Skip to squeegee quick-look results for: S0 | I0 | S1
Memo: Choosing an ACIS Squeegee Mode (08/15/00)
Summary Table for ACIS Telecon (draft)
| Mode | "Dead" | Exposure | Livetime | Pixel Size | Frametime | S0 FWHM | I0 FWHM | Test Exp. |
|---|
| | Rows | Time (sec) | (%) | (arcsec) | (sec) | @ Row 928 (eV) | @ Row 928 (eV) | Time (sec) |
|---|
| | | 1 CCD | 6 CCD | 1 CCD | 6 CCD | | 1 CCD | 6 CCD | 5.9 keV | 1.5 keV | 5.9 keV | 1.5 keV | |
|---|
| No Sq. | 0 | 3.2 | 3.2 | 100.0 | 100.0 | 0.49 | 3.20 | 3.20 | 544 | 268 | 316 | 167 | 3.2 |
| Simple Sq. | 16 | 3.0 | 3.2 | 97.3 | 91.9 | 0.49 | 3.08 | 3.48 | 426 | 209 | 265 | 142 | 3.3 |
| Max. Spec. | 16 | 1.6 | 1.7 | 81.4 | 75.1 | 0.98 | 1.96 | 2.26 | 363 | 186 | 240 | 142 | 1.9 |
| Max. Ang. | 2 | 3.0 | 3.0 | 89.0 | 84.0 | 0.49 | 3.37 | 3.57 | 382 | 190 | 260 | 143 | 3.3 |
| Max. Eff. | 2 | 1.6 | 1.9 | 95.1 | 86.8 | 0.98 | 1.68 | 2.19 | 394 | 201 | 266 | 141 | 1.8 |
| Subarray | 2 | 0.8 | 1.0 | 68.4 | 63.7 | 0.49 | 1.17 | 1.57 | 366 | 182 | 279 | 156 | 1.2 |
Important Notes and Caveats:
- Details on the squeegee modes can be found below
- Squeegee deadtime includes the image to framestore transfer smear time. While this time is not considered dead for standard TE mode, in squeegee mode much of the smear is lost.
- Test exposure time for 1 CCD is as run on ACIS. This frametime includes extra idle time and is not optimized. Exposure and frametime for 1 and 6 CCD operation is optimized as the minimum possible using formulae provided by Peter Ford.
- The frametime calculations are done for full-frame readout with 8 pairs of overclocks per node with the exception of the subarray mode. Changing to a subarray or reducing the number of overclocks would decrease the minimum possible frametime and exposure time.
- Frametime and deadtime calculation for 6 CCDs depends on the operation sequence of which one set of possible options are used here. For the 16-row squeegee and maximum efficiency squeegee modes, the image to framestore transfer and squeegee reverse clocking occur in sequence for each CCD. For the maximum spectral resolution, maximum angular resolution and subarray squeegee modes,the image to framestore transfer is 8 times slower allowing each CCD transfer to be interleaved. The reverse squeegee clocking at normal speed is then done in sequence for each CCD. As a result, each CCD has a different exposure time, with the minimum being listed here.
- FWHM performance is from 1 CCD operation with S0 (CCD 4) which has the worst performance and I0 (CCD 0) which has the best performance of all the ACIS CCDs. Only results from Node 0 are listed. FWHM is calculated using a 64-row bin around row 928 using a local gain. This overestimates the true FWHM by ~10%. Final 6-CCD performance may depend on the frametime chosen.
