Comets!

Comets are wonderful to observe. I've seen many of them over the years. The first time I ever photographed a comet was on film (Yes, I'm old). I captured comet Halley back in 1986 and comets Hyakutake and Hale-Bopp a decade later.

Probably the next comet I photographed was C/2011 L4 PanSTARRS came around in 2013. Then there was C/2020 F3 NEOWISE which was pretty good. I wasn't blogging in 2020, but I did get some decent shots of it, including this:

Self Portrait with Comet

 

Most comets aren't bright enough to see visually or capture with a DSLR camera, but there usually are several that are within easy reach of a small telescope. 

The very first comet observation I made with a Unistellar eVscope was the night of my first light: November 14, 2020 when I caught Comet C/2020 M3 ATLAS.

My settings for the telescope weren't as good as they could have been, but I was happy to catch something that I wouldn't have caught otherwise. The comet's motion in the sky made it look like a blurred streak, but you can see its tail.

The following spring a different Comet ATLAS, C/2020 R4, came pretty close to Earth. I photographed it April 28th when it was just half an astronomical unit (~47 million miles) from Earth.

In this sequence, which covers just 20 minutes of time you can see that the comet has a faint tail.

2021 also had a much more spectacular comet: Comet C/2021 A1 Leonard which was visible in our morning skies in late November and early December. It was a wonderful comet to photograph. 

Here's an animated gif of Comet Leonard that I took with my eVscope2 on the morning of December 3, 2021:

23 minutes of Comet Leonard's motion against the background stars.

 

On the morning of December 6, 2021 the comet was just 0.4 astronomical units (37 million miles) from Earth:

I again took a number of images, but this time I tried stacking them so that they were all aligned on the comet itself to hopefully bring out more detail on the comet's tail and blue-green coma (atmosphere). Here's the result:

The stars in these sorts of images always look a little strange, but I hope you'll agree that comet's tail and coma are more prominent here.

Afterwards Comet Leonard got even better, but that was a sight for observers in the Southern Hemisphere.

So when is our next bright comet coming? No one really knows. According to Visible Comets in the Future our next comet that might reach naked eye brightness is Comet C/2022 E3 ZTF which is expected to be bright enough to see in January and February of next year, though the brightnesses comets are notoriously difficult to predict. 

The brightest comet that is currently visible is C/2017 K2 PanSTARRS. Here's an image of it that I took earlier this month:

Comet PanSTARRS should be a little brighter in July when it is closer to Earth and I will be sure to take a look.

Things That Go Bang in the Night

White dwarfs are hot glowing remnants of stars that were at least somewhat like the Sun. Over billions of years of time isolated white dwarfs gradually cool down (possibly crystalizing into Earth-sized diamonds!) and fade away. But white dwarfs that are located in binary star systems can have a much more spectacular time than just gradually dimming from view. 

Artist's illustration of a white dwarf (right) pulling gas from its companion star. Credit: NASA/CXC/M.Weiss

 

In some of these binary systems hydrogen gas is pulled off of the white dwarf's companion star which piles up on the surface of the white dwarf. Eventually there's enough gas there that it detonates producing a nuclear explosion on the surface of the white dwarf. This is what astronomers call a nova. 

The nova explosion does not destroy either star and can eventually repeat. There are 10 of these recurring novae that have been observed to repeat in our Milky Way galaxy. 

One of these recurring novae is known as U Scorpii (U Sco for short). Normally U Sco is too faint to observe with my Unistellar eVscope, but it is an easy target when a nova outburst occurs. On June 6th I got word that U Sco had an eruption underway so I decided to take a look. 

U Scorpii (bright star at center)

One characteristic of this nova is that it fades in brightness very rapidly. To record its fade I have been looking at it periodically since June 6th. Sure enough, it will soon be back to its normal too-faint-for-me-to-see status. The image below shows U Sco dropping in brightness by a factor of 100 in just 10 days. 

The nova is still dropping in brightness and will soon fade from my view entirely. 

A second type of explosion involving white dwarfs is known as a Type Ia supernova. This is a much bigger deal. Again we are talking about white dwarfs in binary star systems, only instead of an explosion on the surface of the star, the entire thing blows apart, most likely from the merger of two white dwarfs (although, maybe not - astronomers are working on that). 

