MVIC Data Processing for New Horizons KEM 2
Dive into the review of the first version of the New Horizons KEM 2 Ralph/Multispectral Visible Imaging Camera (MVIC) data set. Explore the accessibility, labels, FITS headers, and pipeline processes involved in handling the data for analysis and calibration.
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Presentation Transcript
RALPH/MVIC DATA REVIEW NEW HORIZONS KEM 2 V1.0 BRYAN HOLLER (PRIMARY) PDS SBN REVIEW FEBRUARY 10, 2025
DATA SET DESCRIPTION First version of the New Horizons KEM 2 Ralph/Multispectral Visible Imaging Camera (MVIC) data set MVIC is the color imager on New Horizons and of the Ralph instrument, the other half is the Linear Etalon Imaging Spectral Array (LEISA) 45 total observations 2 observations of NGC 3532 (2023-08-09) 1 observation of Saturn (2023-08-09) 6 observations of Uranus (2023-09-16 2023-09-17) 36 observations of Neptune (2023-09-22 2023-09-23) Instrument 3-letter abbreviation is populated with MVI for all 45 entries in the seq_mvic_kem2.lblx file, indicating that no observing sequences were skipped Would have been N/A if skipped
DATA ACCESSIBILITY Total of 180 raw and 180 calibrated files 45 images in each of the RED, BLUE, NIR, and CH4 filters All raw and calibrated files accessed with astropy.io.fits No issues opening any of the files Minor issue: All file extensions (raw, cal, calibration files) are .fit instead of .fits (see next slide)
DATA LABELS & FITS HEADERS The .lblx files were examined using the PDS4 Viewer FITS headers were examined using astropy.io.fits and ds9 No issues accessing labels or headers Minor issue: Header keyword FLATNAME lists the flat file used for the calibration as .fits, but the file itself has .fit
MVIC PIPELINE Subtract a bias value from every pixel in the Level 1 raw file according to the filter used (RED, BLUE, NIR, CH4) FILTER header keyword, bias values provided in SOC document for SIDE0 For time-delay integration (TDI) exposures (of which all of these are), the flats are 1D and must be applied to each row of the data separately Use the Level 2 SOC-calibrated file to determine which flat was used FLATNAME header keyword SOC-calibrated data have all pixels outside the illuminated region set to -1, so use these data to create a mask for the manually calibrated data Calculate residuals between manually calibrated and SOC-calibrated files
CALIBRATED DATA COMPARISON EXAMPLE Manually calibrated SOC calibrated (mc0_0557172410_0x536_sci.fit) Difference (SOC - manual)
SCIENCE PRODUCT COMPARISON Only related publication is Grundy et al. (2024), which is an LPSC abstract No photometry reported in the abstract, nothing to compare against Many additional steps to make the Level 2 Ralph/MVIC data science quality (distortion correction, unit conversion, etc.), but that level of processing is not made available as part of this delivery Any further comparison is therefore outside the scope of this PDS review Steps described in the SOC document but they require additional external tools and assumptions about the underlying spectrum, etc.
SUMMARY MAJOR ISSUES None MINOR ISSUES File extensions are all .fit but this results in a mismatch between the file names and header keyword values, specifically for the FLATNAME keyword 2 possible mitigations: (1) change all file extensions to .fits or (2) update the FLATNAME header keyword value in the Level 2 files
