• Meet at Abrams
Planetarium at the usual time

First Detailed images of the surface

• By next Tuesday, I would like you each to turn in a one page description of your individual semester project

• Moon position
• Photographing planet motions
• Observing a variable star

• What you need:
– A chart of the night sky showing the constellations visible at the time you are observing (Abrams sky calendar charts are good, but you may need more than the
January chart)

Mark location of the moon with respect to the stars

• The date and time of each observation
• The phase of the moon (make a sketch)
• Do not let your observation be influenced by planetarium software or other predictions

• Do this on perhaps 10-15 nights during the semester
• Use your observations to determine
(a) The sidereal period of the moon
(b) The synodic period of the moon
(c) Estimate the uncertainty of each period
And compare these with the “book” values

• Sidereal period: The “true” orbital period of the Moon. How long it takes the moon to return to the same location with respect to the stars
• Synodic period: How long it takes to return to the same phase; based upon the position of the Sun and Moon with respect to the earth

• For this project, you will need a camera
(most easily a digital camera) that can take time exposures of a few seconds duration
• For this project, it is OK to work as a team of two people

Step 1: Image the planet and the background stars (5 or 6 times in the semester)
• Saturn and/or Jupiter are most easily done this semester

• Measure the position of the planet on the image with respect to several stars
• Use the known right ascension and declination of the stars to determine the right ascension and declination of the planet on each date
• Estimate the uncertainty of your measured positions

• Plot the changing position of the planet and compare your results with the predicted motion of the planet

• Two possible targets
– Delta Cephei
– Algol (easier for naked eye observations from campus)

• Check out the “observing delta Cephei” tutorial at the AAVSO website: http://hoa.aavso.org/observing.html
Following the steps outlined there,estimate the brightness of
Delta Cephei on 12 or more nights during the semester
Calculate the “Julian Date” of each of your observations using the website http://wwwmacho.mcmaster.ca/JAVA/JD.html

• Estimate the pulsation period of Delta
Cephei from your observations
• Calculate the “phase” of each of your measurements:
Phase = Julian Date/period (Keep only the part after the decimal point, i.e., if the phase comes out to be 5.43 keep just the 0.43)

• Plot the observed magnitude versus phase (your plot may not look this nice)

• Brighter than Delta Cephei and higher overhead in the evening (easier to observe without binoculars)
• Use your chart of Algol (you can download another from the AAVSO website if needed) to estimate the brightness of the star, recording date and time

• Measure the brightness of Algol on at least 10 nights
• On at least one night when Algol is predicted to undergo an eclipse, measure its brightness several times over the span of 3 or 4 hours around the time of minimum
– Predicted times of minimum can be obtained at the website
– http://skyandtelescope.com/observing/objects/variablestars/article_108_1.asp

Plot the light curve, as in the case of Delta Cephei
•
In this case, you may use the known period of 2.8673 days if your observations do not let you determine the period independently. You will need to observe more than one minimum if you want to independently determine the period of Algol.

• You may devise an independent project of your own, but you will have to check it out with me before you do it