Supernova #29

 

At 1:30 AM on the morning April 28, it was time to pick a new set of target galaxies during my nightly search for supernovae. My sidereal clock displayed 15:31, so I chose to get a headstart on 16h galaxies. Late April is still considered Galaxy Season, but when 16h is approaching the meridian, the densest part of the Realm of the Galaxies is three hours over to the west and fading fast. 

Looking due south at 16 o'clock sidereal time, you'll see the early summertime constellations (Scorpius, Ophiuchus, and Hercules) just east of the meridian, and the tail end of the springtime constellations (Libra, Corona Borealis, and Boötes) on the west side.

Seasoned backyard astronomers know that 16h is where we transition from observing galaxies to seeking out globular star clusters that have been hiding from us for months. But while globular clusters are great targets to view in the eyepiece of backyard telescopes, they are not the apple of the eye of supernova hunters! For me, when the sidereal clock displays 16:00, my list of target galaxies is very short. Not only that, but the galaxies of my 16h targets list are tiny and unspectacular. 

As we leave the Realm of the Galaxies behind, the feeling I have is very much like you have while driving east out of Denver on I-70 toward Kansas, and watching the mighty Rocky Mountains shrink in your rearview mirror! 

Watching the Realm of Galaxies shrink in the rearview mirror has been especially painful for me this year, because I happen to be in a long drought of no supernova discoveries. I haven't made a supernova discovery since last October. The "Rocky Mountain High" of the 2026 Spring Galaxy Season wasn't enough to lift me out of my slump. And here we are, sailing toward the Summer Galaxy Doldrums!

So, after midnight on April 28th, I opened my 16h target galaxies list with a yawn. And as I typically do, I scrolled down to the bottom of the list, which is the lowest declination, so that I could work my way northward during the next hour. NGC 6070 is the last and lowest galaxy in my 16h list, just above the Celestial Equator with a declination of +0° 43' 0". That puts it in the constellation Serpens Caput (the "Head of the Serpent"). 

The constellation Serpens is split in two. Serpens Caput is the western half, and Serpens Cauda (the "Tail of the Serpent") is the eastern half. Between the two lies Ophiuchus, "The Serpent Holder." Ophiuchus is a rather large constellation, and within its boundaries lie not one, not two, but seven globular clusters that were discovered by the great comet ferret Charles Messier. 

Now, I am a great fan of the French astronomer Charles Messier! And I am a great fan of globular clusters. As a matter of fact, the first deep-sky object I ever saw through a telescope was Messier 13, the Great Hercules Globular Cluster. 

I am also a great fan of comets. The first comet I photographed was Halley's Comet in 1985. That comet was also Charles Messier's inspiration, and in fact, had it not been for Halley's Comet, Charles Messier probably would not have discovered his 110 objects. 

It was while Charles Messier was desperately trying to be the first person in the world to recover Halley's Comet that he accidentally came across Messier 1, the Crab Nebula. 

Yes, in a roundabout way, we can thank Edmond Halley for pointing the way to the deep sky. Before he died, Halley made a prediction to astronomers all over the world about where to search for his comet in 1758 and 1759. A prediction that Charles Messier latched onto and didn't let go. Unfortunately, Messier didn't get the memo when the German astronomer Georg Palitzsch became the first person to recover Halley's Comet, on Christmas Day 1758. Unaware of Palitzsch's success, Messier continued to search for the comet until he found it on January 21, 1759.

And it was Charles Messier who, while searching for a tiny fuzzball of a comet, began to discover and record the positions of nebulous things between the stars that apparently nobody before him (well, maybe a few) ever thought to look for!

Galileo, one of the first humans to turn a telescope toward the stars, made his discoveries of Jupiter's moons, Saturn's "ears," and the phases of Venus, back in the early 1600s. He looked at the Pleiades star cluster through his telescope and saw many more stars than our unaided eyes can see. He scanned the Milky Way and determined that it was made of stars that our unaided eyes are unable to resolve. With his discoveries, Galileo turned the world of astronomy upside down! He made the breakthrough of breakthroughs! The whole world was amazed! 

But then what? Despite the world-changing power of the telescope, there were very few astronomical discoveries made for many decades thereafter. 

People who followed in Galileo's footsteps with their telescopes continued to point them at the stars. There was no reason to look "between the stars." In those years, nobody knew of "star clusters, nebulae, and galaxies," other than a handful of objects (such as the Pleiades) that can be seen with our unaided eyes. 

After Galileo, it took nearly 150 years (the return of Halley's Comet) for someone like Charles Messier to scan the sky in between the stars in search of a comet, to discover the deep-sky objects! What were astronomers doing all the years between Galileo and Messier?

After Messier, other astronomers figured there must be more than 110 deep-sky objects in the universe. The great William Herschel picked up the torch and discovered about 2500 deep-sky objects of his own through the eyepiece of his monster 20-foot-long 18.7-inch aperture leviathan. And he did it by letting those 2500 objects come to him! He didn't scan the skies like Charles Messier, who could freely point his little telescope wherever he wanted to look. No, William Herschel's telescope was too large to move around like that. He employed a crew to point the telescope at a star of known R.A. and Dec., while it was near the meridian, and then he would let the sky drift through his telescope's field of view until a star cluster or some fuzzy nebula would appear. Herschel's telescope was arguably the best telescope in the world in those years, so it would take decades before anyone else could confirm his objects.

