Chasing Comet Lemmon

Last October, excitement was building in the astronomy community about Comet Lemmon (C/2025 A3), which was predicted to reach around 3rd magnitude – bright enough to be seen with the naked eye from a dark site. As the comet’s closest approach to Earth drew near, I began planning a photography mission to capture this icy visitor. With the closest approach set for October 21, I kept a close eye on the weather for Monday the 20th. The forecast was uncertain, with a storm system expected to clear just in time for the evening. I decided to focus on photography, using my trusty 7x50 Celestron binoculars for visual observation. After dusting off the Star Adventurer Tracker – dormant since my trip to the 2023 Annular Eclipse in New Mexico – I began scouting locations within a few hours’ drive.

A light pollution map led me to the Zumbrun Overlook in Green Ridge State Forest, between Hagerstown and Cumberland. Online photos showed a promising platform with a clear western horizon. I opted for an overnight trip, staying in Cumberland to avoid a late-night drive home. I reached out to my astro-photography friend Steve, but he was busy with another shoot. Fortunately, Deb was interested in joining, and we looked forward to enjoying the fall foliage on our drive. After morning appointments, we headed west on I-70, stopping for lunch in Hagerstown before arriving at our hotel in Cumberland.

Zumbrun Overlook

After checking in, I drove out to the Zumbrun Overlook near Flintstone to get familiar with the site. The spot looked ideal, though a tree at the front of the platform meant I’d need to choose my position carefully depending on the comet’s location. My goal was to set up by 6:15 p.m., but dinner at Puccini’s ran late, and I arrived at the overlook around 6:30 p.m. At the overlook, two amateur astronomers from NOVAC had already claimed the front row, so I set up behind them. The sky was very clear, with moderate winds and a limiting magnitude of about 5.5. As twilight deepened, Comet Lemmon became visible in Boötes, just above and to the right of Arcturus. The clouds cleared just in time, and although I had to shoot over the NOVAC observers, the Star Adventurer tracker performed well. Deb joined me at the overlook to enjoy the overhead Milky Way, which was on full display.

Around 7:45 p.m. I spent some time observing Comet Lemmon through 7x50 binoculars. The comet showed a bright coma with a tail extending roughly 1.5° northeast. No greenish color was detected; the coma appeared white. I estimated its brightness at about 4th magnitude – just visible with averted vision. The scene was enhanced by the presence of orange r Boo and blue s Boo in the field. One of the NOVAC astronomers also graciously shared a view of the comet through her 8” SCT (but it seemed to lack a sharp focus).

Comet Lemmon Amid Boötes

Arriving back home the next day I was disappointed to discover my images were slightly out of focus. I salvaged them somewhat using BlurXTerminator in PixInsight on each individual shot before stacking them in Sequator. Despite some streaky clouds photobombing Lemmon, the final image captured was reasonable and serves as a wonderful memento from that night. While not spectacular, Comet Lemmon 2025/A3 was a wonderful visitor from the deep freeze of our outer solar system.

Jupiter's June

With the exception of Mercury at only 0.03°, all the planets have some tilt to their axis. As any fifth grader should be able to explain to you, Earth has an inclination of 23½° and that is what gives us our seasons as we orbit the Sun. As amateur astronomers we can sometimes notice the tilt when observing some of our planetary neighbors. Mars' axial tilt is about a degree larger than Earth's and can present one hemisphere more favorably than another. For example, our best views of Mars are when it comes to opposition right around the time of its perihelion. As it turns out Mars is always close to its Winter Solstice at that point in its orbit, so we see  southern hemisphere features like Hellas and Syrtis Major better because they are tilted towards us while northern albedo markings such as Mare Acidalium are tough to discern (map). 

Hubble captures Titan's Transit - Feb 24, 2009

Saturn, with an inclination of 26¾° is the easiest example of noticing the affect of axial tilt. At its spring and fall equinoxes the rings all but disappear as we view the planet's equator straight on. At its solstices we are treated to the full grandeur of the ring system during maximal display. Another aspect is that only when Saturn approaches its equinoxes will the orbital planes of its moons begin to intersect the globe of the planet from our vantage point. It is only at those points in its ~29-year orbit that we get to see Titan transit and cast its large shadow upon the clouds below. While not as rare as a Venus transit, seeing our Solar System's largest moon cut in front of its home planet is an infrequent event (and one that is on my bucket list for the upcoming equinox!)

And where does Jupiter lie on the axial tilt spectrum? It comes in at a mere 3°, barely tipping towards or away from our view. We never get a nice look at its polar regions as with Saturn, it is consistently featuring its full-on view. Despite Jove's stingy axial tilt, the observant amateur astronomer can still discern evidence of the inclination, even with a modest telescope, by studying the Galilean moons. 

Yesterday (January 20, 2024) on Jupiter the Druids assembled at their Stonehenge to celebrate their Northern Summer Solstice, the maximal tilt of the planet's north pole towards the Sun. About a week earlier I was out imaging Jupiter (under very poor seeing) with a serendipitous alignment three out of the four Galilean moons. Io was about to slip behind the planet, while Europa had just start its trek across the planet's face. Ganymede stood nearby just off the limb awaiting its turn to begin transiting the planet.

Jupiter on Jan 13, 2024 7:39 p.m. EST

Like most planetary moons, the Galilean quartet have their orbital planes roughly aligned to Jupiter's equatorial plane (i.e., if we could see those planes it'd be similar to seeing Saturn's rings). But in my capture we note that despite having orbits lying in that equatorial plane, none of them appear near the planet's equator as they approach Jupiter. We see that the two that are about to cut in front of the globe will do so across Southern hemisphere cloud tops, while the one that is about to duck behind the planet appears at a northern Jovian latitude. This let's us know that Jupiter's northern hemisphere, and by extension the orbital planes of these moons, is currently tilted towards us.

