diff --git a/types/meteor-astronomy/index.d.ts b/types/meteor-astronomy/index.d.ts
index e2be0326b3..686d871bcf 100644
--- a/types/meteor-astronomy/index.d.ts
+++ b/types/meteor-astronomy/index.d.ts
@@ -7,6 +7,7 @@
 /// <reference types="meteor" />
 
 declare namespace MeteorAstronomy {
+    type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;
     type NonFunctionPropertyNames<T> = { [K in keyof T]: T[K] extends Function ? never : K }[keyof T]; // tslint:disable-line:ban-types
     type NonFunctionProperties<T> = Pick<T, NonFunctionPropertyNames<T>>;
     type FunctionPropertyNames<T> = { [K in keyof T]: T[K] extends Function ? K : never }[keyof T]; // tslint:disable-line:ban-types
@@ -54,7 +55,7 @@ declare namespace MeteorAstronomy {
     interface ClassModel<T> {
         name: string;
         collection?: Mongo.Collection<T>;
-        fields: Fields<T>;
+        fields: Fields<Omit<T, '_id'>>;
         behaviors?: object;
         secured?: {
             insert: boolean,
@@ -76,19 +77,19 @@ declare namespace MeteorAstronomy {
         set(fields: Partial<T>, options?: {cast?: boolean; clone?: boolean; merge?: boolean}): void;
         set(field: string, value: any): void;
         get(field: string): any;
-        get(fields: string[]): any[];
+        get(fields: string[]): Partial<T>;
         isModified(field?: string): boolean;
         getModified(): any;
         getModifiedValues(options?: {old?: boolean, raw?: boolean}): Partial<T>;
         getModifier(): any;
         raw(): T;
         raw(field: string): any;
-        raw(fields: string[]): any[];
-        save(options?: SaveAndValidateOptions<keyof T>, callback?: SaveAndValidateCallback): void;
-        save(callback?: SaveAndValidateCallback): void;
-        copy(save: boolean): any;
-        validate(options?: SaveAndValidateOptions<keyof T>, callback?: SaveAndValidateCallback): void;
-        validate(callback?: SaveAndValidateCallback): void;
+        raw(fields: string[]): Partial<T>;
+        save(options: SaveAndValidateOptions<keyof T>, callback: SaveAndValidateCallback): void;
+        save(optionsOrCallback?: SaveAndValidateOptions<keyof T> | SaveAndValidateCallback): void;
+        copy(save?: boolean): Model<T>;
+        validate(options: SaveAndValidateOptions<keyof T>, callback: SaveAndValidateCallback): void;
+        validate(optionsOrCallback?: SaveAndValidateOptions<keyof T> | SaveAndValidateCallback): void;
         remove(callback?: RemoveCallback): void;
     };