Disk Detective Talk

Basic Black Belt Tips

  • jdebes by jdebes scientist, admin

    First off, we want to find stars that are by themselves so that the only source of their IR light is due to dust, rather than a galaxy or nearby visual companion. A good candidate is something that looks round (the size can vary, but it should look like a round, fairly concentrated point of light), stays pretty close to the cross hairs in all the images, and doesn't have anything near it within the red circle. If something passes all of those tests, you have a good candidate!

    Sometimes you run into hiccups in our system--some examples are in the posts below.

    Some additional Black Belt Tips:

    1. SEDs If you're here, you've figured out how to click on the "Discuss" icon
      in the classification page. You'll see a picture of the object you're working on. Click on the SED pane below the image, to see how the object's flux, or amount of light at a given wavelength changes. The points come from 2MASS and WISE. Over time these may get updated. For now, don't worry too much about how they look--there's a blog post about Spectral Energy Distributiions, to help you spot really promising candidates.
    2. SIMBAD You can also click on the "SIMBAD" pane, and if you're lucky, you'll find an entry on the object. Please note the following caveats in this blog post. That said, if you find an entry for a star that seems to have published papers on debris disks, please tag it with #known_disks. We should find a few that are already known, in addition to new ones!
    3. When in doubt, ask a question! The more you do this, the easier it becomes.

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  • lrebull by lrebull scientist, translator, admin

    Good example of "object moves off crosshairs" http://talk.diskdetective.org/#/boards/BWI0000002/discussions/DWI0000141

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  • lrebull by lrebull scientist, translator, admin

    In many of the DSS images, there are long streaks. This can be an asteroid, a satellite, a plane, or even "B52s in formation flying exercises" (Reid et al 1991 PASP). Some examples: http://talk.diskdetective.org/#/subjects/AWI0000dsy http://talk.diskdetective.org/#/subjects/AWI0000fzq tag these with #trails !

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  • lrebull by lrebull scientist, translator, admin

    Example of very bright star: http://talk.diskdetective.org/#/boards/BWI0000002/discussions/DWI0000142

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  • lrebull by lrebull scientist, translator, admin

    Dust speck on DSS http://talk.diskdetective.org/#/boards/BWI0000001/discussions/DWI00000is

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  • lrebull by lrebull scientist, translator, admin

    example of star superimposed on a galaxy http://talk.diskdetective.org/#/boards/BWI0000002/discussions/DWI000010f

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  • DNiergarth by DNiergarth

    Ah! more knowledge will lead to better classifications. This is good info people, thanks!
    I like the network of communication you have set up here.

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  • Shigeru by Shigeru moderator

    Very good info, trying to learn and improve!

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  • jdebes by jdebes scientist, admin

    Here are some more resources to check lightcurves of objects--particularly useful for discriminating against semi-regular variables, which typically are AGB stars and on our "Do not want" list.

    By far, the best resource is the Catalina Surveys Data Release 2: http://nesssi.cacr.caltech.edu/DataRelease/

    From the website:

    Here you will find the second public data release (CSDR2) from the Catalina Surveys that consists of all photometry from seven years of photometry taken with the the CSS telescopeshttp://www.lpl.arizona.edu/css/css_facilities.html. This data release encompasses the photometry for 500 million objects (~40 billion measurements) with V magnitudes between 11.5 and 21.5from an area of 33,000 square degrees. Catalina photometry covers objects in the range -75° < Dec < 70° and |b| > ~15° with the number of observation epochs at each location is as shown above (see FAQhttp://nesssi.cacr.caltech.edu/DataRelease/FAQ2.html). Catalina images will be available in the thirdhttp://nesssi.cacr.caltech.edu/DataRelease/WhatsNew.htmldata release.

    This is a huge chunk of sky, and for our dimmer objects, will be useful in finding interesting variable objects.

