Radio Galaxy Zoo Talk

Short Question About Atlas Pict

  • csunjoto by csunjoto

    I just want to know if radio & infrared data from these pictures posted by Vrooje (page one) at this thread Suggested Hashtags came from ATLAS & SWIRE ?

    Posted

  • ivywong by ivywong scientist, admin

    Hi @csunjoto, No, the "Suggested hashtags" thread is a general guide for both the FIRST+WISE & ATLAS+SWIRE subjects.

    Does this help?
    Ivy

    Posted

  • csunjoto by csunjoto

    Sorry, i'm not give very clear description for my 1st question

    Actually what i mean is for this pict :

    enter image description here

    Is this picture from ATLAS+SWIRE? From my short classifying experience, It's looks like picture from SWIRE but i'm not so sure the radio data came from ATLAS. But if it's from ATLAS, why almost all ATLAS picture that we need to classify doesn't have radio contour like this one? ATLAS picture that we need to classify in majority only have elliptical countour

    Posted

  • ivywong by ivywong scientist, admin

    Ah, I see what you're asking. So the synthesised beam shape of an east-west interferometer such as the ATCA changes with the source declination. So you will find that some ATLAS sources which have beams which are not as elongated. You can imagine that if a source is near the zenith, the synthesised beam will be "rounder" than if the the source is closer to the equator and lower on the horizon.

    More details can be found here: http://www.narrabri.atnf.csiro.au/observing/users_guide/html/chunked/ch01s02.html

    Posted

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

    I think they are all FIRST+WISE images, but the image scale is not the same as what we get to classify. Unfortunately, as those images do not have any metadata (esp no (RA, Dec) coordinates), it's nigh on impossible to independently investigate this ... only vrooje (or perhaps another member of the Science Team) can say where they came from.

    Actually what i mean is for this pict :

    Here's what that particular image looks like, zoomed-in:

    ![alt](http://zooniverse-resources.s3.amazonaws.com/radio-galaxy-zoo/S132_heatmap_contours.png =800x)

    I'll see if I can grab a typical FIRST+WISE image and play with the image scale; maybe I can sorta reproduce the look of vrooje's images ... stay tuned! 😃

    Posted

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

    Here's a screenshot, of ARG0002l7f, in the original size:

    enter image description here

    And here it is squished somewhat:

    ![alt](https://lh3.googleusercontent.com/-6KrNvB_cAJQ/VhPB70GKmnI/AAAAAAAAb9Q/DvTI50xjBns/s471-Ic42/test01.jpg =300x)

    Hmm ... not quite what I was expecting ... I need to minimize the radio ...

    Second attempt; ARG0002q2a this time:

    enter image description here

    Squished, and put next to your example pic:

    ![alt](https://lh3.googleusercontent.com/-rXfyMYuf3Uw/VhPBluiJvKI/AAAAAAAAb9A/NtRPJdWCRJ8/s472-Ic42/test02.jpg =200x) enter image description here

    Still not really comparable ... I guess we really do need the metadata for vrooje's images, in order to check this for ourselves ...

    But to help those who still refer to Suggested Hashtags for guidance, perhaps the images could be replaced with FIRST+WISE ones, supplemented by ATLAS+SWIRE ones (together with all relevant metadata, of couse 😉)?

    Posted

  • csunjoto by csunjoto

    Thanks @ivywong & @JeanTate
    It's still puzzled me why from thousand more picture data from ATLAS we classify, i still not yet find double/triple/hourglass radio contour which also i can identify at NVSS. So far i usually find elliptical radio contour and rarely find double/triple radio contour from ATLAS pict. And this double/triple/hourglass from ATLAS can't confirmed with NVSS. NVSS data showed no radio contour i can identify

    Posted

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

    I've come across very few clear doublelobe or triple radio sources in ATLAS, and not many clear hourglass ones either. Part of the reason is, I think, that the 'point spread function' (or 'beam' as I think it's called in radio astronomy) is nowhere near ~circular in the ATLAS images we get to classify, unlike the FIRST ones. I think it would be helpful to have good examples of at least these three radio morphologies, taken from actual ATLAS data in the regions of the sky where the RGZ images come from (and with the same size and scale). I know that would help me in my clicking anyway.

    Re trying to confirm an ATLAS source with NVSS: I think it's almost impossible ... not only is ATLAS far more sensitive (so the vast majority of ATLAS sources will show up as nothing more than noise, if that, in NVSS), but it's also got a much higher resolution (which means even a quite extended source in ATLAS will likely look little more than a fuzzy point source in NVSS).

