As you may already have heard, Galaxy Zoo has new images in it this week!
You may remember my post in September which described how we’ve added images from SDSS’s ‘Stripe 82′. This is an area of the Sloan survey that has been repeatedly imaged to do things like supernova detection (much like that in Supernova Zoo – you have to look at the same place more than once to see what has changed). A benefit of this is that we can add all these images up to make an image that’s like having a much longer exposure than the ordinary SDSS uses.
The post linked above has some more of the technical details, but the end effect is something like the difference between these two images:
When the initial batch of these images went in, they did rather stand out a bit, for a few reasons. One was that the colour balance was slightly different to standard SDSS images – in general things looked a little redder than they do usually. Also, another big difference was that sometimes these images had quite a lot of background sky noise. We decided initially to go for this, in order to better make use of the extra faint details we can see – scaling up faint details also scales up the background noise, unfortunately.
We’ve had a second go at this however, and Steven’s developed a clever method of reducing the background noise while not affecting the objects in the image, and we’ve also tweaked the colour balance to make things bluer and fit in more closely with the original SDSS imagery. The background noise gets its colour intensity reduced too, which helps with the sometimes quite intense coloured speckling of the old set. It took us a while to reprocess things, but hopefully this will give us an even better set of data to work with!
A spiral seen in Stripe 82, posted by reverendbeer on the forum
You’ll notice quite a few of these images, both from our original Stripe 82 attempt and this new (and we think improved!) set, and we hope you enjoy classifying them and find some gorgeous galaxies out there. There may also be a few artifacts, where the image generation didn’t work out to plan or with more satellites (more images gives more chance for a pesky satellite to get in the way!), so don’t be afraid to hit that artifact button if it looks like there’s a problem.
Have fun classifying!
Very nice!
I thought so! much improved, great work.
The improvements are much appreciated!
Is there a way to find the revised version of an image in My Galaxies?
There was some discussion on the forum many months back about spiral galaxies only having two arms and many people chirped up to say that they occasionally came across 3 and 4 armed spirals.
That sample image looks like a 3 armed spiral to me – possibly even a 4 although the arm at “2 o’clock” looks rather weak.
I hope that these improved images will allow more accurate classification. I think that the big benefit will be separating fainter elongated ellipticals from faint edge-on spirals. In the original Stipe82 images all faint galaxies appeared red and that must have led to an overclassification of ellipticals.
Very exciting and promising new samples, indeed ! Thanks for the explanation, Edd.
JKHC.
I don’t know whether this is the place for this comment but I don’t know where else to go with it. This evening, working at classifying on Galaxyzoo 11, I was presented with an image unlike anything I had seen before. It filled most of the screen in a ;yellow and golden light with in the centre a brighter still patch AND A SMALL BLUE SQUARE. The square was a real square, with corners. ?The whole thing looked like an explosion, but the square was something else altogether. The image disappeared while I was trying to find its number and I was unable to get it back again.
Maybe the boffins can trace it? My usesr name is Yes, if that’s any help.
One of the pics supposed to be of a galaxy showed a big yellow cross thing instead – well suppose it is not really a thing out there, bit scary if it is.
nice……………………………………………………….
such is truth. always deep and beautiful, if u know what i mean.