What is the purpose of the different slit sizes (50, 75, 100 µm) on this Shelyak slit plate?
The wider slits are designed to increase light throughput for spectroscopic analysis of faint objects. The 50 µm, 75 µm, and 100 µm slits allow more photons to reach the sensor, which is essential for targets like dim galaxies or comets. This comes at the expense of spectral resolution; a wider slit results in broader spectral lines.
How do I use the 19 µm hole on the Lhires III wide slit plate?
The 19 µm hole serves as a high-precision tool for calibration and focusing. By placing a bright star in this small, circular aperture, you can accurately adjust the spectroscope's focus to achieve the sharpest possible spectral lines. Once focused, you can rotate the plate to a wider slit for your actual observation.
When should I use the 100 µm slit on my LISA spectroscope for observing a faint quasar like 3C 273?
For an extremely faint target like the quasar 3C 273, the 100 µm slit is the ideal choice. It provides the maximum possible light throughput, ensuring you can capture a detectable signal. While the spectral resolution will be lower, collecting enough photons to identify key features like redshifted emission lines is the primary goal for such a challenging object.
Which slit should I choose for measuring the Doppler shift of a bright star like Vega (Alpha Lyrae) with my Lhires III?
For a bright star like Vega, maximizing resolution is more important than light gathering. Therefore, this wide slit plate may not be the optimal choice. You would typically use a much narrower slit (e.g., 15 or 23 µm) to achieve the high resolution needed to detect subtle Doppler shifts in the star's spectral lines. This plate is specifically designed for faint-object spectroscopy where throughput is critical.
Is a separate slit holder required for this Shelyak wide slit plate?
Yes. This slit plate is an insert and must be combined with the matching slit holder for your specific spectroscope, whether it is the Shelyak LISA or Lhires III. The holder is not included with this plate.
How do I switch between the 19 µm hole and the 100 µm slit?
Switching between apertures is straightforward. The four apertures (19 µm hole, 50 µm, 75 µm, and 100 µm slits) are mounted on a single square plate that can be manually rotated to place the desired slit or hole into the optical path.
