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Kodak moments at Pluto: Help requested
john_s
post Apr 3 2008, 09:54 PM
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Hi folks-

We are deep in the process of planning the Pluto encounter (we're doing it now while all the essential people are still on the payroll!), and following the great success of our Jupiter "Kodak moment" program (thanks Hendric!), we are once again soliciting help from UMSF in planning scenic imaging of the Pluto system. Unlike at Jupiter, the only time when bodies in the Pluto system occult each other is within an hour of closest approach, when we'll be too busy for purely scenic imaging, but there may be interesting alignments or other opportunities at other times.

To help find these opportunities, Henry Throop has kindly made available his New Horizons Geometry Visualizer, NHGV, which is the science team's prime geometry planning tool. It's at http://soc.boulder.swri.edu/nhgv . The tool shows the view of selected targets from the spacecraft at any time during the encounter. Below is some more detailed information from Henry.

More information on the New Horizons instrument capabilities is available here.

We'd like inputs by early June if possible- thanks in advance!
John.

QUOTE
I have developed an on-line, graphical tool for planning and visualizing New Horizons observations. This is a web-based, graphical tool which uses SPICE to plot the position of bodies in the sky, and as they pass through the NH FOVs.

The program is online at http://soc.boulder.swri.edu/nhgv .

Features of NHGV (New Horizons Geometry Visualizer) include:

* Integration with NAIF/SPICE, allowing for accurate positions and observing geometries for planets, satellites, and spacecraft
* Integration with HD and Tycho-2 star catalogs, including access to catalog information such as positions, magnitudes, and stellar types
* Light-time corrections for all computations
* FOVs of all New Horizons remote sensing instruments
* Wireframe images showing position grids and surface lighting
* Albedo and surface composition maps
* Display of Jovian aurora and satelite flux footprints
* Lookup of spacecraft orientation and pointing from SPICE C-Kernels
* Output of all data in graphical and table format
* Flexible input and output coordinates, including both J2000 celestial and ecliptic systems
* Cartesian or spherical projection of sky coordinates.
* Simple web interface
* Observations for a single time or a range of times
* Rapid generation of tables of geometric parameters (distance, phase angle, etc.) over a time interval

It can be thought of along the same lines as Dave Seal's DIGIT or Mark Showalter's Jupiter Viewer, although it has advantages over both (e.g., full access to star catalogs; NH FOV's; web-based; ecliptic coordinates; simple one-page interface). Although it was written for NH, it's really a much more general tool than that. Kernels are currently included for Rosetta, Messenger and Cassini, in addition to NH.

It's used by the NH Science Team for planning future observations, and analyzing previous observations. This is essentially an internal tool that is being released externally on a trial basis, for use in planning potential NH observations. Please let me know of any significant problems.

Extensive on-line documentation, examples, and screenshots are available at http://soc.boulder.swri.edu/nhgv/gv_info.php .

Have fun!

Henry Throop
Southwest Research Institute
Boulder, CO
throop at boulder.swri.edu

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volcanopele
post Apr 3 2008, 10:31 PM
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I guess one quick one would be the last pre-C/A point where I could fit both Pluto and Charon in the same LORRI FOV:

http://soc.boulder.swri.edu/nhgv/gv.php?na...bmit=+++Plot+++
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djellison
post Apr 3 2008, 11:01 PM
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Same rule, with the 'kids' as well.

http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=

I'm sure those with excellent skills in Excel and celestial mechanics (yes, you Hendric smile.gif ) will work their magic smile.gif
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john_s
post Apr 3 2008, 11:02 PM
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Thanks VP and Doug! That reminds me of one more important constraint- our absolute pointing errors can be up to 1 milliradian (0.06 degrees), so we need to leave about this much space around our targets in order to be sure to catch them in the frame. So about 60% of the width of the 5 milliradian LORRI frame is "safe" for pointing in shots like this.

John
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djellison
post Apr 3 2008, 11:32 PM
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I was able to go out to the 26th for look-back's - but not beyond that. Maybe, just maybe, there's a tiny thin crescent full family portrait on the outbound leg as well.

60% of the frame would mean playing with a fov of .18deg to be sure of 'getting' it. The viewer takes that into account already I think, just giving a .18deg FOV for Lorri.

If an outbound P+C ( but not H+N ) pair is possible (I'm guessing there's a sun-pointing keep-out involved at some point here) and assuming the viewer already constrains the LORRI viewing box to take into account the possible pointing errors.

http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=



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tedstryk
post Apr 4 2008, 12:05 AM
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The July 3rd pointing opportunity is good enough that it might justify a two frame mosaic, which would really help with that pointing constraint.


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nprev
post Apr 4 2008, 12:24 AM
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I don't know if I'm doing this right, nor if the time is appropriate, but this looks interesting from LORRI. Charon goes right behind Pluto & emerges on the other side...good opportunity for atmospheric observations by watching Charon refract?

EDIT: Just noticed that the occultation occurs very near Pluto's poles...an opportunity to study atmospheric dynamics in key regions? We know that a lot of action occurs on Titan in these places.


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john_s
post Apr 4 2008, 12:51 AM
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QUOTE (djellison @ Apr 3 2008, 11:32 PM) *
60% of the frame would mean playing with a fov of .18deg to be sure of 'getting' it. The viewer takes that into account already I think, just giving a .18deg FOV for Lorri.


Um, no- the viewer gives the full 0.29 degree LORRI fov...

John.
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nprev
post Apr 4 2008, 02:29 AM
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John, sorry to introduce another possible constraint, but is there a well-defined time frame to exclude yet? That might be helpful.

The occultation of Charon by Pluto I mentioned obviously must lie within the most intensive period of science obs, and Kodaking without true scientific value added at this time is presumably to be avoided.


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claurel
post Apr 4 2008, 03:43 AM
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Here's an alignment of Pluto, Charon, and Nix visible on July 1, 2015:

Attached Image


I found it using a New Horizons add-on for Celestia, then verified it with NHGV. Thanks for making this tool available!

--Chris
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volcanopele
post Apr 4 2008, 05:55 AM
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QUOTE (nprev @ Apr 3 2008, 07:29 PM) *
John, sorry to introduce another possible constraint, but is there a well-defined time frame to exclude yet? That might be helpful.

The occultation of Charon by Pluto I mentioned obviously must lie within the most intensive period of science obs, and Kodaking without true scientific value added at this time is presumably to be avoided.

Very true. You would also have to consider potential smear in the body not targeted in such an image.


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djellison
post Apr 4 2008, 07:44 AM
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Ah - I was being stupid - plot RADIUS. (duhh)

Inbound - it's a few days earlier then for P+C
http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=



And again, a few days earlier for P+C+H+N

http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=
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djellison
post Apr 4 2008, 07:49 AM
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And outbound, it's on the 19th - if the sun angle makes it possible. It'd be a lovely parting shot if it is.

http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=
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volcanopele
post Apr 4 2008, 08:07 AM
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Yeah, if this were the ISS camera on Cassini, those phase angles would be too high (I believe we are limited to phase angles less than 162 deg., unless something is blocking the Sun).

I guess a few others:

Charon Full-frame
http://soc.boulder.swri.edu/nhgv/gv.php?na...bmit=+++Plot+++

Pluto Full-frame
http://soc.boulder.swri.edu/nhgv/gv.php?su...amp;title_plot=

Nix Closest Approach (should be a nice encounter)
http://soc.boulder.swri.edu/nhgv/gv.php?na...bmit=+++Plot+++


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john_s
post Apr 4 2008, 04:57 PM
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Thanks for all these! To answer questions, the Charon occultation by Pluto might be observed (for instance we might use Charon to backlight nighttime hazes on the dark side of Pluto), but science would be the driver (well, 90% of the driver- we like scenery too!). Purely scenic opportunities within three hours either side of c/a are unlikely, I'd say. And regarding outbound sun angles, we think we'll be able to point within about 10 degrees of the sun, and thus image the system on departure. We are likely to have image ghosts to contend with, but that problem should be manageable.

John.

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