1
Time-Delayed Integration/Drift scanning
William van Altena
Yale UniversityBasic Astrometric Methods
Yale University
July 18-22, 2005
2
The Bucket Brigade
3
Observed strip of the sky
4
RA
Sample Drift Scan
5
Geometry of Scan Across CCD
6
Coordinates on the CCD
7
The Celestial Sphere
8
Declination Degradation
9
Normal Declination Limits
10
Going to Higher Dec. Limits
11
star track
star trail
Nor
th <
----
----
----
----
---
----
----
> S
outh
West <----- -------> East
25.0 cm
19.3 cm
Drift-scanning
12
Relative Reductions
13
Aberration of Starlight
14
Declination Overlap Errors
15
RA Overlap Errors
16
Precision of scan to scan registration
17
Sources of Errors
18
Reference Star Catalog Errors
19
Schmidt Telescope Errors
21
Error versus Magnitude
22
Error versus Zenith Distance
23
Precision Limits
24
Accuracy Limits & the Atmosphere
25
Precision Limits & the Atmosphere
26
Precision versus Aperture
27
World’s Largest CCD Cameras
Palomar-Quest112 600x2400
Sloan30 2048x2048
Megacam36 2048x4612
SuprimeCam10 2048x4096
19 cm
28
The Sloan Camera (SDSS)
29
Palomar/Quest Camera
31Orion Nebula Driftscan: BRI-composite, 140-sec exposure
Palomar Quest