Understanding and Creating an O-C Diagram

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In summary, the conversation discusses creating an O-C diagram for an eclipsing binary and the lack of instruction given. The individual has minimum times of light, the period of the system, and cycle numbers, but is unsure about what is observed and calculated in the O-C formula and what to put on the vertical axis. They are directed to an article and excel spreadsheet examples for assistance. Later, the individual's adviser explains the process more clearly but the O-C numbers do not match those published by others. The individual must find unpublished O-C numbers to complete the diagram.
  • #1
oliviam212
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Hello,

I am doing research and I was told that I need to create an O-C diagram for an eclipsing binary. Unfortunately, I haven't been given too much instruction on how to do this. Right now, all I have are minimum times of light, the period of the system, and cycle numbers. I know that O-C is observed minus calculated, but I am not sure what is observed and what is calculated. All that I do know is that O-C is measured in days. Also, I am not sure what to put on the vertical axis (I saw that some O-C diagrams have JDs). Thanks for your help. I am extremely new at the research process.
 
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  • #3
Thank you. My adviser explained it more to me, and this helped!
 
  • #4
So maybe I do not know what I am doing. My graph's are not turning out the way they should. What I did was find a calculated HJD by using the period of my graph, the cycle number that I found, and the HJDnaught. I did in fact get mostly different HJD calculated than HJD observed, but they do not match O-C numbers that other people have previously published... My problem is that some of the O-C numbers are not published so I have to find them.
 
  • #5


Hello,

Creating an O-C (observed minus calculated) diagram for an eclipsing binary is a valuable tool for understanding the orbital dynamics of this type of system. To begin, it is important to have a good understanding of the minimum times of light, the period of the system, and the cycle numbers. These are all crucial pieces of data that will be used to plot the O-C diagram.

The O-C diagram is a plot of the difference between the observed and calculated times of minimum brightness of the eclipsing binary over time. The observed times of minimum brightness are the actual times that the binary system is observed to have its minimum brightness. The calculated times of minimum brightness are the expected times based on the known period of the system.

To create the O-C diagram, you will need to plot the difference between the observed and calculated times on the vertical axis, with the cycle number on the horizontal axis. The vertical axis can be labeled in days, as this is the unit of measurement for the O-C values. Alternatively, you can also use Julian Dates (JDs) on the vertical axis, as some O-C diagrams do. This is a personal preference and either option is acceptable.

Once you have plotted the data points, you will be able to see any discrepancies between the observed and calculated times, which can provide valuable insights into the orbital dynamics of the binary system. This can include changes in the period of the system, variations in the eclipse timings, and even the presence of additional bodies in the system.

I hope this helps guide you in creating your O-C diagram. Remember, the more data points you have, the more accurate and informative your diagram will be. Good luck with your research!
 

1. What is an O-C diagram?

An O-C (observed-calculated) diagram is a graphical representation of the variation in timing of a repeating astronomical event, such as star or planet transits. It compares the observed event times with the predicted times based on a mathematical model.

2. How is an O-C diagram created?

To create an O-C diagram, you need a set of observed event times and a mathematical model that predicts the event times. The observed times are plotted on the y-axis, while the calculated times are plotted on the x-axis. The resulting graph will show any discrepancies between the observed and calculated times.

3. What is the purpose of an O-C diagram?

An O-C diagram is used to study the variations in the timing of astronomical events. It can reveal changes in the orbital period or other factors that affect the timing of the events. This information can help refine the mathematical models and improve our understanding of the events.

4. What can be learned from an O-C diagram?

By analyzing an O-C diagram, scientists can learn about the stability and regularity of the astronomical event being studied. It can also provide information about any external factors that may be affecting the event, such as the presence of a companion star or planet.

5. What are some common challenges in creating an O-C diagram?

Creating an O-C diagram can be challenging due to the need for accurate and precise observations, as well as the complexity of the mathematical models used to predict the event times. Additionally, external factors such as atmospheric conditions or instrumental errors can also affect the accuracy of the data and make it difficult to create a clear O-C diagram.

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