Sky Spectra DR1 Catalog¶
Overview¶
This catalog for DESI DR1 provides over 9,000 sky spectra, accompanied by detailed metadata, derived from the DESI spectroscopic pipeline. These spectra are essential for understanding the sky background, enabling the identification of natural and artificial emission features, and improving the analysis of astronomical targets. The metadata include comprehensive observational parameters, such as exposure time, airmass, Galactic extinction, moon and sun positions, and atmospheric conditions, offering a rich context for each spectrum. The primary purpose of this catalog is to be a resource for studies of atmospheric phenomena, light pollution, and calibration.
Data Access¶
Data URL: https://data.desi.lbl.gov/public/dr1/vac/dr1/skyspec
NERSC access:
/global/cfs/cdirs/desi/public/dr1/vac/dr1/skyspec
Documentation¶
Files¶
sky_spectra_vac_v1.fits- Catalog of sky spectra and associated metadatabasic_plotting.ipynb- Example Jupyter notebook including simple plots.basic_plotting.html- HTML rendering of the example Jupyter notebook.
Data Model¶
Contents¶
| EXTNAME | FORMAT | UNITS | DESCRIPTION |
|---|---|---|---|
| Primary HDU | - | Primary HDU is empty and serves as a placeholder. | |
| WAVELENGTH | FLOAT64[7781] | Angstrom | Wavelength array covering the range from 3600-9824 A with 0.8 A spacing. |
| FLUX | FLOAT32[9176,7781] | 10^-17 erg/s/cm^2/A/arcsec^2 | Flux measurements for 9176 samples and 7781 wavelengths. |
| METADATA | TABLE | - | Metadata describing each observation (see below for column descriptions). |
METADATA¶
| Name | Type | Units | Description |
|---|---|---|---|
| NIGHT | INT32 | - | Observing night in YYYYMMDD format |
| EXPID | INT32 | - | Unique exposure ID |
| TILEID | INT32 | - | Unique DESI tile ID |
| TILERA | FLOAT64 | deg | Right Ascension of tile given in fiberassign file |
| TILEDEC | FLOAT64 | deg | Declination of tile given in fiberassign fileDEC of tile given in fiberassign file |
| MJD | FLOAT64 | d | Modified Julian Date of observation |
| EXPTIME | FLOAT64 | sec | Actual exposure time |
| AIRMASS | FLOAT64 | - | Airmass during the observation, derived from exposure file headers |
| EBV | FLOAT64 | mag | Galactic extinction E(B-V) from SFD maps |
| SEEING_ETC | FLOAT64 | arcsec | Estimated seeing (FWHM) as measured by the Exposure Time Calculator (ETC) |
| TRANSPARENCY_GFA | FLOAT64 | - | Transparency from offline GFA analysis (can exceed 1) |
| SEEING_GFA | FLOAT64 | arcsec | Seeing FWHM measured by the offline GFA analysis |
| SKY_MAG_G_SPEC | FLOAT64 | mag/arcsec^2 | Sky AB synthethic magnitude from the spectroscopy, for the decam g filter (no atmosphere) |
| SKY_MAG_R_SPEC | FLOAT64 | mag/arcsec^2 | Sky AB synthethic mangitude from the spectroscopy, for the decam r filter (no atmosphere) |
| SKY_MAG_Z_SPEC | FLOAT64 | mag/arcsec^2 | Sky AB synthethic mangitude from the spectroscopy, for the decam z filter (no atmosphere) |
| MOONFRAC | FLOAT64 | - | Fraction of the Moon illuminated |
| MOONALT | FLOAT64 | deg | Altitude of the Moon |
| MOONSEP | FLOAT64 | deg | Angular separation between the Moon and the pointing direction |
| SUNALT | FLOAT64 | deg | Altitude of the Sun |
| SUNSEP | FLOAT64 | deg | Angular separation between the Sun and the pointing direction |
| OBSALT | FLOAT64 | deg | Altitude of the pointing direction |
| OBSAZ | FLOAT64 | deg | Azimuth of the pointing direction |
Contact¶
Contact Matthew Dowicz or David Kirkby for questions about this catalog.