More About Individual Term Projects

Next Tuesday

• Meet at Abrams Planetarium at the usual time

Aurora

A few words on Huygens

Titan – Saturn’s largest moon

First Detailed images of the surface

From 16.2 km up

From 8km up

Mosaic of descent images

*Deadline*

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

Sample Projects

• Moon position

• Photographing planet motions

• Observing a variable star

Moon Position Project

• 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

In a notebook record:

• 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

Goal

• 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

Periods

• 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

Planet Motion Project

• 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

Step 2

• 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

Step 3

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

Variable Star Project

• Two possible targets– Delta Cephei– Algol (easier for naked

eye observations from campus)

Delta Cephei Project

• 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

Make a light curve

• 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 a light curve

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

Algol

• 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.

Other independent projects

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