Galaxy Zoo Talk

why has the images changed so much in a short period of time ?

  • sat666leg by sat666leg

    mystery. ? merger and overlap.?
    the central elliptical has signs of a merger / everything is hot not just the hydrogen and DECals DR1. shows 2 Zs at that location Z=0.117. ? in the original image while classifying there was signs of a little tail of hot matter from the top left of the centred galaxy / bottom left of the top galaxy. both galaxies seem to have an undisturbed halo, the time difference between the image taken in SDSS and DECals is aproximatley 10 years, not enough to explain the movement of these 2 galaxies over time. there is no spectra on the upper galaxy or Z that i can find..i would appreciate any help in those area's. the only explanation that i can think of for the movement to be so great at this time is an overlap. and that the distances between the overlap be great in depth.

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  • Budgieye by Budgieye moderator

    The images look the same to me. The SDSS look fuzzier, and the galaxies seem larger.

    enter image description here enter image description here

    DECaLS and SDSS

    http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?ra=349.90610813833575&dec=-1.3118533356449604

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  • c_cld by c_cld

    @sat666leg

    All these images are superposition of 3 gray images from two telescopes in different wavelengths bands and "seeing". Their pipeline processing is a long way of cleaning, stretching, scaling and aligning...

    Then they are colorized, stacked and compressed in .jpeg files for your browser viewer. That's why you can't jump so easily on conclusions of astronometrical displacements!

    The sharpness of images depends greatly on the processing tasks. See a DECaLS DR2 view

    http://legacysurvey.org/viewer/jpeg-cutout-decals-dr2/?ra=349.90611&dec=-1.31185&size=512&pixscale=0.08789

    DR2 45" on a side

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  • Budgieye by Budgieye moderator

    Much better explanation. 😃 😃

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  • ElisabethB by ElisabethB moderator

    Thank you Claude ! 😄

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  • sat666leg by sat666leg in response to c_cld's comment.

    thanks, thats great i understand that.
    .i always poke around at things i don't quite have a full explanation or understand. its how i learn.
    thanks for your time. budgieye and B your included in that..
    ( i'd put a happy face here but i still need to find how to do that ?.)
    CHEERS.

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