Anyone know a fitting tutorial?

[gboyle]

Hi all

I’m now able to plot my light curves - sometimes even in real time.., but to advance my understanding I feel I need to learn more about the fitting process - can anyone point me to a tutorial or something that might help me up the curve.

As a specific example of the sort of thing I am wondering about...some of the exoplanet databases now have pretty comprehensive coverage of planet and star parameters...but when I try to enter them in the exoplanet transit fitting model window changing the TEFF or R* invariably changes some of the other data I’ve just entered. I can never get the model to accept a collection of “correct” inputs.  So... how should i think about this? If I have 3 or 4 parameters from R*, Teff, Rj, density etc which ones shoul i try to plug into the model?

Thanks
Gavin
\

[karenacollins]

Hi Gavin,

Dennis Conti provides a really nice intro to exoplanet observing that covers model fitting at the first link here on his website:
http://www.astrodennis.com/

TEFF and R* do not actually change the transit model fit. All the Host Stat Stellar Parameters do  is convert (Rp/R*)^2 from the transit fit to a physical planetary radius. The Host Stat Stellar Parameters are are all interlinked though, so you should only be entering one of them and then the others are estimated from the value that is entered. If you have a value for R*, that is the best stellar parameter enter.


The only transit parameters that are being fit are the ones along the left under "Parameter". If you want to fix one of those, enable the "lock" button and enter the value. The items along the bottom are calculated from the fitted and locked model parameters and should be considered outputs.

Karen

On 12/30/2018 12:39 PM, gboyle [via AstroImageJ] wrote:

Hi all

I’m now able to plot my light curves - sometimes even in real time.., but to advance my understanding I feel I need to learn more about the fitting process - can anyone point me to a tutorial or something that might help me up the curve.

As a specific example of the sort of thing I am wondering about...some of the exoplanet databases now have pretty comprehensive coverage of planet and star parameters...but when I try to enter them in the exoplanet transit fitting model window changing the TEFF or R* invariably changes some of the other data I’ve just entered.

I can never get the model to accept a collection of “correct” inputs.  So... how should i think about this? If I have 3 or 4 parameters from R*, Teff, Rj, density etc which ones shoul i try to plug into the model?

Thanks
Gavin
\

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[gboyle]

Karen

thanks for this advice - r* is pretty much always available for the transits i am looking at so it looks like I am in good shape.

I also just realised (embarrassingly) that the ohio utility for limb darkening cam derive coefficients and not just work off the previously loaded drop down list..!

So once my machine is back online I should have even better success.

All best,

Gavin

On 31 Dec 2018, at 01:42, karenacollins [via AstroImageJ] <[hidden email]> wrote:

Hi Gavin,

Dennis Conti provides a really nice intro to exoplanet observing that covers model fitting at the first link here on his website:
http://www.astrodennis.com/

TEFF and R* do not actually change the transit model fit. All the Host Stat Stellar Parameters do  is convert (Rp/R*)^2 from the transit fit to a physical planetary radius. The Host Stat Stellar Parameters are are all interlinked though, so you should only be entering one of them and then the others are estimated from the value that is entered. If you have a value for R*, that is the best stellar parameter enter.


The only transit parameters that are being fit are the ones along the left under "Parameter". If you want to fix one of those, enable the "lock" button and enter the value. The items along the bottom are calculated from the fitted and locked model parameters and should be considered outputs.

Karen

On 12/30/2018 12:39 PM, gboyle [via AstroImageJ] wrote:

Hi all

I’m now able to plot my light curves - sometimes even in real time.., but to advance my understanding I feel I need to learn more about the fitting process - can anyone point me to a tutorial or something that might help me up the curve.

As a specific example of the sort of thing I am wondering about...some of the exoplanet databases now have pretty comprehensive coverage of planet and star parameters...but when I try to enter them in the exoplanet transit fitting model window changing the TEFF or R* invariably changes some of the other data I’ve just entered.

I can never get the model to accept a collection of “correct” inputs.  So... how should i think about this? If I have 3 or 4 parameters from R*, Teff, Rj, density etc which ones shoul i try to plug into the model?

Thanks
Gavin
\

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