Supernova in the Deer Lick Galaxy

A couple of nights ago, I found a supernova in galaxy NGC 7331, also known as the "Deer Lick Galaxy." It was the final image I took on the night of August 8, 2025. But I didn't notice the supernova. I didn't see any new stars in the vicinity of the galaxy, and I proceeded to shut down my telescope and camera for the night. But as I downloaded the night's worth of images from my imaging laptop (that's attached to my telescope tripod with double-stick tape), I decided to adjust the contrast and brightness of my image of NGC 7331 and see if a supernova might be lurking in the bright nucleus of the galaxy. To my great surprise, there was, indeed, a supernova in hiding!

In the old days, when we astrophotographers used emulsion films to take pictures of celestial objects, we routinely overexposed the cores of galaxies in order to reveal their fainter spiral arms. We considered the washout of the galactic core to be an acceptable loss in order to gain views of fainter details. And it wasn't just for the case of galaxies. We overexposed the cores of other objects, like emission nebulae and globular clusters, so that we could pick up the faintest details in the outlying regions. 

Digital imaging has delivered a vast increase in dynamic range, and digital-imaging software has made it much easier to access that dynamic range than we could in the darkroom. Dodging and burning was a powerful technique for the photographic printing process, but it was permanent. If you wanted to attempt a better result, you'd have to risk wasting another piece of photosensitive paper, which wasn't cheap. But with digital imaging, there is no film and there is no print. You simply keep adjusting your histogram until you're happy with your results, then save it as a JPEG or other image format that you can share using your favorite social media. 

I don't take "pretty pictures", and I don't make prints, but I do appreciate being able to lower the contrast to see if a supernova might be burned out by the default display scale in my imaging software. It's easy to do, but for whatever reason, I don't always do it.

Take the last time I imaged the Deer Lick Galaxy, for instance. That was on July 27th. Had I adjusted the contrast and brightness to look near the center of the galaxy, I would have made my supernova discovery on that night! But I didn't bother. I simply compared my image of the galaxy with my reference image, saw nothing new, and moved on. 

The image at the top of this page illustrates the problem of "burned-out cores" while searching for supernova in the distant galaxies. The image below, however, demonstrates a better practice for supernova hunting, by comparing a current galaxy image with an older one, using low contrast. (Note: The image here is mirror reversed by the HyperStar. I forgot to fix it before creating the animated GIF.)

Of course, had I discovered the supernova on July 27th, it wouldn't have mattered, because I was still nearly two weeks too late to be the official discoverer. An imaging group known as "GOTO" had been the first to spot the supernova back on July 14th.

No matter. I have long since given up all hope of being "first discoverer" of anything in the cosmos. The competition is just too darned good. I can't shoot as many galaxies per night, and I can't shoot galaxies as faint as the pros can shoot. For me, it's just plain fun to discover supernovae on my own, and if I learn afterwards that somebody already spotted them, well, good for them! It changes nothing about my own experience of finding a supernova.

This particular supernova (SN2025rbs) was my 27th unofficial supernova discovery since 2016. Lately, I've been finding about 5 supernovae per year, having made roughly 10,000 galaxy comparisons during that time. But the pros can make about 12 discoveries per night! And that's because they're taking images of the entire night sky in two days, whereas I can shoot only about 33 galaxies per night, on average. So far in 2025, we've had more clear nights than we had in the past few years, so I've shot more galaxies on more nights, helping me to reach my 5th supernova discovery much earlier in the year than usual.

My telescope/camera system is not automated. I don't run a script each night that commands my telescope and camera to take images of a list of galaxies for me. No. I have to sit there at my PC for the duration of each session, commanding my telescope to point at each target galaxy and then commanding my camera to take a picture of it. 

There are some amateur supernova hunters out there who have automated their searches. They have roll-off roof observatories with cloud detectors. After sundown, if the sky is deemed to be clear by the observatory's sensors, the roof opens, their equipment wakes up, and the telescope and camera will begin to take images of all the available galaxies on their list. The operation will continue all night or else it will shut down if clouds roll in, all without human intervention. Very efficient. And some of these automated observatories even have special software to inspect their night's worth of galaxy images to see if there are any potential supernovae. In the morning, the proprietor gets an email from their observatory's computer, with a list of potential discoveries. Imagine that! These so-called supernova hunters can make discoveries while they're sleeping, or while they're away from home!

I prefer running my supernova searches the old-fashioned way, where I'm at the controls, driving the show. Admittedly, this is very inefficient! I sometimes fall asleep at the helm and lose hours of image-acquisition time. But that's the way it goes! I do the best I can. And after all, it's my supernova search, not a robot's! 

By the way, you may be wondering about that name, the Deer Lick Galaxy, so I'll provide an explanation here. 

In actual fact, NGC 7331 is not called "The Deer Lick Galaxy"! But if you look closely at the left-side image at the top of this page, you'll notice 4 little smudges of light above NGC 7331 that are tiny (i.e., more distant) galaxies that happen to lie along our line of sight to NGC 7331. Those four galaxies were given the name "The Deer Lick Group" of galaxies. 

There has been a little bit of confusion over this name, because it makes people think of a "salt lick." Salt licks are blocks of salt (and other minerals) that are placed in the wilderness for wildlife such as deer and elk. Salt licks provide essential minerals to wildlife that may not get those minerals in their normal diet. 

It is common to find a group of deer around a salt lick. So, it is tempting to think that the name "Deer Lick Galaxy" means that NGC 7331 is the salt lick, and that the small nearby galaxies are the deer that have been attracted to it. But that is not the case!

