A Hubble tension -- any resolution?

[Jaime Rudas]

Agreed however the methods of the paper are useful when it comes to calibration of JWST characteristics.

I don't see how the methods of the paper can be useful in calibrating the JWST characteristics. Could you give an example?

 

[Mordred]

Any method using Cephieds, stars including TRGB stars requires a good understanding of their luminosities particularly on distance measures.

A decent article covering the factors involved for TRBG can be found here

https://arxiv.org/abs/2002.01550

Several of the luminosity relations will differ from Cepheids as their metalicities vary.
You might note that the above paper also references Freedmanns paper from 2019

 

[Jaime Rudas]

Any method using Cephieds, stars including TRGB stars requires a good understanding of their luminosities particularly on distance measures.

Cepheids and TRGB are two very different types of stars.

 

[Mordred]

Yes I know hence needing calibrations for the different filters required.

Here is the paper specific the JW telescope
https://www.google.com/url?sa=t&sou...4QFnoECBEQAQ&usg=AOvVaw2YsM7U8ypG6aX_VdsMDY3y

This article gives a good comparison between Cepheids vs TRGBs and how good calibration can extend the effective distance.
https://arxiv.org/pdf/2308.02474

 

[Jaime Rudas]

Yes I know

If you know, why do you imply that the TRGB are Cepheids?

 

[Mordred]

Where did I do that ?

 

[Jaime Rudas]

Yes I know hence needing calibrations for the different filters required.

Here is the paper specific the JW telescope
https://www.google.com/url?sa=t&sou...4QFnoECBEQAQ&usg=AOvVaw2YsM7U8ypG6aX_VdsMDY3y

This article gives a good comparison between Cepheids vs TRGBs and how good calibration can extend the effective distance.
https://arxiv.org/pdf/2308.02474

None of those papers deals with the calibration of JWST characteristics, which was what you mentioned.

 

[Mordred]

Really ?

"However, with any standard candle, it is first necessary to provide an absolute reference. Here we use Cycle 1 data to provide an absolute calibration in the F090W filter. F090W is most similar to the F814W filter commonly used for TRGB measurements with HST, which had been adopted by the community due to minimal dependence from the underlying metallicities and ages of stars. The imaging we use was taken in the outskirts of NGC 4258, which has a direct geometrical distance measurement from the Keplerian motion of its water megamaser. Utilizing several measurement techniques, we find MF090WTRGB = -4.362 ± 0.033 (stat) ± 0.045 (sys) mag (Vega) for the metal-poor TRGB. We also perform measurements of the TRGB in two Type Ia supernova hosts, NGC 1559, and NGC 5584. We find good agreement between our TRGB distances and previous distance determinations to these galaxies from Cepheids (Δ = 0.01 ± 0.06 mag), with these differences being too small to explain the Hubble tension (∼0.17 mag). As a final bonus, we showcase the serendipitous discovery of a faint dwarf galaxy near NGC 5584."

 

[Jaime Rudas]

Where did I do that ?

In the post #62:

Any method using Cephieds, stars including TRGB stars requires a good understanding of their luminosities particularly on distance measures.

 

[Mordred]

My apologies, poorly worded I can see where the confusion cropped in

 

[Jaime Rudas]

Really ?

Really. What you quote does not refer at all to calibration of JWST characteristics, but to the calibration of the distance by the TRGB method.

 

[Mordred]

How do you calibrate filters used by the JWST without a good reference ? the paper fully details the process including listing any applicable software the JWST uses.

Not sure what your after but quite frankly that paper specifically details calibrations.
Including some of its different methodologies.

If it helps here is another related paper this one better describes some of the noise issues

https://iopscience.iop.org/article/10.3847/2041-8213/ad1ddd/pdf

 

[Jaime Rudas]

Not sure what your after but quite frankly that paper specifically details calibrations.
Including some of its different methodologies.

Yes, that paper specifically details the calibration of distance measurement by the TRGB method, but it does not address the calibration of JWST characteristics.

 

[Mordred]

Then define JWST characteristics for me because quite frankly that includes the filters and software the JWST uses by my way of thinking

 

[Jaime Rudas]

Then define JWST characteristics for me because quite frankly that includes the filters and software the JWST uses by my way of thinking

The paper deals with the calibration of the distance measurement by the TRGB method, but doesn't deal with the calibration of the JWST filters or software.

 

[Mordred]

The two go hand in hand you cannot determine a distance involving brightness using Leavitt without a solid calibration.

 

[Jaime Rudas]

The two go hand in hand you cannot determine a distance involving brightness using Leavitt without a solid calibration.

Yes, it is possible, but, contrary to what you stated, the methods of the paper aren't related to the calibration of JWST characteristics.

 

[Mordred]

Whatever you believe but when I see a paper measuring well established objects as baseline and discusses its filters and software and details its error margins and compares the different components and software the same telescope uses as well as any details relating to noise reduction then that's directly related to its calibration.

