diff --git a/rx/rx-lite.d.ts b/rx/rx-lite.d.ts
index c7a148137..4b5acb81d 100644
--- a/rx/rx-lite.d.ts
+++ b/rx/rx-lite.d.ts
@@ -49,6 +49,8 @@ declare module Rx {
 
 	export module helpers {
 		function noop(): void;
+		function notDefined(value: any): boolean;
+		function isScheduler(value: any): boolean;
 		function identity<T>(value: T): T;
 		function defaultNow(): number;
 		function defaultComparer(left: any, right: any): boolean;
@@ -394,6 +396,50 @@ declare module Rx {
 		defer<T>(observableFactory: () => Observable<T>): Observable<T>;
 		defer<T>(observableFactory: () => IPromise<T>): Observable<T>;
 		empty<T>(scheduler?: IScheduler): Observable<T>;
+
+		/**
+		* This method creates a new Observable sequence from an array object.
+		* @param array An array-like or iterable object to convert to an Observable sequence.
+		* @param mapFn Map function to call on every element of the array.
+		* @param [thisArg] The context to use calling the mapFn if provided.
+		* @param [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
+		*/
+		from<T, TResult>(array: T[], mapFn: (value: T, index: number) => TResult, thisArg?: any, scheduler?: IScheduler): Observable<TResult>;
+		/**
+		* This method creates a new Observable sequence from an array object.
+		* @param array An array-like or iterable object to convert to an Observable sequence.
+		* @param [mapFn] Map function to call on every element of the array.
+		* @param [thisArg] The context to use calling the mapFn if provided.
+		* @param [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
+		*/
+		from<T>(array: T[], mapFn?: (value: T, index: number) => T, thisArg?: any, scheduler?: IScheduler): Observable<T>;
+
+		/**
+		* This method creates a new Observable sequence from an array-like object.
+		* @param array An array-like or iterable object to convert to an Observable sequence.
+		* @param mapFn Map function to call on every element of the array.
+		* @param [thisArg] The context to use calling the mapFn if provided.
+		* @param [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
+		*/
+		from<T, TResult>(array: { length: number;[index: number]: T; }, mapFn: (value: T, index: number) => TResult, thisArg?: any, scheduler?: IScheduler): Observable<TResult>;
+		/**
+		* This method creates a new Observable sequence from an array-like object.
+		* @param array An array-like or iterable object to convert to an Observable sequence.
+		* @param [mapFn] Map function to call on every element of the array.
+		* @param [thisArg] The context to use calling the mapFn if provided.
+		* @param [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
+		*/
+		from<T>(array: { length: number;[index: number]: T; }, mapFn?: (value: T, index: number) => T, thisArg?: any, scheduler?: IScheduler): Observable<T>;
+
+		/**
+		* This method creates a new Observable sequence from an array-like or iterable object.
+		* @param array An array-like or iterable object to convert to an Observable sequence.
+		* @param [mapFn] Map function to call on every element of the array.
+		* @param [thisArg] The context to use calling the mapFn if provided.
+		* @param [scheduler] Optional scheduler to use for scheduling.  If not provided, defaults to Scheduler.currentThread.
+		*/
+		from<T>(iterable: any, mapFn?: (value: any, index: number) => T, thisArg?: any, scheduler?: IScheduler): Observable<T>;
+
 		fromArray<T>(array: T[], scheduler?: IScheduler): Observable<T>;
 		fromArray<T>(array: { length: number;[index: number]: T; }, scheduler?: IScheduler): Observable<T>;
 
diff --git a/rx/rx.async-lite.d.ts b/rx/rx.async-lite.d.ts
index be13320c2..77dc23b57 100644
--- a/rx/rx.async-lite.d.ts
+++ b/rx/rx.async-lite.d.ts
@@ -16,46 +16,46 @@ declare module Rx {
 