There's another piece of information to be gleaned from the image taken on the 13th. If we use WinJUPOS to apply a grid overlay on Jupiter, we can more easily see that the distance the moons lie from the equator varies. Io is closest to the equator at roughly 20°, Europa is about double at ~38°, while Ganymede is doing a more polar crossing at about 55°. If we consider the schematic below that approximates how a set of orbits lying in the planet's equatorial plane might appear with a north-leaning planet tilt, we can see the significance of this. Io must be orbiting closest to the planet since it is nearest the equator. Europa must lie (very roughly) twice as distant. and Ganymede is orbiting at a distance perhaps some 2½ times that of Io. When we check our hypothesis we see that our analysis was an acceptable swag: 

• Io: 422 km
• Europa: 671 km
• Ganymede: 1,070 km

But what about Callisto, the farthest out of the 4 Galilean moons at 1,883 km? If Callisto had been in the frame we would have seen it floating above or below Jupiter given the combination of the moon's more distant orbit and the planet's current maximum northerly tilt (much like the green orbit in our schematic above). 

Of course now that Jupiter has passed the Northern Summer Solstice in its orbit it will be moving towards an Autumnal Equinox roughly 3 years from now. As we head there you'll see the moons gradually fall back towards transiting the planet along its equator, and Callisto will once again join her siblings in crossing the Jovian cloud tops from as seen from our home planet. 

So often we set up the telescope and take a just a quick peek at our target, not tarrying to inspect the view in the eyepiece nor record what was seen. So here's a challenge for you to do something more. Observe Jupiter when a Galilean moon event is set to occur (S&T has a great online tool to predict when these occur, with three opportunities this coming week on the 22nd, 24th, and 29th). In a notebook sketch what you see (and you do not need a large scope to see these events). Continue to do this over the next three years and you'll have a cool record that shows the shifting tilt of the planet as evidenced by the changing appearance of the 4 brightest moons when near or in front of the planet. While you won't get an award for your effort, I bet you'll feel a reward for being able to demonstrate some of the mechanics of our Solar System through a patient recording of what you've seen first-hand.

An Autumn Grab Bag

Overall the past 4+ months have not been kind to amateur astronomers in my area. There seemed to be an above average number of cloudy evenings, and those that were clear often had a haze triggered by smoke drifting down from Canadian wildfires. So to say that the return of some cooler, crisp fall evenings was most welcome is probably an understatement. 

Jupiter and Saturn took some of my attention, but I also made time to check in on some targets among the Astronomical League's Urban List in my ongoing assessment of how easily they can be spotted from suburban skies that suffer from significant light pollution.

August 19, 2023 
Sky: Mostly clear, temps ~65° F, light winds
Transparency: 7/10    
Seeing: 5/10
Limiting Magnitude: 3.2

NGC 6818 
Planetary Nebula in Sagittarius
10” f/6 Newt   15mm Plossl  CGX-L Mount  

It took a 4-star alignment process to get the mount's GoTo working accurately enough to ensure that it was landing on targets with good accuracy, but that was a prerequisite given the light pollution in the southeast where my chosen target lies. But it was worth it, as once I peered into the 25mm eyepiece it was apparent as a small, uniformly round orb with perhaps a slight blue tint to it amid a handful of field stars. Popping in the 15mm enhanced the view of the planetary. There was no structure such as an annulus that I could discern, and it sported an even distribution of light. While a little faint, it bore direct vision well, even without a UHC filter. Alternating between direct and indirect vision yielded no evidence of the central star.

NGC 6934
Globular Cluster in Delphinus
10” f/6 Newt   15mm Plossl  CGX-L Mount  

I know that I have seen this DSO before with my 6” RV-6, but that observation is lost among the many that have gone by the wayside. I wish I had been better about archiving them for later access.

When inspecting the field with the 42mm once the scope completed its slew there was no sign of the globular. I did not tarry long before switching to the 25mm eyepiece with the Baader Moon & Skyglow filter, which revealed it immediately. I followed up with the 15mm which gave a good view of this globular. The field has stars that form roughly an “arrow” asterism pointing to the east. And the globular lies along the shaft of the arrow on the side closest to its apex. It is perhaps 4-5’ in size and can take direct vision but is improved with averted. No resolution of the member stars was noted. The globular is circular and has surprisingly even illumination – no sign of a brighter core discerned in the observation this evening.

September 3, 2023 
Sky: Thin haze, temps ~85° F, calm
Transparency: 7/10    
Seeing: 7/10
Limiting Magnitude: 3.2

IC 4756
Open Cluster in Ophiuchus
6” f/8 Newt  TV 25mm Plossl  HEM27 Mount

Once I verified the HEM27 was working well I decided to target this open cluster. I slewed to Rasalhague and then did a center operation to ensure the hop over to the cluster would be on target. And indeed, as soon as I peered in the eyepiece with the 42mm I could see a loose, large cluster of stars.

Bumping the magnification up to the 25mm came close to filling the field, implying the cluster size at about ¾ degree. There is one bright anchor star, perhaps 7^th or 6^th magnitude, in the south of the cluster – no color noted in it or any of the other members of this cluster. The other members range in brightness from about 8^th magnitude down to limit of visibility. All told about 40 stars are seen, but there is no nebulosity hinting at any mass of unresolved members. Very nice cluster and would be worth checking again under darker skies.

NGC 6709
Open Cluster in Aquila
6” f/8 Newt  8mm TMB  HEM27 Mount

Once the scope finished its slew I checked the area with the 25mm TeleVue Plossl, and my attention was drawn quickly to an eye-catching triple set of stars. West of it seemed to have a slightly above average number of stars, but nothing that screamed “I’m a cluster”!

Dropping in the 8mm TMB I see a few more stars and a dim fourth sun joins that pretty trio. I do a quick online check to verify that I am on the cluster, easily confirmed by the trio-plus-one showpiece of the field. As my night vision adapts, I see perhaps about 15 stars that may be cluster members in what is a coarse and not very rich offering. No hints of any nebulosity, and none of the stars depart from the standard white color. It is small, perhaps 10-15’ in size. While it may be really nice in darker skies, I'd be inclined to drop this one from the Urban List. 

