888 Cam: Visible Light Imaging for P3K / PALMAO

Nicholas Law, Rich Dekany

Nicholas Law888Cam

P3K 12 Nov

888Cam

LuckyCam visible light imager for PALMAO and PALM3K

• A cut-down more permanent version of LAMP instrument first used on PALMAO this summer. Achieved 10-20% Strehls at 700nm. Fast tip/tilt correction and frame selection.

• Cheap: $100K or so total.

• 1K x 1K L3CCD detector: photon-counting, 0.01-100+ FPS

• Pre-PALM3K: pioneer visible-light imaging high-angular-resolution astronomy at Palomar.

• PALM3K: High-sensitivity visible-light imager, push performance further into the blue. Before high power laser upgrade will give 10-20% R-band Strehls on targets down to M(V)=12, using typically 10-20% of data.

• NGS & LGS: LGS mode uses tip/tilt star at M(V) roughly 16-17

Nicholas Law888Cam

P3K 12 Nov

LAMP @ Palomar

• LuckyCam, AO, Aperture Masking & Polarisation @ Palomar: LAMP

• L3CCD camera for Palomar 200” telescope adaptive optics system. Used for first time in July 2007

• Beamsplitter to send 50% of visible light to LAMP, 50% to WFS

• Tested in NGS mode only (for simplicity) but can also be used for LGS

• Three modes: Lucky Imaging, high-contrast polarimetry, aperture masking.

ADC

Filter wheelPupil mask wheelL3CCD

+ dewar

Movable slide forfocal length changes

Light from PALMAO

710nm, 50 frames per second

Lucky Imaging with AO:Raw data from LAMP

Nicholas Law888Cam

P3K 12 Nov

Does the Lucky Imaging make a difference?

Long-exposure behind PALMAO

Same data, fast frame rate Lucky Imaging

10% selection, 710nm, 0.8 arcsec

seeing1.0 arcsec

Nicholas LawLAMP - cheap visible-light AO

Tea talk 12 Nov / 276

Long-exposure

Shift-and-add

1% selection

710nm, 0.8 arcsec seeing

Nicholas Law888Cam

P3K 12 Nov Sub-100mas resolution across the visible

950nm 710nm 500nm 450nm

100mas 100mas100mas100mas

10% selection, seeing ~0.8 arcsec

Seeing-limited (simulated). 1.0” arcsec (from DIMM)

LAMP 20% selection3 colour: i’, 500nm, 660nm

Nebulosity Performance:

Cat’s Eye Nebula

15 a

rcse

c

Nicholas Law888Cam

P3K 12 Nov

Results:Summary of performance

• Strehls of 5-20% at 700nm. Majority around 10%. Diffraction-limited resolution (35-50mas FWHM) in almost all 600-700nm observations which were properly sampled

• Long-exposure (unLucky) Strehls 2-3%.

• Compared to PALM-3000: lower Strehl, much lower SNR, but similar resolution.

• Often limited by non common path (NCP) errors - needs a better calibration method & more stable instrument

670nm, 1.1 arcsec seeing10% selection from 3 minutes @ 20 FPS

NCP error example

Nicholas LawLAMP - cheap visible-light AO

Tea talk 12 Nov / 30

• Emission lines - H-alpha, H-beta, O[III]... jets from young stars, symbiotic binaries, nebulae, etc.

• Resolution - 35 milliarcseconds, equivalent to the best achieved on Keck.

• Sensitivity increase from higher resolution compared to IR

• HST followup: much easier to get time. Track evolution in time much more easily (esp. outflows)

• Optical transient followup - what’s going on in transient environment? Need visible photometry to match transient surveys.

Science with 888Cam10

Nicholas Law888Cam

P3K 12 Nov

888Cam Hardware

Detector

• Andor DU-888E 1024x1024 detector

• 10MHz readout

• Built-in thermoelectric cooling

• 10 FPS full-frame, faster binning & subarray

Ancillary components

• ADC: from JPL, tested in LAMP, software already written

• Filter wheel: standard 12-hole (FLI?)

Optics

• Direct imaging is 33mas/pixel - slightly undersampled

• Simple off-shelf lens arrangement to reimage to Nyquist at 500nm.

• Leaves open option of aperture masks

Nicholas Law888Cam

P3K 12 Nov

Summary

• LAMP routinely achieved diffraction-limited resolution in the visible on P200

• Strehl ratios ranged from 5 to 20% at 700nm; sub-100 milliarcsecond resolution from B-band to z-band

• 888Cam will pioneer visible-light AO on P200 before P3K

• Once P3K is online, high sensitivity visible light imager