Optical Surveys


The Sloan Digital Sky Survey has created the most detailed three-dimensional maps of the Universe ever made, with deep multi-color images of one third of the sky, and spectra for more than three million astronomical objects. Learn and explore all phases and surveys—past, present, and future—of the SDSS.

It’s just 20 years old. See The first high-z quasar of SDSS was observed by Xiaohui Fan and Micheal Strauss on the Thanksgiving morning, 1998.


The Dark Energy Survey (DES) is a visible and near-infrared survey that aims to probe the dynamics of the expansion of the Universe and the growth of large-scale structure. The survey uses the 4-meter Victor M. Blanco Telescope located at Cerro Tololo Inter-American Observatory (CTIO) in Chile. It uses g, r, i, z, and Y bands. DECam has one of the widest fields of view (2.2-degree diameter) available for ground-based optical and infrared imaging.

It can do: supernovae cosmology, BAO, galaxy cluster finder, weak lensing, etc.

I uses DECaLS (DECam Legacy Survey). Dustin Lang made a wonderful skyview map. Currently DES is only a photometric survey.


The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is led by the astronomical communities of Japan and Taiwan, and Princeton University. It’s a photometric survey for 1400 square degrees using Hyper Suprime-Cam mounted on 8.2m Subaru Telescope. It is now the seriously kicking-ass survey for galaxies and cosmology.

The main science goals contain: weak lensing cosmology, high-z galaxies, general galaxy formation and evolution (like stellar-halo connection), etc.

HSC data entrance: https://hscdata.mtk.nao.ac.jp/hsc_ssp/

SQL: https://hscdata.mtk.nao.ac.jp/datasearch/

Image cutout: https://hscdata.mtk.nao.ac.jp/das_quarry/dr2.1/

PSF model: https://hscdata.mtk.nao.ac.jp/psf/6/

SkyMap: https://hscdata.mtk.nao.ac.jp/hsc_ssp/dr2/s18a/hscMap

HSC Public DR2: https://hsc-release.mtk.nao.ac.jp/doc/

  1. Header: ra, dec, layer (such as s18a-wide), z_spec, z_phot, etc.
  2. i-band:
    • image
    • image_header
    • hsc_mask (This is the binary mask produced by HSC pipeline)
    • hsc_mask_header
    • variance
    • variance_header
    • mask (This is the mask used for ELLIPSE)
    • ell_free
    • ell_fix
    • info
      • img_size: size in pix, such as [1000, 1000]
      • m10 or m100
      • bad_mask: if the center of galaxy is obscured by mask
      • mean_interval: such as 20 kpc - 50 kpc
      • mean_e: mean ellipticity within mean_interval
      • mean_pa: mean PA within mean_interval
      • global_bkg: the background measured by sep after masking out satellittes
      • global_rms: the rms measured by sep
      • mean_skyobj: the mean value of skyobj within [1 arcmin, 3 arcmin] and 8.4 arcsec.
  3. r-band
  4. g-band


  • Canon 400mm f/2.8 IS II lens + SBIG STF-8300M CCD
  • Aperture: D = 134 mm
  • CCD: 3326 × 2504 pixels, 43% efficiency in R and G, 2.8”/pixel, 2.6 deg*1.9 deg FOV.
  • Read noise: 10 electrons. Gain: 0.37 electrons/ADU.
  • Dark noise: 0.04 electrons/s.
  • Tracking error: rms = 1.5”.

Redshift surveys


Transient Surveys


Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is a well calibrated telescope for transient surveys.

IFU Surveys

MaNGA survey

The current data release is v2_1_2, containing ~2700 galaxies with redshift ranges from 0 to 0.15.

SAMI survey

CALIFA survey