New Binocular Space Walk audio guide - Clusters in Cassiopeia and Perseus

I've added a new Binocular Space Walk audio guide, "Cruising for Clusters in Cassiopeia and Perseus." The guided tour takes you through the northern constellations Cassiopeia and Perseus to find 16 of the brightest open clusters in that part of the sky, as viewed from mid-latitudes in the northern hemisphere. It lasts about half an hour, but provides many opportunities to pause the recording to admire the objects and take breaks. Here's the link to the page, which is also available under Quick Hops on the right. Enjoy!

Binocular Space Walk - Cruising for Clusters in Cassiopeia and Perseus

Eyepiece cheat codes: Observing Jupiter and Saturn

Jupiter and Saturn, and sometimes Mars, are the planets that will yield the most detail to backyard astronomers. Not only are they bright, but they are large enough for even the smallest telescopes to see them as balls with shading and details. And of course, there are Saturn's rings! Mars generally needs to be at a favorable opposition to see surface details well. 

Jupiter has its four Galilean moons and Saturn has between two and seven moons accessible to typical backyard telescopes. The moons of Mars are generally too close to the planet to spot except when Mars is close to opposition and you have a steady atmosphere with good equipment. 

A night with a steady atmosphere—good "seeing"—will allow you to have much better views than a night where the seeing is soft, turbulent, or mushy. This is probably the single most important factor in how sharp the view will be. Try to observe when the planet is highest above the horizon. Viewing through a lot of "soup" at low altitude will also make for disappointing views, even on a night of good seeing. Heat rising from rooftops, asphalt, and concrete also wreaks havoc with seeing.

If you are observing with a Newtonian reflector, the image will be rotated 180 degrees (generally south is up). In a refractor or Cassegrain with a mirror diagonal the view will be mirror reversed (north up, but mirror reversed). See this explanation of directions in the telescope.

Jupiter

A complete novice can expect to see two main cloud bands on Jupiter and its four Galilean moons. With more practice, not only the South and North Equatorial Belts (SEB and NEB), but temperate belts in each hemisphere may also sometimes come into view, as well as darkened polar areas. 

In addition, features such as festoons, barges, and other spots that represent the turbulent swirls and storms in Jupiter's upper atmosphere become visible with practice and good seeing. 

The Great Red Spot is also sometimes visible when it is rotated towards us, although in recent years it has become rather wimpy in its size and color compared to previous decades. Look at some Jupiter images to see the types of features to look for.

Above: The moon Io and its shadow visible against the cloud tops of Jupiter. Image by Steve Hill, CC by 2.0, via Flickr

Below: The four Galilean moons are aligned on one side of Jupiter in this image by Ivana Peranic, CC by 2.0, via Jeremy Keith/Flickr.

Jupiter's Galilean moons—those that Galileo was able to see in his tiny refractor: Ganymede, Callisto, Io, and Europa—are the only moons, out of the currently identified 95 Jovian moons, that are visible to amateur observers, and can even be spotted in binoculars. Because their orbits are well known, predictions as to transits across the face of the planet and the corresponding shadows, disappearances and reappearances behind the planet or its shadow, and even occasional occultations and eclipses of one moon by another are available. You can plan an observing session to add these to the interesting details you can see in your telescope. 

The easiest are the shadow transits, which show up as dark black dots on the face of Jupiter. The moons themselves are more difficult to see when they pass in front of the planet, and much depends on the level of contrast with the cloud deck below them. I have seen them many times in my 4.5-inch reflector, but have been unable to see them just as many times. 

Averted vision is unnecessary for Jupiter and its moons. In fact, you'll see the most by looking directly at any feature. Bore your vision into the feature, almost as if you are looking through it, to get the most detail to register. Relax your eye and just let the detail burn into your retina. Really stare into it!

Sketching the cloud belts and swirls that you see can really help you focus on the details. You don't always have to sketch what you see, but try it a few times and you'll be surprised at the amount of detail that is actually visible. You may not see it all at the same time, the same with deep sky observing, but you will build up a complete picture with fragmented glimpses. This teaches you to place a detail within the greater context and you'll also see how the features slowly traverse the globe of the planet in an (astronomical) westward direction as Jupiter completes a full rotation in less than 10 hours—the fastest rotating planet in the solar system. For more on observing Jupiter, I recommend How to Observe Jupiter Through a Telescope by BBC Sky At Night Magazine.

Saturn

Of all the sights a beginner can see in the telescope, Saturn is probably the most striking. When I show it to people at public outreach events, most people are thrilled and some even question whether what they are seeing is real.

While Saturn doesn't show nearly the same amount of detail as Jupiter, and it's remarkably smaller in the eyepiece, the sheer beauty and uniqueness of the planet will keep you coming back whenever you can. Something about the rings is precious. Really.

Above: Saturn by John Spade, CC by 2.0, via Flickr

The rings change their tilt over the years, and with Saturn now in the evening sky, the rings are nearly edge-on. This makes it difficult to see the major feature in the rings, the Cassini Division. This thin dark lane is sometimes visible on nights of excellent seeing with the rings tilted towards or away from us at a significant angle. Look for it at the outward ends of the rings, where they become more visible because they begin to curve the other direction and the gap is seen at its fullest width. This gap that appears so tiny to us is actually almost 3,000 miles wide! The next ring plane crossing is in March 2025, when the rings, being an average of only about 30 feet thick, become invisible in our telescopes. The Cassini Division may have to wait.

Above: Saturn's varying ring tilt, image by NASA and the Hubble Heritage Team (STScI/AURA), CC by 2.0, via Flickr. Cassini Division label added.

