Review of 67P proposed Coordinate system
2015-04-30 15:00 ET

Attendance:
Ludmilla Kolokolova
Mike A'hearn
Tilden Barnes
Chuck 
Boris
Peter Thomas
Carol Neese
Dawn Davis
Tony Farnham
Randy

Start 15 minutes late (still missing Randy)

Mike: First time SBN reviews coord system for IAU.  Also ensure adequately documented.

Ludmilla running telecon.




Comments by Peter (provided in p67review_PT.docx)

Problem with significant figures (mentioned in doc).

Ask for clarification in the wording of ellipsoid fit, center coordinate calculation. (mentioned in doc).

Maps reasonable, but are they useful?

(Randy join)




Comments by Randy (will email at later time)

Part A

Personal reference mentioned that is not explained.
--> Chuck: Could replace this with a reference to SPICE/NAIF doc.
--> If you remove all refs to spice, can this doc stand on its own?  Probably not.
--> Later email from Chuck:
===================
As I mentioned on the telecon a bit ago, perhaps the [A7] reference could be changed to something like this:

"SPICE PCK Required Reading"; latest version; http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/FORTRAN/req/pck.html

As the URL suggests, this is for a FORTRAN-focused version of the document. But the parts of the document pertinent to this subject are language independent.
=====================

Need to define where the origin is, which is normally the center of mass, but what should it be in this case? 
--> Mike: Currently is is displaced along the Z-axis a few meters from the center.  
--> Randy: Need to explain what is being used.

No discussion about rotational velocity moving in inertia coord and how it compares to body coord system.  
--> Mike believes there is a statement, but should confirm.

You may want more than 3 reference points (good minimum), but since these points 'could' move, better to have more.  Report should include statement about the control of the reference frame.
--> Tony: there may be lobe movement due to flexing, as opposed to reference points.  Something to keep in mind.

Part B

Explain why things were done (what the thought process is).  Reasons not in document.

Description of equa-distant isn't good.  Should be more precise.

Good to state what fraction of surface has same lat/log vs not.  Good to include a map of this.

Map of Big Lobe is centered on different degrees.  Be nice to include reason why.

Randy will type up comments and send by email.



Tony Comments: (provided powerpoint)

(see red comments in particular)

s3: Biggest issue is with documenting why things were done the way they were.

s5: be consistent with significant digits.

s5: What about past values.  only explained current and possible future.

s6: neck not well defined




After comments:

It is consistent with IAU specifications, but could use more explanation.

Liens list will be written up and reviewed by reviewers before submitting to document provider.

page 5: there is a difference in the numbers being displayed for the body1000012_radii that needs to be explained or corrected.

Should there be a spice kernal pointed to in this document?
--> Mike: it should be, but it cannot be since the shape model is not being released until sometime in the future.

Ended at 16:20 ET