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The Echelle Mode

Echelle spectrometer is based on a 79 lines/mm grating that works between orders 26 and 57 covering 3950-8800 Å spectral range without gaps* between the orders. Cross-disperser is a custom-made N-SF8 prism. Typical spectral resolution is R=15000.

False colors echellogram recorded with a SBIG ST-10 CCD camera.

* with the popular KAF8300 CCD chip (18x13.5mm).

Technical specifications

Spectral range and coverage

Echelle order	Central WL [Å]	Dispersion [Å / pix]*	Order range [Å]*	Left size [Å]*	Right size [Å]*
26	8608.6	0.20	507.2	8354.9	8862.2
27	8289.7	0.20	488.5	8045.5	8533.9
28	7993.7	0.19	471.0	7758.2	8229.2
29	7718.0	0.18	454.8	7490.6	7945.4
30	7460.7	0.18	439.6	7240.9	7680.6
31	7220.1	0.17	425.4	7007.4	7432.8
32	6994.4	0.16	412.1	6788.4	7200.5
33	6782.5	0.16	399.6	6582.7	6982.3
34	6583.0	0.15	387.9	6389.1	6777.0
35	6394.9	0.15	376.8	6206.5	6583.3
36	6217.3	0.15	366.3	6034.1	6400.5
37	6049.3	0.14	356.4	5871.0	6227.5
38	5890.1	0.14	347.1	5716.5	6063.6
39	5739.0	0.14	338.2	5570.0	5908.1
40	5595.6	0.13	329.7	5430.7	5760.4
41	5459.1	0.13	321.7	5298.2	5619.9
42	5329.1	0.13	314.0	5172.1	5486.1
43	5205.2	0.12	306.7	5051.8	5358.5
44	5086.9	0.12	299.7	4937.0	5236.7
45	4973.8	0.12	293.1	4827.3	5120.4
46	4865.7	0.11	286.7	4722.4	5009.1
47	4762.2	0.11	280.6	4621.9	4902.5
48	4663.0	0.11	274.8	4525.6	4800.3
49	4567.8	0.11	269.1	4433.2	4702.4
50	4476.4	0.11	263.8	4344.6	4608.3
51	4388.7	0.10	258.6	4259.4	4518.0
52	4304.3	0.10	253.6	4177.5	4431.1
53	4223.1	0.10	248.8	4098.6	4347.5
54	4144.9	0.10	244.2	4022.7	4267.0
55	4069.5	0.10	239.8	3949.6	4189.4
56	3996.8	0.09	235.5	3879.1	4114.6
57	3926.7	0.09	231.4	3811.0	4042.4

* with the popular KAF8300 CCD chip (18x13.5mm).

Efficiency curve

The measured efficiency reaches nearly 5% maximum at 6000 Å.

Efficiency curve measured on Vega spectrum.

Resolution

Part of an echelle spectrum of HR5340 (Arcturus, α Boo) with some absorption lines highlighted.