In a Shadowrun 4e game I play in, an adept with the Astral Perception power wanted to sit in a bar and astrally spy on something behind the window. SR4A p.191 states :
Non-magical and non-living objects have only gray, lackluster
shadows rather than auras, but pick up impressions from being
in contact with living auras.
It is unclear about transparent materials such as glass, or reflective surfaces, how does this work ?
Best Answer
As explained in Street Magic,
An astral shadow is a "drab reflections of lifeless objects present in the physical world." (p. 112 - Shadows)
p. 114 - Astral Visibility :
So in this scenario, the adept could not see through the window since glass, as any other astral shadow, is opaque to Astral Perception.
The only exception to shadows impairing astral visibility is clothing (Street Magic p.112 - Auras) :
Contrary to cyberware which, by its intrusive nature, leaves shadowy gaps in auras, which are easily perceived by an Assenssing check with 2+ successes, while bioware, being living tissue, needs at least 4 successes (SR4A p.191 - Assensing Table)
EDIT : the sentence "simply impair visibility" being vague at best, let me extrapolate from other sources :
SR4A p.191 - Astral Perception :
While there may be some material "simply impairing" (that is : a material which you can astrally "see" through, but with some malus) a psychic sense, I can think of no reason why simple glass would be such a material. Glass' ability to let light go through itself doesn't justify an ability to let emotions do the same.