Provided with the new echelle slit mask is a line of holes, called the "MultiHole". It is useful for calibrating, e.g., the run of the spectrum as a function of position along the slit, or the relative scale along the slit as a function of order number.

As the echelle spectrum below shows, there is perhaps one too many holes in the set, so that at lower orders (longer wavelengths) the pinhole spectra come very close together, making it hard to define a background for each spectrum. This could be resolved by either blocking one of the holes or recutting the mask with one fewer hole in the pattern.

Fig. 1 An echelle image of the MultiHole mask position, courtesy of Alan Stockton. Note that the spectra begin to get very close to each other at longer wavelengths (to the right in the image) and lower down on the echelle format.

Fig. 2 A close-up of the lower right part of the image above shows the region better, demonstrating that at least in these orders the spectra do not quite overlap. The problem is rather one of getting a symmetric background region on eitehr side of the leftmost and rightmost spectra in each order. Order 6 is only faintly visible at extreme right, with order 7 being the bright set of spectra at right, order 8 to its left, etc.

This figure also demonstrates the high quality of the spectra produced by the holes. Note that spectra belonging to different orders can be matched with other spectra from the same order by comparing the separations and curvatures