1N

N) Length and Number of Exposures Needed
A PDF of a textfile of the commands of this Part are also available:
Chris explains exposure length in this 1:21 video.
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1. Length of Exposures
a.) Overexposure means that some of the pixels have the maximum number of counts in them: they are saturated. The details of the image disappear. Some overexposed images have spikes on some of the stars, but other times it is hard to tell. The image software program, Afterglow Access, has tools to help.
b.) Any underexposed image is a little easier to recognize. The pixels which hold the background light are dominated by “noise” from the camera electronics, so the image looks grainy or speckled. It is hard to remove it with image processing programs. Setting the exposure length takes practice and attention to details.
c.) For the telescope we are using, Prompt6, the exposure length for the Messier objects chosen should be about 30 seconds. The command looks like this:
skynet:SetExposureLength(30.0)
Remember the parentheses tell Quorum to execute the command called “SetExposureLength” . And notice there are no quotes around the number. That is because Quorum reads it as an actual number, not text.
2. Number of Exposures
We can also request more than one exposure at a time. Why would you need to do that? Come up with at least two reasons. Record these in the Journal Box below.
Let’s try 2 exposures in the command below:
skynet:SetNumberOfExposures(2)
Use your Quorum Box to request your fifth image. Use the link below if you do not already have it open in another tab.
You can either reset the box to start over, or change just the commands needed. In either case, pick a new target. Check all your settings against your previous requests.
Don’t forget to record the information about this image in your Observation Journal. If you do not have the Observation Journal open in another tab, the link is below for your conveinience.
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JOURNAL (Why would you need more than one exposure?)

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