Something to Crow About

There is real joy when the pleasant spring weather sets in, providing evenings of cool temperatures that I can tolerate with only a light jacket but the bugs cannot. Our garden spotlight softly illuminates the beautiful azalea newly flush with coral colored blossoms and the nearby deep purple irises. The distinctive clink of an aluminum bat connecting with a pitch let's me know that nearby Towson University is having a game this evening. Well, that and their stadium lights lighting up the tippy top of the trees in the field behind my house is also a dead giveaway. 

After setting up the scope I minimize what light pollution that I can by turning off the yard lights. This evening I'm hunting Crow - some celestial highlights of Corvus as he wings his way towards a midnight rendezvous with the meridian. As my night vision slowly improves I struggle a bit to discern the outline, a geometric pattern of half a dozen 2nd-4th magnitude stars. 

The first stop is an eye-catching asterism known as the Stargate. Lying roughly a degree southwest of M104, there is a good chance you may have already stumbled upon it when looking for the Sombrero galaxy. One could probably sweep it up in a star hop by extending a line from k Virginis and Spica westward about 12°, but I take the easy way out and key in the coordinates. At times with a computerized mount you feel like Picard on the Enterprise, barking out the location and issuing a "make it so!" pronouncement. 

At low power in the 10" Newtonian it is delightful - a triangle of stars within a triangle, each having one of the triad much fainter than the other two. Not really seeing any color here but the arrangement is very cool. A little higher power makes it easier to see the fainter members of each of the dual triangles. So what the heck is a "stargate"? Well, near as I can tell, this is a reference to the spaceship portal used in the 80's sci-fi series Buck Rogers in the 25th Century. Hey - if the Greeks can fashion a crow from a trapezoid on a stilt then a "stargate" ain't half bad!

From an easy asterism I go in search of my next objective - planetary nebula NGC 4361, an entry in the Herschel 400 list. If you can see the top of Corvus' trapezoid it would likely be fairly easy to target this with a Telrad. However, the scope is well-aligned so I succumb to the GoTo siren and ask it to do the work for me. I inspect the field at 25mm without any filter, but there's no sign of anything unusual in the eyepiece. Adding the Lumicon UHC and studying the area once more leads me to believe that there is a faint dab of light when using averted vision. Taking the magnification up to 95x with the 16mm + UHC filter darkens the background a bit more and makes me far more certain that I’ve got this 11th magnitude planetary. I use my makeshift drape/balaclava to block out extraneous light in hopes of getting a better look and maybe even catch the central star which is an incredibly hot Wolf-Rayet star, checking in at 270,000° Kelvin (compared to our Sun at about 5,700° K). While I can see the glowing orb a little better it fails to tease out the nebula's progenitor. The nebula appears circular and fairly evenly illuminated, perhaps twice the size of Jupiter. While given the moniker of "The Water Sprinkler" based on images of it that show internal detail, in my scope I discern a faint, glowing orb best seen with averted vision and lacking any structure. The field it is set in is very sparse, made more so due to the use of the UHC filter.

Next in my Corvian exploration is S1604 (Struve catalog entry #1604), one of the targets listed in the AL's Double Star program. This double is not in a very friendly star-hopping  location with multiple other similar stars near it and no solid anchor point to start from. It isn't listed among the keypad’s roster of double stars, so I do a quick lookup of the RA and Dec and key the coordinates. Having expended the effort at the outset of the session to get a good alignment pays dividends as the scope dutifully moves to the spot. Looking over the field at 25mm there are a couple of candidate suns that may be the target, and I think I see one of them as a double. Bringing the magnification up to 156x and revisiting each one I quickly confirm the right one. S1604 reveals itself as a splendid triple system that closely replicates a right angle. The two comes are very close in magnitude with the brighter one making a N-S alignment (PA ~0°) and the other E-W (PA ~90°) with the primary. This is curious, as Burnham's Celestial Handbook lists the position angles as 91° and 73°, clearly at odds with what I am seeing (and what is listed in the AL Double Star program list). Why the difference - is it an errata in Burnham's? I find it hard to accept that the stars changed position that much (especially given one of them is believed to be an optical alignment rather than a true common pair). Not sure that I am picking up any color here, although the faintest of the trio might have a ruddier glow to it.

Saving the most challenging for last, I set off for the Antennae galaxies - NGC 4038 and 4039. This duo of roughly 10th magnitude interacting galaxies should be doable in a 10" telescope, but the challenge becomes plucking them out from the bad light pollution. While the GoTo had been doing very well, for this item I decided to use my star hopping skills to have certainty that I was over the target. Locating TY Crv lying west and midway between g and e Corvi, I nudge the scope northeast until I encounter the 8½ and 9½ magnitude pair of SAO 157047 157046. From there it’s almost due north to HD 104496 and SAO 157048 where the galaxies should be found more or less midway between these two stars. I navigate the route with a high degree of confidence, reaching the endpoint and earnestly scanning the eyepiece field. Alas, there is nothing there to greet me. I check carefully with the 16mm and then the 9.7mm eyepiece, and then repeat the process using the Baader Moon & Skyglow filter. I even grab the balaclava once more to shield my eyes from extraneous light, but there is simply nothing to be had. Perhaps another, clearer evening, or waiting to try in early morning hours next winter, would bear fruit. Sadly the light pollution wins this round.

Star hopping to the Antennae

It's been a very satisfying evening under the stars with my feathered friend. While I'm tempted to continue looking for other spring objects in the area I decide to pack things up since I'll need to be at work in the morning. And that is part of the beauty of our hobby, the heavens (usually) will offer you another opportunity to explore its wonders, even amid suburban skies.

Lessons from an Owl - Part II

 As noted in the prior blog, I recently spent an enjoyable evening from my driveway tracking down the Owl nebula. It was a challenge to discern it amid Towson's ample light pollution with my modest 80mm refractor, but that made the accomplishment all the sweeter. It also made me revisit a wonderful book, Visual Astronomy of the Deep Sky by Roger N. Clark to refresh my understanding of the science behind the successful observation.

