This page archives Slack comments from Day 2, Session 4 of the Improving JWST Data Products Workshop (IJDPW).
Thomas Williams - Absolutely not useful but the cyclops is from Dragon Quest!
Sarah Kendrew - I would be on board with all our most annoying noises source having a monster-mascot!
Everett Schlawin - Ha, I'm clueless about this!
Jeff Valenti - @Everett Schlawin, is the IEC heater mnemonic in the calibrated engineering database?
Everett Schlawin - I believe not. I found some notes that we can use SI_GZFGPT2AK , which I found in ATOM but not the engineering database
Jeff Valenti - @Everett Schlawin, does the focal plane housing temperature refer to the NIRCam focal plane assembly?
Everett Schlawin - Yes, as I understand it there is a temperature monitor on the "housing" that covers the detectors (both short wavelength and long wavelength).
Michael Regan - We really only need a few DQ values. Most of them carry no information. [Have you looked at the Picture Frame over the time variation? If there is a temp variation you’ll see the picture.
Everett Schlawin - I have not. Do you think that summing all pixels in the picture frame and all inside of it and differencing the two could be sensitive to temperature?
Greg Sloan - @Leo Drake Deming, "one of the brightest sources observed by MIRI" - delta UMi may top R CMa.
Leo Drake Deming - Yes, that's why I said "one of"...!
Greg Sloan - !
Taylor Bell - We've also seen "negative cosmic-rays" in LRS SLITLESS TSO observations and I have no idea what could cause those...
Michael Regan - I can explain the large drop down for the bright pixel. (at least I think so)
Taylor Bell - The drop-downs we've seen in LRS data are <80% saturation, so for the LRS drops we can rule out saturation effects.
Michael Regan - The drops occur in the neighbor of hard saturation pixels.
Taylor Bell - For the LRS data though, there are no hard saturations.
Michael Regan - Well, I can’t explain it. I’ll need to see the uncal file.
Taylor Bell - I'll see if I can find and send one sometime.
David Law - @Leo Drake Deming, one thing to consider is that the DGA wheel isn't perfectly repeatable, meaning that sources will have a slightly different pixel phase each time the source is reobserved. Fringes will thus be somewhat different, most noticeably at short wavelengths where the shifts are larger compared to the pixel sizes.
Leo Drake Deming - Thanks..!
Jane Morrison - @Leo Drake Deming, I want to follow up on the drop downs. I think - as Mike R. - suggested it is related to hard saturation. Send me the PID of the data and I will investigate it.
Leo Drake Deming - Program 1556
Michael Regan - @Néstor Espinoza, your NL correction error is due to forcing the correction to be 1.0 at zero flux. We should not do that.
Thomas Vandal - @Néstor Espinoza, how important is this improved cadence for final transmission spectra? How big is the gain in precision? Are there cases for which CDS is more important than other?
Néstor Espinoza - This is an excellent question that I’m exploring right now. I was particularly interested on this for limb-asymmetries work (e.g., Constraining mornings & evenings on distant worlds: a new semi-analytical approach and prospects with transmission spectroscopy), on which cadence is crucial.I can tell that for certain systems --- in particular for those on which you have large number of groups --- it’s important to consider the “binning is sinning” argument; either through CDS or on ramp-fitting itself.
Everett Schlawin - Excellent talk @Néstor Espinoza! Do you (or @Michael Regan) think the NIR detectors could have some sort of reset anomaly (different from MIRI), this is dominated by the brighter-factor effect or that there are just errors in the non-linearity polynomials? I noticed that NIRCam's de-focused CDS curve has the same shape.
Néstor Espinoza - I’ve been scratching my head for a while on this same question. I don’t know :slightly_smiling_face: --- hence why I do self-calibration of the CDSs.
Timothy Brandt - It might not be relevant, but we did see an exponentially decaying reset anomaly on the H2RG in the ground-based instrument CHARIS: Data reduction pipeline for the CHARIS integral-field spectrograph I: detector readout calibration and data cube extraction
Everett Schlawin - Thank you @Timothy Brandt! Perhaps a longer timescale than the 20 ms could happen. Does CHARIS use an ASIC for readout as well?
Timothy Brandt - yes
Jeff Valenti - @Timothy Brandt mentioned Optimal Fitting, Debiasing, and Cosmic Ray Rejection for Detectors Read Out Up-the-Ramp and fitramp
Macarena Garcia Marin - @Jeff Valenti, any IEC temperature mnemonic should be on the engineering DB
Everett Schlawin - Do you have the mnemonics? I was looking for SI_GZFGPT2AK and didn't find it.
Jeff Valenti - I think "should" means we should put them in the EDB, not that they are already there.
Macarena Garcia Marin - Sorry, bad english. I mean to my knowledge they are there. Whether they are MAST-retrievable Im not sure.
Jeff Valenti - We think the desired mnemonics are not accessible in MAST today, but we want them to be there. Action accepted.
James Davies - @Timothy Brandt, great talk!
Michael Regan - I ran a 245 group cube of NIRSpec with Tim’s code and it took 3 min. That’s twice through. This is super fast compared to the pipeline.
Sarah Kendrew - thanks everyone!
