2.1m Telescope - Cassegrain Spectrometer (es2)

2.1m Telescope

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Cassegrain f/13.7

Cassegrain Spectrometer (es2)

Scientist
Dr. Anita Cochran
(512) 471-1471
anita@astro.as.utexas.edu

ES2 Users Manual [ pdf ]

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 m_v = 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

Dispersion lambda/delta lambda (2 pixel, 1st order, TI1)

300 grooves/mm = 650

600 grooves/mm = 1300

1200 grooves/mm = 2600

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.