Galaxy Zoo Talk

how far away are these Hubble objects?

  • liometopum by liometopum

    What is the red-shift range on these Hubble objects?

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  • Capella05 by Capella05 moderator in response to liometopum's comment.

    This is in no way way an official answer ๐Ÿ˜ƒ but after chatting with a few of the scientists I have gauged that their are a few objects with a redshift > 3, and the average is about 1.x.

    Knowing the redshift should have no impact on the way you classify the image, but it is an interesting question non-the-less. I will get one of the Scientist to post a more expansive answer ๐Ÿ˜ƒ

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  • Budgieye by Budgieye moderator

    Many redshifts on this thread on the old forum

    Redshift of Hubble galaxies, with spectra http://www.galaxyzooforum.org/index.php?topic=277967.0

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  • vrooje by vrooje admin, scientist

    As usual, our moderators are entirely correct -- there's a huge range, from a few fairly nearby things at z ~ 0.25, to a few very, very distant things at z ~ 3 and beyond. Most galaxies in these surveys are between those two redshifts. ๐Ÿ˜ƒ

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  • KWillett by KWillett scientist, admin, translator

    Here's data! The majority of the redshifts are photometric (less precise, fit to broad-band data), but some are spectroscopic. As @vrooje said, most galaxies are between 0.25 and 3.0. There are also about 800 galaxies that are detected, but have no redshift measurements yet.

    Distribution of the redshifts for the ~13,000 new HST images in Galaxy Zoo

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  • Capella05 by Capella05 moderator

    Thank you Brooke and Kyle ๐Ÿ˜ƒ

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  • JeanTate by JeanTate

    Cool! ๐Ÿ˜ƒ

    I have a question which I know how to answer (and I know the Science Team members do too ๐Ÿ˜›); it's one which some zooites might be interested in, either in working out for themselves, or reading the answer (particularly the why):

    Intro: In SDSS images, galaxy colors look ~normal, out to a redshift of ~0.35, beyond that pretty much all look some shade of orange or red (do you know why?). As Kyle says in this thread, "For GOODS, the images are made from four bands with the Hubble filters corresponding to rest-frame B, V, I, and Z." So it's no surprise that many galaxies in GOODS images have colors that do not look too alien, when compared with SDSS ones.

    Q: over what redshift range would you expect GOODS images of galaxies to have colors ~like SDSS ones (0<z<~0.35)? Assuming, of course, that the GOODS galaxies have SEDs which are ~similar to SDSS galaxies.

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  • Capella05 by Capella05 moderator

    If you know the answer, why are you asking the question???

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  • JeanTate by JeanTate in response to Capella05's comment.

    That's actually a good question, Capella05. Thank you for giving me the opportunity to answer it.

    In a GZ Talk thread that's now well over a year old, I wrote "... many zooites not only want to click/classify, but yearn to learn, and we oldbies should try harder to help." And as a good many threads here in GZ Talk attest, quite a few oldbie zooites do just that.^

    However, based on my own experience, working through challenges on one's own often leads to deeper learning than having straight-forward questions answered with straight-forward answers. And a key part of that is being able to recognize that there is much more to most (apparently) simple questions; this is one of the things which professional scientists do (I think Karen made a similar point in a thread here; I can't find it just now though ๐Ÿ˜ฆ).

    And I'd like to encourage the zooites who hang out here in GZ Talk to be bold in thinking deeper, in asking broader questions, etc. My question above is, I hope, one that connects the OP's question with the new sets of GZ images, and digs into why many of the GOODS galaxy images should have colors at least somewhat similar to those from SDSS (and for what range of redshifts that would likely be an incorrect expectation).

    Finally, why this thread? Why not any other, or its own? Because it's liometopum's thread. ๐Ÿ˜„

    I hope this helps.

    ^not only oldbie zooites of course; vrooje, for example, suggested contacting the creator of TOPCAT, to deal with a knotty problem (see How to 'unpack' the Schawinski+ (2010) FITS?); for me that was far more helpful than vrooje making the contact etc herself, and popping back with a nicely packaged solution.

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  • liometopum by liometopum

    Jean Tate understands the reason at least some of us are here... to learn, and to discover things. That is, I am here for selfish motives, and I suspect others are similarly motivated. With that said, some of us have also made efforts to promote GZ elsewhere, to encourage others to join and learn and possibly discover things too. When zooites comment "New voorwerp" you can guess they are hoping to make a discovery.