You don't have to be an amateur astronomer to grasp the concept of dark adaptation - we've all experienced how over several minutes you can begin to pick out dimly lit objects in the bedroom once the lights are doused. While the widening of the iris to take in more light helps, it is the gradual accumulation of "visual purple" that is the principle actor, amplifying the sensitivity thousands of times. It takes about 30 minutes to build up a full compliment of the chemical in the eye's rods & cones, and it can be undone by a brief encounter with a strong light source (even a bright star as viewed through the eyepiece). So lesson one for the suburban astronomer when stalking the Owl is to be as diligent as possible shielding your eyes once you have some night vision. A shroud of some sort to drape over your head to block out the neighbors' lights is an inexpensive but useful tactic.

Another interesting finding reported by Clark is that the eye actually does have an integration capability when it comes to gathering light. It's certainly not like film or CCD sensor, but "for the detection of the faintest objects, the light must accumulate on the retina for around six seconds." This proves yet again that patience and discipline play a key role for capturing faint fuzzies, requiring that you study a section of the field for several seconds rather than looking at a new spot if you do not immediately find something. It's actually a bit harder than it sounds - I know my tendency is for my eye to want to dart around the field in search of my target.

Averted vision is well known among observers. The eye's improved sensitivity to faint light outside the direct area of focus (the fovea) is due to a higher density of rods in that area of the retina. Clark provides diagrams that show the population of rods across the field of view, as well as pointing out the literal "blind spot" we all have. When you're behind the eyepiece it helps to know where this rod dense region is rather than simply looking askance of your suspected DSO. For the record, it is "8° to 16° toward the nose from the center of vision."

One of the more misunderstood concepts is the relationship of magnification to detecting a faint object. You often see people posting on FB or boards that you want the lowest magnification because that gives the brightest image. But that also gives you the brightest background (light pollution) as well, and anyone who has bothered to bump up the magnification of a misty open cluster can attest that the fainter stars are easier to see under that higher power. Many assume that the increased magnification darkens the background sky and makes the object easier to pick out - yet the object is also darkened, so that does not make sense. Clark explains with several graphs how the size of the object plays a significant role in our eye's ability to pick out a faint object. In fact, there is actually an optimal magnification for an object given its size, brightness, and scope aperture.The author kindly provides a handy appendix that list many DSO and their optimal magnification. For M97 and my 80mm Vixen the suggested magnification would be 140x, and indeed I had my best view at 150x. 

To wrap it up, I bagged the Owl by applying most of Clark's suggestions: guard your night vision to the best of your ability, patiently study one area of the view with averted vision for 10-15 seconds, and don't hesitate to increase the magnification if your first inspection turns up no result. If you are a fan of visual astronomy I thoroughly recommend you get a copy of Visual Astronomy of the Deep Sky. He truly treats the topic as a science as well as walking you through how to study an object to get the most from it. Because it is out of print you should be prepared to pay a premium price (north of $100 for a copy available on Amazon). Of course, an even better option if you are a member of HAL would be to check out a copy from the club library as noted here. With star parties resuming this summer it's a great time to learn more about the science and practice of visual observing!

Lessons From an Owl - Part I

For a while now I have been revisiting the objects on the Astronomical League's Urban list using my 80mm Vixen refractor from my driveway. This began out of my curiosity as to what an observer with a modest scope amid significant light pollution might be able to see. Certainly the big & bold stuff would be easy pickings, but after that, where's the limit as to how subtle an object can be bagged?

Bortle 8 Skies from Towson

 

Of course, the first benchmark on visibility that any amateur astronomer invokes is the brightness of the target, i.e. it's magnitude. There are handy charts and online tools that calculate the faintest magnitude star that one can possibly see for a given telescope aperture. Out in the field there will be a host of other factors that influence that value - the most obvious one being just how aggressive the artificial sky glow is at your location. But things from the condition of the scope (clean optics, alignment) to your age will also affect your limiting magnitude.

As the observer quickly learns, magnitude is only half the story when predicting visibility of a non-stellar target. Size is a critical consideration since the given magnitude is going to be more or less spread out across the object. This is why although galaxy M33 is one of the few galaxies above 6th magnitude, it is also notoriously hard to spot from suburban settings because it has that light spread out over 60'x30'. Surface brightness, the average per arcsecond (or arcminute) magnitude for the target, attempts to level the playing field when  ranking the relative brightness of a deep sky object.

Based on some of my observations thus far (below), M97, the famed "Owl" planetary nebula located in the bowl of the Big Dipper, presented as a DSO that might be doable. Some objects fainter than its 21.88 surface brightness had been visible, while one brighter specimen - reflection nebula M78 in Orion - had failed to materialize. Could I capture the Owl? 

The first spring evening of 2021 turned out clear and with reasonable temperature. I decided to set up for an observing session, even with a waxing fat crescent Moon hanging in the sky. Since this evening coincided with the first HAL public virtual star party I set up my phone nearby and listened in as I went through the alignment process. Jim Johnson provided some celestial mechanics relative to the Moon as it traverses the ecliptic throughout the year while getting it centered for viewing. Victor Sanchez took a turn and shared a colorful image of the Orion Nebula using his equipment. It was as if I had the company of fellow observers as I embarked on my quest for the Owl.

https://freestarcharts.com/messier-97

 

With a good alignment obtained I drop in my 9.7mm Plossl with UHC filter and bid the mount to slew over to Dubhe to ensure sharp focus, and then slip over to the nearby Owl. As expected, there was nothing there at first glance except a few dim field stars. Time to apply the tricks and techniques that I've picked up over the years. First up is draping a dark pillow case over my head to shield my eyes from neighbors' house lights. Then it is a matter of just relaxing and allowing my dark vision to gradually improve. I shift my focus to various points in the field so that my averted vision has multiple opportunities to notice anything. When that fails I turn to using the controls to nudge the field a bit, hoping the well camouflaged Owl face will give itself away if it moves slightly. 

