Other articles

  1. RGB tile drawing in hips package

    The hips package now supports RGB tile drawing. To make this possible, the output image dimensions had to be altered according to the following configuration:

    The output image shape is two dimensional for grayscale, and three dimensional for color images:

    • shape = (height, width) for FITS images with one grayscale channel …
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  2. Parameterized testing using Pytest

    Pytest provides a feature for parameterized testing in Python. The built-in pytest.mark.parametrize decorator enables parametrization of arguments for a test function. This allows the user to compare the values for input and output.

    Here is a typical example which shows its usage:

    get_hips_order_for_resolution_pars = [
        dict(tile_width=512, resolution=0 …
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  3. Creating custom decorators in Python 3.6

    In the hips package, often data has to be fetched from remote servers, especially HiPS tiles. One way to cut back on the queries was by introducing the hips-extra repository. This contains HiPS tiles from various HiPS surveys. This allows us to quickly fetch tiles from local storage, which makes …

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  4. HiPS tile drawing

    One of the major part of the hips project is being able to draw HiPS tiles onto a larger sky image. The most important part in this is using projective transformation for computing and drawing a HiPS tile at the correct location. The discussion below is for the tile containing …

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  5. An introduction to coordinate systems used in Astronomy

    Before moving on to the coordinate systems, listed below are some common measures used in astronomical studies.

    RA / DEC

    RA (right ascension) and DEC (declination) are the longitudes and latitudes of the sky. RA corresponds to east/west direction (like longitude), while Dec measures north/south directions, like latitude.

    WCS …

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