Bigger in the Blue 2
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gavinrider
This is a far more extreme example of an object being larger in the blue to near IR than in the 2MASS images, then becoming bigger and less distinct in the WISE images. This is similar to the object identified as a probable nebula in the examples, but in this case the image does not extend outside the red ring in the WISE image. Surely such objects need to be rejected, because they are probably not stars, but there is no category to select to reject them other than "not round in DSS2". That does not very appropriately describe these objects because they can appear round - they are just bigger in the blue than they would be if they were stars.
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jdebes
scientist, admin
A good question. In this case there is a bright star that is saturating the image in the DSS images. You can't tell much from them whether the object is a galaxy or star, but the 2MASS images look reassuringly round.
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jdebes
scientist, admin
In fact, SIMBAD identifies this as a semi-regular pulsating star.
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drumse
Ok, than what I must to choose in this case?
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gavinrider
OK, I guess it should be identified as a good candidate then?
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jdebes
scientist, admin
Yes, saturation just tells you that it's bright in the visible, nothing about whether it's good or bad. You'll need to look at the other images to make your judgement. Generally, such bright objects are nearby stars, so the odds are slightly higher that you're not seeing a galaxy if it's super bright in the visible.
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