MIRI Target Acquisition
The JWST Mid-Infrared Instrument (MIRI) provides target acquisition capabilities for the low-resolution spectroscopy, medium-resolution spectroscopy, and coronagraphic imaging modes.
Overview of MIRI target acquisitions
Parent page: MIRI Operations
Target acquisition (TA) is a procedure that centroids a source and places it accurately within an aperture, region of interest (ROI), or subarray. The filters available for MIRI TA are F560W, F1000W, F1500W, and FND. TA procedures are discussed in the context of the observatory in memos and reports by Gordon & Meixner (2008), Meixner et al. (2006), Nelan et al. (2005), and Meixner et al. (2004).
TA procedures within the Astronomer's Proposal Tool (APT) are available for:
FASTGRPAVG Detector Readout Capability
See also: Understanding Exposure Times
Individual target acquisition frames are only stored in onboard memory during the duration of the integration and target acquisition algorithm (i.e., frames are not saved on the solid state secorder). Since onboard memory can only store the equivalent of 10 full frames of MIRI data at a time, target acquisition in FAST Mode can be limited to a shorter exposure time than desired by the user.
For MIRI target acquisition only, the FASTGRPAVG readout mode is available to users to allow for longer exposure times by averaging a given number of frames together as a group. For example, FASTGRPAVG8 averages 8 frames together, so your maximum integration is 8 times longer than in FAST Mode.
Mid-InfraRed Instrument (MIRI) Target Acquisition Strategies and Use Cases
Gordon, K., 2008, JWST-STScI-001347 (PDF)
Mid-Infrared Instrument (MIRI) Low Resolution Target Acquisition for Faint Sources
Meixner, M. et al., 2004, STScI-JWST-TM-2004-0018A
Mid-Infrared Instrument (MIRI) Target Acquisition Requirements and Strategies
Nelan, E. et al., 2005, STScI-JWST-R-2005-0001
JWST Science Instrument Target Acquisition Concepts