Rubin2020_PCW slack archives day2-tue-slot2f-rrb-minimizing-systematics 2020-07-31---2020-08-11

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@Melissa Graham set the channel topic: Rubin Research Bytes Session F. Minimizing Systematics
RRB Webpage: <https://project.lsst.org/meetings/rubin2020/agenda/session/rubin-research-bytes>
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sthomas Tue 2020-08-11 01:25PM
Thank you!
Will Clarkson Tue 2020-08-11 01:45PM
Question for @Tom J Wilson for the Q&A - we're interested in estimating the astrometric uncertainty, due to unresolved fainter sources in Rubin data in crowded fields biasing the centroid location of the bright star we do see... does your software framework already allow exploration of this? Thanks, great talk!!
Melissa Graham Tue 2020-08-11 01:49PM
@here new transition time 11:15am due to technical difficulties
sthomas Tue 2020-08-11 01:50PM
:+1:
mwv Tue 2020-08-11 01:53PM
@Tom J Wilson : You quote two space missions, which are shot noise dominated, correct?
How much does this change if the faint sources are fainter than the sky background?
mwv Tue 2020-08-11 01:56PM
@Claire-Alice Hebert On a related note, do you find that it's the wings of the PSF that can vary most image to image or the central peak?
mwv Tue 2020-08-11 01:56PM
Or, perhaps phrased better, can different atmospheric effects and sampling create different temporal variation power in the wings vs. the center.
Will Clarkson Tue 2020-08-11 01:57PM
@Tom J Wilson - have you simulated the case where the external astrometric uncertainties are wrong (e.g. the external investigator underestimates the astrometric spread by a factor 2)? [I can take the answer offline if we're running out of time]
mwv Tue 2020-08-11 02:06PM
@M Temple Here's the figure that we're working on that I think directly addresses your question
mwv Tue 2020-08-11 02:07PM
(The lines are artificially offset for each PWV for visibility.)
M Temple Tue 2020-08-11 02:07PM
Thank you!
K-T Lim Tue 2020-08-11 02:13PM
:clap:
Robert Lupton Tue 2020-08-11 02:30PM
I think that @Eli Rykoff has plots recovering PWV from DECam, delta z v. z - y
Eli Rykoff Tue 2020-08-11 02:47PM
Slides 25 and 26 in https://project.lsst.org/meetings/law/sites/lsst.org.meetings.law/files/Project%20Pland%20for%20Photometric%20Calibration%20-%20Eli%20Rykoff.pdf
Tim Lister Tue 2020-08-11 02:33PM
@mwv I think you said these came from dual frequency GPS (badly timed Zoom breakup). Have you compared with the total preciptable water vapor column products from the MODIS instrument on the Aqua/Terra Earth-observing satellites ?
Robert Lupton Tue 2020-08-11 02:33PM
(dual-beam GPS is correct)
Robert Lupton Tue 2020-08-11 02:34PM
@Claire-Alice Hebert : do you have access to stereo-SCIDAR data? I think it's been taken at Paranal
Morgan Schmitz Tue 2020-08-11 02:36PM
Q for Claire-Alice: The last plots of sim vs data are really impressive in terms of |e|. Have you looked at size of the PSF, and do you get it as right?
Morgan Schmitz Tue 2020-08-11 02:37PM
@sthomas If it is okay, could you read my question? I have _a lot_ of background noise right now
sthomas Tue 2020-08-11 02:37PM
I will !
Morgan Schmitz Tue 2020-08-11 02:43PM
@Claire-Alice Hebert Makes a lot of sense. Thanks!
Robert Lupton Tue 2020-08-11 02:38PM
Osborn, J., D. Föhring, et al. (Sept. 2015). "Atmospheric scintillation in astronomical photometry". In: MNRAS 452, pp. 1707-1716. doi: 10.1093/mnras/stv1400. arXiv: 1506.06921 [ http://astro-ph.IM ].
Osborn, James, Timothy Butterley, Saavidra Perera, et al. (2015). "Observations of the dynamic turbulence above La Palma using Stereo-SCIDAR". In: doi: 10.20353/k3t4cp1131607.
mwv Tue 2020-08-11 02:40PM
Sorry, The GPS system doesn't do a good job of measuring PWV when it's really dry. It tends to believe that 2mm is as low as one tends to go.
K-T Lim Tue 2020-08-11 02:44PM
Newbie question: what's the difference between P WV and non-P WV? Why isn't all WV P?
mwv Tue 2020-08-11 02:59PM
All WV is P
K-T Lim Tue 2020-08-11 03:00PM
I guess http://glossary.ametsoc.org/wiki/Precipitable_water says that all WV is P
K-T Lim Tue 2020-08-11 03:00PM
Jinx!
mwv Tue 2020-08-11 03:00PM
PWV explicitly refers to the total column density through the atmosphere
mwv Tue 2020-08-11 03:00PM
I agree that pre-fixing the 'P' doesn't obviously convey that, but it's the term used.
mwv Tue 2020-08-11 03:01PM
Specifically "PWV" means the integrated WV measured through a column straight up
mwv Tue 2020-08-11 03:01PM
So when I say PWV_LineOfSight, I'm somewhat misusing the term.
Robert Lupton Tue 2020-08-11 02:41PM
(Oh. Maybe only La Palma? If so, sorry)
Tim Lister Tue 2020-08-11 02:42PM
Maybe this: https://www.eso.org/gen-fac/pubs/astclim/paranal/asm/scidar/Stereo-SCIDAR/
Robert Lupton Tue 2020-08-11 02:47PM
That summary doc "Stereo-SCIDAR-results.pdf" is really nice
Knut Olsen Tue 2020-08-11 02:44PM
:clap:
mwv Tue 2020-08-11 02:45PM
@Melissa Brucker (she/her) Sorry my answer wasn't entirely coherent.
The PWV is calculated based on the dual-band GPS system + temperature + humidity + pressure
Melissa Brucker (she/her) Tue 2020-08-11 03:05PM
thank you
Tue 2020-08-11 02:45PM
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sthomas Tue 2020-08-11 02:45PM
Thank you all! :clap: