1. Jitter test Responsible Parties Test Goals
Principal: Christopher Willmer
Deputy: TDB
Timeline : immediate, as subsequent tests depend on this test’s results.
Products to: LMATC (optimal exposure time for module+filter combination)
Test Goals
Measure exposure time that will minimize blurring due to jitter because of mechanical vibration
affecting the OMA and modules inside the Red Chamber. This test is critical as the optimal
pulse durations will be used in several other tests during the cryogenic cycles.
Summary of liens against this test
Need to specify which NIRCam filters will be used in this test (all filters ?)

2. Instrument Configuration
OMA: SMART tool to project a point source image onto the FPA.
OMA: HONDA filter in FW2 ND filters with OD = ( 0, 1, 2, 3, 4, 5), blocking filters in FW1
NIRCam : Module A SW C067, LW C090 ; PIL out, FW1, FW2, including weak lenses.
Procedure
Calculate the expected PSF given the illuminating source and filter bandpass being used;
use SMART tool on OMA to produce a point source image on FPA;
focus point source ;
obtain images by looping through a sequence of pulse durations and neutral density filters;
measure the PSF on images and determine the combination of pulse duration + ND filter that
produces the least blurring when compared to the expected.
Pre-requisites
D0, D6, D1 (ASIC tuning; dark/read noise; chamber background)
Instrument in focus ?

3. Test Sequence
For each NIRCam filter being tested, loop through the pulse duration times and HONDA neutral density filters. This will allow measuring the optimal combination that minimizes exposure time, jitter, maximizing S/N of source.
Pre-requisites : SMART tool image must be in focus; need to know the estimate of minimum acceptable signal level in counts.
Configuration/setup
Set pulse duration
Have HONDA ND filter in place
Have NIRCam FW1 and FW2 filters in place, place PIL out of beam
Setup:
Set readout mode = rapid, NGROUPS=3, series of 3 ramps, one with light off to serve as background, two with light on.
Step 1
On OMA place HONDA ND filter in place
Set pulse time, expose sequence

4. Data Analysis
Calibrations: Darks, Bias, Flats, bad pixel maps, possibly linearity; PSF images from Webbpsf;
Software required : ncdhas, IRAF, Webbpsf;
Ncdhas will be used to obtain fully reduced slope images
Iraf will be used to combine reduced images and to subtract the background;
webbpsf will be used beforehand to calculate the expected PSF for the NIRCam filters.
Analysis
Generate slope images
IRAF.imcombine the illuminated images
subtract the background from combined illuminated images
measure FWHM of the PSF and compile table of PSF FWHM vs. pulse duration + ND filter
Calculate PSF FWHM for individual background-subtracted images, and add values to table mentioned above, in order to have an estimate of the uncertainties of a single pulse duration-ND filter setup.
Compare measured PSF with that expected from webbpsf, by calculating ratios and differences, and creating residuals maps.
Examine residual maps and tables to find where FWHM is minimized and where PSF wings are
minimized.

5. Commands
INRC_WHEEL_INIT [MECH= {PUPILSHORTA, FILTSHORTA}] initialize filter and pupil wheels
INRC_PIL [PIL=PILA, POSITION=RETRACT] retract PIL
INRC_PUPIL4[PUPILSHORTA = CLEAR] place pupil wheel on clear position
INRC_CONFIG [DETECTORS=NRCA2, BUFFER=A, NINTS=1, NGROUPS=3, NFRAMES=1, GROUPGAP=0] configure detector for data acquisition
INRC_FILTER4[FILTSHORTA=F070W] place filter in position
INRC_EXPOSE [DETECTORS=NRCA2, BUFFER=1, NDROPFRAMES3=0] expose

6. Test Outputs
Describe the data products or other tangible results from the test, and how to document/present those
A table of FWHM of PSF versus pulse duration, ND filter and total signal will be compiled and will produce an estimate of best pulse duration. This will then be compared to what is the minimum expected total counts for tests using point sources.
These will be compared to the residuals derived from ratios between observed and expected PSFs using Webbpsf models. The expectation is that jitter will increase PSF wings, so that the residuals presenting the least signal in the outer parts will be the optimal ones. If both tests present results that disagree, values of the first one should be used, as it is possible that the PSF models are not entirely adequate.

7. Examples from ETU testing (part C072, currently in Module A, position A1)
F115W filter, 75 msec pulse, FW1=1150NB10,FW2=ND4,
F115W filter, 75 msec pulse, FW1=1150NB10,FW2=ND3
F200W filter, 20 msec pulse, FW1=2000NB10,FW2=ND2
F200W filter, 75 msec pulse, FW1=1150NB10,FW2=open