ALPY 600 Spectrograph Preliminary Review
This is a preliminary review. Once I have had a chance to use the Modules at the telescope I will write more. I think it very important to experiment and make adjustments on the bench before going to the telescope.
I received my ALPY 600 Basic ($760) and Guiding Modules ($850).
The first thing was to couple a CCD camera to the Basic Modules Core Element (which contains the slit plate, lens and grism. Next, is to focus the Core Element and set the rotation for a horizonatal spectrum with the shorter wavelengths (blue to the left. I use an Orion StarShoot G3 monochrome camera for spectrum imaging. It has 19 mm back focus. This is supposed to work, but I had a problem. I used a single neon lamp for the light source for the spectrum focusing. It turns out the only way I could get proper focus on the spectrum was to remove the locking ring on the Core Element. There is a lip on the CCD Camera Coupler that is o.160” high. By milling off 0.060” I was able to get good focus and use the locking ring. The next item was with the Guiding Module. After focus is achieved the locking ring locks the Core Element travel. There are 3 hex screws on the Core Element body. These must be loosened to allow the slit to be rotated so the spectrum is horizontal and with the shorter wavelengths to the left. Using the neon lamp the neon spectrum should be all on the right side for proper orientation.
When using the Guiding Module the slit plate on the Basic Module must be removed and the 23 μm reflective slit (supplied with the Guiding Module) put in its place. The connection to the guiding camera is a C-Mount. Most cameras (all that I have) use a T-thread. An adapter can be purchased from ScopeStuff for $24, item #T2CA. This comes with a washer, but may not be needed. Make sure you get a male T-thread to female C-mount adapter. I use a DSI Pro II monochrome camera for the guiding. It has a low profile adapter from ScopeStuff and the focus was good.
The Guiding Module is a considerable expense, but works well. Shelyak recommends using the Basic Module without the Guiding Module with a flip mirror. While this will work, it will be a challenge. Once the mirror is flipped up there is no easy way to keep the star on the slit. At HPO we are experimenting with a fiber optic coupler and star diagonal. If this works out it will be described in detail in my new books sue out later this summer or early fall from Springer. The complete fiber optic coupler can be made for under $50.
Note: While the Calibration Module can be handy, the expense is a bit extreme. A simple neon ring for under $5.00 can be made that provides an excellent wavelength calibration. In addition once a good wavelength calibration has been obtained it should remain stable for future observation. The neon ring can provide periodic checks. I do not recommend the purchase of the Calibration Module unless you really have the extra money. I do not feel it is needed.
Next is a report from the telescope.
Hopkins Phoenix Observtory