Chapter 17 The Dome in the Eyepiece

The test she settled on was the oldest and crudest one in the trade, the kind of test an instrument maker's apprentice learns in the first month and a professional forgets, because a professional never needs to point a telescope at the ground. She waited for a clear night and she took the mirror off the sky. There is no way to do this quietly. The mount had limits written into it to keep the glass from ever swinging below a certain elevation, because a mirror that large, pointed too low, risks its own cell and its own counterweight and the whole drive, and so a person who wants to point a survey telescope downward has to defeat the limits, and defeating them sets off the dome's alarms, and to do it she had to lie to Saskia. She told Saskia she needed a low-elevation calibration run for the limit switches, which was a real procedure that existed in the handbook and had not been run in years, and Saskia, who cared about the mount the way other people cared about their children, agreed to set it up herself, and stayed in the dome while Viveka ran it, which complicated things, and then uncomplicated them, because after an hour Saskia went down to the galley for supper and left her alone with the machine she had spent twenty years learning to trust. When the door closed, Viveka put the mirror on the ridge. She had gone over the procedure four times before she ran it, because a limit on a mount is not merely a rule; it is a piece of engineering that keeps the glass alive, and defeating it by carelessness would have been the one true crime available to her in a season of smaller ones. So she defeated it by method, taking the software stops off one at a time and logging each removal in her own book, and if the log in her book was the only place the removals were recorded, that was by then a condition she had learned to live with. She aimed it south and low, at the part of the horizon where the surface of the Cinderveld ran away from her toward the rim of the plateau, and she opened the shutter, and she let it take one long exposure of the ground beneath her own feet, and then she went and looked at what it had seen. The image was not what a mirror looking at the ground should see. A mirror pointed at the ground from a mountain is pointed at nothing: it is pointed into the dark, at rock and at cold and at the long fall of the slope, and there is no light there to gather, because the ground beneath a telescope at night is black. The image was not black. It was full of stars. She stood at the console and looked at it for a long time, the way she had looked at every anomalous plate since the first one. It was field seven. Not a field like field seven. Field seven, the same stars, the same arrangement, the same faint sources in the same places, as though the mirror had not moved at all, as though she had been looking at the sky the whole time. There is a way a machine feels when it is doing the forbidden thing, and she felt it through the floor: the mount reaching the end of its travel, the drive taking up a load it was never built to take, the whole structure of the dome waiting to hear whether the thing above it was going to fall. She kept her hand on the console and her eyes on the feed, and she did not let herself think about the glass, because a person who thinks about the glass at a moment like that takes the mirror off the ground and goes to bed. She checked the encoder. The encoder said the mirror was at four degrees above the ground, pointed south, at the plateau. She checked it twice. Then she took another exposure, this time pointed at the ridge to the west, at the rock, and that one came back as field nine, and a third pointed north, which came back as field two, and by then she understood what the survey had been built to do without knowing it, which was to point into the ground and gather the ground and file it under the names of the sky. She told herself, while she waited for the last exposure, that she was running an engineering check and not an experiment, and the lie was thin and she did not believe it, and she kept it anyway, because a person who is about to do the thing that cannot be undone will take any small comfort the language offers. The mount groaned on its low bearing. The alarm light on the panel had been silent for an hour, which meant Saskia had not heard it from the galley, which meant she was alone with the machine and the ground and the dark. She was still at the console when the image she had been half-afraid of came down. It was the last exposure, the one she had taken pointed directly at the summit, at the ridge under the dome, at the place where she was standing. It came back with a brightness in the middle of the field, a small, hard point of light, and around it, faint but unmistakable, the rest of a shape. She expanded it and looked, and the shape was a dome. It stood a long way off, in the image, and it was small, the way a thing is small when it is far, and its shutter was open, and there was a light coming from a window beside it, the small yellow light of the control room in which she was sitting, and there was, if she looked very closely, the figure of a person in the window, at a console, at the moment of the exposure, which was a person looking at a picture of the place she was looking at it from, at a distance that the survey's own geometry had assigned, and the distance was the distance of the object. RV-417 was the observatory. It had always been the observatory. The perfect star was this dome, and this ridge, and the light in this window, mirrored into the sky's own image of the world, and the map had been drawn on the assumption that the thing in the middle of the field was as far away as the numbers said, and the numbers had said a distance, and the distance was the altitude of the ground, and the ground was here. She sat down and did the one thing a survey observer does with a picture, which is to measure it. She put the frame through the same reduction she had put every frame of the season through, and the reduction returned a position, and the position was the object's position to the digit, and she took that and asked the survey's own geometry how large a thing at that position would have to be to fill the frame the way it did, and the geometry gave her the answer it had given on the twenty-third night, the answer she had refused, and the answer was the size of the ridge, and the size of the ridge is where a small domed building stands with a light in its window and a person at the console, and the person was her. She turned off the console, and then she turned it back on, because turning it off is not a thing you can do to a record. She sat in the yellow light of her own window and looked at the picture of the yellow light of her own window, and for a long while she did not move, and the mirror went on turning at four degrees above the ground, gathering the plateau, filing it, and waiting for its limits to be put back. ---