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Visual Observations of the Ring Nebula

SPU-21 Fall 2014

The Ring Nebula, or Messier 57, is a planetary nebula in the constellation Lyra. In this lab, we will visually observe the Ring Nebula and use a reticle eyepiece (an eyepiece with illuminated tick marks) to determine the angular diameter of the nebula. We will return to this object later in the semester to get a CCD observation of it and get a more precise measurement of the angular diameter.

Procedure:

Slew the telescope to Ring Nebula at coordinates RA= 18:53:35.08 DEC=+33:01:45.0 using TheSky software.
First, look through the main eyepiece with the reticle OFF and get an idea of what the faint object looks like in our telescope. Can you see the white dwarf star in the center?
Next, turn the reticle on (adjust the brightness so you can still see the nebula easily) and align the tick marks along the diameter.
Measure the angular separation: count the number of tick marks between the two stars (Each tick mark is ~5.7arcsec).
Take multiple measurements to get an idea of the uncertainty in your measurements.

Analysis:

Calculate the angular diameter of the Ring Nebula in arcseconds from your tick mark measurement. Use the conversion factor of 5.7 arcseconds/ tick mark. Combine your several measurements (in tick marks) to report the average and uncertainty (rms) of your measurement.