Instruments

An instrument file is a Synthesizer instrument saved to disk, filters, PSFs, noise and all, so anyone can produce the same observables without rebuilding it. Synthesizer’s instruments documentation explains how to use one.

Every instrument is one of five types:

photometric

Integrated photometry through a set of filters.

photometric_imager

Photometry and imaging. Adds a resolution, and optionally a PSF and noise map for each filter.

spectroscopic

One-dimensional spectroscopy over a wavelength array.

ifu

Spatially resolved spectroscopy: a wavelength array and a resolution.

collection

Several of the above in one file.

What’s in the file

Whatever Synthesizer writes when it saves an instrument, with InstrumentCollection.write_instruments or an instrument’s to_hdf5. You do not need to add anything by hand.

That is an instrument_type attribute, followed by the groups the instrument has: Filters or Wavelength, and optionally Resolution, PSFs, Depth, SNRs and NoiseMaps. A collection holds one such group per instrument, plus a Header. Synthesizer’s premade instrument files have no instrument_type attribute, and are recognised too.

What an instrument can do (photometry, imaging, spectroscopy) is worked out from which of these groups are present.

Naming

Name an instrument after its observatory and instrument, ending in -instrument, as in euclid-nisp-instrument for Euclid’s NISP photometric imager.

Checks

Errors

These stop an instrument being published.

Problem	Fix
instrument_type is not one Synthesizer recognises.	Save the instrument again with a current version of Synthesizer.
A collection holds no instruments.	Check the file was written with write_instruments.

Warnings

These are reported, but do not stop an instrument being published.

Problem	Fix
A photometric or photometric_imager instrument has no filter codes.	Save the filters with their codes. Without them, the instrument cannot be found by filter in the portal.