Resources
The following resources I have found extremely useful in my astrophotography pursuits. More information will be added in due time.
Image Processing Tools and Documentation
- Image Processing Techniques for the Creation of Presentation-Quality Astronomical Images. By Travis A. Rector, Zoltan G. Levay, Lisa M. Frattare, Jayanne English and Kirk Pu'uohau-Pummill. Download PDF (2.9Mb)
- Producing Optimal CCD Flat fields (also knowns as "flats") for subtraction of dust donuts, vignetting and gradients;
- In order to determine your CCD cameras Flat field exposure time, you must first obtain the "target" saturation value:
- FORMULA: FullWell / ADU Gain * 30-50% = target saturation value of your flats.
- FullWell is the CCD chip manufacturers documented full well capacity.ADU is the CCD chip manufacturers documented ADU (Analog Digital Units) gain. ADU gain is the conversion of photons to electrons.
- 30% to 50% is the well capacity you are trying to reach. I good starting point is 35% to 40%. Too low percentage and your flat will not correct the light image efficiently, too high and the light image will inverse.
- Dark subtract and medium combine your flats into a master (I usually aim to take around 16 flat frames to combine).
- If taking sky flats at dusk or dawn, make sure you alter the exposure length as the sky will be constantly getting dimmer or brighter respectively. You will want to ensure you reach your target saturation value on each exposure. There is a MaximDL plug-in that monitors each flat exposure and compensates for the changing sky brightness. I recommend using this to assist in compiling your flat frame library. It can be scripted to also support flats through different filters. Download here.
Star Catalogs for imaging calibration (G2V) and telescope pointing model refinements
- USNO-A2.0 catalog:
Catalog of 526,280,881 stars - 6Gb download.
- G2V Stars:
Our sun, a G2V star, radiates at a temperature of about 5780 kelvin. Our eyes see sunlight as white. Find a G2V star, image it with red, green and blue filters, and determine the weights to equalize the signals. Use those weights to achieve a white-point adjustment for proper star color balance.
Telescope Mounts and Polar Alignment
- Users of the Losmandy Titan german equatorial mount may wish to reference the following information;
Titan Tips - Great tips and tricks in fine tuning the Losmandy Titan mount
Titan Users Yahoo Group
Gemini Users Yahoo Group
Losmandy Users Yahoo Group
- Achieving accurate polar alignment;
PolarAlignMax: Polar Align Max assists in achieving very accurate polar alignment using a CCD camera. This is an alternative to using the CCD drift alignment method.
- Standardisation of telescope control, filter wheels, focusers and observatory domes;
ASCOM software and documentation
ASCOM Users Yahoo Group
- Dealing with telescope mount worm and gear periodic error;
CCDWare PEMPro: This is an amazing software that can drastically reduce the periodic error of most telescope mounts. Highly recommended if you want to get the most from your telescope mount or into astrophotography. This will reduce the quantity of autoguiding movements resulting in round sharp stars.
Automated Focusing Software
- FocusMax provides an extremely accurate focusing algorthm that can be used with ASCOM compatible focusers.
- Neil Fleming has compiled a fantastic "quickstart" guide about using FocusMax and fine tuning the v-curves. The tutorial can be viewed here.
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