    Anyways, back the core topic. WHY are these Hubble images so poor? I had the impression that Hubble took great images, yet these are poor compared to SDSS images. The poor quality was the reason for the original red-shift question. But given the distances are about the same, I am next guessing these Hubble images are of shorter duration, and therefore have less light gathered, and that is the reason for the poor quality. Is there any truth to that idea?

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  • Budgieye by Budgieye moderator

    No problems, it is already done. In 2010, I (with other Zooite help) made an extensive list of various kinds of galaxies in Hubble images, with the various redshift z , the corresponding SDSS image, and with an analysis of the red and blue portions of the spectral chart.

    I made the thread because of the lack of information about many Hubble images, so at least we could compare our unknown galaxy with another Hubble galaxy that Zooites had worked on.

    Redshift of Hubble galaxies, with spectra http://www.galaxyzooforum.org/index.php?topic=277967.0

    I posted the link on this thread yesterday (see previous discussion) , and also on Hubble-New Images which is a featured and stickied discussion.

    Redshift of Hubble galaxies, with spectra http://www.galaxyzooforum.org/index.php?topic=277967.0 Do you want to know how far away a Hubble galaxy is? Here are some you can use for comparison.

    Hubble stars http://www.galaxyzooforum.org/index.php?topic=277967.msg476361#msg476361

    Hubble ellipticals http://www.galaxyzooforum.org/index.php?topic=277967.msg476362#msg476362

    Hubble spirals http://www.galaxyzooforum.org/index.php?topic=277967.msg476363#msg476363

    Hubble starburst galaxies http://www.galaxyzooforum.org/index.php?topic=277967.msg476364#msg476364

    Hubble clumpy galaxies http://www.galaxyzooforum.org/index.php?topic=277967.msg476365#msg476365

    Hubble OIII galaxies (with OII peak, peas) http://www.galaxyzooforum.org/index.php?topic=277967.msg476366#msg476366

    Hubble quasars http://www.galaxyzooforum.org/index.php?topic=277967.msg476367#msg476367

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  • NGC3314 by NGC3314 scientist

    The Hubble galaxies are typically much more distant than in the SDSS (z~1 compared to z~0.1 as a rough median), and the pixel scale is ~10x finer than for SDSS (depending on just what data path was used for the Hubble data). Photons become even sparser than the distance itself would suggest - the expansion of the Universe makes the average brightness drop by a factor 1/(1+z)^4 compared to nearby galaxies. These have to be sorted through to go after the underlying galaxy-evolution question, which is what changes in the structure of galaxies actually occur once we have eliminated effects in the data due to cosmic expansion, changes in filter bands with redshift, and instrumental senstitivity.

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  • williamaskew by williamaskew

    A Redshift Lookup Table, it should help a bit
    http://apod.nasa.gov/apod/ap130408.html

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  • JeanTate by JeanTate in response to Budgieye's comment.

    This is great work Budgieye, and when we transition to the new Talk I hope there will be a way to capture at least the key parts, without someone having to re-type/re-enter everything.

    There have been quite a few different sets of Hubble images, here in GZ, for us zooites to classify; from memory (this is surely an incomplete list):

    • one with a 'yellow and blue' color scheme
    • a similar one, with an 'orange and blue' color scheme (GOODS?)
    • a set of images in which the 'yellow' and 'blue' were switched (i.e. the color mapping changed from chromatic1 to reverse-chromatic)2
    • 3-color CANDELS images, with chromatic color mapping
    • today's GOODS (and CANDELS), in which the GOODS images have a different color mapping, possibly not even chromatic (see the New GOODS GZ images, a science question thread).

    So even without considering redshift, images of a nice face-on spiral (say) in each of these different versions will have different colors. ๐Ÿ˜ฎ

    1a chromatic mapping preserves the wavelength order; shortest -> B, mid -> G; longest -> R

    2from memory, we weren't told of this switch, but several oldbie zooites picked it up immediately

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  • Budgieye by Budgieye moderator

    I suppose more work could do done on it. As you say, there are several different colour schemes. Also, I never found examples of some objects, eg peas at different distances. As well, the chart could be made into a smaller and more usable from.

    I already have a project going. It will take me months to finish the Index for Talk http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb so that we don't end up doing things that have already been done, like this Hubble chart.

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  • JeanTate by JeanTate in response to liometopum's comment.

    If the several published results of various surveys of citizen scientists are accurate, you are far from alone, liometopum! ๐Ÿ˜ƒ

    Jean Tate understands the reason at least some of us are here... to learn, and to discover things. That is, I am here for selfish motives, and I suspect others are similarly motivated. With that said, some of us have also made efforts to promote GZ elsewhere, to encourage others to join and learn and possibly discover things too.

