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FAQ.md

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Frequently Asked Questions

Q What does a spectroscope's resolution of "R 1000" mean?

A The resolution is the reference wavelength divided by the bandpass of interest. Example:

  • At 5000 angstroms, what is the R value sufficient to resolve 1 Angstroms?

    • 5000/1 = R 5000
  • For the V-Band photometric filter, centered at 5448 Angstroms with a bandpass of 840 Angstroms?

    • 5000/840 = 5.9 or about R 6.

To answer the bandpass of 1000 Angstroms at a wavelength of 5000 Angstroms, divide 5000 by 1000 for the answer of 5 angstroms of resolution.

Q What velocity does a resolution of 5 angstroms (R 1000 spectrograph) translate into:

A The change in wavelength divided by wavelength is equal to the velocity divided by the speed of light.

  • 5 [A] / 1000 [A] = v [km s-1] / 3e5 [km s-1]. The notation of [units] mixes the units of the formula into the values. Note the units completely cancel; the next step is then:

    • 5 / 1000 = v / 3e5

    • 5 * 3e5 / 1e3

    • 5 * 3e2 = 1500 km s-1.

    Not exactly radial velocity speeds.

    Q Is there a Neon lamp data sheet?

    A https://www.digikey.com/en/pdf/v/vcc/cml-neon-application-information