Free and Open to the Public

Astro-imaging with a Portable Telescope
By Steve Grimsley

Most amateur astronomers, like me, have to travel to remote sites for optimal weather and sky conditions, and also for gatherings like Stellafane and the Texas Star Party. This requirement for equipment portability in a temporary setup, can present special challenges to the stability of the setup required for consistent results in long exposure astro-photography. Long exposure times allow for the capture of faint nebula and details in small distant galaxies.

Equipment parameters like f-ratio, image scale, guide scope ratio, polar alignment, and general stability and balance are critical issues that require an understanding and a solution for successful execution of a long astrophoto run. With favorable sampling resolution, sufficient exposure time, alignment, and tracking, the results can be surprisingly good even when compared to similar aperture telescopes located in fixed observatories.

This presentation is divided into three parts. First a discussion of telescope resolution, optical speed, sensor sampling, and camera efficiency and how these parameters play into a quality image capture. Second, a series of astronomy photos will be shown that will demonstrate the advantages of an efficient image acquisition. And lastly, we will look at the complete telescope setup that was used in most of the images shown in this presentation. Comments will be made about general stability, balance, flexure, mount alignment, tracking, and guiding. With the telescope assembled and on display it should be easier for the audience to get a clearer idea of the numerous variables that need to be addressed in order to capture beautiful but very faint and distant deep sky objects.

Free and Open to the Public

Astro-Image Processing with PixInsight 
By Mike Stadtmauer

PixInsight is the most advanced piece of software on the market for astro image processing. It is used by NASA and professional observatories around the world. It is non-intuitive, has a non-standard GUI, has no official manual and is entirely algorithm based - in short, its perfect for us astro geeks who like a challenge. Especially when that effort pays off in stunning images that can not be produced any other way.

Astro-image processing typically invokes taking images shot through L, R, G, and B filters and combing them through extensive processing and manipulation of the data in order to produce a pretty color image. This presentation will walk through the steps of a typical LRGB image processing workflow, using the special tools and features of PixInsight. We will start with raw, straight out of the camera subs and calibrate and stack them into master frames for each filter. Then, I will demonstrate how to clean up those frames to prepare for RGB combination. Next, we will see how to prepare the L master and the RGB master for stretching by performing linear noise reduction and deconvolution (what’s deconvolution? - you’ll just have to come and find out! - but it was invented by NASA for processing the Hubble images so you know its pretty cool). I will demonstrate a number of different stretching techniques where we take the image from its natural linear state to a non-linear state in order to properly visualize the data. Once stretched, we will see how and why we combine the L with the RGB images to create the LRGB master. That final master image will then be taken through a number of techniques designed to optimize, bring out the most detail and the best colors of our data. Finally, we will see how non-linear noise reduction, sharpening, star reduction and some final touches are applied in order to arrive at the finished image.

If all of this sounds like greek to you, don’t worry - there will be a handout to follow and lots of explanation along the way. If you have used other astro processing software, prepare to be impressed by the raw mathematical power of PixInsight!