It turns out that the tiny group of galaxies that were given the name "The Deer Lick Group" were so named because an amateur astronomer named Tom Lorenzin stopped at a place called "Deer Lick Gap Overlook," just off the Blue Ridge Parkway in North Carolina, to set up his telescope and observe some deep-sky objects. Because the sky over the Deer Lick Gap Overlook was so dark, Lorenzin was able to detect the faint group of little galaxies next to NGC 7331 through the eyepiece of his telescope, which he had never done before. He is the one who first called them "The Deer Lick Group," with a nod to his location, and the name stuck. 

But what about NGC 7331? It has no other common name. So, it's like the elephant in the room! If you're going to try and spot the Deer Lick Group, it only makes sense that you would aim your telescope at NGC 7331 and then search nearby for the Deer Lick Group. Right?!!! In this sense, NGC 7331 is "the salt lick." You know the location of the salt lick, and you use that knowledge to search nearby for the "deer." (Hopefully, all hunters agree that baiting deer with salt licks for hunting them is bad sportsmanship! In some states, it is considered illegal.)

I don't know how other amateur astronomers feel about the name, but I think that since NGC 7331 is the most obvious object in the field of "The Deer Lick Group," it stands to reason that it should be included in "the group." Thus, I personally call NGC 7331 the "Deer Lick Galaxy," because it is the one galaxy that you're most likely to be able to see, should you attempt to go looking for the rest of the group.

Deer hunting is an autumn activity in Pennsylvania (where I grew up), so I like the idea of calling NGC 7331 the Deer Lick Galaxy, since its appearance in the morning sky herald's the coming of autumn. There is also the comparison of deer hunting and supernova hunting to consider. Deer hunters and supernova hunters both use scopes to shoot their targets. And both types of hunters use the same search techniques. That is, seasoned deer hunters don't walk randomly through the forest looking for deer. They consider the habitats of deer and look for deer along deer trails, watering holes, and places where deer go for food. In the same way, supernovae are captive stars that live inside of galaxies. Thus, supernova hunters don't search for supernovae by pointing their scopes at random star fields in the sky. They look for supernovae where stars congregate, inside galaxies. 

Although the galaxies in the real Deer Lick Group (NGC 7335, 7336, 7337, and 7340) are very small and far away, they are on my list of target galaxies for supernova hunting. Each time I shoot NGC 7331, I take a quick scan for supernovae in the individual members of the Deer Lick Group, too. 

Another group of tiny galaxies not far away (in terms of degrees of sky) from NGC 7331 is the famous Stephan's Quintet. This group is also on my list, even though its galaxies are, like the Deer Lick Group, too far away and probably too small for the resolution of my scope to record a supernova. They were selected just so that I will keep looking at them and find out firsthand if a supernova in any of them could ever show up in my searches.

Below is an image I took in 2018 of NGC 7331, the Deer Lick Group, and Stephan's Quintet (lower right corner), all within the same field of view. It's a stack of 52 x 22-second images, a total exposure time of 19 minutes. Unlike the above images of NGC 7331, the one here is oriented correctly, with east to the left and north up, as it appears in the sky (and on star charts).

If you look closely at this image, you'll note the presence of many other small galaxies in the field. That's because we're looking at a continuation of "The Realm of the Galaxies." In the springtime, you'll see and hear a lot of backyard astronomers talking about "Galaxy Season." What they're referring to is the fact that in the months of March and April, the section of sky between 11 and 13 hours of Right Ascension is crossing the meridian around midnight. There are an unusual number of big and bright galaxies in that region of sky, which has been affectionately dubbed, "The Realm of the Galaxies," and they're observable practically all night long in the springtime of the year. 

What you usually don't hear backyard astronomers talking about, however, is that six months later, we get to look at an extension of The Realm of the Galaxies, going through the 23 to 01 hours of Right Ascension. Those skywatchers who don't pay attention to Right Ascension may not realize that if your sidereal clock reads 12:00, the Realm of the Galaxies is crossing your meridian (the north-south line passing through the zenith, or overhead point). They also probably don't pay attention to the fact that the 12h line of Right Ascension ends at the North Celestial Pole (+90°). Continuing on that line, from the North Celestial Pole down to your northern horizon, the Right Ascension becomes 0h. 

In other words, if you're out at midnight in March, enjoying the Realm of Galaxies at 12h of Right Ascension that stretches up from Corvus through Virgo, Coma Berenices, Canes Venatici and Ursa Major, your northern horizon blocks you from seeing the other part of the Realm of the Galaxies on the 0h line of Right Ascension that extends from Cepheus downward into Andromeda, Pegasus, Pisces, Cetus, Sculptor, and Fornax. But in the wee hours of August, we can begin to pick up where we left off last April.

Just like springtime gives us views of big spiral galaxies like M 51 (the Whirlpool Galaxy), M 101 (the Pinwheel Galaxy), and NGC 4565 (the Needle Galaxy) at 12h Right Ascension, autumn ushers in the other half of the Realm of the Galaxies along the 0h line, with M 31 (the Andromeda Galaxy), M 33 (the Triangulum Galaxy), and NGC 253 (the Sculptor Galaxy). 

While it may seem strange to the casual observer that there are large and bright galaxies to be seen in both spring and fall skies, when you take the time to learn about the grid of equatorial coordinates, you'll understand that the Realm of Galaxies is merely one long deer trail through the stars.