## 1. Carpe diem and Sagittarius

Carpe diem means, using my interpretation, to start each day with a smile and to enjoy live. I fully support that idea.
My basic current daily activities, in corona time, (part of) are to perform computer simultions of astronomical phenomena. In my particular case are that two phenomena: The movement of the planets around the Sun and the movement of stars around a Black Hole in the center of our Galaxy the Milky way. The first project is called Planet3D because the simulations are based around the 3 dimensions and the second project is called Sagittarius named after the constellation, home of the Black Hole.

For the interested reader a Black Hole is not a hole but a relative small but very heavy object in the order of 100000 Suns. A Black Hole is not a singularity. Most probably BH's are very old. They evolved by collecting stars in their neighbourhood and by contracting, probably in steps. THe whole evolution is a physical process.

Now let me return to the reason of this document. The planet3D project is an evolution which involves almost all my life starting in 1995, while maintaining this homepage. It was more or less finished 10 years ago. The Sagitarrius project is my present day activity in the year 2020. In between there was a small period where I studied the behaviour of BH's. From a mathematical point of view both (all) projects are identical: use Newton's Law. From a physical point they are different.

• The planet3D project, as the name suggest, is a 3D project, but in reality it is more a 2D project, because all the planets move in the same plane. Simple called the X,Y plane. The display showing the positions of the planets only shows these two dimensions.
• The Sagittarius project is physical different in the sense that it is a true 3D project because all the stars move in all different directions around the BH in the center. The central plane in the simulation is the XY plane and each star moves in its own flat plane. The angle between the plane of each star, with the XY plane is called the inclination, which has a value between 0 and 180 degrees. The trajectory of the stars are an ellipse. Each ellipse is specified by two axis: the long and the small axis. The angle between the long axis and dividing line between the plane of the star and the XY plane is called w and has a value between 0 and 360 degrees. Specific these two parameters inclination and w are important in the Sagitarrius project. In the planet3D they are shown but not really tested.
How ever there is a more historical difference.
• The planet3D project evolution started from a 2D project. This is okay because the inner planets all have a different radius, they cannot collide and the main purpose was the simulation of the planet Mercury. Speed was a separate issue. The 2D project included eccentricity. The parameters used were not based on actual observations.
• The planet3D project is different because it is based on actual observations, i.e. the book Astronomical Algorithms by Jean Meeus. That means its results are valid, and as such is does not matter if the calculated values like inclination and w are correct.
• For the Sagittarius project this is different because the starting values are based on the Wikipedia document: https://en.wikipedia.org/wiki/Sagittarius_A*#Orbiting_stars
or https://en.wikipedia.org/wiki/Sagittarius_A*_cluster
A very important parameter in that table is the parameter TP which defines the date when the star is at Pericenter. The parameter Tp is important to calculate the initial position and velocity parameters for each planet at the same instant. To perform both calculations requires that the two parameters inclination and w are properly implemented, including the parameter omega. This are the so called orbital parameters. In fact there are two types of calculations. A forward calculation which calculates the x,y,z (vx,vy,vz) parameters using the orbital parameters of each star and a backward calculation which calculates the orbital parameters based on the calculated x,y,z (vx,vy,vz) values of each star. The orbital parameters in both cases should be the same but they are not incase of inclination, w and omega. That is the problem

### 2. Current plan to solve this issue

The current plan is to temporarily stop the Sagitarrius project. That does not mean that all the physical issues surrounding Blackholes cannot be discussed.
Following are a step of actions to bring more stability:
1. The planet3D project will be improved and tested such that it will show all the 6 orbital parameters correct. A State parameter for each planet will be implemented.
2. The planet3D project will be improved such that it can handle manual entered values for the 6 orbital parameters.
That means there are two independent pathways to perform a simulation.
• One via values based on the book by Jean Meeus indicated above.
• One via "manual entered values"
This will highly improve the stability of the planet3D project.
3. The same modifications will also be implemented in the Sagittarius project. The most important are the capability to handle manual entered values for the 6 orbital parameters.
4. The final part is to test that the Sagittarius project handles the parameter TP correct. That means that all the initial parameters of each star are based on the same date.

### 3. Conclusion phase 1 as of 15 November 2020

When these 4 steps are implemented I hope that the ship of state comes in a more quiet fairway. That I can say: Carpe Diem.

The basic philosophy is to temporarily stop new developments and first make the fundaments stronger. I hope that final result will be that everything becomes easier to test.

A good demonstration that the Sagittarius project is not stable is Display 2 part of this document: VB2019 Sagittarius.program.htm. When Display 2 is selected or not the w parameter changes, which it should not.

