Quote:
Originally Posted by xelasnave
How many hours exposure would be too much.
Say you have group on the net, a thousand or more participants.
All with the same scopes filters cameras, to standardish somewhat.
So would the be any way of looking at dark spots (capturing) in the hubble wide field with members able to down load ten hours each... Could you expect anything. 10,000 hours exposure?
Alex
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I don't think so Alex. For galaxies, the problem is that we rapidly get to a point of diminishing returns below about 25-26 mag/arcsec2, not because we cannot go deeper, but because the things we are looking for get too small as we look further and further out. When the minor axis of a galaxy gets below the resolution cell size (about 2 arcsec in Australian seeing), the pixel signal falls off with 1/distance squared, rather than just with extinction. For small galaxies that happens at roughly 1GLY - much beyond that and we run out of steam and cannot expect to see anything apart from big galaxies in deeper fields, much less resolve any detail. At Hubble resolution though, signal does not fall off rapidly until much further out, so Hubble wins easily, no matter how long we image for. For an average amateur system sampling galaxies at less than 1arcsec, we will probably hit the wall somewhere in the vicinity of a few tens of hours, depending on the exact system and on the sky brightness
For extended objects like dim closer galaxy halos/tidal streams etc, the resolution effect is unimportant and the biggest challenge is the instrumental one of controlling scattered light - and of course there is the sky gradient to deal with over moderately wide fields. Most of our scopes are not all that good re scattered light, since they collect dust in dirty low-altitude air - not pristine air up above the cloud level. We also tend to have stronger sky gradients than the folks who image under those pristine skies.
That is not to say that co-ordinating deep imaging across many scopes cannot be useful - we just have to pick the niche where our inherent limitations are acceptable - and hopefully valuable in a science sense.
