What kind of scientific projects can I do with the Shelyak Alpy 600?
The Alpy 600's R~600 resolution opens the door to many pro-am projects. You can classify stars by their spectral type (O, B, A, F, G, K, M), measure the expansion velocity of a nova, or monitor the changing spectra of variable stars and comets.
How do I choose the right slit size (25µm, 50µm, 100µm, 300µm) for my target with the Alpy 600?
The choice is a trade-off between resolution and light throughput. For the highest detail on bright stars to resolve fine spectral features, use the narrowest slits (25µm or 50µm). For faint, extended objects like nebulae or galaxies where collecting photons is the priority, use the wider slits (100µm or 300µm) at the cost of lower resolution.
Can I use my DSLR camera with the Shelyak Alpy 600?
Yes, but with an adapter. A DSLR with a standard T-ring has a backfocus of about 55mm, which is too long for the Alpy 600's native 10.5-21mm range. You will need the optional Alpy DSLR camera barlow adapter to achieve focus.
What is the advantage of the Alpy 600's R~600 resolution for observing Be stars like Gamma Cassiopeiae?
An R~600 resolution suits Be stars like Gamma Cassiopeiae (Navi). It allows you to clearly resolve the prominent Hydrogen-alpha emission line at 656.3 nm that characterizes these stars. This feature appears as a sharp spike "filling in" the normal absorption line. With the Alpy 600, you can monitor the strength and shape of this emission line over time to track activity in the star's circumstellar disk.
How does the Alpy 600 perform on a bright planet like Jupiter with an 8" SCT?
The slit lets the Alpy 600 work on extended objects such as planets, for example with an 8" f/10 SCT. You can orient the slit across Jupiter's disk to see the absorption bands of methane and ammonia in its atmosphere. By comparing the spectra of the dark belts and bright zones, you can look for differences between them.
Do I need the optional guiding and calibration modules for the Shelyak Alpy 600?
While not required to start, the optional modules significantly improve the scientific workflow. The guiding module lets you see the field of view to accurately place and keep your target on the narrow slit, which is very difficult otherwise. The calibration module provides a reference lamp (Argon-Neon), which is essential for precise wavelength calibration, turning your data from a picture into a scientific measurement.
What is the difference between the Alpy 600's slit mode and a simple slitless grating?
A slitless grating is simpler but merges your target's spectrum with the sky background and any nearby stars. The Alpy 600's slit physically blocks out this unwanted light, producing a clean, high-contrast spectrum. This isolation is essential for accurate calibration, observing faint or extended objects, and producing reliable data regardless of seeing or tracking quality.
What is a "grism" and why does the Alpy 600 use one?
A grism is a combination of a diffraction griting and a prism. The grating spreads the light into a spectrum, while the prism corrects the angle of the light path. This allows the Alpy 600 to have a straight-through, "on-axis" optical design, making the instrument much more compact, rigid, and easier to mount than spectrographs with more complex folded light paths.
What camera sensor size is best for the Alpy 600?
To capture the full 370-750 nm wavelength range, a sensor with a length of at least 8.5mm is required. A sensor longer than 14mm will do. The camera's mechanical backfocus must be within the 10.5mm to 21mm range.
What software is needed to process data from the Alpy 600?
Shelyak provides its own free software, Demetra, which is designed to handle the entire workflow from image acquisition to fully calibrated spectra. It is an all-in-one solution for controlling your camera (via ASCOM), managing observing sessions, and performing the necessary data reduction steps. Other tools like ISIS and AudeLA can also be used.
How is the Alpy 600 focused and aligned?
There are two focus adjustments. First, the spectroscope itself is focused to the camera by threading the main body in or out of the camera adapter to make the spectral lines sharp. Second, you focus the telescope to make the spectrum as thin (vertically) as possible. Alignment is done by rotating the Alpy 600 core inside its body to make the spectrum horizontal in your camera frame.
Is the Alpy 600 sensitive to temperature changes during the night?
No, the Alpy 600 is designed to be robust and insensitive to typical ambient temperature variations during an observing session. It requires few adjustments.
