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Sloan Digital Sky Survey DR18 Celestial Object Properties
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About
Data details 100,000 observations obtained from the Sloan Digital Sky Survey (SDSS) Data Release 18 (DR18). The primary purpose of this collection is for the classification of celestial objects, with each entry assigned a label: a STAR, a GALAXY, or a QSO (Quasi-Stellar Object or Quasar). The observations are quantified by 43 attributes, providing detailed information about the objects' location, brightness (photometric properties), and morphology. This dataset is a highly suitable resource for advanced astrophysics research and for developing machine learning algorithms for automated object identification.
Columns
The dataset contains 43 attributes describing the celestial objects:
- Objid, Specobjid: Unique identifiers for the observed object in the PhotoObjAll and SpecObj tables, respectively.
- ra, dec: J2000 Right Ascension and Declination, defining the angular position of the object in the sky.
- redshift: The final calculated redshift of the celestial object.
- u, g, r, i, z: Magnitudes derived from the better of DeVaucouleurs or Exponential fits across the five photometric bands (ultraviolet, green, red, infrared, and near-infrared).
- psfMag_u to psfMag_z: Magnitudes measured using the Point Spread Function (PSF), which quantifies brightness by approximating objects as point sources. Lower magnitudes indicate brighter objects.
- run, rerun, camcol, field: Observational parameters, detailing the specific run period, reprocessing number, camera column number, and field number (the portion of the sky imaged during a single exposure).
- plate, fiberID: Identifiers for the physical glass plate and the optical fiber used to gather light for spectrographic analysis.
- mjd: Modified Julian Date, tracking the precise time of the observation. This is the number of days passed since midnight, 17 November 1858.
- petroRad_u to petroRad_z: Petrosian Radii for the five bands, serving as a measure of an object's size, calculated based on the petrosian flux profile.
- petroFlux_u to petroFlux_z: Petrosian Fluxes for the five bands, describing the total amount of light emitted from the celestial objects.
- petroR50_u to petroR50_z: Petrosian half-light radii, measuring the radius enclosing half of the total emitted light in each photometric band.
- expAB_u to expAB_z: Axis ratios resulting from exponential fits to the light profile, providing morphological features that describe the shapes of celestial objects like galaxies.
- class: The target classification label, specifying the object type as STAR, GALAXY, or QSO.
Distribution
The data is presented in a tabular structure, typically distributed as a CSV file (SDSS_DR18.csv) with a size of 36.25 MB. The dataset features 100,000 records, each defined by 43 distinct attributes. Quality metrics indicate that all records are valid, with zero missing entries and zero mismatched entries across the 100.0k observations.
Usage
This dataset is ideal for several advanced applications:
- Developing high-accuracy machine learning models for multiclass classification to automatically identify stars, galaxies, and quasars.
- In-depth analysis of the photometric properties of celestial bodies, including the study of brightness, colour indices, and spectral energy distribution.
- Characterizing the morphology and size evolution of extended objects, such as galaxies, utilizing parameters like axis ratios and Petrosian radii.
- Research into the temporal and spatial characteristics of the SDSS survey, using celestial coordinates and the Modified Julian Date.
Coverage
The data is derived from the Sloan Digital Sky Survey Data Release 18 (DR18) observations. The angular scope is established using J2000 celestial coordinates (Right Ascension and Declination). The temporal range is tracked using the Modified Julian Date (mjd). Observations are further defined by the specific survey execution parameters, including run, camera column (camcol), and field numbers, which specify the segments of the sky observed during the campaign.
License
CC BY-SA 4.0
Who Can Use It
- Data Scientists and Machine Learning Engineers: To train and evaluate sophisticated classification algorithms for astronomical pattern recognition.
- Astrophysicists and Astronomers: For performing detailed observational data analysis, studying light emission across different wavelengths, and examining object distribution.
- Students and Educators: As a high-quality, real-world source for teaching statistical analysis, machine learning applications, and fundamental astrophysical concepts related to large-scale sky surveys.
Dataset Name Suggestions
- Sloan Digital Sky Survey DR18 Celestial Object Properties
- SDSS Classification Data: Stars, Galaxies, and Quasars
- Astronomy Object Identification Dataset (DR18)
Attributes
Original Data Source: Sloan Digital Sky Survey DR18 Celestial Object Properties
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