Planetary Imaging with Planetary Imaging with PILOTPILOT

Jeremy BaileyJeremy BaileyAnglo-Australian ObservatoryAnglo-Australian Observatory

March 26th 2004March 26th 2004

Summary

• Advantages of Antarctic Site– Excellent seeing (diffraction limited using selective

imaging - don’t need AO).– 24 hour continuous observations possible.– Low daylight sky brightness.

• Disadvantage– Can only observe planets when they are in the south.

• Science– Studies of atmospheric circulation - provides input to

General Circulation Models (GCMs) of planetary atmospheres.

Selective Imaging(Lucky Imaging)

ANU 0.6m ANU 0.6m Steve MasseySteve MasseyMercuryMercury

Mount Wilson 60-inchMount Wilson 60-inch7.7 arc sec dia.7.7 arc sec dia.27 degrees elevation27 degrees elevation18 degrees from Sun18 degrees from SunIn daylightIn daylightRon DantowitzRon Dantowitz

UKIRT Mars Images (2003)

Long exposure image(Mauna Kea naturalseeing)

Selected best shortexposure image

Further image processing(unsharp masking and smoothing)

UKIRT/UIST 0.06 arc sec pixels. 1.64UKIRT/UIST 0.06 arc sec pixels. 1.64m 1Kx1K m 1Kx1K InSb detector windowed to 512x512, 90ms exposure. InSb detector windowed to 512x512, 90ms exposure.

HST / Ground-Based Comparison

HST Aug 24HST Aug 242003, ACS2003, ACS

UKIRT Sep 4 UKIRT Sep 4 2003, 1.642003, 1.64mm

Selective Imaging - Theory

Probability of a short exposure having phase variationsProbability of a short exposure having phase variationsless than 1 radian (and hence diffraction limited with Strehl > less than 1 radian (and hence diffraction limited with Strehl > 0.37).0.37).

P = 5.6 exp (-0.1557 (D/rP = 5.6 exp (-0.1557 (D/roo))22) Fried, 1978 ) Fried, 1978 JOSAJOSA 68 68, 1651, 1651

Where D is telescope aperture and rWhere D is telescope aperture and r00 is the Fried parameter is the Fried parameter

D/rD/r0 0 = 8 1 in 3800

D/rD/r0 0 = 7 1 in 367

D/rD/r0 0 = 6 1 in 50

D/rD/r0 0 = 5 1 in 9

D/rD/r0 0 = 4 1 in 2

D/r0 at 0.5m0.5 m

( )Aperture metres 0.5Seeing at m 0 ( )r m 0.25 0.5 1 2 4 8 16 323 0.03 7.42 14.84 29.68 59.36 118.73 237.46 474.92 949.842.5 0.04 6.18 12.37 24.74 49.47 98.94 197.88 395.77 791.532 0.05 4.95 9.89 19.79 39.58 79.15 158.31 316.61 633.231.5 0.07 3.71 7.42 14.84 29.68 59.36 118.73 237.46 474.921.2 0.08 2.97 5.94 11.87 23.75 47.49 94.98 189.97 379.941 0.10 2.47 4.95 9.89 19.79 39.58 79.15 158.31 316.610.8 0.13 1.98 3.96 7.92 15.83 31.66 63.32 126.65 253.290.65 0.16 1.61 3.22 6.43 12.86 25.72 51.45 102.90 205.800.5 0.20 1.24 2.47 4.95 9.89 19.79 39.58 79.15 158.310.4 0.25 0.99 1.98 3.96 7.92 15.83 31.66 63.32 126.650.3 0.34 0.74 1.48 2.97 5.94 11.87 23.75 47.49 94.980.25 0.40 0.62 1.24 2.47 4.95 9.89 19.79 39.58 79.150.2 0.51 0.49 0.99 1.98 3.96 7.92 15.83 31.66 63.320.15 0.67 0.37 0.74 1.48 2.97 5.94 11.87 23.75 47.490.1 1.01 0.25 0.49 0.99 1.98 3.96 7.92 15.83 31.66

( )Resolution arc sec 0.50 0.25 0.13 0.06 0.03

D/r0 at 2.0 m2 m

( )Aperture metres 0.5Seeing at m 0 ( )r m 0.25 0.5 1 2 4 8 16 323 0.18 1.41 2.81 5.62 11.25 22.50 44.99 89.98 179.96

