I have been using Voyager to automate my spectroscopy rig. I use the array set-up (but this post is not specific to array). (Leonardo, feel free to move this to another sub-forum).
The spectroscope has a slit mirror - the target needs to be positioned on the slit so that light passes through to the spectroscope - the image from the mirror is diverted to the guide unit like an off-axis guider. I use my guider for focussing and plate solving as well as guiding. The spectroscope is set up as a slave and commences imaging when the master (the guider) has placed the target on the slit.
Unlike other programs, it accomplishes all that I need very well - with one reservation. I’ll post a separate report about my successes separately but I can say that the system is brilliant.
The reservation - I fear I am at the edge of the capabilities of my mount which limits what I can practically do. I suspect that there is nothing that can be done in Voyager to overcome this (though I am happy for any suggestions to the contrary) - if there are any users of Paramount mounts that have tips, I’d love to hear from you.
The FOV of the guider is small - 15 x 9 arc minutes. Voyager and TSX plate solves and undertakes precision slews easily (which I personally find amazing). The slit is 4 pixels wide - my plate scale is 0.84 arc seconds per pixel. For bright targets, target stars are wide enough to cover the slit and I can gather enough data to generate a useful spectrum. However, fainter targets present a challenge - I need to have the target centred on one of the 2 pixels in the middle of the slit. If the target is perched on the edge of the slit, there is insufficient light transmitted to generate a reliable spectrum.
This is an issue in RA only - the slit is aligned with the Dec axis and so an error of as much as 10 arc seconds is fine. But if my pointing is out by 2 pixels in RA, then I am off the slit and the spectrum image is unusable. I can be out by 1 pixel in RA in one direction but not in the other.
As you can tell - precision in slewing is critical. (Once correctly positioned, guiding is rock solid and my scope is F8 so the focus generally can be set at the beginning of an evening and left as is. I also have the calibration regime set up and it runs smoothly)
Now I am using a parameter of 1 arc second in the Mount set up tab for precision slewing. Looking at the logs, after 4 attempts, the actual reported error for precision slews is generally in the range of 0.5 - 1.5 arc seconds with most around 1.3 arc seconds. I can’t seem to get the error down below that. If I am manually controlling the mount, I can jog the scope enough to get the final correction to place the target on the slit. But with Voyager, I can see from the logs that the instructions to the mount are not moving the mount enough to achieve the required precision.
I’m able to automate spectroscopy reliably with targets down to about V mag 9 - 10 which is brilliant. Recently I managed V mag 11.3. Operated manually, I can gather useful data with my set up down to V mag 13.5. I’m very keen to close the gap as all the really interesting targets are in that range - usually transients in outburst.
I use a Paramount MX controlled by TSX. I have refined my T Point model and adjusted the polar alignment. Slewing speeds are reduced to 50% to improve pointing accuracy and I have the 10 second delay after slewing set in Voyager.
Does anyone - especially Paramount users - have any other suggestions?
Pete
