About NIRSPEC Extracted Spectra
In addition to the raw echellograms, KOA serves extracted spectra for NIRSPEC data acquired in the high dispersion mode. These spectra have been generated with an automated Python-based pipeline, the NIRSPEC Data Reduction Pipeline (NSDRP), which is freely available for download from GitHub. NSDRP documentation describes the pipeline, its usage, the data products it creates, and limitations on its applicability.
The NSDRP performs automated order location and tracing, flat fielding, background subtraction, spectral extraction, and wavelength calibration for science files where a flat field has been acquired with the same instrument configuration. Broadly speaking, the NSDRP is optimized for point sources, but extended objects are accommodated if there is a discernible peak in the spatial intensity profile. (Because this peak is found by averaging an order in the spectral dimension, it can sometimes be found even without a discernable continuum).
The NSDRP can reduce a wide range of echelle and cross disperser angles and all of the high-resolution slits. It works best on data that have the following characteristics:
- A single point source in the slit
- Reasonably bright targets with detectable continuum
- Are acquired with the NIRSPEC-1 through NIRSPEC-7 filters
- Well-separated orders without overlapping
- Sufficient exposure times (> 30s) with detectable sky lines
The extracted spectra are intended as a browse product to provide the user with a sense for the quality and content of the data. KOA cannot guarantee that the spectra are suitable for science analysis and recommends that users extract spectra themselves, with particular attention to the type of data under study (e.g. point sources vs. extended sources etc).
Data products include flux and noise spectra and spatial profiles for each order and wavelength calibration line identification tables in ASCII and FITS formats. The spatial profile plots and the log files include estimates of a signal-to-noise ratio (SNR), found by comparing the spatial peak height with background levels, and a peak width, found by Gaussian fitting. A detailed description is given in the NIRSPEC Extracted Data Products Specification . The data products, where generated, are packaged for download as requested by the user. Static images of the products in PNG format are linked from the results tables returned by archive queries.
Given the limitations of the software discussed above and the automated processing of highly variable datasets, the NSDRP has successfully extracted spectra from ~90% of the high dispersion mode data aquired with the NIRSPEC-1 through NIRSPEC-7 filters.
Please acknowledge the use of KOA by including this text in your publications:
This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with the National Aeronautics and Space Administration.
Please also acknowledge the PI(s) of datasets that have been obtained through KOA, and please contact the KOA Help Desk if you publish archival data.
If your research uses data reduced by the DEIMOS DRP or MOSFIRE DRP, please use the PypeIt Citation.
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The Keck Observatory Archive (KOA) is a collaboration between the NASA Exoplanet Science Institute (NExScI) and the W. M. Keck Observatory (WMKO). NExScI is sponsored by NASA's Exoplanet Exploration Program, and operated by the California Institute of Technology in coordination with the Jet Propulsion Laboratory (JPL).