 		fromCallback: {
 			// with single result callback without selector
-			<TResult>(func: (callback: (result: TResult) => any) => any, scheduler?: IScheduler, context?: any): () => Observable<TResult>;
-			<T1, TResult>(func: (arg1: T1, callback: (result: TResult) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1) => Observable<TResult>;
-			<T1, T2, TResult>(func: (arg1: T1, arg2: T2, callback: (result: TResult) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2) => Observable<TResult>;
-			<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: (result: TResult) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
+			<TResult>(func: (callback: (result: TResult) => any) => any, context?: any): () => Observable<TResult>;
+			<T1, TResult>(func: (arg1: T1, callback: (result: TResult) => any) => any, context?: any): (arg1: T1) => Observable<TResult>;
+			<T1, T2, TResult>(func: (arg1: T1, arg2: T2, callback: (result: TResult) => any) => any, context?: any): (arg1: T1, arg2: T2) => Observable<TResult>;
+			<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: (result: TResult) => any) => any, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
 			// with any callback with selector
-			<TCallbackResult, TResult>(func: (callback: Function) => any, scheduler: IScheduler, context: any, selector: (args: TCallbackResult[]) => TResult): () => Observable<TResult>;
-			<T1, TCallbackResult, TResult>(func: (arg1: T1, callback: Function) => any, scheduler: IScheduler, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1) => Observable<TResult>;
-			<T1, T2, TCallbackResult, TResult>(func: (arg1: T1, arg2: T2, callback: Function) => any, scheduler: IScheduler, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1, arg2: T2) => Observable<TResult>;
-			<T1, T2, T3, TCallbackResult, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, scheduler: IScheduler, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
+			<TCallbackResult, TResult>(func: (callback: Function) => any, context: any, selector: (args: TCallbackResult[]) => TResult): () => Observable<TResult>;
+			<T1, TCallbackResult, TResult>(func: (arg1: T1, callback: Function) => any, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1) => Observable<TResult>;
+			<T1, T2, TCallbackResult, TResult>(func: (arg1: T1, arg2: T2, callback: Function) => any, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1, arg2: T2) => Observable<TResult>;
+			<T1, T2, T3, TCallbackResult, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, context: any, selector: (args: TCallbackResult[]) => TResult): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
 			// with any callback without selector
-			<TResult>(func: (callback: Function) => any, scheduler?: IScheduler, context?: any): () => Observable<TResult>;
-			<T1, TResult>(func: (arg1: T1, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1) => Observable<TResult>;
-			<T1, T2, TResult>(func: (arg1: T1, arg2: T2, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2) => Observable<TResult>;
-			<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
+			<TResult>(func: (callback: Function) => any, context?: any): () => Observable<TResult>;
+			<T1, TResult>(func: (arg1: T1, callback: Function) => any, context?: any): (arg1: T1) => Observable<TResult>;
+			<T1, T2, TResult>(func: (arg1: T1, arg2: T2, callback: Function) => any, context?: any): (arg1: T1, arg2: T2) => Observable<TResult>;
+			<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
 			// with any function with selector
-			<TCallbackResult, TResult>(func: Function, scheduler: IScheduler, context: any, selector: (args: TCallbackResult[]) => TResult): (...args: any[]) => Observable<TResult>;
+			<TCallbackResult, TResult>(func: Function, context: any, selector: (args: TCallbackResult[]) => TResult): (...args: any[]) => Observable<TResult>;
 			// with any function without selector
-			<TResult>(func: Function, scheduler?: IScheduler, context?: any): (...args: any[]) => Observable<TResult>;
+			<TResult>(func: Function, context?: any): (...args: any[]) => Observable<TResult>;
 		};
 
