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 Report Format Guide (on sharepoint, linked from the module page on blackboard under "Assignments") and Marking Criteria (proforma and assessment criteria on sharepoint, linked from the module page on blackboard under "Start Here -> Feedback on assessed work").

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