A Preliminary Cycle 1 Calibration Plan for the

JWST Science Instruments

James Muzerolle

Timeline: Launch, ~6 months Commissioning•checkout of mechanisms, early calibrations to enable science

•Commissioning activity requests (“CARs”) now written

•Cycle 1: science obs begin as instrument modes are commissioned – need full calibrations

Cycle 1 Calibration Plan Goals

obtain all internal and celestial observations needed to fully calibrate the science instruments:

• characterization of detector effects not done or completed on the ground

• (spectro)photometric, astrometric calibration

• monitoring/stability of key metrics and effects that may change

• anything else not covered or completed during Commissioning

begin defining a baseline plan by defining the set of likely programs and drafting program “summaries”

use as input into the SODRM (Gordon et al.)

plan conceived and written by instrument leads:

NIRCam: Anton Koekemoer NIRSpec: James Muzerolle

NIRISS: Kevin Volk, Harry Ferguson MIRI: Karl Gordon

status:

all planned program summaries are complete

- 39 programs among the 4 SIs

- available at https://confluence.stsci.edu/display/JWST/Cycle+1+Calibration+plans

modified versions of all have been added to the SODRM

example program summary

grand total of 756 hours:

• 258 hrs likely to be done as parallels

• 82 hrs can be run during slews (internals)

Plan statistics

the vast majority of data volume will be obtained in parallel observations (all darks)

• need to investigate at the visit level to verify within sufficient limits

data categories shared by most/all instruments

• most common are darks, flats, flux calibration

• many external observations share the same targets: astrometric calibration field, photometric standards

MIRI and NIRSpec dominate

• more modes, monitoring, and standard stars

more than half of the programs are monitors

• darks, lamp flats, (spectro)photometric calibration

• cadences mostly notional at this point

Deliverables

• dark reference files

• bad pixel maps

• read noise measurements

• P- and L-flat reference files

• Linearity reference files

• astrometric solution and distortion reference files

• PSF images/characterization

• persistence maps

• Spectral traces

• LSF characterization

• absolute photometric calibration conversion factors

• relative throughput measures

Future work The plan will be maintained by the new JWST Calibration & Commissioning Working Group

• check completeness of deliverables (Van Dixon reference file studies)

• push further coordination with the Commissioning plan

many monitoring programs based on CARs (internals, astrometric & photometric calibration)

better define the boundaries between Commissioning and Cycle 1

• update programs as new ground test results are obtained

• plan ground-based preparatory observations (vetting of appropriate targets, etc)

- expect to phase in Cycle 1 over L+5 to L+6 months

approximate commissioning timeline:

L+ dL

+