Radio Galaxy Zoo Talk

ARG0002sqf - radio emission centered on an object which is not an SDSS PO? #overlap?

  • JeanTate by JeanTate

    Here's the field, centered on SDSS J100249.23+130942.5, the face-on spiral's nucleus:

    enter image description here

    And here are the SDSS PO (photometric objects); yes, this is a classic case of the SDSS photometric pipeline 'smashing' a very nice spiral into a dozen or so tiny pieces:

    enter image description here

    Note that the orange blob - a background galaxy, like z_sp 0.255 SDSS J100247.98+130942.7? - is not a photometric object. Others in the field with z_ph's that are consistent with 0.255 include SDSS J100248.52+130905.9 (0.269 ± 0.0427/0.275 ± 0.0880), SDSS J100250.88+131008.7 (0.253 ± 0.0284/0.217 ± 0.0704), SDSS J100250.29+130846.9 (0.266 ± 0.0542/0.241 ± 0.0646), SDSS J100249.98+130852.0 (0.227 ± 0.0307/0.182 ± 0.0432), SDSS J100252.14+130855.9 (0.306 ± 0.0828/0.260 ± 0.1051), ...

    I'll do a FIRST overlay later.

    Posted

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

    Seems pretty convincing, though there may be a small optical-radio offset:

    enter image description here

    Here's a curious thing: objects or fields that "don't seem quite right" are apparently quite common. For some time now, I've been writing a comment about every RGZ object/field I've classified (some caveats, to do with contours etc missing). More recently, I've started investigating some of those using the 'overlay tool' I developed. Off the top of my head, I'd say ~10% of what I've classified recently seems odd, in terms of what I understood the current state-of-play in radio astronomy to be (of course, I'll be the first to say my understanding is surely quite superficial, and likely wrong in many key respects).

    Perhaps, because it's me, the RGZ software is deliberately giving me unusual objects/fields (however it works that out), rather than simply randomly picking a new Subject? This is not as wild (paranoid, conspiracy-theory-driven) as it sounds; over a year ago zkChris explicitly stated this was kinda the direction the Zooniverse was heading in (see Optimizing for interest : Why people aren’t machines), and a large part of the week-long workshop in Taiwan earlier this year was devoted to just this sort of clever selection (see Wrap-Up from the Workshop on Citizen Science in Astronomy).

    Would a RGZ SCIENTIST please comment?

    I'm curious to study this apparent "an awfully high percentage of FIRST sources are very different from what's in the textbook" (if you get my meaning), but only if I can accurately characterize the selection effect (i.e. just how far from 'randomly' are the Subjects User {JeanTate} gets distributed?).

    <enter image description here>

    Boilerplate: SDSS image per http://skyservice.pha.jhu.edu/DR10/ImgCutout/getjpeg.aspx, FIRST contours derived from FITS file produced using SkyView with Python code described in this RGZ Talk thread. Image center per the ARG image (left; J2000).

    Posted