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--- technical:mtr2 [2026/06/25 09:53] – etienne
+++ technical:mtr2 [2026/06/30 09:51] (current) – [MTR2 spectral resolution] etienne
@@ Line 1: / Line 1: @@
 ===== THEMIS MulTi-Ray spectrograph (MTR2) =====
 MTR2 is the advanced version of the original MulTi-Ray spectrograph of THEMIS. MTR2 enables the production of high-spectral resolution spectrograms simultaneously in different wavelengths. This enables the study of different physical properties of the distinct layers of the solar atmosphere.
-MTR2 spectrograph has an effective Resolving Power, R, of 300 000 to 400 000, mainly limited by the entrance slit width. Typical spectral resolution of MTR2 for a 0.5 arcsec slit width for different lines are:\\
+==== MTR2 spectral resolution ====
-  * 4861.3 Å ; δλ= 19 mÅ \\
-  * 5875.7 Å ; δλ = 25 mÅ \\
-  * 6302.0 Å (Fe I doublet) ; δλ= 27 mÅ \\
+MTR2 spectrograph has an effective resolving power, R, in the range of 300 000 to 400 000, making it one of the most spectrally powerful instrument in astrophysics.
-  * 6562.8 Å (Hα) ;  δλ = 30 mÅ \\
+MTR2 can be setup either with a tunable slit of with a slitjaw mirrors with an effective slit width of about 0.3". The actual spectral resolution depends evidently on the wavelength and entrance slit width as well as the specific angle of the MTR2 gratings, hence exact spectral resolution depends on the specific of each-set-up. Overall THEMIS MTR2 spectral resolution is driven by the entrance slit width, which is thus the main limiting factor. \\
+The following table present typical values of the MTR2 spectral resolution, δλ, for different wavelength and F2 entrance slit width.
+|              |              ^  Wavelength  ^^^^^
+|  :::         |  :::         ^    Hβ      ^  Fe I doublet  ^   He I D3  ^  Fe I doublet  ^  Hα        ^
+|  :::         |  :::         ^  4861.3 Å  ^  5250.0 Å      ^  5875.7 Å  ^  6302.0 Å      ^  6562.8 Å  ^
+^  MTR2        ^  0.5"        |  19 mÅ     |  23 mÅ         |  28 mÅ     |   26 mÅ        |  31 mÅ     |
+^  entrance    ^  0.3"        |  12 mÅ     |  14 mÅ         |  17 mÅ     |   17 mÅ        |  20 mÅ     |
+^  slit width  ^  0.1"        |   6 mÅ     |   7 mÅ         |   9 mÅ     |    9 mÅ        |  10 mÅ     |
+More complete details on the formulas can be obtained in the MTR2 technical document [[this>wdata/WSpectroTools/Spectro_Formulae.pdf | THEMIS spectrograph]] (author: Claude Le Mein).
 <columns 100% 60%>
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        * manual setup of the spectral cameras at the SP2 output
 Data and formulae for the MTR2 can be found in the following document: \\
- [[this>wdata/WSpectroTools/Spectro_Formulae.pdf | THEMIS spectrograph (auth: CLM)]]
+ [[this>wdata/WSpectroTools/Spectro_Formulae.pdf | THEMIS spectrograph ]] (author: Claude Le Mein).
 ==== Spectrograph simulation tools  ====
 These tools allow the observer to quick check the feasibility of a setup
-  * [[this>wdata/Instrument/tools/Rep1/MtrSim.html | MTR spectrograph simulator]] (java web version / auth: CLM)
+  * [[this>wdata/Instrument/tools/Rep1/MtrSim.html | MTR spectrograph simulator]] (java web version / author: Claude Le Mein)
-  * [[this>wdata/WSpectroTools/MTR_Calculator.xls | MTR spectrograph simulator]] (Downloadable excel version / auth: CLM)\\ Please enable macros to get a correct result.
+  * [[this>wdata/WSpectroTools/MTR_Calculator.xls | MTR spectrograph simulator]] (Downloadable excel version / author: Claude Le Mein)\\ Please enable macros to get a correct result.
 Observers can also check the  [[technical:mtr2:maskplates| list of existing available mask plates]] to have an idea of readily available combination.