Unknown, in the tens of millions
Turtolsky is the single moon that orbits the Industrial World of Vostroya, located in the Halo Stars near the Segmentum Obscurus. Vostroya is the homeworld of the famous Vostroyan Firstborn Imperial Guard regiments which have served the Emperor for countless centuries, though in truth they fight to absolve themselves of a terrible shame incurred by their ancestors over ten millennia ago when, during the dark days of the Horus Heresy, Vostroya refused to come to the aid of the Emperor's Loyalists or the Warmaster Horus' Traitor Legions, opting for the safety of neutrality in the galactic civil war. Like its parent world, Turtolsky is a centre of industry, providing raw materials and auxiliary manufacturing capacity for the great manufactoria of Vostroya. Vostroya's moon was referred to as Vostroya 0.1 until the middle centuries of the 37th Millennium. Adeptus Administratum Scrivener Adept Turtolsky was assigned the task of recalculating Vostroya's tithe to the Imperium in alignment with the Adeptus Tithe clarification call in 997.M36. Given a small research base and a motley assortment of Administratum cast-offs, it took Turtolsky nearly 190 standard years to resolve the calculations, by which time the call had been rescinded. Vostroya 0.1 was eventually renamed Turtolsky, in honour of the Scrivener Adept.
- White Dwarf 317 (UK), "Index Imperialis: Firstborn Sons of Vostroya," pg. 47