STIS Cycle-23 Calibration Phase-1

Last Revised: 08/11/15

Proposal ID: TBD

Title: STIS/MAMA Fold Distribution

PI: T. Wheeler

Co-I(s): A. Welty

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# Orbit estimates are TOTAL for all of Cycle-23

Total Prime Orbits: 0

External Parallel Orbits: 0

Internals or no-impact orbits: 2

Comments on orbit estimate: 2 orbit per visit

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# This section should be written with a GO audience in mind -- use

# Calibration plans in WFPC-2 handbook as a guide.

Purpose: The performance of MAMA microchannel plates can be monitored using a MAMA fold analysis procedure that provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of change in the pulse-height distribution of the MCP and, therefore, MCP gain.

Description: While globally illuminating the detector with a flat field, the valid event (VE) rate counter is monitored while various combinations of row and column folds are selected. The process is implemented using special commanding and is the same for the FUV and NUV MAMAs with the exception of the gratings/aperture/lamp combinations used for flat field illumination. This proposal executes the same steps as Cycle 22, Proposal 13998 and is described in STIS ISR 98-02R.

Accuracy: 95%

Comments on Accuracy: Position of the peak in the fold distribution can be measured to about 5% accuracy from this procedure.

Products: Fold Analysis findings are reported to the STIS Science Team and V. Argabright of Ball Aerospace after completion of analysis, typically one-two weeks after the execution of the test.

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# Link to Cycle 23 Science

# Use the GO + GTO Phase 1 exposure listing and derived statistics

# posted on WWW.

Fraction of science programs supported by this calibration: 76.9% of STIS prime exposures use MAMAs, 100% of STIS SNAP exposures use MAMAs.

List categories of science which can't be executed until after this

proposal: None

why: This is a health monitoring proposal and not

an enabling or calibration proposal.

List categories of science which are best performed contemporaneous with

this proposal: None

why: n/a

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# THE REST OF THIS FORM IS FOR INTERNAL USE

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Observation summary: Globally illuminate the detector with a flat field. Monitor the valid event (VE) rate counter while various combinations of row and column folds are selected. The process is the same for the FUV and NUV MAMAs with the exception of the gratings/aperture/lamp combinations used for flat field illumination.

# Target information (copy for each target)

Target Name. : n/a (internal)

RA. : n/a

Dec. : n/a

Flux (and units). : n/a

Visibility window (if known or relevant): n/a

Comment on choice of target : n/a

# Exposure list plan at the Phase I level. Be as complete as reasonable.

# If possible information should be complete enough to allow easy

# submission of a Phase 2 from this form. However, if you have to leave

# some of the fields blank below, or want to provide the information

# in another format, that is acceptable. (Make sure you do the BOP checking

# though, as this is a phase-1 issue.)

Table of exposures (copy for each exposure as appropriate/desired):

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**** This list of exposures needs to be repeated once every 6 months ****

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Note (1)

Bright Object Protection Considerations

(a) This proposal uses aperture/mirror/lamp combinations which are designed

to produce count rates of ~100,000-200,000 count/sec. They should not

be changed without consultation with the P.I.

(b) During the execution of the fold analysis some anode folds are

disabled. Consequently, the OR counter does not provide a true

representation of the OR count and so the Software Global Monitor (SGM)

does not trigger until the enabled folds provide enough counts to the

OR counter to trigger the SGM's threshold. To compensate, while the

fold analysis is running the SGM threshold is reduced to 150,000 counts

(130,000 counts are used due to ground system restrictions) in a 1.0

second interval, from its nominal value of 77,000 counts in a 0.1

second interval.

hub area, this test should only be run with the STIS external shutter

closed.

Visit 1, Exposure 1: FUV Fold Test Setup

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : FUV MAMA (M1)

Operating mode : Data

Spectral Element : n/a

Aperture : n/a

Central Wavelength : n/a

Exposure Time : 240s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: Sequence 1-3 NON-INT

Set SGM Threshold = 15000, Integration Period = 0.1 s

Configure Mechanisms

Turn on HITM2 lamp at 10mA current

Special commanding: Instruction = EOFOLDSET1

Visit 1, Exposure 2: FUV Fold Test Accum

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : FUV MAMA (M1)

Operating mode : Accum

Spectral Element : MIRROR

Aperture : F25ND3

Central Wavelength : n/a

Exposure Time : 300s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: This image is a flat field exposure with the HITM2 using special

commanding so that the lamp remains on after the exposure.

Visit 1, Exposure 3: FUV Fold Test

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : FUV MAMA (M1)

Operating mode : Data

Spectral Element : MIRROR

Aperture : F25ND3

Central Wavelength : n/a

Exposure Time : 2300s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: Special commanding: Instruction = EOFOLDTST1 – See below for details.