 		fromNodeCallback: {
 			// with single result callback without selector
-			<T>(func: (callback: (err: any, result: T) => any) => any, scheduler?: IScheduler, context?: any): () => Observable<T>;
-			<T1, T>(func: (arg1: T1, callback: (err: any, result: T) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1) => Observable<T>;
-			<T1, T2, T>(func: (arg1: T1, arg2: T2, callback: (err: any, result: T) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2) => Observable<T>;
-			<T1, T2, T3, T>(func: (arg1: T1, arg2: T2, arg3: T3, callback: (err: any, result: T) => any) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<T>;
+			<T>(func: (callback: (err: any, result: T) => any) => any, context?: any): () => Observable<T>;
+			<T1, T>(func: (arg1: T1, callback: (err: any, result: T) => any) => any, context?: any): (arg1: T1) => Observable<T>;
+			<T1, T2, T>(func: (arg1: T1, arg2: T2, callback: (err: any, result: T) => any) => any, context?: any): (arg1: T1, arg2: T2) => Observable<T>;
+			<T1, T2, T3, T>(func: (arg1: T1, arg2: T2, arg3: T3, callback: (err: any, result: T) => any) => any, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<T>;
 			// with any callback with selector
-			<TC, TR>(func: (callback: Function) => any, scheduler: IScheduler, context: any, selector: (results: TC[]) => TR): () => Observable<TR>;
-			<T1, TC, TR>(func: (arg1: T1, callback: Function) => any, scheduler: IScheduler, context: any, selector: (results: TC[]) => TR): (arg1: T1) => Observable<TR>;
-			<T1, T2, TC, TR>(func: (arg1: T1, arg2: T2, callback: Function) => any, scheduler: IScheduler, context: any, selector: (results: TC[]) => TR): (arg1: T1, arg2: T2) => Observable<TR>;
-			<T1, T2, T3, TC, TR>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, scheduler: IScheduler, context: any, selector: (results: TC[]) => TR): (arg1: T1, arg2: T2, arg3: T3) => Observable<TR>;
+			<TC, TR>(func: (callback: Function) => any, context: any, selector: (results: TC[]) => TR): () => Observable<TR>;
+			<T1, TC, TR>(func: (arg1: T1, callback: Function) => any, context: any, selector: (results: TC[]) => TR): (arg1: T1) => Observable<TR>;
+			<T1, T2, TC, TR>(func: (arg1: T1, arg2: T2, callback: Function) => any, context: any, selector: (results: TC[]) => TR): (arg1: T1, arg2: T2) => Observable<TR>;
+			<T1, T2, T3, TC, TR>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, context: any, selector: (results: TC[]) => TR): (arg1: T1, arg2: T2, arg3: T3) => Observable<TR>;
 			// with any callback without selector
-			<TR>(func: (callback: Function) => any, scheduler?: IScheduler, context?: any): () => Observable<TR>;
-			<T1, TR>(func: (arg1: T1, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1) => Observable<TR>;
-			<T1, T2, TR>(func: (arg1: T1, arg2: T2, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2) => Observable<TR>;
-			<T1, T2, T3, TR>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TR>;
+			<TR>(func: (callback: Function) => any, context?: any): () => Observable<TR>;
+			<T1, TR>(func: (arg1: T1, callback: Function) => any, context?: any): (arg1: T1) => Observable<TR>;
+			<T1, T2, TR>(func: (arg1: T1, arg2: T2, callback: Function) => any, context?: any): (arg1: T1, arg2: T2) => Observable<TR>;
+			<T1, T2, T3, TR>(func: (arg1: T1, arg2: T2, arg3: T3, callback: Function) => any, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TR>;
 			// with any function with selector
-			<TC, T>(func: Function, scheduler: IScheduler, context: any, selector: (results: TC[]) => T): (...args: any[]) => Observable<T>;
+			<TC, T>(func: Function, context: any, selector: (results: TC[]) => T): (...args: any[]) => Observable<T>;
 			// with any function without selector
-			<T>(func: Function, scheduler?: IScheduler, context?: any): (...args: any[]) => Observable<T>;
+			<T>(func: Function, context?: any): (...args: any[]) => Observable<T>;
 		};
 
 		fromEvent<T>(element: NodeList, eventName: string, selector?: (arguments: any[]) => T): Observable<T>;
diff --git a/rx/rx.async-tests.ts b/rx/rx.async-tests.ts
index 9c3bce516..4f8c102c4 100644
--- a/rx/rx.async-tests.ts
+++ b/rx/rx.async-tests.ts
@@ -10,8 +10,8 @@ module Rx.Tests.Async {
 	var sch: Rx.IScheduler;
 
 	function start() {
-		obsNum = Rx.Observable.start(()=> 10, sch, obsStr);
-		obsNum = Rx.Observable.start(()=> 10, sch);
+		obsNum = Rx.Observable.start(()=> 10, obsStr, sch);
+		obsNum = Rx.Observable.start(() => 10, obsStr);
 		obsNum = Rx.Observable.start(()=> 10);
 	}
 
@@ -27,38 +27,34 @@ module Rx.Tests.Async {
 		// 0 arguments
 		var func0: (cb: (result: number)=> void)=> void;
 		obsNum = Rx.Observable.fromCallback(func0)();
-		obsNum = Rx.Observable.fromCallback(func0, sch)();
-		obsNum = Rx.Observable.fromCallback(func0, sch, obsStr)();
-		obsNum = Rx.Observable.fromCallback(func0, sch, obsStr, (results: number[]) => results[0])();
+		obsNum = Rx.Observable.fromCallback(func0, obsStr)();
+		obsNum = Rx.Observable.fromCallback(func0, obsStr, (results: number[]) => results[0])();
 
 		// 1 argument
 		var func1: (a: string, cb: (result: number)=> void)=> number;
 		obsNum = Rx.Observable.fromCallback(func1)("");
-		obsNum = Rx.Observable.fromCallback(func1, sch)("");
-		obsNum = Rx.Observable.fromCallback(func1, sch, {})("");
-		obsNum = Rx.Observable.fromCallback(func1, sch, {}, (results: number[]) => results[0])("");
+		obsNum = Rx.Observable.fromCallback(func1, {})("");
+		obsNum = Rx.Observable.fromCallback(func1, {}, (results: number[]) => results[0])("");
 
