![]() ![]() This is achieved by combining each of the 92 single fibers (46 per spectrograph) that sample sky regions away from astronomical targets into a super-sampled spectrum of the night sky background. Since the night sky is quite bright at optical and near-infrared wavelengths (especially in the vicinity of OH emission lines), the pipeline next creates a model of the background sky to subtract from the data so that the underlying galaxy or star light can be isolated. mgSFrame and mgFFrame are science data after background sky substraction and flux calibration, respectively. mgFlat, mgArc, and mgFrame are extracted flatfield, arc-lamp, and science respectively. MaNGA red camera extracted spectra for different 2d pipeline stages. The extracted science spectra are saved in mgFrame files, while the extracted flatfield and arc-lamp calibration spectra are saved in mgFlat and mgArc files respectively. The integral of each of these gaussian profiles is then recorded as the total flux for a given fiber in that row, and the spectrum of each fiber is constructed as the vector of fluxes across all rows. For each row on the detector, we model the counts in the row as the linear sum of Nfiber gaussian profiles plus a smoothly varying background to account for scattered light. Science exposures (and calibration exposures) are extracted from the two dimensional detector images using a gaussian profile fitting method. This exposure allows us to calibrate the relative wavelength-to-pixel solution of each fiber spectrum, in addition to measuring the effective spectral resolution from the width of the arc-lamp emission lines. The second calibration exposure is of a bright Neon-Mercury-Cadmium lamp, which produces bright spectral emission lines at well-determined wavelengths. This bright flatfield exposure is used to measure the precise location and width of each fiber spectrum on the detector (since they change over time due to gravitational flexure), and to calibrate the relative throughput of each fiber (since dust on the fiber bundles and various optical stresses can alter performance). The first calibration exposure is of a bright quartz flatfield lamp that uniformly illuminates every fiber with a bright background. The resulting cleaned camera images show the spectra of each fiber dispersed vertically along the detector.Įach MaNGA science exposure is preceded by two calibration exposures. (2016).Įach of the four raw camera images (blue and red cameras for each of two spectrographs) for a given exposure are preprocessed to remove quadrant-dependent biases from the four readout amplifiers, identify cosmic ray tracks by looking for features sharper than the detector PSF, and estimate the typical uncertainty in each pixel based on the raw counts and the detector read noise. MaNGA raw science data for a single blue camera. ![]() ![]() DRP Software Versions Data ReleaseĮach version of the DRP contains a userguide within the svn product detailing how to install and run the DRP and its dependent software products and data directories. The DR15 DRP lives in an svn-controlled repository mangadrp and is generally similar to both DR13 and DR14 (see differences here) for detailed information see the technical pipeline paper ( Law et al. In this page we provide a basic overview of the major steps in the MaNGA DRP as of DR15 (the DAP is described here). These science-grade data cubes are then processed by the MaNGA Data Analysis Pipeline (DAP), which measures the shape and location of various spectral features, fits stellar population models, and performs a variety of other analyses necessary to derive astrophysically meaningful quantities from the calibrated data cubes. The DRP consists of two primary parts: the 2d stage that produces flux calibrated fiber spectra from raw individual exposures, and the 3d stage that combines multiple flux calibrated exposures with astrometric information to produce stacked data cubes. The MaNGA Data Reduction Pipeline (DRP) processes the raw data to produce flux calibrated, sky subtracted, coadded data cubes from each of the individual exposures for a given galaxy. ![]()
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