# DPDD units for Ixx, Iyy, Ixy are incorrect

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#### Details

• Type: Bug
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
• Team:
Architecture

#### Description

These quantities have units of (angular size)^2, but the units listed for them in the DPDD tables (Tables 1, 2, and 4) are nmgy asec^2.

#### Activity

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Tim Jenness added a comment -

If it's just a case of changing the units in the table to be (angular size)^2 then I can do that (although it's not entirely clear how we write that unit in code).

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Tim Jenness added a comment - If it's just a case of changing the units in the table to be (angular size)^2 then I can do that (although it's not entirely clear how we write that unit in code).
Hide
Jim Bosch added a comment -

The algorithms will produce measurements in pixels^2, which will be converted to angular units via the WCS just prior to or just after database loading. It's likely that conversion will involve an intermediate step in radians, since that's our angular unit in the rest of the codebase, but given the rest of the table in the DPDD it looks like the final units will be arcsec^2.

Show
Jim Bosch added a comment - The algorithms will produce measurements in pixels^2, which will be converted to angular units via the WCS just prior to or just after database loading. It's likely that conversion will involve an intermediate step in radians, since that's our angular unit in the rest of the codebase, but given the rest of the table in the DPDD it looks like the final units will be arcsec^2.
Hide
Tim Jenness added a comment -

I've just pushed a fix for this. Can you please check I got it correct (red text means it will be removed when DPDD is accepted by change control board).

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Tim Jenness added a comment - I've just pushed a fix for this. Can you please check I got it correct (red text means it will be removed when DPDD is accepted by change control board).
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Jim Bosch added a comment -

Looks great, thanks!

(I only looked at the last commit on this branch; I assume the rest will be reviewed elsewhere).

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Jim Bosch added a comment - Looks great, thanks! (I only looked at the last commit on this branch; I assume the rest will be reviewed elsewhere).
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Tim Jenness added a comment -

Yes, although I think there is only one commit on that branch (the base branch is dmsr-refresh).

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Tim Jenness added a comment - Yes, although I think there is only one commit on that branch (the base branch is dmsr-refresh ).
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Tim Jenness added a comment -

Merged to the development branch (dmsr-refresh).

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Tim Jenness added a comment - Merged to the development branch ( dmsr-refresh ).

#### People

Assignee:
Tim Jenness
Reporter:
Jim Bosch
Reviewers:
Jim Bosch
Watchers:
Jim Bosch, Tim Jenness