UVIS Team Meeting
June 16-18 2014
RTWT and Science Planning Report
UVIS Team Meeting January 8, 2014, CalTech
1
Solstice Mission Inclination Profile
Now
UVIS Team Meeting January 8, 2014, CalTech
2
Ring Science SM Status Update
• 21 IN1 occs completed to date:
–Alpha Canis Majoris (168, 169 - joint w/ VIMS)
–Kappa Canis Majoris (168, PIE, Particle Tracking)
–Zeta Canis Majoris (169, PIE, Particle Tracking)
–Zeta Pupis (171, PIE)
–Gamma Pegasi (172)
–Alpha Virginis (173, PIE)
–Epsilon Canis Majoris (173, 174)
–Gamma Columba (173, PIE)
–Alpha Lyrae (175, PIE - joint w/ VIMS)
–Kappa Velorum (183)
–Delta Centauri (183, 185)
–Beta Libra (187, B=16 deg.)
–Lamba Tauri (188, PIE, B=18 deg., close to Daphnis)
–Theta Carinae (190, bright, B=67 deg.)
–Delta Dentauri (191, 194)
–Alpha Lyrae (202, 202 - joint w/ VIMS)
UVIS Team Meeting January 8, 2014, CalTech
3
SM PIE Occs
• Tracking occs:
–Eps Sgr (1.1 km/s) in 2016
–Kap CMa in 2012 (June 29, completed)
–Zet CMa (0.1 km/s) in 2012 (July 23; completed)
–Zet Pup (1 km/s) in 2012 (September 3, completed)
• Azimuthal structure:
–Bet Cru (496 km from Bleriot) in 2017
–Zet Cen (147 km from Daphnis) in 2016
–Lam Tau (79 km from Daphnis) in 2013 (completed)
• Occs with VIMS (Alpha Lyrae, 3 completed, 1
more integrated)
• Orionis occs (low elevation angle to rings)
• Kap
Ori
10
hour
occ
(2015-049)
UVIS Team Meeting January 8, 2014, CalTech
4
UVIS Rings Science Goals for
F ring and Proximal Orbits
Josh Colwell, Larry Esposito,
Todd Bradley, Tracy Becker,
Miodrag Sremcevic
Science Goals Overview
A1: Observe ring structure at high resolution to extend
the temporal baseline through to the end of mission.
(RC1a, RC1b)
A2: Measure particle properties using synoptic
occultations with VIMS. (RC1a, RN2a)
A3: Measure small-scale particle structure at key areas
in the rings that have not previously been observed at
high resolution. (RC1a, RC1b, RN2a)
B: Measure ring UV reflectance at high spatial
resolution across the rings and at specific regions not
previously resolved in the UV. (RC1b, RN1c)
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A1. Extend Temporal Baseline of High
Resolution Measurements of Ring Structure
Measurement: Full radial stellar occultations
observed at large B angles.
Geometry: There is a series of Alpha Eridani
occultations on revs 271 (and later) that cover the
whole ring system. There are additional occs in the
F ring orbits that are unique, some of which are
better than ALPERI and some not as good.
Conflicts: ALPERI occultations occur at -1.5 to 0
hours from periapse. F ring occs tend to be further
from periapse.
7
A2. Measure Particle Properties Using
Synoptic Observations with VIMS
Measurement: Full radial stellar occultations of stars with good
signal for VIMS and UVIS to obtain information on the
population of small particles throughout the rings and
specifically in regions that previous observations have hinted
may have significant small particle populations.
Geometry: There are three Sirius observations on revs 272, 273
and 274 that are chord occs. Rev 274 cuts through full ring
system twice, meeting measurement goal of previous slide as
well. Backup on rev 275 gets A and B rings only on one side.
(There are two observations of Vega on revs 249 and 250 as
well.)
Conflicts: These occultations occur at -2 days out, lasting 8-10
hours.
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A3. Measure Small-Scale Structure
at Key Locations in the Rings
Measurement: Targeted stellar occultations that
capture ring structure at unprecedented resolution at
certain locations or observe azimuthally varying
structure not previously observed at UVIS resolution.
The former are “particle tracking occs” where the
speed of the stellar footprint in the ring particle frame
is small. The latter are occultations that pass close to
embedded moons or propeller objects.
Geometry: Varies
Conflicts: Varies
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A ring “tracking occ” example
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Detection of Bleriot Wakes
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Stellar Occultation Requests
in F Ring and Proximal Orbits
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Stellar Occultation Requests
in F Ring and Proximal Orbits
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Stellar Occultation Requests
in F Ring and Proximal Orbits
14
B: Ring Spectral Reflectance in UV
Science Justification:
Dynamically and spectrally distinct regions in the rings, such as
the strong resonance density wavetrains, associated “halos”, and
the trans-Keeler region, have not been resolved in the UV with
the exception of unlit-face low-SNR SOI observation.
Take advantage of unique F ring and proximal orbit geometries
to obtain highest resolution spectral maps of targeted ring
regions.
Measurements:
1. Optimize pointing in VIMS-design for F ring and Proximal
orbit scans.
2. Dedicated targeted UVIS observations of key ring regions.
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B1. Riding with VIMS: F Ring Orbit Drift Scans
First Inbound Drift Scan (COMPLITA)
1612
F ring orbit (rev 255) drift scan: - 6 to -4 hours before periapse; Optimize for UVIS
by orienting UVIS slit ~radially across the rings. Improves resolution by ~2x.
COMPLITA
Phase angle ~ 46°; about the
same brightness as SOI.
Resolution ~ 250 km; about the
same as SOI.
Ring coverage and time on
rings better than SOI.
13
B2. Riding with VIMS: F Ring Orbit Drift Scans
Second Inbound Drift Scan (Blue, COMPLITB)
1814
F ring orbit (rev 255) drift scan; - 4 to -1.5 hours before periapse;
Optimize for UVIS by orienting UVIS slit ~radially across the rings.
Improves resolution by ~2x.
COMPLITB
Phase angle ~ 55°; about the
same brightness as SOI
Resolution ~ 100-150 km;
better than SOI.
Ring coverage and time on
rings better than SOI.
15
B3. URASPEC1: F ring orbit targeted A ring scan: - 4
to -1.5 hours relative to periapse.
Phase angle ~ 60°; same
brightness as SOI.
Resolution ~ 80-180 km; up to
~2x better than SOI.
Duration gives SNR ~2x SOI.
16
B4. URASPEC2: F ring orbit targeted A ring drift scan:
- 6 to -4 hours relative to periapse.
Phase angle ~ 68°; about the
same brightness as SOI
Resolution ~ 200-25 km; about
the same as SOI.
Increased duration gives ~2x
better SNR than SOI.
17
B5. URHRSPEC: F ring orbit targeted A ring observation
at - 1.5 to -0.4 hours before periapse
Phase angle ~ 10-30°; ~2x
brighter than SOI.
Resolution ~ 30-60 km; ~5x
better than SOI.
Geometry and duration gives
SNR ~2x SOI.
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F ring orbit ring spectral
observation requests
• Ride-along with VIMS drift scans: request secondary axis
orientation to optimize UVIS spatial resolution.
• URASPEC1: 1 targeted A ring observation at (about) -4 to
-1.5 hours from periapse (priority 1).
• URHRSPEC: 1 targeted A ring observation at -1.5 to -0.4
hours from periapse (priority 1).
• URASPEC2: 1 targeted A ring observation at -6 to -4 hours
from periapse (priority 2).
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B6. Riding with VIMS: Proximal Orbit Drift Scans
First Inbound Drift Scan (Red, COMPLIT)
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Proximal orbit (rev 275) drift scan: - 3 to -1.5 hours before periapse;
Optimize for UVIS by orienting slit radially across the rings.
COMPLIT
Phase angle ~ 70°; comparable
brightness to SOI.
Resolution ~ 150 km; 25%
better than SOI.
SNR comparable to SOI. Full
radial scan improves on SOI.
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B7. Proximal orbit targeted A ring observation: - 3 to -1.5
hours before periapse. URASPEC2
Phase angle ~ 70°-61°
Phase angle ~ 65°; comparable
brightness to SOI.
Resolution ~ 150 km; 25%
better than SOI.
Duration gives SNR ~2x SOI.
22
B8. Proximal orbit (rev 275) targeted C ring scan: - 1 to -0.2 hours
before periapse. URHRSPEC.
Phase angle ~ 100°;
comparable brightness to SOI.
Resolution ~ 20-80 km; ~5x
better than SOI.
SNR comparable to SOI.
23
Proximal orbit ring spectral
observation requests
• Ride-along with VIMS drift scans: request secondary axis orientation to
optimize UVIS spatial resolution.
• URASPEC2: 1 targeted A ring observation at -3 to -1.5 hours from periapse
(priority 2).
• URHRSPEC: 2 targeted inner ring system observations at -1.5 to -0.2 hours
from periapse (priority 1).
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Ring UV Imaging Requests
in F Ring and Proximal Orbits
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