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Applications of EMCCDs to Faint Occultations

Applications of EMCCDs to Faint Occultations. Bruce Holenstein, Russ Genet, and Steve Conard 31st Annual Meeting of the International Occultation Timing Association 04-06 October 2013 Toronto, Canada. Agenda. What is considered faint ? What are emCCDs ?

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Applications of EMCCDs to Faint Occultations

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  1. Applications of EMCCDs to Faint Occultations Bruce Holenstein, Russ Genet, and Steve Conard 31st Annual Meeting of the International Occultation Timing Association 04-06 October 2013 Toronto, Canada

  2. Agenda • What is considered faint? • What are emCCDs? • Some SNR theory and tests • Some projects

  3. What is considered “faint”?A desirable occultation out of the reach of typical IOTA equipment • Targets are faint • TNO occultations – 14th+ magnitude • Fast cadence & HTRA • Diffraction patterns – 200+ fps • Small scopes are in use for portability • Well under 1-m typical • Lowland observing & program objects at low altitudes • Lots of atmospheric extinction

  4. What are emCCDs?CCD cameras with an extra set of registers to multiply electrons before readout. Top row from left: PhotometricsCascade 512BemCCD, 512BemCCD w/UV enhanced, 1kemCCD, CoolSNAPK4 Bottom row: Supercircuits164CEX-2, Andor Luca-S emCCD, Watec902H2-Ultimate, two 902H2’s (PAL), Two JAI 6740GEGigEthernet Above: Andor iXonEM+ 887 and 897 emCCDs

  5. How emCCDs work Source: Photometrics Cascade user manual

  6. emCCD Noise Reduction CCD read noise reduced from 10’s of electrons per pixel to under 0.1 per pixel. Back illumination increases QE. QE curves: Andor iXonEM+ and Photometrics Cascade 512B’s use CCD-97 (top curve) CCD Read noise drops off as em gain increases Sources: Andor iXonEM+ 897 & Photometrics Cascade brochures

  7. Camera specs

  8. emCCDs Mounted on small scopes Top two photos: Photometrics Cascade 512B mounted on a 10” SCT, Right: Luca-S on 8” SCT, Far right: 512B on a 10” Newtonian

  9. 10” SCT with Andor Luca-S, Orion filter wheel, Barlow, iXonEM+ and Van Slyke Instruments Slider II (setup for speckle interferometry)

  10. SNR Theory for 14” f/4 SCT • SNR for four cameras vs object mag. 30-fps, 100-m elevation, 1.2 airmass, Sky: 20th mag./sq.as. • Each magnitude fainter worked is about 300% more targets (2.5 mag. is ~30x more!)

  11. Camera comparison on 14” f/10 SCT NGC 7031- above the top of the Cygnus cross (stars ID'ed down to mag ~17) LINEARITY CHECK – Video Rate (33ms) StellacamEX Photometrics512BemCCD

  12. Camera comparison on 14” f/10 SCT SNR COMPARISON – Video rate (33ms) StellacamEX Photometrics512BemCCD (Note scales are not the same)

  13. mu Gem Lunar Occ. 1314Mar11 16.5 mas fit (red) 0.1 mas fit (red) Media, PA C8, Luca-S at 333fps, unfiltered, LiMovie Scintillation limited SNR!

  14. FPS (speed) - Pi Sgr at Villanova, August 10, 2011 • Villanova C8, 164CEX-2 CCD, no filter, 30fps • 9.4mas per datum • Gravic C8, Andor Luca-S emCCD, Sloan r filter, 120fps • 2.4 mas per datum • Again Scintillation limited SNR

  15. Some Projects • Programmable timing trigger device (Arduino, GPS shield) • Alt-AzTelescope Initiative Projects • Larger scopes are needed to further improve SNR Hubble Optics UL20

  16. 1-M Meniscus Mirror Telescope Prototype Weight under 400 lbs Fits in back of Dodge minivan & Jeep Cherokee On-axis f/4 light bucket w/possible active optics “Big Blue” – from Russ Genet

  17. Orion Observatory 1.5-m • 60” scope designed and built by Russ Genet; CalPoly students MounirEl-Koussa, Laura Rice, and Mike Vickery; mirror cell by Donny Mott; SiTech donated controller/drive; DOTI donated mirror; scope finalized by Reed and Chris Estrada

  18. Scaled up design to 2.4-m Designed by Mounir El-Koussa, R. Genet, B. Holenstein, D. Mott; funding by Gravic and Collins Foundation

  19. ConclusionsemCCDs cameras can help IOTA in certain situations • emCCDs have a 2 to 3 magnitude advantage at video rates over typical IOTA cameras • On “photon challenged” (sm. aperture) scopes • Low altitude or contrast events where a better SNR is needed Challenged in certain situations • Cameras are expensive, heavier, less portable, and need more power • Scintillation noise hampers fast cadence & HTRA measures so one needs larger scopes 0.5-m & up

  20. Contacts • Emails: bholenstein@gravic.com, russmgenet@aol.com, steve.conard@comcast.net • Alt-Az Telescope Initiative Website - www.AltAzInitiative.org • Yahoo Discussion Group - http://groups.yahoo.com/group/AltAzInitiative

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