Department of Physics AstroLab

Questions for AstroLabers (Part 2)

  1. Why is it unwise to use the telescopes to observe objects at Dec greater than 65° ?

  2. What is the sky area (field-of-view) in arcminutes that the CCDs cover on the AstroLab telescopes? How does this compare to the size of the Moon? What is the CCD scale in arcsecond per pixel?

  3. If the telescope power is switched off, i.e. telescope not tracking, how long does a star at Dec=0 take to drift 15 arcmin across the field-of-view?

  4. On the Autostar-II handset what are nine slew speeds that are available? When moving your target to the field centre what is the most appropriate slew speed to use?

  5. If the power dips off (e.g. you accidentally pull out the cable from the LX200 handset), how do you recover the telescope pointing?

  6. You are trying to observing your target on the meridian at midnight. However you forget to pack up and automatic procedures shutdown procedures failed. Estimate the time when disaster strikes.

  7. Why is the sidereal tracking of the LX200 mounts so good, i.e. 3 arcsec rms at best? (Hint: SmartDrive). How is the telescope tracking likely to depend on where the telescope is pointing?

  8. What is the theoretical optical resolution for a 12-inch f/10 telescope (West-14)? What is the magnification with the standard 26mm eyepiece on a 14-inch f/10 LX200 telescope?

  9. Why does the focus position of the telescopes change? What is the best way to focus the AstroLab telescopes?

  10. What limits the FWHM PSF ( Full-Width-Half-Maxmimum Point-Spread-Function ) that you are likely to achieve with your observations?

  11. The flux from the star Vega, which has a V-band magnitude of about zero, outside the atmosphere is about 1000 photons per square cm per second per Angstrom at a wavelength of 5500 Angstrom. Make a very rough estimate of the number of photons per second that your CCD receives from a star of magnitude zero? How many counts will be recorded on your CCD? How many counts will be recorded from a star of magnitude 15?

  12. Estimate the magnitude limit for East-14? How does this depend on the FWHM PSF achieved?

  13. What limits how well you can determine the instrumental magnitude of an object?

  14. What limits how well you can determine the position of an object?

  15. What are the random and systematic limits of your experiment?

  16. How can you really impress the AstroLab Supervisor? What are the best ways to really annoy the AstroLab Supervisor?

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