Welcome to http://www.handsonuniverse.org/activities/Explorations/SSCyg/

SS Cyg is a cataclysmic variable star in CYGNUS, the Swan.

A.  Open images of SS Cyg.

B.  Learn how to get finder charts from AAVSO.

C.  Learn how to view finder charts with SkyView.

D.  Calculate the Magnitude of SS Cyg.  Use formulas. Use calculators on Macintosh or Windows computers. 

E.  Record and Graph SS Cyg's changing magnitudes.

A.  Open the .fts images of SS Cyg and comparison stars.  North is up and East is to the left in these images.  Image sets are dated with the first numbers and letters of the image. Images pictured here are from June 25, 1999.  Compare stars on the same date.

B.  View and print the finder chart for the starfield from AAVSO (www.aavso.org). You will probably need chart (e).  This chart is very large.  Note: When printing the finder chart from AAVSO, go to page set up in your browser, choose landscape orientation and 25% for the printing size. When you are done, reset your page setup as it was set up previously.  This chart has South up and West to the left.  To use it with SkyView charts and the HOU images here, turn the chart upside down so North is up and East is to the left.  The picture here is just a portion of the finder chart. Magnitudes of comparison stars do not include a decimal.  So, 109 really means magnitude 10.9.  

C.  Use SkyView to get a finder chart.  Here is a finder chart for SS Cyg. However, to get such a chart yourself from the Skyview web site follow these directions. 

Go to http://skyview.gsfc.nasa.gov/skyview.html   Choose Advanced.

• Type SS Cyg for Source.
• For Survey, click on Digitized Sky Survey
• Under Optional Parameters, select or type in:
  Image Size (pixels): 450 by 450
  Image Size (degrees): type in  .3
  Brightness Scaling: Linear
  Grid:  Yes
  Color Table:  B-W Linear

• Hit the Submit button. 
• Wait and then print the resulting chart, which may pop up in a separate browser window.
• If you need more information about objects or stars, just add selected catalogs to the above configuration.  (In this chart, numbers will appear over the stars to match catalog information sources.)

D.  Calculate the magnitude of SS Cyg by comparing it to other stars of known magnitudes.  Refer to the HOU HS Curriculum Module: Measuring Brightness, SA 14.

Note:  When using the calculator in Windows PC computers, follow this procedure.

1. Find the calculator.  Start; Programs; Accessories; Calculator
2. Make sure you are using the scientific view.  View:   Scientific
3. To find the magnitude of the target star such as SS Cyg, follow the formula by entering data and operations in this order.  In this case the known star counts and magnitudes refer to the comparison star.  The unknown star counts refer to ss cyg.
4. known star counts/unknown star counts = log * 2.5 = + known magnitude =

Note:  When using a graphing calculator as often found on MACs, follow this procedure:

1. Go to the apple in the upper left corner of the computer screen.   Choose Graphing Calculator.
2. Enter the formula as follows: 2.5 log known star counts / unknown star counts + known magnitude =
   

June 15, 1999 example: For counts 45806 of the known star of magnitude 9.9, and counts of SS Cyg 17703, then the resultant magnitude for ss cyg is 10.9 

June 15, 1999 second example:  For counts 17392 of the known star of magnitude 10.9, and counts of SS Cyg 17703, then the resultant magnitude for ss cyg still calculates as 10.9

E.  Record and Graph SS Cyg's changing magnitudes.

Now working with HOU image processing software and your downloaded .fts files for SS Cyg, calculate the magnitude of SS Cyg on several dates.  Create a graph showing how SS Cyg changes magnitude.  What is the brightest magnitude you calculated?  The dimmest magnitude?  Can you create a spreadsheet in Excel that will calculate magnitudes and graph your results?