2.1m Telescope

Cassegrain f/13.7


Cassegrain Spectrometer (es2)
Scientist: Dr. Anita Cochran, (512) 471-1471, anita@astro.as.utexas.edu

A low-to-moderate resolution spectrometer (600-2,500). The CCD detectors are CC1 and TI1. TI1 should be used for the blue region and CC1 for the red. Various gratings are available to provide wavelength coverage from 0.3 to 1.1 microns. The spectrometer has long slit (120 arcsec) capability. There is a selection of slits of predetermined sizes from 0.5 to 12 arcsec. Limiting magnitude mv = 18 mag. A STAR1 CCD system provides remote guiding, but not autoguiding. The TV system can be used to guide off the slit or in an offset mode.

Available Gratings:
Grating No. Blase Å Grooves/mm
1 3000 300
2 5000 600
3 12500 600
4 5000 300
5 1500 600
6 4200 300
7 4000 600
8 4000 1200
21 7500 300
22 5000 600
23 7500 600
24 7500 1200
25 5000 1200
26 8000 150
"Potter's" 5000 150


Nominal Resolution (2 pixel, 1st order, TI1)
300 grooves/mm = 6.5Å
600 grooves/mm = 3.3Å
1200 grooves/mm = 1.7Å

For CC1, resolution is 12/15 that of TI1. Only one grating may be mounted at a time and wavelength setting is not overly reproducible.

ES2 has only predefined slits to use. These are on a wheel in the instrument and are set remotely with a selector switch. The slits are reasonably reflective for purposes of guiding.

Available Slits:
Position Width
1 large hole
2 pinhole
3 0.65 arcsec
4 1.1 arcsec
5 1.6 arcsec
6 2.1 arcsec
7 3.1 arcsec
8 4.1 arcsec
9 5.1 arcsec
10 7.1 arcsec
11 9.1 arcsec
12 12.1 arcsec

Slits 3-12 are nominally 120 arcsec long.

The instrument is attached to the telescope with the Telescope Utility Bin (TUB). The TUB contains argon and neon comparison lamps, as well as slit control and TV position control. The TV may view the slit directly or a field or offset position. The TUB is controlled by a switch box (not software) and is accessible from either the dome floor or the control room.

The ES2 spectrograph is typically used with the STAR 1 guider, which should be specified in the request for telescope time.

       
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15 September 1999
UT Astronomy Program • The University of Texas at Austin • Austin, Texas 78712
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