ingress and egress settings
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Hi Karen,
just joined the forum and getting into the observing and analysis of exoplanet data and light curves. I'm going to investigate any variation in min time of a transit and the duration time of chosen exoplanets using AIJ. At first glance it would seem that the ingress and egress time are set prior to any analysis and are based on prediction. Is it possible to trial the data for best fit using the ingress/egress times as a variable? Or failing that to have an ingress/egress output based on that sessions observed data. Many thanks, Eric |
Re: ingress and egress settings
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Hi Eric,
My understanding is that Dennis Conti's course covers light curve fitting, but if it does not, I think a good starting point is his Exoplanet Observing Guide here: http://www.astrodennis.com/Worksheet.xlsx There is also this post on the forum that ahs some tips for fitting: http://astroimagej.1065399.n5.nabble.com/Transit-Fitting-plus-referencing-software-in-paper-td199.html#a229 And more information in the Extended version of the free AIJ paper here: https://arxiv.org/abs/1701.04817 I may not be perfectly clear on your question though. Are you trying to find the best fit time of transit minimum? That is given on the fitting panel as Tc. The predicted ingress and egress vertical markers actually have nothing to do with fitting. They are just for display purposes. However, the "left" and "right" values in the "Fit and Normalize Region Selection" subpanel on the Multi-plot Main page are used as best estimates for the start of ingress and end of egress. These should be set just outside the (hopefully obvious) transit signal. The average of these two values gives the *starting* point for the Tc fit. The ingress and egress times are actually not fitted parameters in the Mandel and Agol transit model used by AIJ. But you can calculate the values from the best fit Tc and the T14 (i.e. transit duration) value give below the fitted parameters. Start of ingress is then of course Tc - T14/2, and end of egress is just Tc + t14/2. Let me know if the above explanation and documents do not answer your question. Karen On 2/27/2018 8:45 PM, Eric [via AstroImageJ] wrote:
Hi Karen, |
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Hi Karen,
thanks for the reply which does help in some respects. If I'm trying to measure changes in transit duration then I think I will need another method to determine this. I've come across a piece of coding, " Exopanet Data Reduction Pipeline v2.1" by Kyle Pearson that takes a look at the deviation of the light curve before and after what may be the ingress and egress and assigns a start and end time. Many thanks, Eric -----Original Message----- From: karenacollins [via AstroImageJ] <[hidden email]> To: Eric <[hidden email]> Sent: Wed, 28 Feb 2018 3:55 Subject: Re: ingress and egress settings
Hi Eric,
My understanding is that Dennis Conti's course covers light curve fitting, but if it does not, I think a good starting point is his Exoplanet Observing Guide here: http://www.astrodennis.com/Worksheet.xlsx There is also this post on the forum that ahs some tips for fitting: http://astroimagej.1065399.n5.nabble.com/Transit-Fitting-plus-referencing-software-in-paper-td199.html#a229 And more information in the Extended version of the free AIJ paper here: https://arxiv.org/abs/1701.04817 I may not be perfectly clear on your question though. Are you trying to find the best fit time of transit minimum? That is given on the fitting panel as Tc. The predicted ingress and egress vertical markers actually have nothing to do with fitting. They are just for display purposes. However, the "left" and "right" values in the "Fit and Normalize Region Selection" subpanel on the Multi-plot Main page are used as best estimates for the start of ingress and end of egress. These should be set just outside the (hopefully obvious) transit signal. The average of these two values gives the *starting* point for the Tc fit. The ingress and egress times are actually not fitted parameters in the Mandel and Agol transit model used by AIJ. But you can calculate the values from the best fit Tc and the T14 (i.e. transit duration) value give below the fitted parameters. Start of ingress is then of course Tc - T14/2, and end of egress is just Tc + t14/2. Let me know if the above explanation and documents do not answer your question. Karen On 2/27/2018 8:45 PM, Eric [via AstroImageJ] wrote:
Hi Karen, If you reply to this email, your message will be added to the discussion below:
http://astroimagej.1065399.n5.nabble.com/ingress-and-egress-settings-tp966p967.html
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