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  • jdebes by jdebes scientist, admin

    Also, sometimes it's hard to tell in the visible whether something is resolved or not--if it's an object that was covered in the Sloan Digital Sky Survey (some objects have visible images with filters labeled with 'SDSS') you can check them out by taking the WISE identifier, breaking it into the coordinates and searching at this interface: http://skyserver.sdss3.org/dr10/en/tools/quicklook/quicksummary.aspx?id=0x112d0bd7808f0047&spec=0x12ac808aa4006800

    If you click on the right hand menu "Search by" with the RA,Dec option, you'll bring up a little dialog window.

    Here's how you would do it: Let's say you start with http://talk.diskdetective.org/#/subjects/AWI00007g5

    It's WISE identifier is: J082324.76+602110.7

    You can immediately tell that it's coordinates on the sky (in right ascension and declination see here: http://en.wikipedia.org/wiki/Equatorial_coordinate_system)

    In this case the right ascension or RA is 08:23:24.76 and it's declination or DEC is +60:21:10.7 This object would usually be visible in the spring to summer and in the Northern hemisphere.

    You would go into the SDSS interface and put those coordinates into the RA and DEC fields and hit enter to see a picture, a spectrum if it's present, and even a possible description of an object type (defined as whether an object is spatially resolved or identified as a Galaxy, or an object that is unresolved or identified as a star).

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  • lineman36 by lineman36

    I am very ignorant and new to this but am enjoying it. What is the best way to learn what I am looking at instead of guessing

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  • abans by abans scientist, moderator

    Hi lineman36,

    Besides for the tips listed on the first page in this help board, I think a great way to learn more about the objects is to ask in the discussion window of said object what other people think it is. Our moderators and science team members have been at this whole classification thing for a while, so even though sometimes we can never be 100% sure what a given object is, we can definitely help!

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  • Reyajh by Reyajh in response to jdebes's comment.

    Whenever I try to use the sdss3 site I get this runtime error: "Server Error in '/dr10' Application.
    Runtime Error
    Description: An application error occurred on the server..." Blah, blah blah... 1st time was a couple days ago and each time, I've tried using both your example coords and other coords so I'm assuming it's not because no obj was found or so, but an error on my end.. Can anyone help with this?

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  • voyager1682002 by voyager1682002 moderator in response to Reyajh's comment.

    Hi Glenn, for this particular object : http://talk.diskdetective.org/#/subjects/AWI00007g5 , you click on "More info on SIMBAD" and copy the coordinates : 125.8531966 60.3529877 and paste them on SDSS skyserver "Search by Ra, dec" For "dec" you have to add "+" : +60.3529877

    You should be able to get this screen : http://skyserver.sdss3.org/dr10/en/tools/quicklook/quicksummary.aspx?id=0x112d10a8c0ac00a4&spec=0x1d48561164006800

    I also got the same error messages when I entered 08:23:24.76 +60:21:10.7

    I hope this helps 😃

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  • Reyajh by Reyajh

    Awesome!! Awesome!! Something that makes sense when noAO!!!! And more spectrum data to study w()()T!!!

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  • Reyajh by Reyajh

    Ok the next one I tried brought the same error but I was able to get to a different (Actual data) screen where I could input data manually as well. When I did for said object it gave me a message saying something like: "Target is outside the SDSS footprint." Is that what's going on, that some of these are outside that survey's range?

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  • Reyajh by Reyajh

    The data was for this object: coord 251.1549712-45.8939316

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  • voyager1682002 by voyager1682002 moderator

    Hi Glenn, I have randomly picked an image : http://talk.diskdetective.org/#/subjects/AWI0000j2p and checked http://skyserver.sdss3.org/dr10/en/tools/quicklook/quicksummary.aspx?id=0x112d10a7802d0046&spec=0x0aa0568898006800, I was able to get a result. So, I guess the object you were looking at was not covered in the Sloan Digital Sky Survey.

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  • Reyajh by Reyajh

    Thanks again for your help Lily!!! Yes, I've noticed that those objects with a negative declination (maybe not all) that I've come across thus far, all have that same message. Note how the J Coord for your example (J23174259+0005349) as with all my successful attempts have all had a positive dec. 😗

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