Set SGM Threshold = 130000, Integration period = 1.0 secs

(a) Collect counter samples during flat field illumination

Collect 5 samples X events

Collect 5 samples Y events

Collect 5 samples Z events

Collect 5 samples W events

Collect 5 samples VE events

Collect 5 samples EV events

Collect 5 samples OR events

(b) Disable MAMA Folds: C2, C3, C4, C5, C6, R2, R3, R4, R5, R6

Collect 5 samples VE for following 19 combinations of MAMA folds:

(1) Enabled: C2, R2; Disabled: C3, C4, C5, C6, R3, R4, R5, R6

(2) Enabled: C2, R3; Disabled: C3, C4, C5, C6, R2, R4, R5, R6

(3) Enabled: C3, R2; Disabled: C2, C4, C5, C6, R3, R4, R5, R6

(4) Enabled: C2, R4; Disabled: C3, C4, C5, C6, R2, R3, R5, R6

(5) Enabled: C3, R3; Disabled: C2, C4, C5, C6, R2, R4, R5, R6

(6) Enabled: C4, R2; Disabled: C2, C3, C5, C6, R3, R4, R5, R6

(7) Enabled: C3, R4; Disabled: C2, C4, C5, C6, R2, R3, R5, R6

(8) Enabled: C4, R3; Disabled: C2, C3, C5, C6, R2, R4, R5, R6

(9) Enabled: C3, R5; Disabled: C2, C4, C5, C6, R2, R3, R4, R6

(10) Enabled: C4, R4; Disabled: C2, C3, C5, C6, R2, R3, R5, R6

(11) Enabled: C5, R3; Disabled: C2, C3, C4, C6, R2, R4, R5, R6

(12) Enabled: C4, R5; Disabled: C2, C3, C5, C6, R2, R3, R4, R6

(13) Enabled: C5, R4; Disabled: C2, C3, C4, C6, R2, R3, R5, R6

(14) Enabled: C4, R6; Disabled: C2, C3, C5, C6, R2, R3, R4, R5

(15) Enabled: C5, R5; Disabled: C2, C3, C4, C6, R2, R3, R4, R6

(16) Enabled: C6, R4; Disabled: C2, C3, C4, C5, R2, R3, R5, R6

(17) Enabled: C5, R6; Disabled: C2, C3, C4, C6, R2, R3, R4, R5

(18) Enabled: C6, R5; Disabled: C2, C3, C4, C5, R2, R3, R4, R6

(19) Enabled: C6, R6; Disabled: C2, C3, C4, C5, R2, R3, R4, R5

(d) Enable MAMA folds C2, C3, C4, C5, C6, R2, R3, R4, R5, R6

at completion of exposure.

(e) Check lamp stability by checking EV and VE

Collect 5 samples events (EV) to check lamp stability

Collect 5 samples Valid Events (VE) to check lamp stability

(f) Turn off HITM2 lamp

(g) Collect event counter data for detector dark count rate

Collect 5 samples X dark events

Collect 5 samples Y dark events

Collect 5 samples Z dark events

Collect 5 samples W dark events

Collect 5 samples VE dark events

Collect 5 samples EV dark events

Collect 5 samples OR dark events

(h) At completion of procedure reset SGM to nominal operating level

Visit 2, Exposure 1: NUV Fold Test - Fold Test Setup

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : NUV MAMA (M2)

Operating mode : Data

Spectral Element : n/a

Aperture : n/a

Central Wavelength : n/a

Exposure Time : 240s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: Sequence 1-3 NON-INT

Set SGM Threshold = 15000, Integration Period = 0.1 s

Configure Mechanisms

Turn on HITM1 lamp at 3.8mA current

Special commanding: Instruction = EOFOLDSET2

Visit 2, Exposure 2: NUV Fold Test - Accum

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : NUV MAMA (M2)

Operating mode : Accum

Spectral Element : MIRROR

Aperture : F25ND3

Central Wavelength : NONE

Exposure Time : 120s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: This image is a flat field exposure with the HITM1 using special

commanding so that the lamp remains on after the exposure.

Visit 2, Exposure 3: NUV Fold Test - Fold Test

Target or lamp : Dark

Type of Acquisition : n/a

Detector for observation : NUV MAMA (M2)

Operating mode : Data

Spectral Element : MIRROR

Aperture : F25ND3

Central Wavelength : n/a

Exposure Time : 2300s

Number of Iterations : 1

BOP Predicted Local Count Rate for MAMA : Note (1)

BOP Predicted Global Count Rate for MAMA: Note (1)

ETC PID IDs for Count Rates :

Special Requirements or options : Special Commanding

Comments: Special commanding: Instruction = EOFOLDTST2 – See below for details.