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A1: Webb Office Hours. Type your question into the WebEx chat. We will asynchronously copy questions from the chat to this main page and work through them as a group. If you have images to share please give WebEx permission to share your screen (you may need to log out and log back in again to enable this feature.)
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Q2: How accurate is the absolute flux calibration in the latest version of the pipeline for MIRI MRS, especially in channel 4? We tried running our data through the updated MRS notebook, but our target is much fainter (milliJy) than the example shown in the notebook (Jansky). Due to the faintness, our source is more prone to artifacts than the bright target in example notebook. Our data look noisy in channel 4, with a dip in the spectrum around 18 microns (between channels 3 and 4). This dip is seen in different targets, so it's unlikely to be astrophysical in origin.
A2: Please share the data cubes in a help desk ticket for the MIRI team to take a closer look. You can also extract a spectrum from a background region. If the feature is an artifact induced by inaccurate flux calibration, it should be present in the background spectrum. You could also check the target position in cube to see if there is maybe something weird in the cube building step. Note that a discontinuity is seen in the background spectrum with a peak at 18 microns. When subtracting this background spectrum, it would cause a dip in source spectrum.
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Q3: The new pipeline reduction of a MIRI MRS observation shows bumps and wiggles right below 15 microns. These features are not present in previous pipeline reduction. Are these features real or artifacts?
A3: This question was posed to the help desk. The MIRI team will investigate.
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Q4: How accurate is the wavelength calibration in MIRI MRS? We're trying to assess whether observed trends with wavelength are astrophysical in origin or whether they are an artifact from inaccurate calibration.
A4: The MIRI team is unaware of any issues with the wavelength calibration accuracy, or jumps between channels/bands. The current MRS wavelength calibration accuracy is reported on JDox here: MRS: https://jwst-docs.stsci.edu/jwst-calibration-status/miri-calibration-status/miri-mrs-calibration-status#MIRIMRSCalibrationStatus-wavelength_calibWavelengthcalibration. There can be higher uncertainty at the edges of the bands (70-80 km/s) relative to the center of the bands. Submit data to the help desk and the MIRI team can take a closer look.
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Q5: There was a proposal to measure the redshift of galaxies until z =10. Was this proposal approved?
A5: You can find the approved Cycle 3 programs here: https://www.stsci.edu/jwst/science-execution/approved-programs/general-observers/cycle-3-go. The list of approved abstracts are also available. You can search approved programs by investigator here: https://www.stsci.edu/jwst/science-execution/program-information
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Q6: When will data from programs be publicly available?
A6: This depends on the exclusive access period for a program. The visit status page (linked from the Program Information page; https://www.stsci.edu/jwst/science-execution/program-information) reports when a program has been observed. The program information page reports the exclusive access period. Data are publicly available at the end time of a program + the exclusive access period.
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Q7: How do I identify programs where JWST observations are used to study the ages of galaxies?
A7: An ADS search (https://ui.adsabs.harvard.edu/) on abstracts and published papers is the most reliable way to find this information. For accepted JWST programs, a search like bibcode:"202?jwst.prop*" AND abs:"galaxy" AND abs:" age" would return this information.