These explosions are big enough for my little telescope to be able to see them from distances of tens of  millions of light years (whereas U Sco is just ~60,000 light years away). 

Last year I was able to observe one of these explosions, supernova 2021hiz, in an obscure galaxy known as IC 3322A. I followed up my observation a year later to produce this comparison showing the galaxy with and without the supernova:

The galaxy is just a faint smudge of a line (it's a spiral galaxy seen from the side) and the supernova is the bright dot on the upper edge that blinks on and off. Notice that the light of the supernova is actually brighter than the rest of the entire galaxy. 

Think about that. One supernova explosion can outshine all the light produced by hundreds of millions of stars. That's amazing.

Another bright Type Ia supernova (sn 2022hrs) took place this spring in a galaxy known as NGC 4647. NGC 4647 is conveniently in the sky next to one of the galaxies in the Messier Catalog, M60. Last year I photographed all of the objects in the Messier Catalog, which means that I had a before image to go with the new image of the supernova. 

Here's the before and during comparison:

This supernova exploded some 63 million years ago and light from it arrived on Earth in mid April 2022. I am happy to have had the opportunity to catch it. 

By the way, the last supernova observed in our Milky Way galaxy was also a Type Ia supernova. It was recorded by Johannes Kepler back in the year 1604. 

Observing Spacecraft

Even though it has been a while since I've updated this blog I've still been doing a lot of backyard astronomy. I've been looking at all the usual stuff (comets, galaxies, asteroids, etc.), but I've also seen a lot of spacecraft. Most of them have been annoying to look at, like this trail from a geostationary satellite crossing into my image of part of the famous Orion Nebula:

Satellites are an ever increasing problem for astronomy as tens of thousands of them are being launched into low-Earth orbit. This is an annoyance for amateur astronomers, but can present serious problems for astronomical observatories both on Earth and in Earth orbit. 

Occasionally it is desirable and even useful to have a look at a satellite or spacecraft. For instance last  November the European Space Agency's (ESA) Solar Orbiter made a close flyby of Earth.

The flyby, which brought the spacecraft less than 300 miles from Earth, was perfectly placed for telescopic observers in North America. Unistellar asked people within their network to observe the event in science mode for ESA and provided an ephemeris which made it easy to know exactly where to point a telescope to observe it. And it was pretty amazing to see.

I observed simultaneously with 2 eVscopes. One was collecting data in science mode, while the other took the image above. The line in the image above is a trailed image of the spacecraft which was visibly moving across the image as the exposure was being taken. The animated gif below shows a speeded up version of the motion of the spacecraft across the field of view (which is rotated from the image above).

The event was a success, I have heard that ESA was happy with the observation campaign and I am glad that I was able to contribute.

About a month later on Christmas day the James Webb Space Telescope finally launched into space and as it moved out to its permanent location in space it was visible to small telescopes here on the ground. 

Here is a sequence of images I took of JWST on January 1st, 2022.

It is visible in the image above as a streak moving from the center towards the upper right. JWST is poised to make significant contributions to astronomy and I was happy to be able to see it. I was one of several observers who contributed science observations of it and we were able to spot changes in brightness as the sunshield unfolded along with other results that will soon be published.

Finally, one other target of note: the International Space Station. The ISS is the largest and brightest of Earth's artificial satellites and it currently has seven people living there. Many amateur astronomers have taken spectacular images of the ISS that show tremendous detail and I was curious to know if I could even spot it at all using a telescope. Thankfully, Unistellar's Ephemeris Generator allows observers to point their telescope at the ISS. The Unistellar telescopes can't track the space station, but instead the telescope it pointed at where it will be at a particular time. 

My first attempt at spotting the station was successful, but the image was pretty terrible:

I was happy that I saw it all, but decided that I could do better and I June 1st I gave it another try. Here's what I saw:

If you blow up one of the frames it looks like this:

Much better. I suspect that I can still improve but the solar arrays, especially on the right, are clearly visible and it is vastly better than my first attempt from May. 

Clear skies!

Asteroid Encounters

This year I have observed more asteroids than ever before with 29 detected so far. Some them have been as a part of the Unistellar Citizen Science campaigns, but most of them have just been for fun. For instance, earlier this week I looked at the asteroid 626 Notburga which was in the constellation of Cassiopeia.

The image above is an animated gif of two images taken 75 minutes apart showing Notburga's motion though the sky. The individual exposures were short so it wasn't easy spot the nebula that was nearby it in the sky. So in between these two images I took a longer one to try to bring out a part of the Heart Nebula.
 

Here the asteroid appears as a line and there's some hint of the red hydrogen gas of the Heart Nebula across much of the upper right portion of the image. 

Since asteroids look like moving dots or streaks it is sometimes more interesting to catch them when they are near some other astronomical object in the sky. A great resource to find out when as asteroid will be near a bright star, a deep sky object or even another asteroid are the observing guides at MinorPlanet.info. I've used that to find all of the close encounters on this page.

Here are asteroids 712 Boliviana (top right) and 89 Julia (below center) from back in October:

Just this week asteroids 1 Ceres and 1140 Crimea have been passing the bright star Aldebaran.

Aldebaran is the bright star at center. Asteroid (and dwarf planet) 1 Ceres is the bright moving object to its lower right. Much fainter is 1140 Crimea. It is the faint moving dot in the upper left. At the time of the images Crimea was actually 25 million miles closer to Earth than Ceres. That doesn't help it much in brightness though because it is much smaller. 1146 Crimea is just 17 miles across while Ceres is 587 miles across!

In early October asteroid 27 Euterpe passed directly in front of one of my favorite globular star clusters: Messier 22. I caught the event on two nights as the asteroid was near the cluster, but it was cloudy the night it passed in front of it.

Euterpe is to the right of the cluster. At the time it was 21 light minutes from Earth, while the star cluster is some 10.600 light years away.

An even bigger disparity in distance was back in March when asteroid 70 Panopaea passed directly in front of spiral galaxy NGC 3344. 

That night asteroid 70 Panopaea was 17 light minutes from Earth while the spiral galaxy is more than 22 million light years from our Milky Way Galaxy.

In the coming weeks and month I will be looking for more interesting asteroid encounters and posting some of them here.
 

The Messier Catalog

I don't know about you, but I finally kept a New Year's resolution. What was it? To use my Unistellar eVscope to observe and photograph all 110 objects of the Messier Catalog. Yes, I know some people do Messier marathons and catch them all in just one evening, but it takes time if you want to take a photograph each and every one of them. Besides, I do like to sleep. 

I caught my first Messier object this year, the famous Orion Nebula (M42), on January 3rd. The last one that I observed was on October 9th: the galaxy known as M77.

I will certainly be revisiting each and everyone of these objects in the future (especially since I'll will soon have the eVscope2), but for your visual enjoyment here are a few mosaics of the objects of the Messier Catalog.

Messier 1 through 20: 

Messier 21 - 40:

Messier 41 - 60:

Messier 61- 80:

Messier 81 - 100:

 and finally Messier 101 - 110:

I've previously blogged about the globular star clusters and the nebulae of the Messier Catalog and I've still got a few things left to say about the whole thing, but I'll save those thoughts for another time.

Andromeda and Her Attendants

Our galaxy the Milky Way is one of several dozen galaxies that make up the Local Group of galaxies, which itself is on the outskirts of the much larger Virgo Cluster of galaxies. The largest and most dominant member of the Local Group is the famous Andromeda Galaxy (M31). M31 is thought to be bigger than our Milky Way in just about every way. It is physically larger, more massive and has more stars than the Milky Way.

If you have dark skies and know where to look on these fall evenings you can see M31 with your own eyes as a fuzzy smudge. It is worth making the effort to see it, especially knowing that this galaxy is far enough away that its light travels for 2.5 million years to reach us, making it the farthest thing that humans can usually see without a telescope (Some have claimed to see galaxy M33, which is farther, but spotting that is much more rare and difficult).

A telescope will reveal M31 as a much larger and brighter fuzzy smudge that more than fills up the field of view. It is only through photography that details such as its dark dust lanes become visible. 

