# δ Cephei: Worksheet #1

 Fall 2010 ASTR 110L, Sec. 1 Name: ________________

Use this worksheet to record your estimates of the magnitude of the variable star δ Cephei.

 Date Time Estimate #1 Estimate #2 Estimate #3 Average 28-Sep ____________ ____________ ____________ ____________ ________________ 05-Oct ____________ ____________ ____________ ____________ ________________ 12-Oct ____________ ____________ ____________ ____________ ________________ 19-Oct ____________ ____________ ____________ ____________ ________________ 26-Oct ____________ ____________ ____________ ____________ ________________ 09-Nov ____________ ____________ ____________ ____________ ________________ 16-Nov ____________ ____________ ____________ ____________ ________________ 23-Nov ____________ ____________ ____________ ____________ ________________ 30-Nov ____________ ____________ ____________ ____________ ________________ 07-Dec ____________ ____________ ____________ ____________ ________________

### Instructions

• Remember that magnitudes are backwards; fainter stars have larger magnitudes!
• δ Cephei varies between about magnitude 3.5 at its brightest to magnitude 4.4 at its faintest.
• Convenient comparison stars are ζ Cephei, magnitude 3.6, and ε Cephei, magnitude 4.2; see the chart on the other side of this handout.
• Use the correct line for each date you observe, and record the time of each observation -- without them, you won't be able to plot your data!
• Make three independent estimates of delta Cephei's magnitude, and write them down in the table.
• Later, take the average of the three estimates you made, and write that in the final column.

 Joshua E. Barnes      (barnes at ifa.hawaii.edu) Updated: 28 September 2010 http://www.ifa.hawaii.edu/~barnes/ast110l_f10/delta_cephei_ws1.html