2.5 0.21 1.17 2.34 4.69 9.37 18.75 37.49 74.98 149.972 0.27 0.94 1.87 3.75 7.50 15.00 29.99 59.99 119.97

1.5 0.36 0.70 1.41 2.81 5.62 11.25 22.50 44.99 89.981.2 0.44 0.56 1.12 2.25 4.50 9.00 18.00 35.99 71.981 0.53 0.47 0.94 1.87 3.75 7.50 15.00 29.99 59.99

0.8 0.67 0.37 0.75 1.50 3.00 6.00 12.00 23.99 47.990.65 0.82 0.30 0.61 1.22 2.44 4.87 9.75 19.50 38.990.5 1.07 0.23 0.47 0.94 1.87 3.75 7.50 15.00 29.990.4 1.33 0.19 0.37 0.75 1.50 3.00 6.00 12.00 23.990.3 1.78 0.14 0.28 0.56 1.12 2.25 4.50 9.00 18.000.25 2.13 0.12 0.23 0.47 0.94 1.87 3.75 7.50 15.000.2 2.67 0.09 0.19 0.37 0.75 1.50 3.00 6.00 12.000.15 3.56 0.07 0.14 0.28 0.56 1.12 2.25 4.50 9.000.1 5.33 0.05 0.09 0.19 0.37 0.75 1.50 3.00 6.00

( )Resolution arc sec 2.013 1.007 0.503 0.252 0.126 0.063 0.031 0.016

Diffraction limited imaging

• Diffraction limited planetary imaging with PILOT should be possible most of the time in the IR.– 0.25 arc sec at 2m, 0.13 arc sec at 1m.

• And in the best seeing in the visible as well.– 0.06 arc sec at 0.5m.

– Comparable with HST.

• Don’t need AO– Just as well since AO doesn’t work on bright planets.

24 Hour Monitoring

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UT (Hours)

Elevation (degrees)

Venus - Nov 7 2005 Elevation from Dome CVenus - Nov 7 2005 Elevation from Dome C

When planets are in the When planets are in the South they can be South they can be observed continuously.observed continuously.

When they are in the When they are in the North they are always North they are always below the horizon.below the horizon.

The next few oppositions The next few oppositions of Mars are all in the of Mars are all in the north. However 2018 will north. However 2018 will be really good.be really good.

Daylight (Summer) Observing

• Venus can only be observed in daylight.

• It is bright enough in IR for this to be quite feasible.– IR Daylight sky background is probably low

due to low aerosol levels.

Science• Venus cloud dynamics

– 2.2-2.4m imaging of night side.

– 2.0m imaging of day side (?)

– 0.35m imaging of day side.

• Compare with Venus GCMs

CASPIR - Sep 2002CASPIR - Sep 2002

Venus Upper Atmosphere Photochemistry and Dynamics

• Use 1.27m airglow line.

• Study variability over 24 hours.

CASPIR Sep 2002CASPIR Sep 2002

Mars• Imaging in 2m CO2 band.

– Measures surface atmospheric pressure - key input required for Mars GCMs.

– Study thermal tides, midlatitude instabilites.

• Imaging in CO2 ice absorption bands.– Polar cap structure and seasonal changes.

• Imaging in H2O ice band (3m)– Water ice clouds, water ice in the polar cap.

• Imaging water vapour distribution?

• Spacecraft can’t provide global imaging, local time coverage, high time resolution, 24 hour monitoring.

UKIRT 2.2UKIRT 2.2m albedo UKIRT COm albedo UKIRT CO22 band depth MGS MOLA topography band depth MGS MOLA topography

Aug 17 2003Aug 17 2003

Sep 4th 2003Sep 4th 2003

Other Planets

• Jupiter, Saturn– Much easier than Mars or Venus as diameter

doesn’t change much.– Continuous monitoring to study atmospheric

dynamics.

• Small objects (Jovian satellites, Titan, Uranus, Neptune)– Visible imaging.

Instrumentation

• In Visible– 2K x 2K pixels, 0.03 arc sec, 60 arc sec field– Short exposures (<10ms)– Fast frame rates

• In IR– 512 x 512 pixels, 0.1 arc sec, 50 arc sec field– Short exposures, fast frame rate.

• Commercially available cameras may be suitable.