Stellar Observations Network Group (SONG): SONG in New Mexico

There is a spectrograph computer, spec1m, that controls the spectrograph camera (QHY600) and the spectrograph focuser (Esatto). The computer is a OnLogic CL210-G, same as the pwi1m computer, running Windows 11.

The original QHY is liquid cooled, but the camera has no internal protection against overheating should the cooling loop fail. To try to add a layer of safety, we have a couple of thermocouples taped to the body of the camera. We also run the spectrograph power through a Peltec watchdog, and have a relay that resets the watchdog every minute if the thermocouples are reading acceptable values.

The thermocouples are read by a USB device, a Yoctopuce. The relay is a Kmtronix 2-channel USB relay, controlled by serial interface.

The PrimaLuce Esatto focusser has some internal lights that scatter into the spectrograph at a low level. The only way to remove these is to power the focuser down. This is plausible given that the spectrograph is supposed to be stable. We have run the USB to the focuser through a WandererAstro Ultimate PowerBox V2, which allows for turning the USB off and on, via a simple serial interface that I wrote an Alpaca switch driver for.

We run the QHY600 USB through the Wanderer as well, in case we ever need to reconnect the USB.

The entire spectrograph is enclosed in a box made of 2“ Thermasheath foam insulation (R13.1) purchased from Distribution International in El Paso. It is made of 7 different panels; the top side panels are designed to be removable. There is a pass-through for the fiber on one end, and for cables to the camera, focuser, and thermal sensors on the other end.

The box is put together using PVC along the panel edges, and bolting/clipping panels to each other.

There is no bottom to the box, it rests on a couple of foam yoga mats.

We also have a pair of Avtech TemPageR units for monitoring temperatures. Each box has a sensor inside the box, and connectors for two external thermocouples (?). These four sensors are placed in various location inside the spectrograph box.

Here is a photo of the system components.