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PS1 has taken X images from 2010 to 2015. These images are detrended, astrometrically calibrated, warped, and stacked. Difference images are created by subtracting single epochs from the stacked images

Contents

  • Warped Single Epoch Images
    •   Tessellation - projection cells, sky cells
  • Stacked Images (Armin)
    •  ->Tesselation
  • Difference Images (Armin)
  • Image Headers
  • Image Anomalies - glints, bad pixels, background errors
  • Mask Image (Armin)
    • -> Data Quality Flags
  • Weight Image

Raw Images

After an exposure is taken at the summit, the raw image files of the 60 OTA CCDs are corrected for persistence issues and then handed over to the IPP processing for further analysis. The PS1 public archive does not provide these images.

Camera Images

The camera images are created by detrending the raw images (e.g., masking, bias subtraction, flat fielding), and applying an astrometric and photometric calibration. The PS1 public archive does not provide these images.

Warps

Warps are the result of resampling and realigning the camera images onto regular areas (called skycells) on the sky (basically aligned N-S, E-W). How this is done depends on the particular tessellation. Different surveys may have different tessellations. A warp will generally consist of several different OTAs, therefore there are gaps between the OTAs, as well as the smaller gaps between the cells. Warps are astrometrically and photometrically calibrated. These images can be accessed and downloaded through the PS1 archive.

Stacks

Stacks are the 'optimal' combination of multiple warps on the same skycell. For the 3pi this may only be 10 or so warps, but for the Medium Deeps it can be several hundred. Stacks are also astrometrically and photometrically calibrated. These images can be accessed and downloaded through the PS1 archive.

Difference Images

Difference images are created by subtracting a warp from another image, in general the stack, after matching the PSFs and normalization. All static objects like galaxies and constant stars are subtracted out, and only the excess flux from the different epochs is left. Even though the differences images are not stored on disk, they can be created, and it is planned to make them accessible through the PS1 at a later release.

Image:NGC_894

3pi Survey
Chip Images
Warp Images 
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