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Contact: Hooshang Nayyeri (hnayyeri@uci.edu) and Vivian U (vivianu@uci.edu)


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HW2 - 

Understanding JWST detectors questionnaire


1. What is the difference between the JWST NIR and MIR detectors?

2. What is the fundamental difference between a CCD and a JWST detector readout?

3. What is a frame?

4. What is a group?

5. What’s the meaning of “group gap” or “dropframes” in the JWST NIR detectors?

6. What is a reset?

7. What is an integration?

8. What is an exposure?

9. Suppose you have data from a CCD and from a JWST detector. They both reach the saturation level in one-half of the total integration time. Can you describe what the main difference is? Can you recover information in the saturated pixels?

10. What will be the impact of a cosmic ray in a JWST integration? Can information be recovered?

11. a) What is the practical difference between a MIRI SLOW mode exposure and a NIR exposure with NFRAMES=8? b) Which has a higher data rate: a single MIRI Si:As

detector running in SLOW mode or a single NIRCAM H2RG detector using the MEDIUM8 readout pattern?

https://jwst-docs.stsci.edu/mid-infrared-instrument/miri-instrumentation/miridetector-overview/miri-detector-readout-overview/miri-detector-readout-slow

https://jwst-docs.stsci.edu/observatory-functionality/jwst-data-rate-and-datavolume-limits

12. Given a certain readout pattern, why is the group time different for full and subarray mode?

https://jwst-docs.stsci.edu/near-infrared-camera/nircam-instrumentation/nircamdetectors/nircam-detector-subarrays

13. If a user defines a single NIRCam exposure (i.e. no dithers) with all modules in FULL array and BRIGHT1 readout pattern, that uses 10 groups and 1 integration, the exposure time is 203.99 second. 10 groups and 2 integrations result in 418.73 seconds. Why the total time of 2 integrations is not twice as long as one? Can you guess why that would not be the case for MIRI?

https://jwst-docs.stsci.edu/jppom/visit-overheads-timing-model/instrument-specificoverheads/nircam-overheads


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HW1 -

Cross Instrument

In addition to the required questions in bold-faced, answer an additional 1 question from this

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