Galaxy Zoo Talk

Big object it is not recognised by system

  • RichardHB by RichardHB


    This big object it is not recognised by system. It reminds me a little the Crab Nebula.

    1. (

    What could be the reason?



  • NGC3314 by NGC3314 scientist

    As you may know, that's the bright irregular galaxy NGC 4449 (about the closest to a rectangular galaxy I know of). Very large and bright galaxies confused the SDSS automated measurements (since their outer regions could be mistaken by the algorithms for a variation in sky brightness), so in the interest of more uniform statistical data, areas around such large and bright galaxies were simply skipped in later SDSS data releases. (This makes it weird to find the SDSS images for some of them - you kind of have to sneak up on a location from one side to use the image-retrieval tools from Explore.)


  • Budgieye by Budgieye moderator

    image of big object


  • JeanTate by JeanTate

    I came across yet another of these yesterday, NGC 4753:

    enter image description here

    I always find it odd that some well-away parts are devoid of photometric objects (POs), yet the algorithms are quite happy to pick up other POs deep inside the bright optical glow ...