Aug 27, 2013

PixInsight: Creating a Luminance Mask

A view from above Kofa
Photo by Chris Hanrahan
I had big plans to do some real writing this weekend, but we had four days of rain in Arizona.  For me, this meant a trip out to the desert to play in the rain.  With temperatures 40 degrees (Fahrenheit) below normal the day was spent hiking in the Kofa National Wildlife Refuge - my favorite place on Earth.  

As a result, not much actual writing got done.  And when I say "not much", I mean no writing got done.  Instead, for the uninitiated, here's a step by step process on creating a luminance mask in PixInsight.  As you'll see - it's really easy.  And in PixInsight, this is a technique you'll use in various ways over and over and over.  Enjoy!!

Creating a Luminance Mask

Aug 7, 2013

PixInsight Deconvolution

 After commenting recently on a thread in the AZ-Observing mailing list about PixInsight it sparked multiple side conversations with other list members asking some questions about deconvolution in PixInsight.  This animation does pretty much sum up the experiences of many including myself when it comes to getting good results.  After much trial and error and gnashing of teeth I have reached a point where I can get some decent results.  The conversations from the mailing list encouraged me to go ahead and put together a video and post on deconvolution in PixInsight.  I'm not saying it's the best way, but it does work and I've enjoyed some good results with it.

World class imager Manuel Jimenez put together a tutorial some time ago that taught me much about PixInsight's implementation of deconvolution.  His tutorial can be found at his website. There are a few points to remember in order to get the best results.

1 - Do deconvolution on a linear image.  Before you stretch.
2 - There's only so much deconvolution can do.  It can't rescue a bad image, but it can make a decent one really "pop".
3 - Use the Dynamic PSF process module.  It's your friend.
4 - Create a star mask for local deringing support in your image.
5 - Create a luminance mask to limit the process to high signal areas.

The Final Result

Like the image in the video I also did deconvolution on the OIII and SII data that I had collected in my attempt to recreate the Pillars of Creation image.  Shown below is the end result.  This was shot with my Explore Scientific ED152 f/8 Apo triplet from southern Arizona.  It's a total of 37 hours of exposure time and processed entirely in PixInsight.  Thanks for watching.  Please contact me if you have any questions, comments or improvements to my process.

Here's a link to a larger version of this image:
M16 - Eagle Nebula in Hubble Palette
37 hours of exposure

Jun 19, 2013

Grand Canyon Star Party

Each June for 23 years now the National Park Service has hosted the Grand Canyon Star Party.  It's always around new moon and always in June.  If you're planning a trip to the Grand Canyon (and you should!) and you're astronomically minded this is the best of both worlds.  If you're curious about future dates as you plan that vacation they can be found here.  If you want the quick answer - the 2014 edition will be held from June 21 to June 28.  This is from last quarter right up to new moon so the skies will be inky dark every night.   The star party is made possible by volunteers.  Generally speaking, the festivities at the South Rim are coordinated by the Tucson Amateur Astronomy Association and the indefatigable Jim O'Connor.  The North Rim edition is coordinated by Steve Dodder and the Saguaro Astronomy Club based in Phoenix, Arizona.  

Which Rim Is Best?

That really depends on what you're hoping to find.  The star party at the south rim is much, much larger and features many more astronomers.  it's bigger in every way than the star party at the north rim.  It's also much easier to get to for most people than the north rim.  it's just a short drive off of Interstate 40 to get to the south rim.  You can even take a train right to the rim from Williams.  Crowds are much larger and lines for the telescopes can be long.  It is probably the ideal place for many would be attendees.  Personally, it is not for me.  But that's not because of the star party - it's just the south rim in general is not my typical flavor.  I'm very much into the outdoors and enjoying the natural beauty of my state and the amount of development necessary to accomodate 5 million visitors per year.  Bus stops and shuttles are not my idea of natural scenic beauty.  The canyon is still beautiful but the atmosphere isn't really my cup of tea.  Still, if the canyon is a stopping point on a larger vacation - the south rim is a great place to attend the star party.  

A panoramic view from Widforss Point, about a 5 mile hike inside the Grand Canyon National Park
on the North Rim.

The north rim is an entirely different world and one well suited to everything I love about amateur astronomy and being outdoors.  Less than 10% of the park's visitors go to the north rim so crowds are much smaller. It tends to be a destination where people stay for a few days rather than a stopover point.  It takes about 3 hours longer to get there than the south rim from my home near Phoenix, but it's worth every extra minute.  The star party is much smaller featuring about a dozen telescopes.  Those telescopes though are setup on the veranda of the North Rim Lodge and feature devastatingly beautiful views of the canyon.  Both years that I have volunteered at this star party my telescope has been less than 30 meters from the rim of the canyon.  Check out the time lapses from this year's star party.  Both were shot from the north rim and show what you can expect from this star party.  I hope to be there again next year showing the night sky to anyone who will stand at the eyepiece.