So, there's a rich history of Galileo and his telescopes, Edmond Halley and his comets, and Charles Messier and his globular clusters, which every backyard astronomer can appreciate! We all follow in the footsteps of Galileo, Halley, Messier, and Herschel. But hunting for supernovae has nothing to do with comets or globular clusters or emission nebulae! It's all about the galaxies!

You can stare at globular cluster Messier 13 with your backyard telescope every night you can for years and it will likely never change. And you can look at Messier M 42, the Great Orion Nebula, with your backyard telescope every night you can for years, and it, too, will likely never change. These two objects, despite their glorious appearance in the eyepiece and in photographs, are just two extremely tiny regions of the Milky Way. The Milky Way is more than 100,000 light years across with over 100 billion stars. A supernova can occur anywhere within the Milky Way, on the order of one or two times per century.

The distant galaxies, however, look very small because they are very far away. When you point your backyard telescope at an NGC galaxy, the entire galaxy fits inside the field of view of your eyepiece (or within the field of view of your camera image). When a supernova explodes, it is so bright, it can outshine its entire host galaxy! And that supernova will continue to shine for months on end. So even though supernovae may appear once or twice every 100 years in any galaxy, you stand a pretty good chance of discovering a supernova if you can look at lots of galaxies on each clear night! One astronomer's estimate that stuck with me early on in my supernova hunting was that if you can look at 400 galaxies per night, you can expect to find a supernova every 90 days. 

Of course, it's all still luck and probabilities! I can't shoot 400 galaxies per night, but I try to shoot 1,000 galaxies per month. The beauty of supernovae is that they last a long time, so if I shoot a galaxy tonight and there's no supernova in it, I can come back to that same galaxy the next night, or maybe a week later, and there's still a chance that a supernova has erupted somewhere in its confines since the previous time I looked at it. I try to look for supernovae in the same galaxies several times each month. But sometimes, it takes a few months to come back around, and when I finally do, I might find a supernova that was already officially discovered by someone else several months ago! 

When I aimed my telescope at NGC 6070 on April 28, I was quite pessimistic about discovering a supernova in it. Up until that night, I had found 28 supernovae in 10 years, but never once did I find a supernova in a galaxy at 16 hours Right Ascension! And you might ask, "Why would it matter if a galaxy is at 16 hours or 12 hours of Right Ascension? Doesn't every galaxy have the same chances of having a supernova in it?"

And this is where we enter the muddy waters of probabilities! It helps to compare supernova hunting to playing the state lottery! 

While it is certainly possible for a person to win the lottery with the very first lottery ticket they've ever purchased, it is more probable that a lottery winner has played the lottery more than once. Not only that, but it's certainly possible for a person to buy a lottery ticket once a week and eventually become a winner. But it is more probable that a lottery winner is someone who buys two or more tickets per week. 

Remember, we're talking about unbelievable odds here! It's extremely unlikely (though possible) that you'll play the lottery once and win. But you could also purchase 100 lottery tickets per week for a year and still not win! We can only say that our chances of winning improve with the more tickets we purchase. 

Likewise, when it comes to discovering supernovae, a person could certainly luck out and discover a supernova on the very first night of looking. But for everybody else, it's a long and uphill battle against the odds! You'll increase your chances of discovery if you shoot more galaxies. However, it turns out that the sky is not as evenly sprinkled with galaxies as you might suppose! At least for the average backyard telescope. 

The brightest and best galaxies are in the Realm of Galaxies between Right Ascensions of 11h to 13h. And if you follow those RAs north to the North Celestial Pole, they cross over to 23h to 01h of Right Ascension that come back around to grace our skies in the fall. Technically, both spring and fall are Galaxy Seasons. Summer and winter, when the night sky is dominated by our home galaxy, are Emission Nebulae and Star Cluster Seasons. 

It follows then that it is more probable that you'll find a supernova in a galaxy that falls in the spring and fall constellations. There are simply more galaxies to look at in those parts of the sky. My own supernova discoveries bear this out. If I separate my 29 discoveries by Right Ascension, it turns out that in galaxies lying in the 21h to 02h range of RA, what might be considered the full range of Fall Galaxy Season, I have made 8 discoveries. For galaxies in the 03h to 08h range of RA, which might be considered the Winter Open Star Cluster Season, I have made 5 discoveries. In the 09h to 14h range, which could be considered the full range of Spring Galaxy Season, I've made 11 discoveries. And for galaxies in the 15h to 20h range of RA, which could be called the Summer Globular Star Cluster and Emission Nebulae Season, I have made 5 discoveries. 

Putting the Spring and Fall Galaxy Seasons together, I've made 19 discoveries. And putting the Summer and Winter Star Cluster and Nebulae Seasons together, I've made 10 discoveries. Nearly 2:1. 

One way to compare my supernova hunting in these two seasons (Galaxy Season vs Star Cluster and Nebulae Season) is that I have a lot more galaxies in my spring and fall target galaxy lists. But another way to compare them is the hours of darkness I have each night. During winter, I have longer nights which allows me to shoot more targets. During summer, I have the shortest nights. But summer is also the rainy season where I live. So, in summer (15h to 20h RA range) I have the fewest number of galaxies to choose from, and I shoot the fewest number of galaxies each night due to weather and short nights.

You might say it was against all odds, then, that in the wee hours of April 28, I aimed my telescope at NGC 6070, the very first galaxy from my 16h target list, and discovered a supernova! A six-month drought of no supernova discoveries ended when I started working on my least likely, early-summer targets list! How bizarre! But it probably won't surprise you to learn that the supernova had already been discovered two months prior!