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What size of the grating on GAIA RVS spectroscope ?

How many lines on mm, or what defraction angle for 850 nm wavelenth light ?

I find some more details here: http://sci.esa.int/gaia/44092-gaia-rvs-grating/ and http://sci.esa.int/gaia/44093-state-of-the-art-grating-for-gaia/ The GAIA RVS grating has dimensions of 20.5 cm × 15.5 cm and 302.11 grooves per mm.

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  • $\begingroup$ For RVS, Gaia uses two prisms, a blue and red one. That's a good thing to google. $\endgroup$ – AtmosphericPrisonEscape Jan 2 '18 at 12:54
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    $\begingroup$ You are wrong. Prisms uses in the photometric instrument - spectrometer of low resolution. RVS (radial velocity spectrometer) use the grating, see sci.esa.int/gaia/40129-payload-module/?fbodylongid=1916 $\endgroup$ – tsikraserg Jan 4 '18 at 5:29
  • $\begingroup$ Also see the question on this sight - Why does Gaia use only calcium NIR lines for stellar radial velocity measurements? - astronomy.stackexchange.com/questions/18374/… $\endgroup$ – tsikraserg Jan 4 '18 at 5:40
  • $\begingroup$ Ah you're right, I confused those two parts. The calcium triplet is simply very well detectable in most stars, just as the document you've linked also states. $\endgroup$ – AtmosphericPrisonEscape Jan 4 '18 at 16:42

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