From: Nicolas Altobelli <[email protected]>

Date: June 15, 2006 5:51:32 PM PDT

To: [email protected]

Subject: question: PDS volume VG_2810

Mark,

I recently tried to work with the PDS ISS Voyager volume VG_2810,

containing radial profiles of I/F, generated from different images.

Apparently, there is a typo in the description field of the object

SERIES of thefiles IS1_P0001_V01_KM002.LBL and IS2_P0001_V01_KM002.LBL,

as for2 different emission angles (one<90 and one 90) the description

says it is the unlit side. So I guess that the one with emission

angle ~ 66 deg is the lit side, is that right?

Yes. The labels have been corrected to reflect that all of the

Voyager 2 profiles are for the lit side of the rings.

Such radial profile are very interesting for me, as I am trying to relate temperature variations of small-scale structures of the ring (CIRS FP3) to a possible albedo effect. Ultimately, I want to quantify the relative contribution of the optical depth variations and of the albedo

to the temperature.

There are apparently only 2 different geometries for such Voyager I/ F profiles. Is it planed to add more? (Different phase angle for example).

I am not familiar with the Voyager ISS data, so I apologize for any unrealistic expectations...

We have no plans to produce more profiles. These were generated to
support a request from the Cassini Ring Science group made prior to SOI.
The goal was to provide a Voyager baseline for reference during Cassini
data analysis.

Do you know if such profiles have been derived from Cassini ISS data?

(I could not find an equivalent of your radial profile on the Cassini ISS PDS, but maybe I do not know where to search exactly...The big advantage would be to have the same geometry than for the CIRS observations...)

Some members of the Cassini imaging team may have generated equivalent
profiles, but we do not have any such ring profiles within the PDS. Realistically, your best bet is to produce the profiles you need. We
describe the process we used in the file PROFILES.TXT located in the
DOCUMENTS subdirectory of the data set. It should be fairly
possible to extend the process to Cassini ISS images as well.

Thank you for any comments on this,

Best regards,

Nicolas Altobelli