Cassegrain f/13.7 focus

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 mv = 18 mag. Autoguiding is available using software optimized for guiding on a slit or a guide star 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.

2.1 m (82") Otto Struve Telescope

Prime f/3.9 focus

Argos

Cassegrain f/13.7 focus

Sandiford Cass Echelle Spectrometer (SES)

Cassegrain Spectrometer (es2)

CCD WHT Camera

Imaging Grism Instrument (IGI)

CQUEAN