Kast Double Spectrograph User's Manual: Quick Reference

Quick Reference

General Parameters

Scale at Cassegrain focus 3.86 arcsec/mm

Arcsecs/pixel (neglecting anamorphic mag) Red Side: 0.43
Blue Side: 0.43

Monochromatic beam size (both sides) 82.6 mm

Collimator focal length (both sides) 1416 mm

Camera focal length (both sides) 188.7 mm

Approximate Range of Good Performance

Blue lens 3000-7000 Angstroms

Red lens 4000-11000 Angstroms
Approximate Range of Resolution

Blue side 700 - 1700

Red side 500 - 3000

Decker

Predefined Settings

Position Name

0 Home

1 Open

2 Asymmetric Slot 1

3 Asymmetric Slot 2

4 Asymmetric Slot 3

5 Asymmetric Slot 4

6 2 arcsec long

7 15 arcsec long

8 30 arcsec long

9 60 arcsec long

10 Spect

11 Finger

12 2 arcsec rectangular blocker

13 4 arcsec rectangular blocker

14 6 arcsec rectangular blocker

15 8 arcsec rectangular blocker

16 9 arcsec circular blocker

17 6 arcsec circular blocker

18 3 arcsec circular blocker

Maximum decker opening = 145 arcsec

Slit

Predefined Settings

Position Name

0 open

1 0.5 arcsec

2 1.0 arcsec

3 1.5 arcsec

4 2.0 arcsec

5 2.5 arcsec

9 9.0 arcsec

Minimum slit opening = 0.4 arcsec

Maximum slit opening = 145 arcsec

User Filter Wheel Assembly

Position Upper Lower User

0 open open open

1 -- BG14++ --

2 Spinrad NS OG570 --

3 ND 5.0 ND 6.25 --

4 ND 1.25 GG455 --

5 ND 7.5 CuSO4 n/a

6 ND 2.5 GG385 n/a

7 calcite GG495 n/a

Grisms

Grism Grooves/Blaze Straight
Through A/pix Range Nominal
Coverage

1 452/3306 4780 1.41 2890 3150-6200

2 600/4310 4340 1.02 2090 3300-5520 (matches D55)

3 830/3460 3880 0.63 1290 3200-4550 (matches D46)

Collimator Settings

Side Typical Focus Setting Range

blue 15 mm -28 mm to +42 mm

red 0 mm -24 mm to +23 mm

Gratings

Grating Grooves/Blaze A/pix Range Tilt Formula* Useful Range

1 600/5000 1.30 3470 2.23(c)-4687 3800-10000

2 600/7500 1.30 3470 2.23(c)-4687 3800-10000

3** 830/8460 0.94 2490 3.15(c)-5039 3800-10000

4 1200/5000 0.65 1720 4.70(c)-5818 3800-7310

5*** 300/4230 2.53 6760 1.09(c)-4413 3800-11000

6*** 300/7500 2.55 6785 1.09(c)-4388 3800-11000

7 600/3000 1.29 3445 2.20(c)-4372 3000-????

* Where c is the desired central wavelength in angstroms.
** 830/8460 grating in second order yields 0.47 A/pix, range is 1245A, and the second order central wavelength is given by 6.49(c)-5107. The max tilt of 25,500 restricts lambda < 4816A.
*** Note that the 300/7500 is more efficient than the 300/4230 for all lambda greater than ~5400 A. Also, note that 300/7500 in second order can be confused with the 600/7500 grating, but the throughput is very poor and it should not be used in second order.

Polarimeter Module

Position Upper Lower User

0 Home Home Home

1 Open Open In

2 Filter B Out

3 Polaroid V n/a

4 nNone R n/a

5 Empty I n/a

Filter Trays

Position Blue Red

0 Home Home

1 Open Open

2 U GG455

3 wide G GG495

4 empty OG550

5 n/a Spinrad NS

X-Y Stages

Red Side: N/A
Blue Side: 67 pixels/mm
Increasing setting moves to:

Side X (lambda) Y (row)

blue lower higher

Side Spectral Window
(nr nc sr sc) Direct Window
(nr nc sr sc) Orientation
at TUB=90.0

blue 330 2048 995 0 330 330 995 850 North is Right, East is Up

red 2725 525 675 409 350 410 2020 424 North is Down, East is Right

Dichroics and Mirror

To get Select

clear Clear

dichroic D46 or D55 or D57

mirror Mirror

Support Astronomers (sa@ucolick.org)

Last modified: Thu Jul 17 11:35:17 PDT 2025

User's Guide to the Kast Double Spectrograph

Table of Contents

Quick Reference