Sample interview questions: How do you ensure accurate photometric or spectrophotometric calibration during observations?
Sample answer:
Accurate Photometric and Spectrophotometric Calibration During Observations
- Regular Flat Field Correction:
- Acquire images of a uniformly illuminated target to correct for pixel-to-pixel sensitivity variations.
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Ensure the flat field is taken under identical conditions (exposure time, focus, etc.) as the science data.
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Bias Frame Subtraction:
- Collect a series of images with the telescope shutter closed to remove dark current and electronic offsets.
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Subtract the bias frame from all science data to eliminate systematic errors.
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Dark Frame Correction:
- Obtain images with the telescope shutter closed and a dark slide in place to account for thermal noise and cosmic ray hits.
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Subtract the dark frame from science data to reduce background noise.
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Use Standard Stars for Photometric Calibration:
- Observe well-characterized standard stars with known magnitudes to calibrate the photometric system.
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Compare the measured magnitudes to known values and apply corrections … Read full answer