Specifications

Section 2 - The First Day with the Camera
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RA (X)
DEC (Y)
telescope
cord
chip
Figure 2.3 - Camera Orientation
If you haven't done so already, power up the CCD camera and computer. Under the Misc
menu use the Telescope Setup command to enter your telescope information. For the Aperture
item enter the clear aperture in square inches (for example an 8" SCT is 43 square inches). The
focal length will be close to the product of the telescope diameter and the f-ratio (for example an
8" f/10 has an 80" focal length). Finally enter your name in the User item. These parameters are
saved with each image in the image header.
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2.2.1. Focusing the Camera
The telescope should be polar aligned and tracking. Since at this point you can be fairly far out
of focus, we recommend you start with a relatively bright star (2nd Magnitude or brighter).
Visually center the telescope on the star using your finder/guide scope or by sliding an
eyepiece in and out of the telescope without readjusting the telescope focus knob.
Use the Focus command in the Camera menu and set up for a 1 second exposure, Full
frame, Automatic update, Zero delay and Auto grab disabled. When you hit the Enter button,
the software will start taking images, displaying them on the screen one after another.
What you will typically see is a huge, out of focus star image. On an SCT if the focus is
off enough, you'll see an image of a donut with the telescope's central obstruction showing in
the middle of the star. On refractors there won't be any central obstruction. At this point you
adjust the telescope's focus, causing the star's image to shrink until it is a fairly small, bright
spot. When you get close to focus, you will see the star starts to bloom, with streaks protruding
above and below the core of the star. In fact, the signs of a really good focus is when the
blooming tails are their longest. For now don't worry about getting a perfect focus, just get
close. When you think you are focused hit the ESC key to exit from focus mode.
Now, reposition the telescope on a dimmer star, 5th or 6th Magnitude should work well.
We want to do the critical focus on a star that won't saturate the camera. Reenter the Focus
command using a 3 second exposure and the Planet frame mode. The 3 second exposure allows
the camera to average out some of the atmospheric effects. The Planet frame mode takes a full
frame image and then allows you to position a box around the star using the mouse or
keyboard in order to reduce download time. You can also resize the default box as desired.
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Refer to Section 5, the Software Reference section for a more detailed description of the Telescope
Setup command.