shelyak Alpy 600 - Third Pass

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CHAPTER 3. ALPY 600 - STELLAR SPECTROSCOPY IN SLITLESS MODE

wavelength Line

3835 Å Hη (eta)

3889 Å Hζ (dzeta)

3970 Å Hǫ (epsilon)

4102 Å Hδ (delta)

4340 Å Hγ (gamma)

4861 Å Hβ (beta)

6563 Å Hα (alpha)

These lines are located as below:

With this information, you can establish the cali-

bration law - select a 4th degree polynomial (because

there are several available lines).

When the polynomial is available, re-run the data

reduction process, including the wavelength calibra-

tion. You will get the same proﬁle, but now calibrated

in Å(see the scale in the bottom axis - note that the

spectrum has been cropped between 3650 and 7300

Å):

3.4.3 Third pass

The last operation is to establish the instrumental

response curve. In this document, we used Regulus

as reference star. This is a B7V. In the ISIS database

(Pickles), there is no B7V, but we can select a B8V -

the difference is not signiﬁcant at our level. Display

this proﬁle, and save it in the current directory:

The spectrum has a much wider range than yours:

it goes from 1.000 to 10.000 Å. Reload your spectrum,

and click on “Response”:

Click on OK, to get just the raw response curve. Re-

move the lines and smooth the curve to reduce the

noise: