During the past few months, I have been working on the other half, and would like to publish the results. Since it would just be updating the first paper, we want it to be a short (1-2 pages) paper.
The question is where to publish it and what to publish it as. The first paper was in Icarus, which also allows "notes". These are short papers, but it says on the website they should be on "...especially topical subjects..." that need to be published rather quickly. I don't think this paper falls into that category.
I know Astronomy & Astrophysics has a section for short papers (research notes) that "...are short papers that contain either new results as an extension of work reported in a previous paper, or limited observations not urgent enough to be published as a Letter...". That definitely describes the content of the paper better, but would it be strange to publish the update in a different journal?
If it's okay to publish an update in a different journal, what other options are there?