Calibration obviously isn't restricted to just components which I believe your getting at but the links I provided also includes error margins of the components

A common baseline object used being NGC 4285.

The article you linked for example lists 3 independent measurements. That's excellent for calibration the more independent measurements the better. Another common independent measurement for calibration purposes being interstellar parallax.

How else do you establish a zero point baseline

 

[Jaime Rudas]

Contrary to what you stated, the methods of the paper aren't related to the calibration of JWST characteristics.

 

[Mordred]

I disagree but that's fine. Calibration includes hardware, software, noise reduction of measurement hence filters and filtering software, envoronmentsl noise reduction. Technically any form of error margin reduction is a means for calibration. Those papers discuss those factors.

 

[Mordred]

I don't see how the methods of the paper can be useful in calibrating the JWST characteristics. Could you give an example?

If you recall I was originally answering this. You have multiple independent measurements (yes on different star types ) done by the equipment using different filters, software from the same satellite.
Can you not see the usefulness to JWST calibration ?

Why restrict calibration to just JWST characteristics when any error margin applies

 

[Jaime Rudas]

I disagree but that's fine. Calibration includes hardware, software, noise reduction of measurement hence filters and filtering software, envoronmentsl noise reduction. Technically any form of error margin reduction is a means for calibration. Those papers discuss those factors.

Yes, they may analyze those factors. What they don't analyze is the supposed usefulness of the methods described in those papers for the calibration of the JWST characteristics, which is what you have insistently stated.

If you recall I was originally answering this. You have multiple independent measurements (yes on different star types ) done by the equipment using different filters, software from the same satellite.
Can you not see the usefulness to JWST calibration ?

Of course I see the usefulness of JWST calibration. What I definitely don't see is the supposed usefulness of the methods described in those papers for calibrating the characteristics of the JWST, which is what you have insistently stated.

Why restrict calibration to just JWST characteristics when any error margin applies

Because what you have insistently stated is precisely that the methods of those papers are useful when it comes to calibration of JWST characteristics.

 

[Mordred]

You asked for usefulness of your paper for calibration. Your the one insisting calibration entails nothing more than JWST characteristics.

Not me any research whatsoever that can be used to fine tune detectors and eliminate error margins and unwanted noise such as background noise from intervening plasma directly affects what is needed to eliminate those factors.
Using multiple points is a huge advantage when you can apply different independent measurements.
running comparisons between Cepheid and TRGB measurements is a useful step

You cannot do a calibration unless you study the interference to factor out that noise etc etc. Nor can you calibrate for distance measures without a good baseline reference.
The Paper you posted directly relates to establishing good baseline references. It even describes realignment

"Accomplishing this imposed constraints on the placement of the scientific apertures, as well as on the allowed rotation angles of the telescope. For each target, the offset values of the NIRCam aperture were set so as to minimize loss of Cepheid coverage over large ranges of allowed telescope rotation angles, thereby maximizing schedulability at a minimal science loss. For observing the JAGB stars, additional constraints on the telescope’s commanded position angles were determined using deep ground-based imaging from the DECALS legacy imaging survey (Dey et al. 2019), as well as HI maps of the target galaxies when available. The goal was to sample each galaxy’s thick disk component while minimizing the likelihood of dust extinction systematically biasing a JAGB measurement. Finally, (T)RGB stars were either targeted with (some portion of) the module of NIRCam that was not aimed at the Cepheids or with parallel NIRISS observations, depending on the angular extent of the target galaxy. In some cases, there existed ACS/WFC observations of the TRGB from the Carnegie Chicago Hubble Program (Freedman et al. 2019). Sampling some portion of those imagesets was taken into consideration in order to leverage both optical and NIR photometry and better understand the TRGB magnitude-color relation (as in the present study). "

That's from your article.

 

[Jaime Rudas]

Agreed however the methods of the paper are useful when it comes to calibration of JWST characteristics. Which evidently we both agree on lol

False. the methods of the paper aren't useful when it comes to calibration of JWST characteristics. And it is also false that I agree with that.

 

[Mordred]

Do you not understand the TRGB color dependence in the very title of the paper and how that color dependence requires calibration?

It's literally what it is describing

 

[Jaime Rudas]

Then you don't recognize where TRGB calibrations mentioned in the last part of my quote from your paper isn't described by that paper ?

Then you don't recognize the difference between TRGB calibrations and the calibration of JWST characteristics?

 

[Mordred]

Please define for me JWST characteristics if it's not the filters applied for the equipment it contains and the software it uses.

That's your terminology not mine so please define what you mean.

 

[Jaime Rudas]

Please define for me JWST characteristics if it's not the filters applied for the equipment it contains and the software it uses.

Sorry but the calibration of JWST characteristics isn't the topic of the original post.

That's your terminology not mine so please define what you mean.

False.

 

[Mordred]

Thank you it isn't the topic of the original post. We obviously have a differing opinion of what entails characteristics. Let's leave it at that

 

[Jaime Rudas]

Thank you it isn't the topic of the original post.

False.