The Coude Echelle Spectrographs (Expert Information)


Appendix C12:  Finding a new UHRF wavelength

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From the echellogram table in Appendix A3 find the order in which your wavelength appears, and from the following table get the UG value for the blaze peak in that order, which occurs at UT 33000. Run the program 22DECUHRF to get mm positions for USC and UFC, and then run the programs USC and UFC to convert these to encoder units (ADUs). Configure the spectrograph to those UT, UG, USC, and UFC settings, at 0.3M resolution. Using the quartz lamp, locate the order, and then follow it to longer or shorter wavelengths with the ThAr lamp to identify the target wavelength.

For the Tek, Increasing UT moves you to shorter wavelengths (to see lines higher up the XMEM display), and will require an increase in UG to compensate the order tilt. The Tek chip dimensions are roughly UT = 2500 ADU, UG = 1200 ADU.

The following tables list the approximate UG values at which the peak of the blaze is found for each grating and each order.
 

U Grating

Order UG Order UG Order UG Order UG
131 435 144 9215 157 16868 170 23155
132 1090 145 9850 158 17405 171 23586
133 1755 146 10490 159 17923 172 24017
134 2435 147 11110 160 18427 173 24445
135 3130 148 11725 161 18917 174 24872
136 3810 149 12330 162 19423 175 25300
137 4500 150 12940 163 19935 176 25710
138 5190 151 13510 164 20400 177 26120
139 5880 152 14100 165 20870 178 26520
140 6560 153 14665 166 21336 179 26920
141 7239 154 15235 167 21800 180 27305
142 7910 155 15787 168 22245 181 27695
143 8565 156 16337 169 22700

B Grating

Order UG Order UG Order UG Order UG
120 550 136 9650 152 17100 168 23050
121 1100 137 10150 153 17520 169 23380
122 1650 138 10650 154 17950 170 23710
123 2250 139 11150 155 18330 171 24050
124 2850 140 11700 156 18720 172 24360
125 3400 141 12150 157 19100 173 24680
126 4000 142 12650 158 19480 174 25000
127 4550 143 13150 159 19860 175 25310
128 5150 144 13600 160 20220 176 25600
129 5750 145 14050 161 20580 177 25910
130 6350 146 14500 162 20950 178 26200
131 6900 147 14950 163 21320 179 26500
132 7450 148 15400 164 21680 180 26780
133 8000 149 15825 165 22010 181 27070
134 8550 150 16250 166 22350
135 9100 151 16680 167 22700

 

V Grating

Order UG Order UG Order UG Order UG
82 7900 97 20200 112 28900 127 35425
83 8875 98 20855 113 29400 128 35800
84 9810 99 21530 114 29900 129 36175
85 10725 100 22150 115 30350 130 36550
86 11645 101 22800 116 30810 131 36900
87 12530 102 23400 117 31270 132 37250
88 13390 103 24020 118 31720 133 37600
89 14200 104 24590 119 32280 134 37950
90 15030 105 25200 120 32610 135 38275
91 15835 106 25750 121 33040 136 38600
92 16590 107 26300 122 33440 137 38920
93 17345 108 26850 123 33850 138 39245
94 18070 109 27360 124 34350 139 39570
95 18800 110 27900 125 34650 140 39870
96 19500 111 28400 126 35050

 

R Grating

Order UG Order UG Order UG Order UG
67 34400 74 43900 81 51320 88 57565
68 36000 75 45000 82 52380 89 58350
69 37400 76 46000 83 53240 90 59150
70 38900 77 47100 84 54140 91 59900
71 40200 78 48200 85 55020
72 41300 79 49280 86 55900
73 42500 80 50330 87 56780



Ray Stathakis (ras@aaoepp.aao.gov.au)
Last Update: 22 June 2000