Presentation of x,y,z spacecraft coordinates in orientation file, and all future position files

[eburnsastro]

The unifying specification of position information for spacecraft is typically the x,y,z position information, referenced to the Earth inertial frame. While this can easily be calculated from longitude and latitude, it would likely be beneficial for all position files, both for simulations and those we produce for HEASARC, to provide x,y,z position information directly. There are similar derived information which can be extremely useful to know, including v_x, v_y, v_z. Can look at Fermi position files (position history files for GBM, I forget the LAT ones) for a list of things to consider

[ckarwin]

Thanks for pointing this out. Indeed, the current orientation file we are using is only a preliminary version of what will eventually become the spacecraft file. For example, for DC3 we added the Earth zenith in Galactic coordinates as a convenient way to account for Earth occultation. But as you said, it would be better to provide the spacecraft x,y,z position referenced to the Earth inertial frame. Other quantities can be easily derived from this such as the Earth zenith in the Galactic frame. I'm not sure exactly when we will start to incorporate the spacecraft file (DC4 or DC5), but yeah we should also look into the Fermi position files for more guidance.

[israelmcmc]

I agree. Here's the LAT format @eburnsastro was referring to: https://fermi.gsfc.nasa.gov/ssc/data/analysis/documentation/Cicerone/Cicerone_Data/LAT_Data_Columns.html#SpacecraftFile

COSI's will likely look very similar, indeed. I think @ckierans has been working out the details with HEASARC.

I think the actual requirement to meet HEASARC's format in cosipy is not until DC5. We could start making progress toward that, but it may not be at the top of the list of priorities.

[ckierans]

COSI flight data formats and their compatiblilty with HEASARC are in the works! Though I agree with Israel that this isn't top priority, it will definitely be there by DC5.