 		// 2 arguments
 		var func2: (a: number, b: string, cb: (result: string) => number) => Date;
 		obsStr = Rx.Observable.fromCallback(func2)(1, "");
-		obsStr = Rx.Observable.fromCallback(func2, sch)(1, "");
-		obsStr = Rx.Observable.fromCallback(func2, sch, {})(1, "");
-		obsStr = Rx.Observable.fromCallback(func2, sch, {}, (results: string[]) => results[0])(1, "");
+		obsStr = Rx.Observable.fromCallback(func2, {})(1, "");
+		obsStr = Rx.Observable.fromCallback(func2, {}, (results: string[]) => results[0])(1, "");
 
 		// 3 arguments
 		var func3: (a: number, b: string, c: boolean, cb: (result: string) => number) => Date;
 		obsStr = Rx.Observable.fromCallback(func3)(1, "", true);
-		obsStr = Rx.Observable.fromCallback(func3, sch)(1, "", true);
-		obsStr = Rx.Observable.fromCallback(func3, sch, {})(1, "", true);
-		obsStr = Rx.Observable.fromCallback(func3, sch, {}, (results: string[]) => results[0])(1, "", true);
+		obsStr = Rx.Observable.fromCallback(func3, {})(1, "", true);
+		obsStr = Rx.Observable.fromCallback(func3, {}, (results: string[]) => results[0])(1, "", true);
 
 		// multiple results
 		var func0m: (cb: (result1: number, result2: number, result3: number) => void) => void;
-		obsNum = Rx.Observable.fromCallback(func0m, sch, obsStr, (results: number[]) => results[0])();
+		obsNum = Rx.Observable.fromCallback(func0m, obsStr, (results: number[]) => results[0])();
 		var func1m: (a: string, cb: (result1: number, result2: number, result3: number) => void) => void;
-		obsNum = Rx.Observable.fromCallback(func1m, sch, obsStr, (results: number[]) => results[0])("");
+		obsNum = Rx.Observable.fromCallback(func1m, obsStr, (results: number[]) => results[0])("");
 		var func2m: (a: string, b: number, cb: (result1: string, result2: string, result3: string) => void) => void;
-		obsStr = Rx.Observable.fromCallback(func2m, sch, obsStr, (results: string[]) => results[0])("", 10);
+		obsStr = Rx.Observable.fromCallback(func2m, obsStr, (results: string[]) => results[0])("", 10);
 	}
 
 	function toPromise() {
diff --git a/rx/rx.async.d.ts b/rx/rx.async.d.ts
index 9370c828b..783f31d52 100644
--- a/rx/rx.async.d.ts
+++ b/rx/rx.async.d.ts
@@ -8,33 +8,33 @@
 
 declare module Rx {
     interface ObservableStatic {
-		start<T>(func: () => T, scheduler?: IScheduler, context?: any): Observable<T>;
+		start<T>(func: () => T, context?: any, scheduler?: IScheduler): Observable<T>;
 
