Front Yard CCD Astrophotography January 11, 2007

My Recommendations for starting Learn! Purchase/read “The New CCD Astronomy” by Ron Wodaski Purchase/read “Photoshop for Astrophotographers” by Jerry Lodriguss SBIG users group Websites: http://www.rc-astro.com/ (Russell Croman) http://www.robgendlerastropics.com/ (Robert Gendler) http://www.mistisoftware.com/astronomy/ (Jim Misti) Club expert/mentor (John Boudreau) Webcam and planets/moon

What can I do? Start: Photographs of the moon and planets Webcam Registax Good scope Moderate tracking ability Works from light polluted areas (bright objects) Good results with minimal investment obtained from stacking hundreds of images

What can I do? Deep-sky objects from Andover Light pollution effects photograph quality (increased sky background noise ) Long exposure times >5 hours/object Practical implications of seeing conditions Good to high level quality equipment produce better quality photos (expense/investment) Produce good quality photographs Digital Development Processing algorithms (DDP) and photo-processing “workflows” can correct many problems

Deep Sky CCD – Mount Selection Spend 60% of money on Mount Periodic error correction (PEC) 30 sec exposure less important 30 min exposure requires good PEC and tracking (auto guiding) Telescope focal length significant factor Accurate auto-guiding Worm-gear design Motor design

Deep Sky-Mount Suggestions I use Astro-Physics 900 GTO Mounts others have used Losmandy (G11 and Titan) Takahashi Paramount Mountain Instruments Meade (RX400, LX200) Celestron (CGE)

Learn characteristics of your mount-Auto-guiding Balance “Slight” east weighting Appropriate selection of weights to center moment arms Adjust worm gear / mesh Software or mount firmware PEC correction

Deep Sky CCD – Telescope Focal Length (ref: “The New CCD Astronomy”) Seeing Aperture Targets Flexibility 400-800 Rarely 3-6” Big targets Good-add Barlow 800-1500 A consideration 5-10” More targets Good if focal reducers available 1500-2000 Always matters 8-16” Many more targets

Deep Sky – Telescope Selection Better optical quality provides sharp correct color round stars Recommend match telescope with CCD camera (ref: http://www.sbig.com/sbwhtmls/online.htm) Telescope Field of View CCD chip size CCD chip pixel size Flat field needed Adapter for telescope (field flattener) Optical design with flat field (modified Petzval) Astro-Physics sells adapter for SBIG cameras that fits in front of camera (http://www.astro-physics.com/ -CCD Telecompressor (CCDT67))

My Deep Sky Telescope Selection Takahashi FSQ 106 N APO fluorite refractor Modified Petzval - 88mm circle flat field image 4” focuser 3600 camera angle adjuster Aperture 106mm Focal length 530mm Compatible with large CCD chips currently on market

Modified Petzval Design

Deep Sky-CCD Camera Selection Anti-Blooming Gate (ABG) Easier to use Less sensitive Non-Anti-Blooming Gate (NABG) More sensitive Careful planning of exposure time needed (experience) Minor blooming can be fixed Software Photo Processing takes more time

Camera Designs One-shot color camera Black and white with filter wheel Filters located on chip – no filter wheel Easy to use –good example is planets via webcam Less flexible Black and white with filter wheel Flexible – can use many different types of filters More complex to photo-process to color image Better control over quality and composition of color image

Match Camera, Telescope and Mount Telescope focal length (ref: http://www.sbig.com/sbwhtmls/online.htm) Ability of mount to track and guide effectively Compensate for longer exposure times needed for ABG NABG better if short exposure times are needed to match mount capability Light pollution-NABG offers advantage

Auto-guiding options Separate CCD and scope for guiding Camera with built-in guide chip (Santa Barbara Instrument Group, Inc (SBIG)) Don’t guide Webcam Short exposures (30 sec) and stack 50 – 200 images Improve signal to noise

My Camera Selection SBIG ST-2000XM (ref: SBIG website)

My Camera Selection SBIG ST-2000XM (ref: SBIG website)

My Camera Selection SBIG ST-2000XM

My Camera Selection SBIG ST-2000XM

Photo Session-Focus Maxim DL Software View of star size and number of small faint stars Optimize for maximum intensity for star (signal) Optimize for Full Width at Half Maximum (FWHM)

Focus Zen-Maxim DL Gross focus with imaging chip at 2 bin Fine focus small selected area of CCD at full resolution 1bin Set exposure time at >2 sec so that changes in seeing are not major factor Watch temperature FSQ in focus range is 35 microns Temperature change >20F causes stars to bloat and loss in signal Focus-aid: Plan to purchase Robo-Focus

Photo Session – Object Study object Size (mosaic will need to be planned) Color Brightness Globular cluster uniform Galaxy Bright core faint outer region Nebula have strong narrow band emissions Filter selection Luminance for white light detail (L) Red, Blue, Green (RGB) for color Halpha (656.26 nm) narrow band filter for red nebula Narrow band filter composites Match filters to object and combine (LRGB, RRGB, HalphaGB, LHalphaRGB)

Photo Session – Frame and Lock Locate object Roughly frame object on image chip Find suitable guide-star (>25000 ADU for filter transmitting lowest signal – Halpha) Finalize object framing Lock on guide star Auto-guide

Photo Session-CCD Camera Correction Frames Dark Frames. Correct for dark current that increases as a function of time and temperature (Thermal signal) Bias Frames. Bias that occurs when pixel is read by camera (Zero light exposure)

Photo Session – Flat Field Correction for Optics

Taking Flat Field Frames