Effective Area 3D #281
Effective Area 3D #281
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…ensions The different methods use binning in different coordinate systems - effective_area_3D_polar uses a polar coordinate system with radial FOV offset and azimuthal FOV position angle bins - effective_area_3D_nominal uses a nominal coordinate system with FOV longitude and FOV latitude bins
These calculate the number of showers in each bin for different coordinate systems - calculate_n_showers_3D_polar uses a polar coordinate system with radial FOV offset bins and azimuthal FOV position angle bins - calculate_n_showers_3D_nominal uses a nominal coordinate system with FOV longitude and latitude bins
…into effective_area_3d
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| in the sky. | ||
| """ | ||
| phi = position_angle( | ||
| events["pointing_az"], |
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I am not sure this definition matches the defintion in GADF given here:
https://gamma-astro-data-formats.readthedocs.io/en/v0.3/general/coordinates.html#field-of-view
| fov_offset_bins: astropy.units.Quantity[angle] | ||
| The field of view radial bin edges in which to calculate effective area. | ||
| fov_position_angle_bins: astropy.units.Quantity[radian] | ||
| The field of view azimuthal bin edges in which to calculate effective area. |
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not sure if this could lead to confusion, but a 2D azimuthal coordinate and position angle are not quite the same: the polar azimuth starts on the positive X-axis and goes counter-clockwise, while position angle starts on the positive Y-axis and goes clockwise, so there is a 90 deg phase shift and different direction. Perhaps just to avoid this, say "Field-of-view azimuthal (from Y-axis, toward positive x) bin edges...". Probably this should be shown as a figure somewhere in the general PyIRF documentation...
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This is going into the same direction as the comment above about being clear how we define these coordinate systems and adding tests for the cases spelled out by GADF.
One confusing thing here is that the position angle is defined relative to the original coordinate system axes (AltAz or RaDec) but the FoV lon has the opposite direction to the original lon. Which I think makes the polar angle go counter-clockwise when looking at in a common plot of field of view coordinates where the cartesian like axes are FoV lon/lat...
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If I understand it correctly the GADF FOV position angle definition is exactly the same as the usual definition of the azimuthal angle in polar coordinates, right? (Angle increasing counter-clockwise)
So following this definition there shouldn't technically be a difference between the two, although I understand that just calling it the azimuthal angle here might still cause confusion.
Since we are following the GADF conventions anyways, would it be agreeable to just change "field of view azimuthal bin edges" to "field of view position angle bin edges" and maybe showing a figure somewhere to clarify as suggested?
Adds two methods of calculating the effective area in bins of energy and two spacial dimensions. These methods differ in the coordinate frame used for the spacial dimensions.
calculate_effective_area_3d_polaruses a polar coordinate system with FOV pointing position offset and position angle coordinatescalculate_effective_area_3d_nominaluses a quasi-cartesian coordinate system with FOV longitude and latitude coordinates centred on the pointing positionAlso adds respective functions to calculate the number of showers expected in the 3D bins from simulation info to the SimulatedEventsInfo class (
calculate_n_showers_3d_polar,calculate_n_showers_3d_nominal), as well as a utility function to calculate the position angle w.r.t. the pointing from an event table (calculate_source_fov_position_angle).