Personal Inside the Bok by Jesse Rogerson|Published 17 February 2014|2 comments Here’s me standing under the Bok 90inch (that’s 2.3 meters for you metric peoples). The instrument we’re using is called 90prime, which is located at the top of the ‘scope. More on that below. The control room for the Bok 2.3m. On the left are the computers that control the instrument (i.e., filters, exposing), on the right is the telescope operations (i.e., slewing to new positions, moving dome, etc.). We had a little trouble with our filter wheel on the second night of our observing run. The filter wheel is a mechanical wheel built into 90prime that holds different filters; the filters are designed to let only certain ranges of light to pass through. Since 90prime is located at the top of the scope, we had to tip the telescope over to get at the instrument. Mike, staff at the Steward Observatory, is helping us diagnose and fix our filter wheel issue. The image shows him working on the instrument. 90prime sits at the prime focus of the telescope (which is why we have to tip the telescope on its side to work on it). 90prime is an imager with a field of view of 1 square degree. To get an idea of the size, 1 square degree would be able to fit 4 full Moons in an a given image, since the Moon is about 0.5 degrees in angular size. Also note in the image we’re looking down at the 2.3 meter mirror. The star-like pattern is the opened mirror cover. When we want to protect the mirror we close the mirror cover. The telescope is pointed at the white screen bathed in light from the halogen bulbs below. This is what astronomer’s call ‘flat fielding.’ When you build a CCD, not every pixel is going to respond the exact same way to light. In order to calibrate for this, you shine every pixel with the same amount of light, which then tells you how each pixel behaves differently. You can then ‘flatten’ the field using that image. Also…. it looks spooky. Ready and waiting for twilight to end. The dome has been opened and the scope is ready to start.