[BART-devel] solar system 'constants'

[aj-foster]

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From: pa***@oe*** (Patricio Cubillos)
Date: Sun, 26 Jun 2016 13:25:31 +0200
Subject: [BART-devel] solar system 'constants'

Hi all,

Last month there was this IAU resolution, which suggested nominal values for some solar-system values: http://arxiv.org/pdf/1605.09788.pdf

I think it’s a good idea to adopt explicitly stated values for these ‘constants’. So I suggest to follow the values from this resolution. What do you think?

Another quick question on the radii, given the observing geometry of an eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter planetary radii (=sqrt(equatorial radius * polar radius)). On the downside, this probably is not a standard practice. Any opinion?

Thanks,
Patricio.
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[aj-foster]

From: pc***@fu*** (Patricio Cubillos)
Date: Sun, 26 Jun 2016 13:26:33 +0200
Subject: [BART-devel] solar system 'constants'

Hi all,

Last month there was this IAU resolution, which suggested nominal values for some solar-system values: http://arxiv.org/pdf/1605.09788.pdf

I think it’s a good idea to adopt explicitly stated values for these ‘constants’. So I suggest to follow the values from this resolution. What do you think?

Another quick question on the radii, given the observing geometry of an eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter planetary radii (=sqrt(equatorial radius * polar radius)). On the downside, this probably is not a standard practice. Any opinion?

Thanks,
Patricio.
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[aj-foster]

From: sa***@kn*** (sally.blumenthal)
Date: Mon, 27 Jun 2016 13:52:12 +0000
Subject: [BART-devel] solar system 'constants'

Hey,

I skimmed over the paper for about 20 minutes. This makes sense. Do you mind if I distribute this paper among the Goddard Exoplanet group here?

As for:

Another quick question on the radii, given the observing geometry of an

eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter > planetary radii (=sqrt(equatorial radius * polar radius)). On the downside,

this probably is not a standard practice. Any opinion?

The calculation in question is used in transit? What is currently being used?

• Sally

---

From: BART-devel <ba***@ph***> on behalf of Patricio Cubillos <pc***@fu***>
Sent: Sunday, June 26, 2016 7:26:33 AM
To: BART development
Subject: [BART-devel] solar system 'constants'

Hi all,

Last month there was this IAU resolution, which suggested nominal values for some solar-system values: http://arxiv.org/pdf/1605.09788.pdf

I think it’s a good idea to adopt explicitly stated values for these ‘constants’. So I suggest to follow the values from this resolution. What do you think?

Another quick question on the radii, given the observing geometry of an eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter planetary radii (=sqrt(equatorial radius * polar radius)). On the downside, this probably is not a standard practice. Any opinion?

Thanks,
Patricio.
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[aj-foster]

From: jh***@ph*** (Joe Harrington)
Date: Mon, 27 Jun 2016 16:16:47 -0400
Subject: [BART-devel] solar system 'constants'

The paper is not about the actual radius of Jupiter, but about the
values to use when using the radius of Jupiter (or the mass, or the
soler mass, etc.) as a unit of measure. Really, it's simply codifying
existing practice, and cleaning up the loose ends of people doing it
slightly differently, so we all know what 2.2 Rj means.

The standard practice is to use Rj == 71492.0 km, which happens to be
the equatorial radius.

Yes, it makes more sense to use the geometric mean, and there are cases
where you would need to use RpRe. However, when used as a unit of
measure, Rj is exactly 71,492 km. I can't explain why, but possibly
it's because the first thing that the unit was used for was distance to
the orbits of ring features and satellites, which are mostly in the
equatorial plane (or were before they discovered 50+ other tiny
satellites).

--jh--

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From: Patricio Cubillos <pc***@fu***>
Date: Sun, 26 Jun 2016 13:26:33 +0200
To: BART development <ba***@ph***>
Subject: [BART-devel] solar system 'constants'
Reply-To: BART development <ba***@ph***>
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Hi all,

Last month there was this IAU resolution, which suggested nominal values for some solar-system values: http://arxiv.org/pdf/1605.09788.pdf

I think it’s a good idea to adopt explicitly stated values for these ‘constants’. So I suggest to follow the values from this resolution. What do you think?

Another quick question on the radii, given the observing geometry of an eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter planetary radii (=sqrt(equatorial radius * polar radius)). On the downside, this probably is not a standard practice. Any opinion?

Thanks,
Patricio.

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[aj-foster]

From: jh***@ph*** (Joe Harrington)
Date: Mon, 27 Jun 2016 16:20:25 -0400
Subject: [BART-devel] solar system 'constants'

Just found this on page 7:

"If the jovian radius is not explicitly qualified as equatorial or
polar, it should be understood that nominal jovian radius refers
specifically to the equatorial radius, following common usage in the
literature."

--jh--

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From: Joe Harrington <jh***@ph***>
To: BART development <ba***@ph***>
Cc: ba***@ph***
Subject: Re: [BART-devel] solar system 'constants'
In-Reply-To: <E0***@fu***> (message from Patricio Cubillos on Sun, 26 Jun 2016 13:26:33 +0200)
Reply-to: jh***@ph***
CC: jh***@ph***
Date: Mon, 27 Jun 2016 16:16:47 -0400
Content-Type: text/plain; charset=utf-8

The paper is not about the actual radius of Jupiter, but about the
values to use when using the radius of Jupiter (or the mass, or the
soler mass, etc.) as a unit of measure. Really, it's simply codifying
existing practice, and cleaning up the loose ends of people doing it
slightly differently, so we all know what 2.2 Rj means.

The standard practice is to use Rj == 71492.0 km, which happens to be
the equatorial radius.

Yes, it makes more sense to use the geometric mean, and there are cases
where you would need to use RpRe. However, when used as a unit of
measure, Rj is exactly 71,492 km. I can't explain why, but possibly
it's because the first thing that the unit was used for was distance to
the orbits of ring features and satellites, which are mostly in the
equatorial plane (or were before they discovered 50+ other tiny
satellites).

--jh--

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From: Patricio Cubillos <pc***@fu***>
Date: Sun, 26 Jun 2016 13:26:33 +0200
To: BART development <ba***@ph***>
Subject: [BART-devel] solar system 'constants'
Reply-To: BART development <ba***@ph***>
Content-Type: multipart/mixed; boundary="===============8781674200220535279=="

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Hi all,

Last month there was this IAU resolution, which suggested nominal values for some solar-system values: http://arxiv.org/pdf/1605.09788.pdf

I think it’s a good idea to adopt explicitly stated values for these ‘constants’. So I suggest to follow the values from this resolution. What do you think?

Another quick question on the radii, given the observing geometry of an eclipse/transit, I’m inclined to use the geometric mean as the Earth/Jupiter planetary radii (=sqrt(equatorial radius * polar radius)). On the downside, this probably is not a standard practice. Any opinion?

Thanks,
Patricio.

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