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Last updated
19 December 2001 17:03:39
Maintained by
martel
1. Overview
The thermal vacuum (TV) tests of ACS at GSFC will be used to gather a variety of calibration data for the CCDs and the MAMA detector. The tests will be conducted in two phases. In early 1999 the instrument line-up will include the Build#2 WFC, the Build#2 HRC, and the one and only SBC MAMA. The WFC detector that will be flown is expected to be Build#3. Consequently much of the emphasis in the first phase of the TV tests will be on the SBC and HRC detectors. The plan given here describes this first phase of the TV tests. In July 1999, the instrument with the WFC Build#3 will be tested.
2. Calibration Items
The data gathered during the first TV campaign will be used to address eleven calibration items (A - K) defined as properties of the instrument or detectors to be characterized. These items either can only be measured in TV, or do not significantly impinge on the time needed for TV. These items will be measured using a set of data taking procedures with suitable data analysis. Here the procedures are given a number (1 - 10) followed by a letter code denoting which detector will be used (w : WFC, h : HRC, s : SBC).
| Item | Title | Detectors | Procedures |
|---|---|---|---|
| A. | CCD properties | WFC, HRC | 1w 1h 10h |
| B. | Charge Transfer Efficiency | WFC, HRC | 2w 2h 5w 5h |
| C. | Detector defects | WFC, HRC, SBC | 1w 1h 6w 6h 6wh 6s 10h |
| D. | Dark structure | WFC, HRC, SBC | 1w 1h 6w 6h 6wh 6s |
| E. | Image stability | HRC, SBC | 10h 10s |
| F. | Internal calibration system verification | WFC, HRC, SBC | 1w 1h 3w 3h 3s 9s |
| G. | Flat field uniformity | WFC, HRC, SBC | 1w 1h 3w 3h 3s 4s |
| H. | Flat field repeatability | WFC, HRC, SBC | 4s 1h |
| I. | Flat field beam illumination difference | SBC | 8s 4s |
| J. | SBC Throughput | SBC | 7s |
| K. | UV Contamination/Throughput monitor | SBC | 7s 8s |
3. Procedures
| Proc. | Name | Exposures | Time (hr) | Command mode |
Gain | TCCD | Light Source |
|---|---|---|---|---|---|---|---|
| 1w | Basic Monitor (WFC) | bias, dark, 4 flats (2 levels), dark, bias | 1.78 | SMS | 1 2 8 | T-1 T0 T1
T2 T3 |
Tungsten |
| 1h | Basic Monitor (HRC) | bias, dark, 4 flats (2 levels), dark, bias | 1.03 | SMS | 1 2 4 8 | T-1 T0 T1
T2 T3 |
Tungsten |
| 2w | CTE Monitor (WFC) | bias, 5 flats (serial FPR), 5 flats (parallel EPER), bias | 2.19: | SMS | 1 2 | T-1 T0 T1
T2 T3 |
Tungsten |
| 2h | CTE Monitor (HRC) | FPR : bias, 5 flats (serial), 5 flats (parallel), bias | 0.48 | SMS | 1 2 4 | T-1 T0 T1 T2 T3 |
Tungsten |
| 3w | Internal flats (WFC) | bias, g, r, i, z, bias | 0.97 | SMS | 1 | T0 | Tungsten 1,2 |
| 3h | Internal flats (HRC) | bias, F250W, g, r, i, z, bias | 0.48 | SMS | 1 | T0 | Tungsten 3,4 |
| 3s | Internal flats (SBC) | dark, 8 (shallow) flats, dark - all filters | 1.94: | PSTOL | n/a | n/a | D2 |
| 4s | Deep external flats (SBC) | dark, tweak, 10-15 1hr flats | 10.88 - 16.04 |