After perhaps 10 minutes of effort it is time for the next tactic and I boost the magnification slightly with an 8mm TMB eyepiece. I again start off at Dubhe for a focus check and then swing over to where M97 should be. The same now familiar field stars are there to greet me while the planetary still refuses to emerge. I begin my stalking routine again and then it happens. I think I see something there to the right of the three brighter field stars! I spend the next five minutes directing my focus to various points in the field in an effort to give my averted vision its fullest advantage. Finally I am convinced enough that the faint, shapeless specter is indeed M97 and not just imagination. Success!

The elusive Owl Nebula captured!

 As I work up a sketch of the Owl I notice that it becomes a little easier to see. This is likely because drawing an object involves some study, allowing your brain & eye collaboration to bring out the more subtle features of the field. But even given that, M97 remains an averted vision only object, impossible for me to honestly comment on size or form given its tenuous nature.

Out of curiosity I decide to push things a little and add a 2x Barlow into the optical path. A quick refocus on Dubhe and I'm off to the Owl again. This time I am able to see the glow a bit more readily, enough that I can judge that it is more or less round in shape. It's still an averted vision only object, but the higher magnification seems to darken the background a bit and make the planetary slightly easier to see. 

The Owl had been a challenging target, possibly at the limit of what I can do in terms of this equipment and location. I saw yet again that surface brightness does not provide an infallible predictor of whether an object can be seen, only an estimate (something I plan to explore in part II). But without question this observing session served to reinforce some of the best practices when trying to pluck a DSO from skies bathed in city lights:

• Guard your dark adaptation, even if your neighbors may think you're a bit weird sitting in your driveway with a pillow case over your head.
  
  
• Averted vision should be applied thoroughly and systematically when inspecting the field.
  
  
• Just as a camouflaged animal gives itself away when moving, inducing a little movement in the field can sometimes unveil a faint target.
  
  
• Contrast is crucial. To that end a light pollution filter (UHC, OIII) can improve the view if the target is an emission nebula and bright enough to overcome the light loss caused by the filter. Boosting the magnification is another way to enhance the contrast and will work regardless of object.
  
  
• Patience - above all, patience! Study the entire field carefully, giving each section a few moments of attention and then review them again. While our eyes don't build up an image over time like a CCD, your eye & brain do collaborate to gradually reveal dimmer objects as you spend time at the eyepiece.

 

Mars Pays a Visit

Every two years & two months we are treated to a celestial show as Mars comes calling for a visit. For most of that 26 month interval the size of our brother planet is diminutive - under 5 arcseconds for nearly a year of that time, hovering around Uranus' size (3.8") for nearly 6 months.And as many amateur observers know, not all alignments are equal. Because of Mars' fairly elliptical orbit, the meetup can happen when Mars is at its farthest point from the Sun (aphelion) or when it's near its perihelion (or somewhere in between, obviously!). The difference is significant in terms of how large the disk will appear in the eyepiece (chart below). So perihelic oppositions are almost generational events, taking place every 15-17 years and boasting nearly twice the size of an unfavorable aphelic approach. It's little wonder that the excitement and anticipation for Mars fans has been growing all summer. Heck, I've even seen a lot more interest from the neighbors out for an evening stroll who know that Mars is "up there somewhere". It's a shame that Covid keeps me from sharing more than the image on my computer screen, and my hopes for a fun Halloween activity for the kids is gone as well.

Mars Size Over 2 Year Period

Range of Opposition Sizes

This apparition culminated in a closest approach on the night of October 6th, and opposition almost a week later on October 13th. That may seem odd at first - after all, all the other outer planets have their closest approach synced up with their opposition date. But for Mars we need to factor in its faster orbital rate compared to the gas & ice giants along with its orbit eccentricity. By October Mars was already past its perihelion point of its orbit, so that means with each passing day it draws farther from Earth. So it stands to reason we hit closest approach as a sweet spot a little before opposition since the two planets are pulling away from one another. So here's a pop quiz. The 2018 opposition took place before Mars' perihelion. Would the closest approach happen a few days before or after that opposition?

As if the orbital machinations aren't enough to make a good view of Mars elusive we need to add a wild card into the equation - dust storms. Planet-wide, rover-killing dust storms are not uncommon as the Martian atmosphere warms. And of course, warming is going to be at its most pronounced during the planet's perihelion. The much anticipated perihelic opposition of 2018 fell victim to an impressive global storm that hid features from our prying eyes and instruments for weeks.

But here's the good news - so far this opposition has been relatively free of dust storms, and at over 22" in size the views have been great! I had hoped to have my 10" reflector back in commission in time for the event but that did not pan out. My old reliable 6" RV-6 classic Newtonian has come through, however. On closest approach night using a light red filter (Wr23A) and an 8mm TMB planetary eyepiece (150x) I could see the wedge shaped Syrtis Major/Mare Tyrrhenum feature on the central meridian. A little pearl sat atop the south pole, the receding ice cap as summer has just occurred a few weeks ago for Mars' southern hemisphere. On the setting limb a distinct peninsula albedo feature, Mare Cimmerium, was easy to pick out. One thing I found quite interesting was the rather subdued appearance of Hellas which lies between Syrtis Major and the polar cap. Normally Hellas is quite a bright feature, but this time around it is muted for some reason. You could almost envision the combination of albedo markings looking like a steer head silhouette.

A few nights later near opposition evening I was able to get out and observe a slightly different portion of the Red Planet's globe with the same equipment. Here Syrtis Major was not visible, getting ready to rise on the limb. But Mare Cimmerium was in full view as well as dusky regions south of it where Mare Chronium also appears to be a little darker than I would have expected. And even though it's only been a week, I struggled this night to pick out the polar cap.

