Cycle 1 Calibration - NIRISS

The activities listed below are those parts of the Cycle 1 Calibration plan for the Near-Infrared Imager and Slitless Spectrograph (NIRISS) that have a dedicated observational component.  It is important to remember that the Cycle 1 Calibration plan is not final.  The plan as laid out here is based on our current understanding of the telescope, instruments, and all other planned observations in Cycle 1.  This program should be considered provisional and may change in response to system developments and the final science program. 

The text for each calibration activity below includes a title, program ID number, and the abstract also included with the APT file.  The program ID number links directly to the STScI webpage for that program.  Users interested in obtaining APT files can either follow that link or retrieve the file by running the APT and retrieving it by its program ID.

Program 1497 - CAL-NIS-001 - Full Frame Darks (NISRAPID)

Program 1498 - CAL-NIS-002 - Full Frame Darks (NIS)

Program 1499 - CAL-NIS-003 - Subarray Darks

Program 1501 - CAL-NIS-005 - Astrometric Cal

Program 1503 - CAL-NIS-008 - Internal Flats Cal

Program 1504 - CAL-NIS-011 - AMI Intra-pixel Response Cal

Program 1506 - CAL-NIS-013 - NRM Fractional Throughput Cal (Full Frame)

Program 1507 - CAL-NIS-014 - NRM Fractional Throughput Cal (Sub80)

Program 1508 - CAL-NIS-016 - NRM Phase Cal

Program 1509 - CAL-NIS-017 - NRM Pixel Linearity Cal

Program 1510 - CAL-NIS-018 - WFSS Wavelength Cal

Program 1512 - CAL-NIS-021 - SOSS Trace and Wavelength Cal

Program 1514 - CAL-NIS-024 - Low Temperature Photometric Standard Check

Program 1515 - CAL-NIS-025 - Stability Monitoring

Program 1516 - CAL-NIS-026 - AMI Charge Transfer Characterization


Program 1497 - CAL-NIS-001 - Full Frame Darks (NISRAPID)

Parallel dark current observations are needed for NIRISS in the NISRAPID read-out mode.  These are used to produce the dark current reference file and also for general health analysis for the instrument

Program 1498 - CAL-NIS-002 - Full Frame Darks (NIS)

Parallel dark exposures are taken in the NIS read-out for detector monitoring and the production of reference files for the JWST data reduction pipeline.  The current proposed cadence is one set of darks per 2 months, and hence 6 sets per year. Each set consists of 4 parallel observations.  The individual observations are for 5 integrations per exposure with 30 groups per integration, to be under the 10000 second limit for observations to avoid HGA moves.  It is likely that the HGA moves are of no concern for the dark measurements, but this is required to avoid errors in the APT file.

Program 1499 - CAL-NIS-003 - Subarray Darks

Dark exposures are taken in the different science and calibration sub-arrays to produce the pipeline reference files for these read-out patterns.

Program 1501 - CAL-NIS-005 - Astrometric Cal

The initial astrometric calibration for NIRISS will be done in commissioning.  Subsequent astrometric observations may be required to revise and improve the initial astrometric calibration.  This program carries out an astrometric calibration assuming that the initial solution is known to the required accuracy (5 milli-arc-seconds RMS precision) and that we need to carry out additional observations to refine the existing solution.  The three observations in the commissioning CAR are redone here, linked together.  The first such set of three observations should be done 2 to 4 months after the end of commissioning, and the second set of three observations should be done 4 or more months after the first set.

Program 1503 - CAL-NIS-008 - Internal Flats Cal

This program provides internal lamp flat observations to be carried out during slews.  These observations allow a direct comparison with ground-based data taken in CV3 and OTIS testing to see whether the detector properties have changed.

Program 1504 - CAL-NIS-011 - AMI Intra-pixel Response Cal

A series of exposures of a single star with sub-pixel offsets will be used to characterize the variations in the AMI PSF with the position of the star within the pixel.

Program 1506 -CAL-NIS-013 - NRM Fractional Throughput Cal (Full Frame)

Observations will be made of a standard star in regular full frame imaging and then with the NRM in the beam to calibrate the fractional throughput of the mask for photometric calibration purposes.  A similar program is planned for the SUB80 sub-array, but that uses brighter targets than can be observed in full frame imaging.

Program 1507 - CAL-NIS-014 - NRM Fractional Throughput Cal (Sub80)

Observations will be made of the single star HD 49306 in the SUB80 read-out in regular imaging and then with the NRM in the beam to measure the fractional througput of the mask for photometric calibration purposes.  This measurement differs from the full frame measurement because there will be signal losses out of the small sub-array, hence the fractional throughput measured here will not be the same as measured with the full frame imaging.

Program 1508 - CAL-NIS-016 - NRM Phase Cal

A high S/N observation of a single star will be taken in the three medium-band NIRISS AMI filters.  These observations will be used to determine the AMI closure phases.

Program 1509 - CAL-NIS-017 - NRM Pixel Linearity Cal

NIRISS/AMI observations of three bright stars will be taken to characterize the linearity response of the peak pixels in the PSF to better precision than can be obtained in ground-based linearity measurements.  The observations will be taken with dithering between the 4 primary positions, so this will also provide some persistence data for analysis.

Program 1510 - CAL-NIS-018 - WFSS Wavelength Cal

Observations of a compact planetary nebula in the southern continuous viewing zone will be used to derive the grism wavelength solutions for the GR150R and GR150C grisms in the six blocking filters.  A 3x3 mosaic of pointings is used to move the nebula around within the NIRISS field of view.

Program 1512 - CAL-NIS-021 - SOSS Trace and Wavelength Cal

Observations of a bright star of known spectral type in the continuous viewing zone will be used to determine the GR700XD dispersion solution and the "standard" trace position for the NIRISS SOSS mode.

Program 1514 - CAL-NIS-024 - Low Temperature Photometric Standard Check

Observation of a low temperature source are to be made to test for possible long wavelength filter leaks in the NIRISS imaging mode.  The target is assumed to be a 5 km diameter asteroid at a distance of approximately 2.6 AU.  The actual object to be used will need to be selected at the time the observation is to be scheduled, or at least when an approximate time slot for the observation can be identified.

Program 1515 - CAL-NIS-025 - Stability Monitoring

We propose to make a short observation of a star field in a single NIRISS filter at 1 month intervals to assess the stability of the instrument with time.

Program 1516 - CAL-NIS-026 - AMI Charge Transfer Characterization

Observations of standard stars in NIRISS AMI mode with differing peak ramp counts and the same total exposure time are to be taken to assess the effects of charge migration on the interference pattern.  In this preliminary test, the F430M and F277W filters are used, and in the wide filter a smaller total number of photons is collected per ramp set-up.



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