Get the active time from Eventlog, login event.

Get-ActiveTime.ps1

#Initialize
$Weekday=@("Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday")
$LoginData=@{}
ForEach($w in $Weekday){
	$LoginData[$w]=@{}
	0..23 | % {$LoginData[$w][$_]=0}
}

#Get the data from Eventlog
$i=0
Get-EventLog -LogName Security | Where EventID -Eq 4624 | Select TimeGenerated | % {
	$d=([DateTime]($_.TimeGenerated)).DayOfWeek
	$h=([DateTime]($_.TimeGenerated)).Hour
	$LoginData[([String]$d)][$h]+=1
	$i++;Write-Host "Calculating:"$i
}

#Show weekday vs hour table
&{
	Write-Host "[Hour]`t" -n 
	ForEach($w in $Weekday){
		Write-Host $w.SubString(0,3)`t -n
	}
	Write-Host
	ForEach($h in (0..23)){
		Write-Host $h -n
		ForEach($w in $Weekday){
			Write-Host `t $LoginData[$w][$h]  -n
		}
		Write-Host
	}
}