Wednesday, June 20, 2007


Last week was so annoying that I was thinking of writing a post entitled Open Cluster F**k. I intended to redo the open cluster positions by hand, but decided I'd have one last search of the literature before I took that fairly large project on. As it turns out I found a resource that had everything I needed to greatly improve the cluster data! I must admit, however, to some frustration with myself for not being previously aware of this catalog and with nearly missing it entirely. But there was also a catch (there always seems to be one). In the new catalog each cluster is identified with only one designation and the positions of the clusters had changed, sometimes dramatically. That made it difficult to match them to the clusters in my existing database (this is unfortunately a requirement). So I had to write yet another program to do the matching. It turned into a nasty little problem. Sometimes it feels like matching objects is all I do. I need a break!

At 4 AM one morning I awoke suddenly, realizing that the power was out. I worried about my now-silent computer that had been so busy crunching stars while I slept. Had the UPS shut it down gracefully? I had a look outside and the sky had cleared. Imagine having the lights go out in the surrounding community and you can't tell the difference! I am very lucky. The other amazing thing is that you could still clearly see everything in my observing area, illuminated by nothing but starlight. One thing I discovered when I moved to the top of a 9000ft mountain is that a "dark" transparent sky isn't really dark at all. But I digress.

I waited in vain for the power to return the next day. It didn't come
back until 24 hours later, and I was again asleep. The next day I had to go to Las Cruces, so I lost two full days of work. By the time I got back to it, I had trouble remembering what I had been working on so enthusiastically. I hate that.

Anyhow, once again I can report that it all turned out well in the end. The Open Cluster database is improved dramatically with data that was not available when I built ST2. And my computer picked up where it had left off, marching right on with matching those millions of stars for the new stellar database.

Speaking of that, I have to admit to some second
guessing regarding my project to create a much larger stellar database. People keep asking me, "Is that really necessary?" This is what always happens when I come up with one of my big ideas. It seems like everyone I know tries to shoot it (and me) down. Don't get me wrong--they mean well, but I have this tendency to go out on a limb with some new innovation and most of the time the people around me don't see it the way I do. Add to that my own fears and insecurities about being out there on that limb and it can be disheartening. Fortunately most of my innovations have turned out for the best, but for a few spectacular exceptions, But the "proof is in the pudding" as they say, and I naturally worry that I'm making a mistake, particularly when it is a long-term project. On the one hand having a much deeper database seems like a no-brainer, but on the other there is that nagging question: do people really need that many stars?

What if I build it and they don't come?

The Pudding Comes out of the Oven

At 5:33 PM today an historic moment occurred (at least for me). The last star was added to the new "pro" stellar database, bringing the total number of stars to over 522 million. Yowza! Leave it to me to be off by a factor of two in my estimate! Apparently I overestimated how many stars would be excluded due to various reasons. SkyTools 2 in comparison, like all other current software, ships with a mere 20 million (or so) stars. So is this a revolution in the making?

Oddly, I also managed to get my estimate for the final size of the database wrong by a factor of two. Thankfully, I overestimated that one. The map database comes to just under 4.3 GB, which is small enough to fit on a single DVD-ROM. This development opens up some interesting possibilities with regard to how we may offer the "pro" version. But again, I digress.

As the database neared completion I was able to play with the parts of the sky that were available. I used ST3 a lot to check out the new open cluster positions and sizes. It looks great. And there sure are lots of stars! There is also a more subtle effect: so many more of the stars now have colors that the display is very pleasing. I got used to it very quickly.

Then I had the "wow" moment. I was looking at NGC 7142
, an open cluster dear to my heart, in the ST3 Interactive Atlas when I had the idea to compare it to the old ST2 view. I fired up ST2 and was immediately struck by the difference. As you zoom in with ST2 you quickly reach the point where the existing stars merely get bigger and no new stars appear. You can see for yourself below:

Click here for a much better comparison

After spending so much time with ST3, not only did it feel like most of the sky was missing in ST2, but the position and size of the cluster is, well, rather embarrassing! So do I feel like I've wasted my time with these databases? No Way!

What a relief.

Thursday, June 7, 2007

Working Vacation

Well, sort of. This past week Mrs. Skyhound has been away at a conference and the Skyhound kids are out of school. Between feeding them, clothing them, taking them to their baseball games, following both the Stanley Cup and Louis Vuitton Cup finals with them, and separating the two of them when they fight, I haven't had a lot of time to work.

Nonetheless there have been some important milestones. In addition to working in here and there the tying up of little loose ends, I added even more improved data to the planetary nebula database (it's really looking good).

But the big news is that I finished the end-to-end testing of the new stellar database and it passed with flying colors. The final count was 16,330,450 stars, including over 50,000 variables and 72,089 multiple star systems. I don't have a final count for the total number of double-star pairs, but it is likely close to 100,000. I also ran many tests on special cases, such as the long-period binary pair BL Cet and UV Cet, Barnard's star, etc. Everything is go.

It was time to start creating the full database for the "pro" version, which will add large numbers of faint stars down to magnitude 20. There are a total of 24 declination bands, of which 3 are now complete. At the current rate it looks like it may take a week running continuously to finish the database, bringing the total number of stars to something around 250 million. SkyTools is really impressive when targeted in the bands already completed. It seems like you can zoom in forever and the stars just keep coming!