    Here are a couple of write-ups: Who Are The Zooniverse Community? We Asked Themโ€ฆ (Zooniverse blog post, not even a month ago); Who, How, and Why? (notes on a CosmoQuest survey, a couple of years' old now). And here's Raddick+ (2013) ("Galaxy Zoo: Motivations of Citizen Scientists") that you'll see referred to.

    Yes, there are certainly many zooites who are still 'at school'1; equally, there are many who have university degrees, including a lot with PhDs; in fact, zooites with university degrees are heavily overrepresented, compared with the US internet population ๐Ÿ˜ฎ

    Zooites with past or present STEM2 careers/jobs also seem to be over-represented, cf the average population.

    Consistently, across just about all surveys, zooites report this about their motivation (from TTFN's Zooniverse blog post):

    When asked why they take part in Zooniverse projects we find that the most-common response (91%) is a desire to contribute to progress. How very noble. Closely following that (84%) are the many people who are interested in the subject matter. It falls of rapidly then to โ€˜entertainmentโ€™, โ€˜distractionโ€™ and โ€˜otherโ€™. We are forever telling people that the community is motivated mainly by science and contribution, and for whatever reason they usually donโ€™t believe us.

    Here are a couple of comments from Discuss, in Snapshot Supernova (source):

    [AstroMax] I would also like to thank all the zooties whom helped others or participated in this project. You are the lifeblood to these projects and they couldn't be done without your motivation.

    [HuntingSupernova] there were a lot of fantastic community members who went above and beyond just classifying, some wrote code etc and had really valuable ideas to contribute

    Myself, I not only enjoy clicking-to-classify (Radio Galaxy Zoo is my current fave), but also helping my fellow zooites understand and learn about the astronomy that these Zooniverse projects are contributing to. Following the lead of people like vrooje, sometimes I like to helping others learn and understand by asking questions, hopefully building on their motivation so they become more active learners.

    Can we clone you, liometopum? ;-D

    1 As the various surveys did not include people whose self-declared ages were under 18, we cannot know how many younger zooites there are

    2 "Science, Technology, Engineering, Mathematics", an acronym common here in the US; I think there are similar ones in other countries

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  • Capella05 by Capella05 moderator

    Quote from @JeanTate

    Myself, I not only enjoy clicking-to-classify (Radio Galaxy Zoo is my
    current fave), but also helping my fellow zooites understand and learn
    about the astronomy that these Zooniverse projects are contributing
    to. Following the lead of people like vrooje, sometimes I like to
    helping others learn and understand by asking questions, hopefully
    building on their motivation so they become more active learners.

    Hi Jean, I really hope you extend your statement to include other volunteers such as @budgieye and @ElisabethB and @C_cld who spend an incredible amount of time helping the Zooites, whilst trying to encourage further interest.

    Also, this discussion is about redshift and the images - if you would like to discuss the motivation of volunteers, I would suggest creating a new one ๐Ÿ˜ƒ

    Cheers ๐Ÿ˜ƒ

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  • williamaskew by williamaskew

    Get out the cane!

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  • Capella05 by Capella05 moderator in response to wtaskew's comment.

    @wtaskew

    Get out the cane!

    That's a bit unfair - JeanTate is more than welcome to create another discussion - but the original poster has specifically requested that the thread reverts back to his/her original question - redshift and the quality of the images.

    Anyways, back the core topic. WHY are these Hubble images so poor?

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  • Budgieye by Budgieye moderator in response to liometopum's comment.

    These galaxies are very far away. The Hubble images are much better than the SDSS images. If you look at

    Redshift of Hubble galaxies, with spectra http://www.galaxyzooforum.org/index.php?topic=277967.0

    there are comparison images there, with Hubble and SDSS side by side. Often, SDSS has nothing except a blur where Hubble has a galaxy.

    These clumpy galaxies are extremely distant, Many of the Hubble images that we see published are of relatively "nearby" galaxies.

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  • ramberts by ramberts in response to Budgieye's comment.

    I've looked some up that show great detail as well on spirals and edge-ons, SDSS looks like blob with this survey every time I plugged in the coordinates, and sometimes it's not even in the SDSS database at all. But I do agree there's a lot of blob with the Hubble images, but when you get to one with fun features it's worth going through IMO.

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  • vrooje by vrooje admin, scientist in response to liometopum's comment.