PSTOL | n/a | n/a | STUFF PtNe |
| 5w | Thorough CTE test (WFC) | bias, 17 flats (serial FPR), 17 flats (parallel EPER), bias | 7.59 | SMS | 1 2 | T0 | Tungsten |
| 5h | Thorough CTE test (HRC) | FPR : bias, 18 flats (serial), 18 flats (parrallel), bias | 1.31 | SMS | 1 2 4 | T0 | Tungsten |
| 6w | Long darks (WFC) | bias, dark (repeat as needed) | 1.50 | PSTOL | 1 | T-1 T0 | n/a |
| 6h | Long darks (HRC) | bias, dark (repeat as needed) | 1.23 | PSTOL | 1 | T-1 T0 | n/a |
| 6wh | Semi-parallel HRC + WFC darks | bias, dark (one set each detector) | 1.33 | SMS | 1 | T-1 to T3, 1C increments |
n/a |
| 6s | Long darks (SBC) | 1dark (repeat as needed) | 1.20 | PSTOL | n/a | n/a | n/a |
| 7s | UV throughput (SBC) | tweak, external pinhole, dark | 0.74 | PSTOL | n/a | n/a | STUFF Kr, Xe |
| 8s | Deep pinhole (SBC) | tweaks, long external pinhole, dark | 2.37: | PSTOL | n/a | n/a | STUFF PtNe |
| 9s | SBC unknown light - safe open | none | < ~1.0 | PSTOL | n/a | n/a | D2, STUFF - all lamps |
| 10h | HRC stability | 3x(bias, 15 flats) | 1.01 | SMS | 1 | T0 | STUFF PtNe |
| 10s | SBC stability | 32 flats | 3.40 | SMS | n/a | n/a | STUFF PtNe |
For details on a procedure, click on the procedure number. Some procedures come in different versions (a, b, c, d, ...) if they need to be executed numerous times with slightly different configurations (i.e. gain, filters, etc...).
In the above table, the time given is the estimated duration of one iteration of the procedure. For the most part, these estimates assume 10 minutes of setup (stuffing around) time, 10 min overhead for each WFC read-out and 2 min overhead for each HRC or SBC read-out. For the procedures for which we have already created SMSs, the estimated time is the time required to run the SMS, plus five minutes of overhead.
Many of the procedures are amenable to be run automatically as SMSs. We have written EXCEL spreadsheets characterizing these SMSs, most of which have already been created at Ball and in many cases dry-run tested at GSFC.
Much of the WFC and HRC data will be obtained at one of seven CCD temperature levels, defined to adequately sample the full commandable range of the TECs, to represent TCCD levels we will use commonly on orbit, and to meet contractual obligations. They are defined as follows :
| Mnemonic | Definition | |
| T-1 | = | The minimum stable TCCD at cold operation. We expect this to be T-1 ~ -90 C. |
| T0 | = | The minimum stable TCCD at hot op. We expect this to be T0 ~ -83 C. This will be the nominal operating temperature of the CCD. |
| T1 | = | -80 C |
| T2 | = | -76 C |
| T3 | = | -72 C |
| T4 | = | -67 C |
| Tno-ASCS | = | The minimum stable TCCD without the Aft Shroud Cooling System (ASCS). If this fortuitously corresponds to any of the above levels, then no extra tests at this TCCD are needed. |
The exceptions are the dark frames. We will be able to obtain so many of these that a finer TCCD will be allowed.
