01 Feb 2019

Combined Sprat/SHOC is way to go.

Working out from Nasmyth:

• "Inside" Nasymyth is autoguider. This can patrol half of the field of view, and will hopefully have a focus mechanism.
• Nasmyth mounting:
  • James to provide details of this mounting as used on Wide Field Camera on opposite port.
  • 1/4 of the field of view will be for a High Resolution Spectrograph (HRS) fibre feed
  • 1/4 of the field of view with be for SPRAT/SHOC
  • A cable wrap (copy of that on opposite port) will be provided. James to provide details.
  • There is possibility of pneumatic supply
• Deployable calibration mirror (to feed flat/arc)
• Deployable slit
• Field Lens
• Collimator Lens
• FILTER SLIDES (3). Hopefully <50mm thickness. To house maybe 5 filters each. Note one filter will need to be order blocker (4000-8000 Angstroms) for SPRAT. James to design to fit to an interface in SPRAT.
• Grism Assembly
• Camera Lens and CCD.

General Design Points

• Filter slides need to be in collimated beam to avoid focus shifts
• Try and minimise cables on/off mount. So mount control computer with instrument. Note SHOC software requires GPS feed (serial; currently using serial to USB, Amanda to check latest GPS hardware).
• USB for camera rather than PCI Card
• Use existing SHOC CCD readout (via andor SDK)
• Use existing Apache Thrift infrastructure
• LJMU responsible for all mechanism control, including filter slides
• Use wiki to keep one version of documentation/files etc.

Actions:

• IAS: Check/modify optical design to make space for filter slides
• James: Provide details of mounting plate/wider field camera (STEP File); provide information on cable wrap being used on other port
• Carel: Provide details of SHOC software to Chris Mottram so he can try and built a local copy at LJMU
• Amanda: Look at trade off between deep depletion (higher red QE, higher dark current) and standard EMCCD