NEID DRP Version History

Versioning Style

The NEID Data Reduction Pipeline uses Semantic Versioning of format X.Y.Z (Major.Minor.Patch). The pipeline team does not recommend mixing processed data from different minor versions. Within a minor version, data from different patch versions is compatible.

Upon release of a new Major or Minor version, all NEID data will be reprocessed. Upon release of a new Patch version, only data affected by the patched code will be reprocessed.

Release History

Minor version v1.4.0 was released in December 2024 and contained substantial updates to the algorithms used to derive the wavelength calibrations, nightly drift measurements, CCFs, and other derived products. This verison incorporated vetting the LFC exposures based on the quality of the fits to the ensemble of LFC lines. This has increased the reliability of the derived wavelength calibrations.

Patch version v1.4.1 was released in February 2025 and contains the following significant changes:

  • Handle calibration sequences when only a single LFC passes quality control checks

  • Handle a bug where missing flat fields result in zeros for part or all of the extracted spectrum flux

  • Changes the blue wavelength edge of the LFC that is used for wavelength solutions and drift correction after installation of the new PCF in August 2024 to be order index 40 (echelle order 134) @ 458nm. In v1.4.0 this was index 30 (echelle order 144) @ 426nm. See below for more details.

For details on versions v1.3.x and earlier, see the CHANGELOG.

LFC Calibrations affecting v1.4.0

The week of August 24, 2024, the LFC was upgraded with a new Photonic Crystal Fiber (PCF) that provided light blueward of 510nm. This represented a significant upgrade to NEID and facilitated using spectral orders significantly bluer than previously available to derive per-night wavelength solutions and the nightly instrument drifts. In the future, the expanded LFC range will be used to create new master wavelength solutions (used during fallback nights) and map the LSF bluer than it currently is. DRP v1.4.0 was released using light down to 426nm for the LFC-based wavelength solution and drift correction (spectral order index 30, echelle order 144). However, over the course of the 2024B semester the PCF spectral envelope degraded, and light at the bluest wavelengths became too faint to be suitable for fitting the individual LFC modes. DRP v1.4.1 changed the blue LFC cutoff to 458nm (spectral order index 40, echelle order 134).

The choice of cutoff wavelength affects the overall zero point of the derived RVs: making a change would introduce a new RV Era. Consequently, to avoid this complication we intend to reprocess all 2024B data using v1.4.1. Data taken prior to this semester used an older style PCF that produced light only down to ~510nm, so the change at the beginning of 2024B necessarily forced the introduction of a new era. Data prior to 2024B continues to use the ~510nm cutoff for LFC-based wavelength solutions and drift measurements. Consequently, such data is agnostic to whether it was processed with v1.4.0 or v1.4.1 and can safely be intermixed.

Last Updated: 2025-02-18, DMK