    Anyways, back the core topic. WHY are these Hubble images so poor? I had the impression that Hubble took great images, yet these are poor compared to SDSS images. The poor quality was the reason for the original red-shift question. But given the distances are about the same, I am next guessing these Hubble images are of shorter duration, and therefore have less light gathered, and that is the reason for the poor quality. Is there any truth to that idea?

    It's as @Budgieye and @NGC3314 say -- the distances aren't the same at all. Hubble images generally have much longer exposure times, but they are looking much farther than the SDSS. Also, the telescopes are about the same size in terms of mirror diameter, so they collect about the same amount of light, but the design of the surveys are really different.

    Hubble is great at taking really deep exposures of smaller patches of the sky compared to ground-based surveys like the SDSS. The SDSS covers about two-thirds of its visible sky (from horizon to horizon). The GOODS fields, on the other hand, are so small on the sky that you could cover them up with your thumbnail held out at arm's length. Yet there are thousands of galaxies in each field, and Hubble's resolution is so great that it can resolve enormous detail where most ground-based telescopes would only see a fuzzy blob. Most of those galaxies, even the nice and resolved ones, are much smaller on the sky than the apparent width of a single human hair held at arm's length.

    Incidentally, Hubble is great at getting images of much nearer galaxies with incredibly fine resolution. Those are the pictures we're used to seeing in the news! Check out hubblesite.org for some of those, and then have a look at the data from the PHAT survey, the largest survey (in terms of telescope time) ever using Hubble. A lot of our volunteers are very, very familiar with PHAT images! ๐Ÿ˜ƒ That survey was resolving individual stars in Andromeda, which is a testament to Hubble's incredible resolution.

    No matter what the technology, scientists will always push it to its limit, and Galaxy Zoo is doing that as much as every other astronomical project. There were little fuzzy blobs in SDSS too:

    enter image description here

    and now that we can resolve the SDSS blobs with Hubble, we're pushing much further out until all we can see with Hubble is a blob. The Hubble blob limit happens to be so far out that we're looking at the Universe as it was when it was only a few billion years old, much farther than with SDSS, but there's still farther to go. Once we have the next generation of super-high-resolution telescopes, we'll push those to their limits too. It's just to try and squeeze every last drop of science out of the data!

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  • c_cld by c_cld

    Minor processing changes between Zoo3 and current GZ

    example in GOODS_N

    AHZ300006q 50001186 26260 AGZ00081ea

    AHZ30000v8 50007533 18257 AGZ00080ae

    AHZ300008q 50001592 23986 AGZ0008123

    In GOODS-S

    AHZ40006za 90043167 15007 AGZ00084cr

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  • dj_tjitso by dj_tjitso in response to C_cld's comment.

    That first image, could that be gravitational lensing?

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  • vrooje by vrooje admin, scientist

    Thanks, @C_cld, those are lovely examples that show how the view changes when moving from colors based on 2 filters to 4! ๐Ÿ˜ƒ

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  • liometopum by liometopum

    I see some people can find the redshifts, and even discuss them, comparing which objects are the farthest away. I know we don't need redshift for classifying, but I REALLY WANT TO KNOW what the redshifts are. Where can we find that data? I have been looking, but so far without luck.

    And thanks for all this great information from everyone. It is very clear now what is going on with the image quality.

    Vrooje... Thanks for posting the comparison image of a spiral using SDSS and Hubble. I'd seen those 'tails' before, but never really understood what they might be.

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  • ramberts by ramberts

    It's a beta, and I've seen a lot that don't seem right for the ones over 3 RS, but when you are at the end of the classification process to the, "DISCUSS
    Would you like to discuss this object?" click yes. The next page there is a "Open in Tools" button on the top right side next to the social media buttons.

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  • liometopum by liometopum

    THANKS! It is so much more fun now. And I can use Aladin to check, and it works. Thanks again!!

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  • Budgieye by Budgieye moderator

    The redshifts are also usually on NED, which you can get to from Galaxy Zoo examine, which is under the image.

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  • Budgieye by Budgieye moderator in response to C_cld's comment.

    Great comparison, C-cld, The new GOODS N images have more information and are easier on the eye.

    How did you find the two images? An excellent memory and looking through the old posts in the forum? Or you understand the databases?

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

    I used visual memory of old Zoo3, although I'm frustrated not having access to tables of Zoo IDs with Ra, Dec for matching purposes...

    Another pain is Url's changes.

    @ Zookeepers, @vrooje Why such hindrance of old catalog information put upon volunteers?

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