I also achieved a life-long desire to image Mars successfully. Two years ago my attempts were undermined by the dust storms and still learning the ropes a bit, acquiring better software and tools over the interval. My most recent addition has been a Baader UV-IR cut filter which serves to enhance images obtained with a color video camera. Playing with PIPP and Autostakkert!3 have also allowed me to tease out as much detail as I can. While I'm no where near the level of the incredible images I see in my role as ALPO AAC (posting images to the gallery), I feel pretty pleased with what I can produce with a smaller instrument and a setup far less costly than the leaders in amateur planetary photography. And after all, it's more about learning and improving, arriving at something that brings you joy and a sense of accomplishment. 

So, if you are an amateur astronomer I urge you to give this a go - Mars won't be this good again for 15 years. You don't need a big scope - I have caught albedo features and the polar cap using my 80mm Vixen earlier this summer (Of course by the time you read this the polar cap will likely be dissipated). If you are new to planetary observing then be sure to take your time at the eyepiece. At first you may not make out anything, but keep looking, waiting for those moments of atmospheric stability where you'll grab a quarter of a second of good seeing and pick out a dark marking. As your eye and brain work together you'll end up "integrating" those moments of clarity to fashion an image in your mind of what the planet looks like. Be sure to use a relatively high magnification, perhaps 30-50x your aperture in inches. Hopefully you have tracking ability so that you can relax while viewing the ocher orb, but even if you have to play bump & observe with your Dob, it's still worth it! I'd also suggest a rough sketch of what you are seeing as you observe, it not only gives you a memento for later but will improve your observing skill.

Mars with Pastel & Charcoal

Finally, even with just your naked eye, go out and admire that brilliant orangish beacon rising in the east. Drink in the setting, the place from which you are seeing it, the terrestrial scenery and sounds that accompany Ares as he rises amid the stars of Pisces. Let your mind ponder that at this moment we have rovers on its surface and orbiters whizzing above it, beaming back amazing images of this world. Take comfort in the rhythm and predictability of the heavens, especially now. And perhaps dream that, just maybe, the next time Mars gleams this bright you'll be able to say that humans have set foot on the Red Planet!

Doorstep Mars

Answer to pop quiz: Opposition was July 27 and closest approach happened 4 days later on July 31

Improv at the Impromptu

Last Saturday was blessed with a dome of high pressure over the mid-Atlantic, bringing transparent but frigid skies. Despite the chill Chris Miskiewicz announced he'd open Alpha Ridge for a HAL Impromptu star party. As soon as he called it I fired up Telescopius and elected galaxy NGC 2841in UMa as my primary target for a photography session. If I could hold out against the cold I'd also attempt a wide field of Messier duo of M97\M108. Little did I know that despite my best efforts of being prepared for my evening under the stars I'd need to circumvent a variety of unexpected challenges!

I started packing up the equipment into the Rogue about 5pm. First in was the Orion Atlas EQ mount - but wait! What the heck!? One of the tripod leg tips was missing! I spent 10 minutes scouring the area where I usually observe from home and in the garage where the tripod is stored but no luck. I decided that I could still make it work for the evening by extending the affected leg a bit. Improvisation #1.

Made it to Alpha Ridge as twilight was fading fast and the temps dropping. I transferred the equipment to my observing spot and roughly aligned the mount on the North Star. Turning on laptop and the PoleMaster camera I thought I had Polaris in the field, but soon realized it was an imposter. Nudging and bumping the mount this way and that brought no other suitable candidate star onto the screen, so finally I resorted to taking the camera off and sighting it through the shaft as was my custom prior to PoleMaster. This improvisation allowed me to get Polaris onto the screen when I reattached the camera - all at a cost of time. Finally, about an hour after my arrival I was ready to target NCG 2841 and begin taking my series of 30 second exposures.

I popped on the Telrad and reached for its On lever, only to find it was already on. Nooo! I cranked up the rheostat in hopes that maybe it had happened when loading the Telrad into the car but the poor batteries had no juice left to give me. Sigh - and no spare batteries with me. Alright then - we'll do it using the Vixen scope's finder. Improvisation #3.

I get the Tiger Eye galaxy in the eyepiece and begin to attach the Canon and establish its WiFi to my tablet. Boom - my Orion red headlamp I'm wearing shuts off. Did I bump it? No, apparently I'm having the worst dead battery night I've ever had. Fortunately for this bump in the road I did at least have a hand held red-light flashlight that I dig out from my observing toolbox. With improvisation #4 I'm finally connected and snapping photos.

Sketch NGC 2814

The allure of these clear February skies keep me from being bored while firing off round after round of 30 second exposure. I drink in the showy winter constellations: Orion and his dogs, the Twins, the Bull - all old friends who have crested and are riding the night tide to the western horizon. Over the dome of HALO the Big Dipper stands on its handle as if to vault itself high overhead. Leo climbs his way up the eastern sky as the subtle Hydra crawls beneath his feet. No matter how high-tech the gadgets become and what they can do, there is still something in the amateur astronomer's very being that finds joy in taking in a starry sky with nothing more than one's eyes.

By 9:15 p.m. the cold is beginning to win - I clearly do not have the perseverance to start a new session targeting the Owl Nebula and nearby galactic neighbor M108 - that will need to wait for another spring evening. I take my final 30 second light shot and go to get my home-made "light box" that I use to take my flats. Arrghh - are you kidding me!? I guess with the distraction of finding my peg-legged tripod I neglected to pack it. Think, think, think - how can I get a diffuse light source for these flats? I wonder if - maybe I can find a way to make my Samsung 10" tablet display an almost completely white screen? Can I find some web site or document to meet my need? A quick Bing search and - by Jove - there it is! The "White Screen Page" is exactly what I need for Improvisation #5. I load the page on my tablet and hold the tablet over the Vixen 80sf dew cap and rattle off my flat shots. Wow, that improvisation worked great!