Squeegee Quick Look Results on S0 (CCD4)
R4
- ObsID 62047
- May 22, 2000
- 16-row squeegee
- normal readout speed (40 µs)
|
R5
- ObsID 62030
- June 9, 2000
- "Maximum spectral resolution"
- 16-row squeegee
- 2x2 on-chip summation
- 8 times slower readout (320 µs)
|
R6
- ObsID 62023
- June 15, 2000
- "Maximum angular resolution"
- 2-row squeegee
- 8 times slower readout (320 µs)
|
R7
- ObsID 62876
- July 13, 2000
- "Maximum efficiency"
- 2-row squeegee
- 2x2 on-chip summation
- normal readout speed (40 µs)
|
R8
- ObsID 61968
- August 12, 2000
- "Maximum angular resolution
w/ subarray"
- 2-row squeegee
- 8 times slower readout (320 µs)
- 256 row subarray near top of CCD
|
Comparison of squeegee modes on S0
| Mode | CTI @ Mn-K | CTI @ Al-K | Mn-K FWHM | Al-K FWHM |
|---|
| (x 10-5) | (x 10-5) | @ Row 928 (eV) | @ Row 928 (eV) |
|---|
| standard readout | 20.30 ± 0.04 | 39.00 ± 0.17 | 544 | 617 | 593 | 564 | 268 | 341 | 285 | 252 |
| R4 | 17.71 ± 0.02 | 33.70 ± 0.09 | 426 | 492 | 457 | 428 | 209 | 242 | 236 | 211 |
| R5 | 16.37 ± 0.03 | 33.51 ± 0.16 | 363 | 393 | 423 | 389 | 186 | 224 | 212 | 207 |
| R6 | 18.18 ± 0.02 | 36.99 ± 0.11 | 382 | 422 | 423 | 398 | 190 | 204 | 214 | 204 |
| R7 | 17.37 ± 0.01 | 34.32 ± 0.06 | 394 | 436 | 380 | 363 | 201 | 237 | 224 | 206 |
| R8 | ... | ... | 366 | 432 | 397 | 369 | 182 | 199 | 208 | 191 |
Some plots of squeegee results on S0 (average of four nodes)
Note: FWHM in eV is calculated using the local gain. This overestimates the true FWHM by ~10%.
Squeegee Quick Look Results on I0 (CCD0)
L1
- ObsID 62042
- May 30, 2000
- 16-row squeegee
- equivalent to R4
|
L2
- ObsID 62019
- June 21, 2000
- "Maximum spectral resolution"
- equivalent to R5
|
L4
- ObsID 62007
- July 1, 2000
- "Maximum angular resolution"
- equivalent to R6
|
L7
- ObsID 61981
- July 30, 2000
- "Maximum Efficiency"
- equivalent to R7
|
L9
- ObsID 61949
- Aug 30, 2000
- "Maximum angular efficiency
w/ subarray"
- equivalent to R8
|
Comparison of squeegee modes on I0
| Mode | CTI @ Mn-K | CTI @ Al-K | Mn-K FWHM | Al-K FWHM |
|---|
| (x 10-5) | (x 10-5) | @ Row 928 (eV) | @ Row 928 (eV) |
|---|
| standard readout | 10.93 ± 0.03 | 21.03 ± 0.15 | 316 | 376 | 377 | 312 | 167 | 188 | 190 | 168 |
| L1 | 9.45 ± 0.02 | 18.62 ± 0.08 | 265 | 312 | 306 | 276 | 142 | 173 | 161 | 152 |
| L2 | 8.48 ± 0.01 | 17.63 ± 0.09 | 240 | 285 | 270 | 235 | 142 | 162 | 162 | 147 |
| L4 | 9.59 ± 0.02 | 19.91 ± 0.08 | 260 | 305 | 304 | 267 | 143 | 162 | 159 | 157 |
| L7 | 9.50 ± 0.01 | 19.05 ± 0.08 | 266 | 314 | 302 | 283 | 141 | 167 | 169 | 144 |
| L9 | ... | ... | 279 | 331 | 328 | 302 | 156 | 185 | 177 | 160 |
Some plots of squeegee results on I0 (average of four nodes)
Note: FWHM in eV is calculated using the local gain. This overestimates the true FWHM by ~10%.
Squeegee Quick Look Results on S1 (CCD5)
R9
- ObsID 61942
- September 5, 2000
- 16-row squeegee
- equivalent to R4
|
Comparison of squeegee mode on S1
| Mode | Parallel CTI | Serial CTI |
|---|
| Mn-K (x 10-5) | Al-K (x 10-5) | Mn-K (x 10-5) | Al-K (x 10-5) |
|---|
| standard readout | 2.67 ± 0.02 | 7.17 ± 0.08 | 15.13 ± 0.07 | 28.86 ± 0.33 |
| R9 | 2.34 ± 0.03 | 5.20 ± 0.13 | 14.92 ± 0.10 | 29.43 ± 0.46 |
Some plots of squeegee results on S1 (average of four nodes)
Last updated Wed Sep 7 14:25:11 EDT 2000
Web page by Catherine E. Grant (cgrant@space.mit.edu )
Center for Space Research
Massachusetts Institute of Technology
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