4. Time Line
| TV Plan Ref. |
Description | Procs | Iter. | Time (hr) |
Cal. Items |
Notes |
|---|---|---|---|---|---|---|
| 9.4.4.(6,8) | Cold Op. TB #3 | T-1 determined for HRC & WFC | ||||
| 9.4.5 | 9s | 5 | < 4.5 | ... | After functional: STUFF check-out. Run safe open for : 1. PtNe1 + spectralon (Full) 2. PtNe1 + MMA (Full) 3. STUFF + Kr1236 + 4mm pinhole (Full) 4. STUFF + Xe1469 + 4mm pinhole (Abbreviated) 5. D2 lamp (Full) - determine if exposures to be obtained in functionals will be safe. |
|
| 7s | 2 | 1.48 | J K | Kr, Xe + 4mm pinhole; F115LP | ||
| 9.4.6.3 | Transition to hot op. TB #4 | Calibration opportunity | ||||
| 9.4.7 | TB #4: Hot op @-10C MAMA sensitivity |
7s | 2 | 1.48 | J K | SBC monitor: STUFF Kr, Xe + 4mm pinhole; F115LP |
| 9.4.8.3 | Hot op. @-2C | Calibration opportunity | ||||
| 9.4.8.(5,7) | T-1 determined for HRC & WFC | |||||
| 9.4.9.3 | Hot op. w/o ASCS | Calibration opportunity | ||||
| 9.4.9.(5,7) | Tno-ASCS determined for HRC & WFC | |||||
| 9.5.1.1 | Transition to hot soak #1 |
Calibration opportunity | ||||
| 9.5.2 | Hot soak #1 functional | 7s | 2 | 1.48 | J H K | After functional; Kr, Xe + 4mm pinhole; F115LP. |
| 9.5.4.4 | 1st cold functional |
7s | 2 | 1.48 | J H K | After functional. STUFF Kr, Xe + 4mm pinhole; F115LP. |
| 9.5.4.16 | 10h | 1 | 1.01 | E A H | Deploy coronographic arm, then run this test once before transition. Leave arm in place. | |
| 9.5.5 | Transition to hot soak #2 |
10h | 12+ | 12.12+ | E A H | Coronographic arm remains deployed during transition. Do as many iterations of 1h as possible. |
| 9.5.6.4 | Hot soak #2 functional | 10h | 1 | 1.01 | E A H | After functional: deploy coronographic arm, then run this test once before transition. Leave arm in place. |
| 9.5.7 | Transition to cold soak #2 |
10h | 12 | 12.12+ | E A H | Coronographic arm remains deployed during transition. Do as many iterations of 1h as possible, during cool down. |
| 9.5.7.8 | Turn off HRC when very near the lowest environmental T, keeping arm deployed. | |||||
| 9.5.8.(3-6) | Cold soak #2 functional | 10h | 1 | 1.01 | E A H | Do one last 10h before cold functional starts, then arm may be retracted during functionals |
| 9.6.1.1(?) | 9s | 1 | < 1 | * Deploy coron. arm at end of functional,
in prep for SBC image stability check. * Abbreviated Safe open with STUFF + PtNe + MMA + F150LP, * adjust STUFF NDs to produce global count rate close (as possible) to but below 3e5 Hz. |
||
| 9.6.1.? | Transition to calibration |
10s | 6+ | 20.4+ | E | During transition, take as many 300s F150LP flat fields as possible. Keep coron. arm in place throughout. |
| 9.6.2 | CALIBRATION: SBC |
7s | 4 | 2.96 | J K | Throughput: STUFF Kr, Xe + 4mm pinhole; F115LP. Two
iterations: * Before flatfields * After doing four SBC flats and darks (4s, 6s, see below). |
| 6s | 8 | 9.60 | D | Needed to analyze long flats, pinholes. Intersperse with 4s (below) | ||
| 4s | 8 | 87.04 - 128.32 |
G | Run once for each filter. Intersperse with 6s (above). | ||
| 7s | 9 | 6.66 | J K | STUFF Kr, Xe + 4mm pinhole. Run once for each valid lamp + filter combo. | ||
| 6s | 1 | 1.20 | D | Needed to analyze long flats, pinholes | ||
| 8s | 2 | 4.74: | I K | Pinhole & Kr1236 + F115LP, Xe1469 + F140LP | ||
| 6s | 1 | 1.20 | D | Needed to analyze long flats, pinholes | ||
| 4s | 1 | 10.88 - 16.04 |
H | STUFF + PtNe lamp, F140LP | ||
| 6s | 2 | 2.40 | D | Needed to analyze long flats, pinholes | ||
