VIMOS: Atmospheric Effects.

The following figures illustrate the atmospheric effects, including field differential refraction and chromatic dispersion, in the VIMOS field of view, at different field declinations, in the red and blue spectral domains, from -3 hrs before meridian to +3 hrs after meridian. This illustrates the importance of carefully choosing the slit orientation versus the time of the observations. The green lines indicate the direction and position of the slits, aligned N-S for the illustration. Note the varying scale from figure to figure. Much of this material is further explained in Cuby, Bottini and Picat, 1998, SPIE 3355, 36-47 .


Blue domain + 25o declination

Northern field (+25 degrees), blue domain


Blue domain - 25o declination

Zenithal field (-25 degrees), blue domain.


Blue domain - 75o declination

Southern field (-75 degrees), blue domain.


Red domain + 25o declination

Northern field (+25 degrees), red domain.


Red domain - 25o declination

Zenithal field (-25 degrees), red domain.


Red domain - 75o declination

Southern field (-75 degrees), red domain.