Before I pack it in I take a few minutes to do a visual observation. At 60x in the 80mm refractor the galaxy is readily seen as a soft, elliptical glow running more or less in a N-S orientation. There's no core visible but the star field is pleasant with a tight, white double at the southern edge of the field competing for one's attention - the sort of pair whose symmetry of magnitude and coloration make it stand out. There'd be no hope of seeing the subtle light of this distant island universe from my driveway, so I linger a few moments to enjoy the benefit of Alpha Ridge's skies.

The next day I do some preliminary work with the image files in DSS and PixInsight. It's always a bit like Christmas morning when you open up that stacked photo to see what you have. The result is decent for a first pass but I think that there's more in there that can be teased out - if only I knew the intricacies of PixInsight better. The good news is that with the data in hand and safely dropped onto the cloud storage, NGC 2841 can await a cloudy night in the future to have its details extracted from the hour's worth of exposures. 

NGC 2841, the "Tiger's Eye" galaxy

Oh - and that eye-catching double? Turns out that's STF (Struve) 1341, a near equal 9th magnitude pair with a separation of 20" and sun-like spectral class G5. And to top it off, the preceding one of this E-W aligned pair [HD 80606] actually has an exoplanet associated with it weighing in at about 4 Jovian masses and whipping about the star once every 111 days. 80606b also sports an amazing orbital eccentricity of e=0.927 - check out the diagram below from NASA website "Earth Observatory" to get a sense of how elongated the orbit is (Pluto is e=0.25 for comparison). As Spock would say, "Fascinating..."

Orbital Eccentricity

Regal Gems

One of the best aspects of amateur astronomy is the rhythm of the seasons as reflected in the night sky. As we move deeper into fall we have the return of the familiar "W" asterism in the northern sky - Queen Cassiopeia. The constellations that we bid goodbye to in spring now return. It’s like visiting a familiar vacation spot - we want to see those tourist attractions but we also relish a chance for new road trips and opportunities to experience new vistas.

Like any proper monarch our queen is adorned with jewelry – open cluster are littered across the confines of this constellation. We often think of the northern terminus of the Milky Way to coincide with Cygnus, but that perspective arises from residing in the east coast light corridor. Even when we slip away to darker skies it is rare to get a good appreciation of the winter Milky Way as it flows through Cassiopeia and Auriga. I recall many years ago my friends Bill and Doris Burbridge had a place in western Maryland that they observed from. They invited several of us up one October evening for some observing. Perhaps it was just a night of wonderful transparency coupled with minimal light pollution but the sky was stunning. You readily saw the winter Milky Way, and clusters that I had to tease out from Towson were screaming their presence. Evenings like those constitute an astro-high that we photon junkies of the universe constantly want to recreate!

Setting up in my driveway I am confronted by the realities of suburban living as I strain to see Kappa, the faintest of the six stars that outline the queen’s seat in the heavens. I align the mount and set my 80mm Vixen upon it. First stop this evening is a visit to my friend the Owl, a.k.a. NGC 457. This fun cluster is bright, an easy star hop, and has more than enough stars in it to be readily recognized as an open cluster. The two brightest stars form the eyes of the wise bird, and the fainter members to the northwest constitute body and outstretched wings.

NGC 457

The avian eyes, Phi¹ and Phi² are not only beautiful but amazing suns. Phi¹ is actually a yellow supergiant (bordering on hypergiant) that is some 65 times larger than our Sol and, according to Hipparcos data, an absolute magnitude of -7.8! Think about that for a moment – that value represents an object 40x brighter than how Venus appears to us. For comparison Sol has an absolute magnitude of 4.8, so in a sky where all stars are placed at the same distance from the observer, Phi¹ is an incredible beacon that’d be easy to see in our daytime sky, while our Sun would be lost in the light pollution from most of our region. That’s one heck of a star! The companion star (not a true double) is a blue supergiant checking in at some 83,000 times more luminous than our Sun. So together the Owl’s gaze represents stellar furnaces of a scale that we humans find hard to truly appreciate.
I admire the cluster at 30x, a beautiful object set amid a wonderful star field. I think I can see a slight yellow cast to Phi¹ but it may be my imagination. There are probably close to two dozen cluster members that make up our feathered friend in my eyepiece. I have my camera prepped and ready to go so I take the time to grab several 25 sec shots that can be my indoor entertainment on a cloudy night as I process them.

The next item I want to attempt is NGC 7790, an open cluster NW of Beta Cassiopeiae that I saw years ago working the Herschel 400 list using my 6” reflector. As I recall it was small but pleasantly rich. I’m just not sure I can snare it from this location with my 80mm refractor but it seems worth a try. As I am panning the area in my quest I see another old friend pass through the field. This queen of ours has placed two gems – a sapphire and a ruby – together in her collection of double stars. Known as WZ Cassiopeiae, the primary is a ruddy 7th magnitude carbon star while the companion lying about an arc-minute due east is an 8th magnitude spectral class B (as in blue) star. The relative closeness in magnitudes, the easy separation, but especially the red-blue contrast – all add up to make WZ a fabulous if unsung double star. I linger on it, trying different magnifications to see which eyepiece gives the most aesthetic result. Smaller aperture scopes usually do not have enough light gathering power to do color justice, so I’m really pleasantly surprised how well WZ holds up under a smaller instrument. I decide to swap in the camera again to grab a few shots of my colorful friend.

WZ Cas

Back to my search for NGC 7790. I pan the region, critically examining each field for hints of a cluster. Finally I notice something – a small patch that is exhibiting that ultimate tease of barely showing some stars with averted vision but never robustly enough to allow you to position them in a sketch. This has to be a cluster, likely my quarry. It does have one star that can be seen, perhaps 9-10th magnitude, on the cluster’s trailing edge. The body appears as an ellipse of unresolved nebulosity that is at least partially, if not entirely, based in faint stars just beyond the aperture’s reach. With clusters like these it is easy to understand how over a century ago astronomers were suffering from aperture fever in an effort to prove that all nebulae were collections of unresolved stars. How fortunate for us they were wrong and we instead have a far more interesting universe to explore. I sketch the view of this attractive cluster for later confirmation and then start to break down the equipment due to the hour and my body saying it’d had quite enough cold weather observing for one evening.

