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Time-Delayed Integration/Drift scanning

William van Altena

Yale UniversityBasic Astrometric Methods

Yale University

July 18-22, 2005

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The Bucket Brigade

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Observed strip of the sky

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RA

Sample Drift Scan

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Geometry of Scan Across CCD

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Coordinates on the CCD

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The Celestial Sphere

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Declination Degradation

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Normal Declination Limits

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Going to Higher Dec. Limits

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star track

star trail

Nor

th <

----

----

----

----

---

----

----

> S

outh

West <----- -------> East

25.0 cm

19.3 cm

Drift-scanning

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Relative Reductions

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Aberration of Starlight

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Declination Overlap Errors

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RA Overlap Errors

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Precision of scan to scan registration

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Sources of Errors

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Reference Star Catalog Errors

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Schmidt Telescope Errors

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Dynamic Range

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Error versus Magnitude

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Error versus Zenith Distance

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Precision Limits

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Accuracy Limits & the Atmosphere

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Precision Limits & the Atmosphere

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Precision versus Aperture

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World’s Largest CCD Cameras

Palomar-Quest112 600x2400

Sloan30 2048x2048

Megacam36 2048x4612

SuprimeCam10 2048x4096

19 cm

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The Sloan Camera (SDSS)

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Palomar/Quest Camera

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31Orion Nebula Driftscan: BRI-composite, 140-sec exposure

Palomar Quest

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