The image above is a partial mosaic (that I really need to finish) of the Andromeda Galaxy that I made with my Unistellar eVscope. It reveals two of Andromeda's many companion galaxies. The round, fuzzy object to the upper left of the central portion of M31 is the dwarf elliptical galaxy known as M32 and in the lower right is M110, another dwarf elliptical galaxy that orbits M31. 

To give you a sense of depth, M32 is about 110,000 light years farther from us than M31 is, while M110 is around 400,000 light years past M31.

But M31 has more companions that can be photographed with the eVscope. One of them is NGC 147, the faint smudge at the center of the image below:

 It's not immediately obvious the NGC 147 is a companion to M31, especially since it lies some seven and a half degrees from it in our sky, but they are together in space separated by some 300,000 light years.

NGC 147's nearest neighbor in the sky is NGC 185, another satellite galaxy of M31 (below, center).

These two galaxies are both found in the constellation of Cassiopeia nearly one degree apart from each other. Of the two, NGC 185 is closer to us by some 500,000 light years, which helps to explain why it is the brightest of the two. 

Wikipedia lists more than two dozen other galaxies that are companions of M31 and I believe that all of them are out of reach from my 4.5" telescope, except possibly for one of them. Aside from M31 and the Milky Way Galaxy there is one other spiral galaxy in the Local Group, M33 in the constellation of Triangulum. It's the smallest of the three and might be in orbit around M31, we aren't certain.

At a distance of 2.73 million light years M33 is farther away than M31 and it has a much lower surface brightness too, but it has some interesting structure to it, with both star clusters and nebulae visible within it making it possibly a fine attendant of the princess Andromeda.

Finding Himalia

 You probably already know this but Jupiter has a lot of moons. At last count there are 80 of them.

The orbits of Jupiter's moons shown in SkySafari Pro

Four of the 80 are big, famous and easily seen in just about any telescope. Galileo saw them back in 1610 and they are often referred to as the Galilean Moons. 

From left to right: Europa, Jupiter, Callisto, Io and Ganymede.

Those four moons of Jupiter are often viewed by amateur astronomers, but what about the others? Can they be seen? As it turns out, yes they can. They are small, faint and difficult targets because they are also located somewhat close to the glare of Jupiter.

The largest of Jupiter's moons that isn't one of the famous four Galilean ones is Himalia. Himalia has never been seen from close range by spacecraft, but it is thought to be possibly over 100 miles across.

Himalia's orbit is located far outside the orbits of the Galilean Moons

Himalia is so far from Jupiter that it takes about 250 days for it to complete an orbit. Compare that to Earth's Moon which takes 27 1/3 days or Jupiter's Moon Io which circles Jupiter in just 42 hours. 

While Himalia is far from Jupiter it is still a difficult target to see. The best time to catch Himalia is when Jupiter is closest to Earth. This means that Himalia will be somewhat brighter and there will be a larger apparent gap between it and Jupiter.

I took a look for Himalia about a week after Jupiter's most recent closest approach and found two things. 1) SkySafari, which is an otherwise excellent app, doesn't accurately plot Himalia's position. That's okay, there are other ways to get accurate coordinates for a planetary moon. 2) The glare from Jupiter is excessive. Take a look:

That's an image from August 27th taken with my Unistellar eVscope. Himalia is easily bright enough to be seen with the telescope, but the glow of Jupiter complicates things. When I took a close look at the image I found one star-like object that wasn't where a star should be. To make sure I had the right thing I needed to look again to see if it moved. Himalia's distant orbit around Jupiter means that it is moving pretty slowly through space, but Jupiter itself is moving around the Sun, as is Earth, and means that looking again the next night would place the moon in a different location against the background of the sky. 

Here's my image on August 28th:

The glare from Jupiter is different, but I do have overlapping stars. To see if I caught Himalia I just needed to align and blink the images. Here is the result:

Can you spot it? Yeah, it's difficult. Look on the leftmost third of the image, or, better yet just look below where I cropped and zoomed the images and circled Himalia:

I checked its relative location and relative brightness and I'm confident that I actually bagged it, but I confess that it was trickier than I thought it would be. 

I'll give this a shot next year when Jupiter again is in the proper position to find Himalia.