subject: Interested in low res IR spectroscopy on APO 3.5m?


Submitted: Tue, 23 Sep 2003 11:37:58 -0600

Message number: 708 (previous: 707, next: 709 up: Index)

To: APO 3.5m Users and Potential Users

There is a possible opportunity for access to a low-resolution near-IR
spectrograph on the 3.5m, likely in exchange for some observing time
for the instrument builders. The purpose of this message is to provide
some information about this instrument to determine whether there is
significant scientific interest on the part of the 3.5m user community
to warrant pursuing this possibility. Initial testing of the instrument
could begin early in 2004, and if successful, the instrument could be
available for part-time use for an indefinite period of time.

CorMASS is the spectrograph originally built by Cornell and U.Mass to
work on the Palomar 60-inch telescope.  It has been in continuous use
for 4 years and is currently in use at the 1.8m VATT (Mt. Graham).
It is a low-resolution (R~300), cross-dispersed spectrograph with a
NICMOS 3 detector, giving sensitivity from ~0.8 to 2.5 microns. There
is a slit, but because the spectra are cross-dispersed, the slit is
relatively short.  Using the existing instrument on the 3.5m would give
a slit of about 6x0.75 arcsec. Overall throughput is around 10 percent
but varies across the near-IR. A limiting magnitude for spectroscopic
targets of roughly K=15 (10 sigma, 3600 sec) is expected for the 3.5m.

The instrument includes a K-band imaging mode used to place objects on
the slit. Data acquisition is through a straightforward command line
interface.  It should be straightforward to incorporate this into the
new remote user interface.  Recipes for reducing the data in IRAF have
been developed by previous instrument users.

Much of the scientific work done with this instrument to date has been
for identification of cool point sources.

More detailed information and some sample images, etc. can be found at
the CorMASS home page:

and in an article in PASP 113, 227 (2001):

For comparison, GRIM has spectroscopic modes of R=200,400, and 800
with corresponding slit widths of 1.4, 0.7, and 0.35 arcsec. It is not
cross-dispersed, however, so the entire near-IR cannot be covered in a
single exposure. Perhaps even more importantly, the detector in CorMASS
is likely to be substantially better than that in GRIM.

If you feel that you have scientific interests in, or questions about,
using this instrument, please communicate these to Jon Holtzman,, (505) 646-8181, and I can accumulate these and pass on
expressions of interest to Ed Turner and questions to the instrument

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