In hindsight I wish I had grabbed a shot or two of this one as well, because when I went to confirm it the (ahem!) stars didn’t align. Ok, so what was it then? Well I likely need to revisit and grab a better sketch or a couple images but I’m thinking I landed on next door open cluster NGC 7788. It has the same orientation and, most importantly, that single bright star on its trailing boundary. So that’s my working theory and good excuse to observe again the next opportunity I get.

This serendipitous uncovering of a new (for me) cluster served to highlight how there are often little treasures out there that we pass by either in our haste to get to the main target or simply because we didn’t know to look for something. A few days after my session Richard Orr posted his observation of NGC 436, an open cluster below the feet of the Owl. (Richard also gave a vigorous defense of NGC 457 being a Dragon Fly – but certainly an Owl is a far more regal creature for Queen Cassiopeia!). His posting made me realize I had overlooked it while soaking in NGC 457. It was clearly in view – the picture serves as incriminating evidence of my oversight. So now I have yet another item for my agenda the next clear night – observe NGC 436 with intent!

Snowball Fight

One of my current astronomy projects is to tackle the Astronomical League's Urban List from home using my Vixen 80mm refractor. The program was created about 20 years ago and is designed to suggest a variety of celestial showpieces that should be doable under suburban or even urban venues.

For certain 2018 has been challenging to get out under the stars - near record rainfall and of course the clouds that come with it have given fewer opportunities. Last night my CSC predicted so-so observing conditions but when I stepped outside the skies were pretty crisp and clear - time to get a little observing in!

About a week ago I went in search of NGC 7662 in Andromeda (a.k.a. the "Blue Snowball"). I've picked up this 8th magnitude planetary many times before in both my 6" and 10" reflectors. The biggest challenge is usually the star hop with no nearby stars easily visible, at least where I live. The Great Square of Pegasus is almost always visible, and on most nights I can also pick out Omicron Andromeda (mag 3.6). So the plan of attack was a triangle with the northern side of the Great Square as its base, Omicron my helper to set the height. Looked like a can't fail plan.

Telrad Attack on NGC 7662

Famous last words. I spent well over an hour in search for that little fuzz ball, sweeping at both 30x and 60x over fields where it should be. Made sure I had my "distance glasses" on when sighting the Telrad. Checked the Telrad alignment. Raised the height of the tripod a little to make it easier on my neck. Plenty of pretty pinpricks of light but nary a chubby star that could be my snowball.

I figured I would give it one more go but would change the technique, this time equipping myself with charts that could let me hop to Iota Andromedae and then cascade down the couple of degrees to my planetary, using stars SAO 53202, 53151, and 53039 to pull right up to the Blue Snowball.

It's a great fall evening as I set up the equipment, cool and clear. I can just barely see Kappa with averted vision and glasses on, but I'm able to get it centered. Just as I do I catch a voice from the street "Wow - is that a telescope?" I look up to see a young man - in shorts and a t-shirt as opposed to my scarf and knit hat - checking me out. Well wth, it happens to be "Astronomy Day", right? I call him over and he seems reluctant but then joins me. Hmmm - what to show him? Ah, Saturn is still up, so I pivot the scope 180 degrees for Saturn just before it hits the treeline. With a little coaching he manages to see it at 60x in the eyepiece as he voices his delight. He then mentions that he's seen Saturn before, down at Fells Point, some guy had a scope there. I nod and confirm that it was more than likely Herman Heyn, Baltimore's sidewalk astronomer for many years. I bid him good evening and he meanders up the road. I take a few minutes to admire Saturn myself. Now where was I? Ah yes, trying to get Kappa Andromedae, right.

With Kappa reacquired and at 30x on the scope I have over 2 degrees field of view, so little problem picking up Iota in the same field. But manipulating the scope is cumbersome, as it so often is when getting objects that are coming close to their culmination and in the northern sky. I decide to shift the scope, rotating it east about 60 degrees, sacrificing tracking for easier sweeping. Back again on Kappa I identify to its east SAO 53202 & 53151, which then point me to 53039 (13 And). A little sweep SE and - bingo! Right there, a star that is a little bloated - the Blue Snowball is captured. Let me just grab my sketch book and - oh my, that cop car is stopping and the officer is emerging.

Star hopping down to the Blue Snowball

"Good evening officer," I call out. "Everything OK?"

"Someone called in about a suspicious person in the area. Seen anything?"

I proceed to fill her in about my visitor who might have appeared a bit out of place. I suspect he may be participating in the halfway home farther in town but an easy walk to our neighborhood. I suggest that he is probably just bored and out for an evening stroll and let her know which way he was headed. She hops back in the car and cruises away.

OK, with no tracking the snowball has scurried away from view. But I'm in the area, so in a few minutes it is recentered. Popping in the 2x Barlow to bump the magnificaton to 60x makes it quite obvious that this is a planetary nebula, although it lacks any green-blue color that we sometimes pick up on. It is still small even with the 20mm + 2x Barlow, maybe 10-15" in size, and bright enough to withstand direct vision. No evidence of the progenitor star and no hint of structure - just a fairly homogeneous orb of soft gray light. I swap out eyepieces again for 75x, which the nebula withstands well. No real gain in detail so I think the 60x view wins as one could include 13 And on the edge of the field while keeping NGC 7662 somewhat center stage, making for a nice field star to complement the nebula.

I sketch the view at 60x, noting the stars and approximating the size and intensity of NGC 7662. Just as I wrap up my friend is back, wanting to know if I am seeing anything. I let him know I'm done for the evening but if he sees me out another time he can feel free to ask what's up. "Cool!" he replies. "Well see you later, I think I'm going to go up to Starbucks." And the thought occurs, if I ever want to do some suburban sidewalk astronomy when I retire I bet outside a Starbucks would be a fabulous venue.