Slit Wheel

This notebook demonstrates how to use the various slits in METIS. They are defined in a SlitWheel effect, which works in the same way as FilterWheel. The notebook uses imaging mode to show the slits directly.

from matplotlib import pyplot as plt

import scopesim as sim
sim.bug_report()

# Edit this path if you have a custom install directory, otherwise comment it out.
sim.link_irdb("../../../../")

If you haven’t got the instrument packages yet, uncomment the following cell.

# sim.download_packages(["METIS", "ELT", "Armazones"])

cmd = sim.UserCommands(use_instrument="METIS", set_modes=["img_lm"])

In imaging mode, "!OBS.slit" is false by default, i.e. there is no slit in the path. However, slits can be used in imaging as well by setting !OBS.slit to one of the slits available in the METIS package.

cmd["!OBS.slit"] = "C-38_1"

metis = sim.OpticalTrain(cmd)

The following slits are now available and can be selected with metis["slit_wheel"].change_slit() as demonstrated below.

metis["slit_wheel"].get_table()

implanes = dict()
for slit in metis["slit_wheel"].slits:
    metis["slit_wheel"].change_slit(slit)
    metis.observe()
    implanes[slit] = metis.image_planes[0].data

plt.figure(figsize=(15, 5))
for i, slit in enumerate(metis["slit_wheel"].slits):
    plt.subplot(2, 3, i+1)
    plt.imshow(implanes[slit][600:1450,], origin="lower")
    plt.title("Slit " + slit)

Adding a slit to the slit wheel

The slit wheel holds a number of default slits (defined by the configuration for the instrument used). A custom slit can be added using the method add_slit. A “slit” is an object of class ApertureMask and the various methods for instantiating such an object can be used.

newslit = sim.effects.ApertureMask(
    name="Square",
    array_dict={
        "x": [-1, 1, 1, -1],
        "y": [-1, -1, 1, 1]
    },
    x_unit="arcsec",
    y_unit="arcsec",
)
metis["slit_wheel"].add_slit(newslit)
metis["slit_wheel"].get_table()

metis["slit_wheel"].change_slit("Square")
metis.observe()
implane = metis.image_planes[0].data
plt.imshow(implane[600:1450,], origin="lower")
plt.title("Slit " + metis["slit_wheel"].current_slit.meta["name"]);