What is the current radius of cosmological event horizon? Doing some crude calculations (using the value of $H_0$ at this point of time only, since it is time dependent but not distance dependent thanks to Johannes answer) what is the radius of cosmological event horizon at this point of time? (not looking for the changes of CEH through time) 
From here we have for $H_0 $:
$$H_0 = 73.8 \pm 2.4 (\frac{km}{s})\frac{1}{Mpc}\tag{I}$$
We are seeking the distance $L$ s.t. $H_0L = c = 3\times 10^6 \frac{km}{s}$
$$L=\frac {c}{H_0} = \frac {3\times 10^6}{73.8 \pm 2.4} Mpc \tag{II}$$
Where 1 pc = 3.26 light years ($ly$), 
$$ L=\frac {c}{H_0} = \frac {3\times 10^6\times10^6\times3.26}{73.8 \pm 2.4} ly \tag{III}$$
$$ L= \frac {9.78\times 10^{12}}{73.8 \pm 2.4} ly \tag{IV}$$
$$L=1.3\pm0.1\times 10^{11} ly \tag{V}$$
Is this calculation correct?
Would the correct calculation make sense? (By making sense I mean it would seem in accordance with some observation and not in contradiction to some other observations? Or results like this are unconfirmable, just mere flights of fancy were they do not relate to anything physical?
The only thing I could use to see it is not invalid (yes double negative, I cannot say it was valid) is the fact that observable universe is $45.7×10^9 ly$ but then again by that account $L=10^{123}ly$ would seem just as valid.
 A: The Hubble length $c/H_0$ does not coincide with the radius of the observable universe. 
Your calculation assumes a Hubble parameter that doesn't change over time. This is not correct: the Hubble parameter $H$ changes over time, and $H_0$ (the Hubble constant) indicates the current value of $H$. To refer to $H_0$ as a 'constant' is a bit of a misnomer, it is effectively a constant in space, not in time.
Also note that if $H$ would have been constant over time, the Hubble time $1/H$ would be the time taken for the universe to increase in size by a factor of $e$. It is a coincidence that the current value for $H$ leads to a Hubble time very close to the current age of the universe.
A: The answer by Johannes is correct - the proper horizon distance in the concordance cosmology is ~46 billion light years. The reason that the answer in (1) was three times larger than that, when it should have been three times smaller, is that the value of c used was incorrect: The speed of light is $3 \times 10^5\ \mathrm{km}/\mathrm{s}$.
