Release Notes for v2.2.1

• FIDELITY: Better Glass Index of Refraction function using Sellmeier function (MAH)

• FIDELITY: Generalization of optics perturbation (removed hardcoded functionality; necessary for future control system/camera updates) (NT)

• FIDELITY: Generalization of optics design for different glasses & non-alternating surfaces (does not affect LSST) (JRP)

• FIDELITY: Water vapor affecting flat normalization bug (JRP)

• FIDELITY: QE pixel variation should not affect bleed trail (JRP)

• FIDELITY: Renormalized seeing so agrees with site data (does not matter when seeing taken from OpSim?) (JRP)

• FIDELITY: Added positional offset for side telescopes (JRP)

• FIDELITY: Switched to 20 screens: reduces ellipticity; correlation length; seeing variation; astrometric offsets (JRP)

• FIDELITY: Adjust optics constants based on detailed engineering flowdown breakdown & refined validation (JRP)

• FIDELITY: Update to table model of vignetting for background (incl. wavelength-dep effects) (JRP)

• FIDELITY: Fix Justin's background twilight function for current background SEDs (JRP)

• FIDELITY: Fix atmospheric dispersion bug (EP)

• FIDELITY: Remove minus sign that enforced ra going to left on images (JRP)

• FIDELITY: Fix chip rotation bug (were over-rotated) (JRP)

• EFFICIENCY: Determine if ghosts on is viable option for large runs & make default (EP)

• EFFICIENCY: Simplification of e2adc to not have so many files (JRP)

• EFFICIENCY: Generalization of metascripts for corner raft (JRP)

• EFFICIENCY: Finish Vanilla condor environment port (EP)

• EFFICIENCY: Finish new front end testing (EP)

• EFFICIENCY: OSG (Open Science Grid) job submission tested (EP)

• EFFICIENCY: Finish new file system (lsst.rcac.purdue.edu) testing (EP)

• EFFICIENCY: Bright star efficiency optimization improvements (slow simulation of star on edge problem + ghost refinement) (JRP)

• VALIDATION: Task 1A: Compare diffraction & non-diffractive screen calculation (JGJ)

• VALIDATION: Task 1B: screen convergence test; ~converges (JRP)

• VALIDATION: Task 1C: atmospheric PSF validation; agrees qualititatively with Subaru short exposures (JRP)

• VALIDATION: Task 1D: atmospheric astrometry trail; comparison with LBT seems reasonable (JRP)

• VALIDATION: Task 2A: spot diagram accuracy test is accurate to sub-micron (agrees to high accuracy) (JRP)

• VALIDATION: Task 2B: optical perturbations/tracking are in line with engineering flow down expection (NT)

• VALIDATION: Task 2C: system throughput agrees with 1777; largest error is with QE in red at 10% (non-Y-bands are accurate to <1%) (JRP)

• VALIDATION: Task 2D: monte carlo diffraction calculation agrees with Fraunhofer integral to fraction of percent (JRP)

• VALIDATION: Task 3A: analytic model & photon simulation of diffuse simulation are consistent (agrees to <0.2%) (JRP)

• VALIDATION: Task 3B: electron diffusion simulation agree with Fe 55 event topology measurements within limitations (MH)

• DOCUMENTS: Photon Simulator description & Validation Task document (JRP & JGJ)

• DOCUMENTS: Explanation of Validation Results document (JGJ & JRP)