# δ Cephei: Worksheet #1

 Fall 2011 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 27-Sep ____________ ____________ ____________ ____________ ________________ 04-Oct ____________ ____________ ____________ ____________ ________________ 11-Oct ____________ ____________ ____________ ____________ ________________ 18-Oct ____________ ____________ ____________ ____________ ________________ 25-Oct ____________ ____________ ____________ ____________ ________________ 01-Nov ____________ ____________ ____________ ____________ ________________ 08-Nov ____________ ____________ ____________ ____________ ________________ 15-Nov ____________ ____________ ____________ ____________ ________________ 22-Nov ____________ ____________ ____________ ____________ ________________ 29-Nov ____________ ____________ ____________ ____________ ________________ 06-Dec ____________ ____________ ____________ ____________ ________________

### Notes

• 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 right 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: 21 August 2011 http://www.ifa.hawaii.edu/~barnes/ast110l_f11/delta_cephei_ws1.html