-        toAsync<TResult>(func: () => TResult, scheduler?: IScheduler, context?: any): () => Observable<TResult>;
-		toAsync<T1, TResult>(func: (arg1: T1) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1) => Observable<TResult>;
-		toAsync<T1, TResult>(func: (arg1?: T1) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1) => Observable<TResult>;
-		toAsync<T1, TResult>(func: (...args: T1[]) => TResult, scheduler?: IScheduler, context?: any): (...args: T1[]) => Observable<TResult>;
-		toAsync<T1, T2, TResult>(func: (arg1: T1, arg2: T2) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2) => Observable<TResult>;
-		toAsync<T1, T2, TResult>(func: (arg1: T1, arg2?: T2) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2?: T2) => Observable<TResult>;
-		toAsync<T1, T2, TResult>(func: (arg1?: T1, arg2?: T2) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, arg2?: T2) => Observable<TResult>;
-		toAsync<T1, T2, TResult>(func: (arg1: T1, ...args: T2[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, ...args: T2[]) => Observable<TResult>;
-		toAsync<T1, T2, TResult>(func: (arg1?: T1, ...args: T2[]) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, ...args: T2[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3?: T3) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2?: T2, arg3?: T3) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, arg2?: T2, arg3?: T3) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, ...args: T3[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, ...args: T3[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2?: T2, ...args: T3[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2?: T2, ...args: T3[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, TResult>(func: (arg1?: T1, arg2?: T2, ...args: T3[]) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, arg2?: T2, ...args: T3[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, arg4: T4) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, arg4?: T4) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3, arg4?: T4) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3, arg4?: T4) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3, arg4?: T4) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2?: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3, arg4?: T4) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, arg2?: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, ...args: T4[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3: T3, ...args: T4[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3, ...args: T4[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => TResult, scheduler?: IScheduler, context?: any): (arg1: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
-		toAsync<T1, T2, T3, T4, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => TResult, scheduler?: IScheduler, context?: any): (arg1?: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
+        toAsync<TResult>(func: () => TResult, context?: any, scheduler?: IScheduler): () => Observable<TResult>;
+		toAsync<T1, TResult>(func: (arg1: T1) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1) => Observable<TResult>;
+		toAsync<T1, TResult>(func: (arg1?: T1) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1) => Observable<TResult>;
+		toAsync<T1, TResult>(func: (...args: T1[]) => TResult, context?: any, scheduler?: IScheduler): (...args: T1[]) => Observable<TResult>;
+		toAsync<T1, T2, TResult>(func: (arg1: T1, arg2: T2) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2) => Observable<TResult>;
+		toAsync<T1, T2, TResult>(func: (arg1: T1, arg2?: T2) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2?: T2) => Observable<TResult>;
+		toAsync<T1, T2, TResult>(func: (arg1?: T1, arg2?: T2) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, arg2?: T2) => Observable<TResult>;
+		toAsync<T1, T2, TResult>(func: (arg1: T1, ...args: T2[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, ...args: T2[]) => Observable<TResult>;
+		toAsync<T1, T2, TResult>(func: (arg1?: T1, ...args: T2[]) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, ...args: T2[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3: T3) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3: T3) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3?: T3) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2?: T2, arg3?: T3) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, arg2?: T2, arg3?: T3) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2: T2, ...args: T3[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, ...args: T3[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1: T1, arg2?: T2, ...args: T3[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2?: T2, ...args: T3[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, TResult>(func: (arg1?: T1, arg2?: T2, ...args: T3[]) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, arg2?: T2, ...args: T3[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, arg4: T4) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3: T3, arg4: T4) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, arg4?: T4) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3: T3, arg4?: T4) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3, arg4?: T4) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3, arg4?: T4) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2?: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3, arg4?: T4) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, arg2?: T2, arg3?: T3, arg4?: T4) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3: T3, ...args: T4[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3: T3, ...args: T4[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2: T2, arg3?: T3, ...args: T4[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => TResult, context?: any, scheduler?: IScheduler): (arg1: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
+		toAsync<T1, T2, T3, T4, TResult>(func: (arg1?: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => TResult, context?: any, scheduler?: IScheduler): (arg1?: T1, arg2?: T2, arg3?: T3, ...args: T4[]) => Observable<TResult>;
 	}
 }
 
diff --git a/rx/rx.time-lite.d.ts b/rx/rx.time-lite.d.ts
index a5b102827..7a7d8f46f 100644
--- a/rx/rx.time-lite.d.ts
+++ b/rx/rx.time-lite.d.ts
@@ -49,8 +49,8 @@ declare module Rx {
 	interface ObservableStatic {
 		interval(period: number, scheduler?: IScheduler): Observable<number>;
 		interval(dutTime: number, period: number, scheduler?: IScheduler): Observable<number>;
-		timer(dueTime: number, period: number, scheduler: IScheduler): Observable<number>;
-		timer(dueTime: number, scheduler: IScheduler): Observable<number>;
+		timer(dueTime: number, period: number, scheduler?: IScheduler): Observable<number>;
+		timer(dueTime: number, scheduler?: IScheduler): Observable<number>;
 		generateWithRelativeTime<TState, TResult>(
 			initialState: TState,
 			condition: (state: TState) => boolean,
diff --git a/rx/rx.time.d.ts b/rx/rx.time.d.ts
index 6efd7d9cf..2cdb1d56a 100644
--- a/rx/rx.time.d.ts
+++ b/rx/rx.time.d.ts
@@ -17,8 +17,8 @@ declare module Rx {
 	}
 
 	interface ObservableStatic {
-		timer(dueTime: Date, period: number, scheduler: IScheduler): Observable<number>;
-		timer(dueTime: Date, scheduler: IScheduler): Observable<number>;
+		timer(dueTime: Date, period: number, scheduler?: IScheduler): Observable<number>;
+		timer(dueTime: Date, scheduler?: IScheduler): Observable<number>;
 
 		generateWithAbsoluteTime<TState, TResult>(
 			initialState: TState,