Elodie archive Help

imatyp: Image type.

imatype describes the focal plane configuration used for the observations. The Elodie bonnette at the Cassegrain focus of the 1.93-m telescope houses two different twin-optical fiber sets which are used to transfer light to the spectrograph. One set called 'direct' uses simple fibers and the other, called 'scrambled', includes optical scramblers in the path for improved radial velocity stability.
For each set, one fiber is reserved for the object spectrum and the other for either the sky spectrum or the Thorium spectrum, but it can be also be blocked.
The most frequent values for imatyp are:

OBJOd : object fiber only, direct fibers
OBJOs : object fiber only, scrambled fibers
OBJ2d : object fiber and sky in second fiber, direct fibers
OBJ2s : object fiber and sky in second fiber, scrambled fibers
OBTHd : object fiber and Thorium in second fiber, direct fibers
OBTHs : object fiber and Thorium in second fiber, scrambled fibers

Prior to 1997, only one set of fibers (the 'direct' set) was available, and thus only OBJO, OBJ2 and OBTH are found.

Note: Users should note that for image types OBTH, OBTHs and OBTHd the presence of the Thorium-Argon orders interleaved with the stellar orders may lead to pollution of the stellar spectrum by highly saturated Argon lines which bleed into the adjacent stellar orders.

This archive is actively maintained. We thus welcome feedback from the user to help us detect anomalies and improve the website.

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