ZSpec operations and commands

Scope: VIS and NIR mechanisms, slit viewers, shutters, and B/G/R plus YJ/H/K science readout.

Connections: ZSpec VIS and ZSpec NIR. Related operations: environmental services, digital functions, and calibration and acquisition procedures.

Mechanisms

Function	Settings and commands	Status and feedback	Details still needed
VIS/NIR ADC	Set correction; track/hold; individual prism adjustment	Prism positions, correction, tracking state	Coordinate conventions and tracking inputs
Field rotators	Set angle/offset; track/hold; stop	Angle, rate, reference state, limits	Field/pupil modes and coordinate conventions
NIR cold-pupil rotator	Set/track pupil orientation	Angle and tracking error	Relationship to field rotation and any mechanical coupling
X/Y steering	Set position or offset; halt	Requested and measured position	Coordinate conversion and usable range
Slit selectors	Select named slit; engineering position adjustment	Requested and sensed slit, moving/unknown/fault	Slit set, widths, and calibrated positions
VIS slit-view focus, if fitted	Set focus	Position	Whether an adjustable mechanism is needed
Detector focus	Set per-channel focus; get/set focus curve; start/stop maintenance	Position, active curve, process input	Units, warm/cold limits, and update interval
Relative VIS/NIR focus	Set relative focus	Requested and actual position	Units, reference, and actuator arrangement
VIS/NIR shutters	Exposure triggering; engineering controls as needed	Open/closed/unknown, fault	Trigger logic, sensing, and engineering modes

The steering calibration uses slit-view coordinates, with slit-relative offsets derived from the measured slit footprint. The calibration procedures develop that relationship.

Tracking and exposure overlap

VIS and NIR have independent steering, rotation, and ADC. Slit guiding and nod patterns are described in digital functions. Tracking needs current pointing/time inputs and a defined response when those inputs stop updating.

Focus maintenance during observing and the allowed overlap of mechanism moves with exposure/readout remain to be worked through for each path.

Shutters

The VIS entrance shutter and NIR cold shutter are triggered by an OR of their Archon signals. Exposure timing uses that hardware path.

Shutter	Trigger sources	Details still needed
VIS entrance	B/G/R Archons	OR implementation, opening/closing times, position sensing
NIR cold	YJ/H/K Archons	OR implementation, opening/closing times, position sensing

The effect of a shared shutter on independent channel cadence, dark exposures, and a failed trigger input still needs to be resolved.

Science detectors and slit viewers

Function	Inputs	Status and results	Details still needed
Configure science readout	Channel, exposure, readout mode, supported detector settings	Applied settings and readiness	Per-channel modes and cadence
Acquire, finish, or abort	Channel or series	Progress, completed and partial frames	Finish/abort behavior
VIS slit-view stream	Exposure, window, gain where supported	Images, timestamps, settings, source/slit measurements	Camera and interface selection
NIR slit-view stream	CRED2 acquisition settings	Images, timestamps, settings, source/slit measurements	Camera interface and supported modes
Detector characterization	Bias/pedestal, dark, gain, noise, linearity/persistence measurements as applicable	Images and acquisition settings	Measurement procedures

The NIR slit viewer is a CRED2 outside vacuum. Its power, data, and cooling connections are in the ZSpec NIR harness.

Partial operation and recovery

VIS must remain usable with NIR warm, removed, or unavailable. A channel or controller failure needs a recovery path that preserves the usable configuration of the remaining instrument. Cooling and vacuum support continue according to the affected assembly’s needs.

Team notes: The next additions are the actual slit options, controller/channel assignments, shutter logic, and focus behavior during observing. Slit-view focus remains conditional. Normal and standalone roles for the NIR computer also need agreement.