    Posted

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

    I've come across very few clear doublelobe or triple radio sources in ATLAS

    ARG0003rh1, containing a triple, is one of those very few. Here it is in NVSS (smaller scale than usual, but the image is still bigger than the ATLAS one):

    enter image description here

    Posted

  • csunjoto by csunjoto

    Perfect timing, Edd & HAndernach comment at this Image ARG0003r59. Radio contour almost stretch along the picture. The picture size is 2x2', z from the supposed to be Host is ~0.7 and the real size 820 Kpc. Well i think if there's giant at ATLAS picture we classify, its radio contour will stretch from bottom to top (or right to left) of the picture.

    Posted

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

    Cool! 😃

    Here's the NVSS image (500x500 pix, size "0.09", which is 5.4'?):

    enter image description here

    Posted

  • 42jkb by 42jkb scientist, admin

    ATLAS comes from two separate fields on the sky. One is the Chandra Deep Field South (CDFS) and the other is the European Large Area ISO Survey South 1 field (ELAIS S1). The radio images are form the Australia Telescope Compact Array (ATCA) and the infrared are from SWIRE. The resolution of the ATLAS images is 2x lower than FIRST, around 10 arcseconds. SWIRE on the other hand has 2x better resolution than WISE. The ATLAS images are 2 x 2 arcminutes whereas FIRST images are 3 x 3 arcminutes.

    As a result, the majority of the ATLAS images will be ellipitcals (sorry 😦 ). The great thing about these ATLAS data is that we are the pilot study for the upcoming ASKAP survey EMU and the MEERKat survey MIGHTEE. What we do with ATLAS we will be doing with these surveys and getting everything ready for when the 7 million + radio galaxies from the southern hemisphere need to be analysed. On that note, is there anything that we can do to RGZ that would help with these ATLAS images that we can get ready for RGZ 2.0?

    For ATLAS, there is also no FIRST and very litttle NVSS coverage and no SDSS for these sources as the fields are too far south. We are working with other surveys in the South (e.g., SkyMapper) to bring in the other wavelengths to examine. However, these surveys are just starting to bring in data and it will be at least a year before we can link everything together.

    Posted

  • ivywong by ivywong scientist, admin

    If you have the approximate coordinates of the host galaxy, you may be able to find the optical fits images from these online repositories:

    http://skyview.gsfc.nasa.gov/current/cgi/query.pl
    http://ned.ipac.caltech.edu/

    Posted

  • ivywong by ivywong scientist, admin in response to JeanTate's comment.

    Hi JeanTate,

    I think that you can download the entire CDFS field in a FITS format from here: http://www.atnf.csiro.au/research/deep/data_release/index.htm

    Posted

  • 42jkb by 42jkb scientist, admin in response to ivywong's comment.

    That is the data release 1 FITS images. I will see where the data release 3 images are as this is where the RGZ ATLAS sources come from.

    Posted

  • 42jkb by 42jkb scientist, admin in response to ivywong's comment.

    Also, another radio survey in the south is SUMSS and the image cutout server is http://www.astrop.physics.usyd.edu.au/cgi-bin/postage.pl. The resolution is similar to NVSS at 43 x 43 arcsec but the frequency is 843 MHz instead of 1.4 GHz that NVSS is.

    Posted

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

    Thanks Ivy and 42jkb! 😃

    Unfortunately, we still don't have an answer to csunjoto's original question! 😦

    I just want to know if radio & infrared data from these pictures posted by Vrooje (page one) at this thread Suggested Hashtags came from ATLAS & SWIRE ?

    Are they from ATLAS+SWIRE? Or FIRST+WISE? Or something else?? In either case, what is the field size (in arcmins; it almost certainly is not either 2'x2' or 3'x3')?

    Posted

  • 42jkb by 42jkb scientist, admin in response to JeanTate's comment.

    The images in the post by Vrooje are ATLAS-SWIRE but the hashtags should be used for both sets of images.

    The FIRST-WISE cutouts are 3x3 arcmin and the ATLAS-SWIRE cutouts are 2x2 arcmin. In the example image for the hastags, the field sizes are larger and I can't remember what the sizes actually were. Maybe 4x4 arcmin.

    Posted

  • csunjoto by csunjoto

    Thanks Julie 😃
    At last i have better understanding (and feeling) how big is an object at SWIRE+ATLAS picture. Bigger view for the radio contour already provided. So everything OK for now

    Posted

  • KWillett by KWillett scientist, admin, translator

    The original examples were at 5x5 arcmin, I think (but would have to double check).

    Posted