Pulsating Variable Star

Project Aims

• to determine the light curve and period (plus uncertainty) of a RR Lyrae star (a pulsating variable) using observations taken primarily at Durham and supplemented by occasional measurements with the La Palma pt5m
• to search for changes in the period via an O-C diagram

Project Notes

1. Learn how to use the telescope and CCD system efficiently

   • Attend the observing training sessions
   • Review the L1 User's Guide material to refresh your understanding of the apparent movement of objects in the night sky
   • Study the provided reference material on the telescope, CCD and software

2. Research background material

   • Understand the aims of the project
   • Study the Web-based information linked from the provided References page
   • Revise the material covered in the "Observational Techniques" part of Level-2 "Stars and Galaxies" module
   • Read the Chapter 8 (Photometry) of "The Handbook of Astronomical Image Processing" by Berry and Burnell
   • Review the V-band filter characteristics
   • Review your understanding of the photometry errors of objects on CCD images (see e.g. John Simonetti's short article (local copy)
   • appreciate the points listed on the How to get good photometric data page
   • Search out additional sources of information

3. Plan your project

   • Study the published work on your variable star
   • Download a 30'x30' DSS image centred on your variable star and decide on the best field position in order to include the comparison stars in your exposures; compare with the archival data
   • Search out information on your comparison stars. e.g. via SIMBAD
   • Estimate the best exposure time for your field
   • Estimate how many observations you will need for your study
   • Plan your project write-up; consult the online DUO Report Format Guide and Marking Criteria

4. Write-up the "Introduction and Background" sections of your project

5. Explore the provided software

   • Understand and test the provided software for measuring the relative brightnesses of stars on your CCD images: are the quoted errors reasonable?
   • Understand and test the provided software for determining the period of the variable star: is the light-curve model adequate?
   • Explore the random and systematic uncertainties of the software
   • Write-up your understanding of the software

6. Make observations of the variable star regularly, as the weather permits, during the term (and request occassional observations with the pt5m on La Palma).

   • Ideally you will be able to gather a thousand exposures on the variable star field during the term
   • Measure the relative brightness of the variable star using the provided software. You can automate this by developing a short script.

7. Photometric zero-point calibration

   • Determine the apparent magnitudes of the comparison star(s) in your variable star field via the UCAC4 catalog and hence determine the zero-point calibration
   • Estimate the uncertainty of your zero-point calibration

8. Period determinations

   • Measure the period (and the uncertainty) of the variable using the provided software and compare your results with published values
   • Use archival and literature data to derive an improved period, e.g. construct an O-C diagram
   • Explore other software to make an independent determination of the period, e.g. Andreas Wijaya's PDM or Starlink's PERIOD package
   • Write-up your results and conclusions

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jrl

2020-Jun-17 12:49:20 UTC