Hyades Star Cluster

Project Aims

• to determine the distance to the Hyades star cluster by the moving-cluster parallax method using observations from Durham and the La Palma pt5m for the fainter targets

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
   • Study Exercise III ("Determination of the vertex of the Hyades cluster") in "Selected Exercises in Galactic Astronomy" by I. Atanasijevic (copy available in the AstroLab)
   • Revise the material covered in the "Observational Techniques" part of Level-2 "Stars and Galaxies" module
   • Read Chapter 7 (Astrometry) of "The Handbook of Astronomical Image Processing" by Berry and Burnell
   • Search out additional sources of information

3. Plan your project

   • Compile a list of suitable Hyades stars to observe.   (The limited dynamic range of the old scanned photographs restricts the sample to the fainter members of Hyades)
   • Estimate the likely exposure times required for your targets
   • Estimate how many Hyades stars 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 report

5. Understand how astrometric measurements are made.

   • Learn how to use the Astrometria programme by undertaking the Brief Tutorial
   • Measure the positions of a few Hyades stars on archival CCD images
   • Study Herbert Raab's paper on "Detecting and Measuring faint Point Sources with a CCD"   (local copy)
   • Demonstrate that Astrometria gives reliable results
   • Use the provided Python scripts to independently measure the astrometric positions of your targets
   • Assess the random and systematic uncertainties in your astrometric measurements (see e.g. Farnocchia et al.)
   • Write-up your understanding of the mapping used by Astrometria and the limitations

6. Make observations of the Hyades stars as the weather permits during the term and measure their current astrometric positions (and request observations with the pt5m on La Palma for the fainter targets)

   • Ideally you will be able to observe about 50 Hyades stars during the term
   • Aim to gather at least ten CCD images per Hyades star and stack the images to achieve a higher S/N
   • Measure their current astrometric position using the Python script provided
   • Adopt the ~1950 epoch positions at the J2000 equinox from the USNO-A2.0 catalogue, calibrate onto UCAC4
   • Measure the proper motions of the Hyades stars and compare with their published values
   • Write-up your conclusions for your report

7. Develop a simple programme to derive the Hyades distance via the moving-cluster parallax method

   • Test your programme using high quality proper motion measurements from the Hipparcos astrometric satellite or from simulated data
   • Apply your programme to your data
   • Assess the random and systematic uncertainties of your method
   • Compare your derived distance with the recognised values
   • Write-up your results and conclusions

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jrl

2020-Jun-17 13:36:19 UTC