### 4. Phase 2 - as of 8 January 2021

Figure 1.412.1 on page 27 of the Explenatory Supplement to the Astronomical Almanac shows the 3 angles: Omega, inclination and w.
The programming error is based on the different combinations possible. Omega runs from 0 to 360 degrees. Inclination runs from 0 to 180 degrees and w runs from 0 to 360 degrees.
Display 1 and Display 2 shows the three angles Omega, w and inclination.
Display 1 shows Omega = 60 and Omega = 150 (When selected)
Display 2 shows Omega = 240 and Omega = 330 (When selected)
 The angle Omega starts from a point of the positif x axis, goes through the origin O, to point N. The direction is counter clock wise. When Display 1 is not selected omega = 60 degrees. When Display 2.is not selected omega = 240 degrees. The angle w (argument of the pericenter P), starts from the point N, goes through the origin O, towards point P (Perihelium). The direction is also counter clock wise. W ((longitude of the pericenter) is the sum of Omega and W. The inclination starts at point R, goes through point T towards point P (perihelium). The line PR defines the z value, the line ORx the x value and the line ORy the y value of point P. The calculation of the 3 angles goes in three steps First omega has to be calculated in the ground plane. Secondly the 3 cordinates x,y,z of point P Using those 4 parameters the angles inclination and w can be calculated. Two perform these calculations two state parameters are used: state and state1. The parameter state is used to calculate the coordinates of point P in the tilted plane. Both parameters state and state1 have 4 values 1,2,3 and 4 When the object is at perihelium the parameter state is 2. When the object is at aphelium the parameter state is 4. The parameter state1 is used to calculate omega in the ground plane. At the beginning of the simulation when z0 less than 0 then state1 = 1 else state1 = 3 This is the case when z0*z1 are less than zero. z0 = current value. z1 = previous value. In that case: When state was 4 (was at aphelium) the state becomes 1 else the parameter state (was 2) becomes 3. When state1 = 1 (that means z was less than 0) and z0>0 than state1 = 2 When state1 = 3 (that means z was greater than 0) and z0<0 than state1 = 4 In that same situation the parameter omega can be calculated. That means that when either state = 1 or state=3 omega can be calculated when state1 = 2
 When Display 1 is not selected (omega=60) then when the object is at point N then (in that case the object moves upwards towards perihelium) The parameter state = 1 (was 4 at aphelium) The parameter state1 = 2 (parameter z becomes positif) and now the parameter omega can be calculated when the object is at point NN then (in that case the object moves downwards towards aphelium) The parameter state = 3 (was 2 at perihelium) The parameter state1 = 4 (parameter z becomes negatif) and now the parameter omega can not be calculated When Display 2 is not selected (omega=240) Then when the object is at point NN (in that case the object moves downwards towards aphelium) then The parameter state = 3 (was 2 at perihelium) The parameter state1 = 4 (parameter z becomes negatif) and now the parameter omega can not be calculated when the object is at point N then (in that case the object moves downwards towards aphelium) The parameter state = 1 (was 4 at aphelium) The parameter state1 = 2 (parameter z becomes positif) and now the parameter omega can be calculated

### 5. Upgrade from Windows 7 to Windows 10

This upgrade became mandatory after a disc failure. The disc has to be replaced and the Visual Studio 2019 to be reinstalled with its latest version.

### 6. Upgrade from Visual Studio 2010 Applications to Visual Studio 2019 Applications

This upgrade was required because the VB2010 programs (running under Visual Studio 2010) could not be changed any longer because of Installation Key issues.
Implementing these same programs using Visual Studio 2019 causes serious problems.
See: Visual Basic 2019 16.9.3 Evaluation and Criticism
See: Visual Basic 2019 16.9.4 Evaluation and Criticism

### 6.1 Upgrade from Visual Studio 2019 Applications to Visual Studio 2022 Applications

In general it is easier to build a Visual Basic 2022 Application compared with a Visual Basic 2019 Application. However there are still serious issues with Visual Studio 2022 Applications.
See: Carpe Diem versus Evaluation and Criticism Microsoft in 2023

### 7. New Release of VB2019 Sagittarius program

As of 24 April 2015 the VB2019 Sagittarius program is running as expected.
I'm still working on the documentation of the program, but the results of the simulations are stable and in line of what can be expected.
Of course the main problem is that I currently can not run the program VB2019 Planet3D because of registration key issues.

### Feedback

None

Created: 15 November 2020
Modified 10 March 2021
Modified 25 April 2021
Modified 1 September 2023