Stacking software: Finding what's right for you

KISS.

Keep it simple, stupid.

That is sound advice when it comes to post-processing images in astrophotography. Because, god knows, post-processing is enough to drive a beginning astrophotograper insane. Or was that just me?

When I joined iTelescope I knew that, in order to get the best images, I had to stack multiple images. My first attempt was to find something free. I know that the old "you get what you pay for" adage and I was quite worried about it at first. However, there are a few stacking software packages out there are quite good.

But what I discovered is that you need to find software that works for you.

Let’s list some of the freebies:

Registax

Nebulosity

DeepSky Stacker

Keith's Image Stacker

The costly ones:

CCD Stack

MaximDL

Pixinsight

(I know there are others, but I'm just listing some of the more popular ones.)

Now, on top of the issue of cost versus free, there’s the Mac vs. PC issue. And if you’re a Mac owner, you lose. Most stacking software is made for PCs, unfortunately (she says as a Mac user). But there are ways around that, like running Windows inside virtualization software, like Parallels, Fusion or Virtual Box. If you can't do that, then the best bet is to use Nebulosity 

I used that and found that its simplicity worked for me. Though, admittedly, after using some other software programs, I discovered that it can be quite limiting. I tried using Keith's Image Stacker, as well, but really didn't like it. It just wasn't for me.

I did end up purchasing CCDStack, which I immediately fell in love with. 

M101 processed with CCD Stack

But this isn't meant to be a review of programs.

Basically, when looking at software, the thing you need to do is look for what works for YOU. I like to keep things simple. I like CCD Stack's simplicity, but then again, so is Nebulosity. I can't have anything too technical, though I'd love to try MaximDL as I hear very good things about that software.

What about you? What software do you use?

Year of the Comet

If there were such thing as an Astronomical Calendar, last year would have been the “Year of the Sun” following the total solar eclipse, the annular eclipse and the Transit of Venus. And this year it would be the “Year of the Comet.”

Comet C/2011 L4 (or just Comet Pan-STARRS), was discovered by the Pan-STARRS 1 telescope in Haleakala, Hawaii, and first made an appearance in the southern hemisphere in 2012. People were treated to a spectacular show as the comet neared an estimated brightness of around +1. People in the northern hemisphere enjoyed Pan-STARRS in March 2013. Although it’s still visible, it’s not nearly as impressive as it has been.

But in 2013 we are going to get a very special treat. Coming soon to a sky near you is Comet C/2012 S1 (ISON), which most people simply call Comet ISON. Discovered in September 2012. There is some speculation that this could be the best comet in years.

Of course, we all love seeing comets, and we also know that there’s a lot more detail available to comets than what we can see with the naked eye. So what about using iTelescope to image comets? It can be done.

And if there’s anyone who knows about imaging comets, it’s iTelescope member Rolando Ligustri who lives in northeastern Italy. I asked him a few questions about his experiences and how he got into imaging comets. 

When did you start becoming interested in astronomy?

When I was young, I saw men land on the moon and fell in love with space immediately. I received my first telescope in 1973. It was a small but excellent refractor: a 76/910. With it I began to observe the sky. My first target was the Pleiades, and then Saturn. When I first saw it, I was overcome with emotion: it was a three-dimensional planet!

Then I continued to observe the sky. I only stopped when I was an officer in the Italian Navy. In 1986, I bought my first real telescope for astroimaging — to photograph Halley’s Comet! In 1995, I bought my first CCD and after that another, I imaged hundreds of objects and dozens of comets. 

When did you start becoming interested in comets?

My interest began with the observation and photographing of Halley’s Comet. It was too bad that the 1986 passage wasn’t very bright. Then, with the creation of the CAST Observatory (MPC235) [an observatory in Italy], I began to study them more and more. As of today I have photographed almost 150 comets, and thanks to remote telescopes like iTelescope, I have had several of my photographs appear as an Astronomy Picture of the Day (APOD).

Which iTelescopes do you use to image?

There is no one telescope in particular that needs to be used for photographing the comets. Every set-up in the various sites around the world can go well with astrophotography — you just need to know what you want to achieve (beautiful photograph or scientific measurements) and the size of the target. In principle, the telescopes with short focal length are useful for creating beautiful images; ones with longer focal lengths can be used for searching out details inside the coma or in the first part of the tail in addition to measurements of position and light. What is important is to always pay attention to the resolution of the telescope and the movement of the comet. If you’re making measurements, 1 pixel of blur is acceptable. However, if you’re just imaging for the pure beauty, it can move 6 to 8 pixels, which you can fix in post-processing.

 Can you give advice to those looking to image comets?

As I said above, you first need to decide the field of view, both in terms of the size of the comet, or for any deep sky objects nearby. A photo of a comet must always be studied, even for how to frame it. Once you decide how to frame it and know the resolution of the instrument as well as the apparent speed of the comet, you need to determine the maximum exposure.