| 7s | 2 | 1.48 | J K | STUFF Kr, Xe + 4mm pinhole; F115LP | ||
| CALIBRATION: internal lamp checkouts |
3s | 1 | 1.94: | F | D2 lamp check-out. | |
| 3w | 2 | 1.94 | F | Tungsten lamps 1,2 check-out. | ||
| 3h | 2 | 0.96 | F | Tungsten lamps 3,4 check-out. | ||
| CALIBRATION: Detector properties versus TCCD |
1w | 1 | 1.78 | A B D H | * Set interface plate to -10C or less. * Set TCCD at the appropriate T-1 of each detector. * Use GAIN=1 for 1h, 1w. * If T-1 of both detectors can not be maintained simultaneously run procedures 6w and 6h instead of 6wh. |
|
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 2 | 2.66 | ||||
| 1w | 1 | 1.78 | A B D H |
* Set TCCD of each detector to its appropriate
T0. * Use GAIN=1 for 1h, 1w. |
||
| 5w | 1 | 7.59 | ||||
| 1h | 1 | 1.03 | ||||
| 5h | 1 | 1.31 | ||||
| 6wh | 2 | 2.66 | ||||
| 7s | 2 | 1.48 | J K | Throughput interlude: STUFF Kr, Xe + 4mm pinhole; F115LP | ||
| 1w | 1 | 1.78 | A H D B |
* Set TCCD = T1 on each detector * Use GAIN=1 for 1h, 1w. |
||
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 2 | 2.66 | ||||
| 1w | 1 | 1.78 | A H D B |
* Set TCCD = T2 on each detector * Use GAIN=1 for 1h, 1w. |
||
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 1 | 1.32 | ||||
| 1w | 1 | 1.78 | A H D B |
* Set TCCD = T3 on each detector * Use GAIN=1 for 1h, 1w. |
||
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 1 | 1.32 | ||||
| 1w | 1 | 1.78 | A H D B |
* Set TCCD = T4 on each detector * Use GAIN=1 for 1h, 1w. |
||
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 1 | 1.32 | ||||
| 1w | 1 | 1.78 | A H D B |
* Set TCCD = Tno-ASCS on each detector * Use GAIN=1 for 1h, 1w. |
||
| 2w | 1 | 2.19: | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 6wh | 1 | 1.32 | ||||
| CALIBRATION: Various |
7s | 2 | 1.48 | J K | STUFF Kr, Xe + 4mm pinhole; F115LP. | |
| 1w | 2 | 3.56 | A H D B | Set TCCD = T0; GAIN = 2,8 (1w); GAIN = 2,4,8 (1h) | ||
| 1h | 3 | 3.09 | ||||
| 6wh | <=29 | <=38.57 | C D | Obtain darks at TCCD values not already sampled. | ||
| CALIBRATION: last monitors |
1w | 1 | 1.78 | A B H | last CCD, CTE monitors. Use TCCD = T0, GAIN=1. | |
| 2w | 1 | 2.19 | ||||
| 1h | 1 | 1.03 | ||||
| 2h | 1 | 0.48 | ||||
| 7s | 2 | 1.48 | J K | STUFF Kr, Xe + 4mm pinhole; F115LP. |
The first column gives the section reference in the Thermal Vacuum Plan. In some cases, a more precise indication of the timing is included in the Notes column. The Procs column lists the calibration procedures to be run. The Iter. column indicates the number of iterations the procedure should be run. The total duration for all iterations is indicated in the Time column. The Cal. Items column lists the calibration items being addressed with the tests.
Some of the calibration observations may be obtained earlier than the official calibration phase. In particular, calibration opportunities may occur during thermal transitions (these are noted in the time line), or when anomalies halt the normal flow of the TV test but allow calibration activities to continue.
Note: The above timeline includes the WFC Build#2 in the first TV campaign. This required significant redesign and remanufacture work (on a short time-scale) of the WFC radiation shield. If the WFC Build#2 is not functioning at the time of the TV campaign, all WFC procedures will be stripped from the above timeline, and procedure 6wh will be replaced with 6h.
Original version by : G. Meurer
