Type Ia Supernovae As Not-Quite-So-Standard Cosmological Candles
And to add, this is why people often refer to Ia's as "Standardizable Candles". :)
Best skywatching equipment at my disposal:
I've recently observed with the SMT (remotely). It's a good telescope and you all do a great job running it!
Credit Card Swipe Fees Begin Sunday In USA
(it seems that gasoline station owners here in Massachusetts got a different memo, though)
Despite the fact that the outcome is similar, there's a legal difference between "surcharge for credit" and "discount for cash". The former is/was illegal, the latter is legal. Presumably gas stations in MA and elsewhere are doing the latter.
Astronomers Witness Whopper Galaxy Collision
Well, in some cases, astronomy is an order of magnitude science. As this collections of objects doesn't seem to have any gravitational lensing associated with it, there is no way to independently determine the mass of the system. A rough guess at the mass can be determined by assuming a mass to light radio since we know how bright it is (and presumably how far). That would lead to the mass estimates.