If you look carefully you will usually see a slightly darker band around Saturn and perhaps some subtle shading elsewhere, especially at the poles. Saturn is much smoother than Jupiter, but it does have very infrequent storms visible in our telescopes, such as the great white spot of 2011.

For Saturn's moons, you'll have to use averted vision for all except the largest, Titan, and Iapetus when it is furthest out on the western side of Saturn and its bright icy side is turned toward Earth. Iapetus strays pretty far from Saturn in its wide orbit and can easily be confused with background stars. The inner moons are dimmer, but with good seeing, patience, and a telescope of around 4 inches or more, you should be able to pick out Rhea, Tethys, Dione, and possibly Enceladus. Mimas is quite difficult, Hyperion requires a larger telescope of 10 inches or so, and you won't have a chance at any of the other moons of Saturn, which currently number 146 and counting.

Jupiter and Saturn observing resources:

Cloudy Nights Planet Gallery (more recent images at top)

Cloudy Nights Major and Minor Planetary Imaging thread (latest images)

Online interactive observing tool for Jupiter's Moons (Sky & Telescope)

Great Red Spot transit times (Sky & Telescope) (when it crosses the planet's central meridian)

Online interactive observing tool for Saturn's Moons (Sky & Telescope)

Apps:

Moons of Jupiter and Saturn (Android)

JupitersMoons (iOS)

SaturnsMoons (iOS)

Mounting a RACI finderscope on a collapsible tabletop telescope

I recently bought a Sky-Watcher Virtuoso GTi 150P tabletop 150mm (6-inch) telescope. This is a slightly larger variation, with a go-to mount, of a popular design sold by Astronomers Without Borders as the OneSky, a 130mm (5-inch) altitude-azimuth mounted collapsible tabletop telescope, shown at left.

These telescopes have a Vixen-style dovetail bar attached to the solid part of the tube—the green thing in the pictures of my telescope below. This is how the tube attaches to the mount, which has a Dobsonian style groundboard for the azimuth (side to side) axis and a half-fork with dovetail saddle for the altitude (up and down) axis. The tube can be removed from the saddle and clamped back on with a single threaded knob, the knob sticking up from the blue tube in the picture of the OneSky, making this portable design even more portable.

The problem

For finding objects, or in the case of the go-to model, aligning the mount or finding objects when the go-to isn't cutting it, the scopes are equipped with a straight-through red dot finder that projects a red dot on a window in front of the stars. A clever design with many variations, but like some people, I have trouble—no, make that pain—bending my neck enough to comfortably look through one, especially at objects high in the sky. 

On my other two scopes I have added azimuth circles and a digital angle gauge to find objects by looking up their alt-az coordinates in an app like Sky Safari Pro, moving the scope so that the coordinates are set on the azimuth circle and the gauge, and then using a right angle correct image (RACI) finderscope to zero in on the target. A RACI finder doesn’t require neck contortions and shows a correctly oriented view like you would see in binoculars.

I wanted to add a RACI finder to the Sky-Watcher tabletop telescope, but the problem is that the front ring that holds the secondary mirror and focuser is extended out on two truss tubes so that the whole front half can collapse into the solid rear half that holds the primary mirror, making it quite compact. There is no good place to add a finder on the front ring and it would make the scope quite front-heavy, requiring some sort of counterweight for manual operation. Others have added reinforcement to the front plastic ring or have drilled holes in the tube to add a finderscope, but I didn’t want to do either of these things. 

The solution

I added a universal dovetail shoe (base) to a block of wood attached to the scope's dovetail bar (the green thing) and swap my RACI finder between my 4.5-inch and this telescope. Looking at the design, the long dovetail bar attached to the telescope tube has two channels that run its length and a single 1/4-20 threaded hole close to the front end of the bar. The hole is presumably for mounting on a tripod, but it’s at a very poor location for balance. I had seen others mount a laser pointer and finder on that part of the dovetail bar, so I experimented with mounting a Svbony SV182 6x30 RACI finder that I have on my 4.5-inch reflector. I zip tied it in place to see how it worked. The problem was that, sticking out straight from the dovetail bar, the finder was too far from the observer’s position and I had to get up and either lean over or walk around the back of the scope to the other side to use it.

If I were to fasten a block of wood to the end of the dovetail bar at a 90 degree angle, then I could mount the RACI finder on the end of it, bringing the eyepiece to a much better position, even better than if I had drilled a couple of holes in the solid tube to mount it. After doing just that, I noted a post on the OneSky megathread on Cloudy Nights that did something similar, but by drilling and tapping a dovetail clamp instead of using a block of wood. Same end result.

Here’s how to do it

I cut all the pieces using a basic mitre box and a hand saw.

I cut a 5” piece of 2x2 baluster (vertical railing piece) that I had left over from making the legs for the telescope’s table mount. I cut a 45 degree corner on one end so I wouldn’t have a sharp corner sticking out. These balusters tend to vary slightly in cross section width, so I checked a few pieces before I found one where the dovetail finder shoe, or base, fits tightly in one direction—one more way to make it even more solid. Note: I used balusters rather than the 8’ lengths of 2x2 that they have because the balusters tend not to be as warped as the long pieces and they were actually cheaper per foot.

I glued and screwed two small pieces of wood to the block to sit in the bar channels and keep the block from rotating on the single bolt. I cut the two little pieces from a large size paint stirring stick (1/4” thick). The pieces are 7/16” wide and 2-1/4” long. I sanded them so they fit tightly into the bar channels.

This side will face the observer sitting at the telescope.

I dry fit the block and the two channel pieces to make sure they fit tightly in the dovetail bar. There are two screws in the dovetail bar at the bottom of each channel 1/8” from the front end of the bar. The block would need to sit behind these screws with the channel pieces butting up against them to add stability. I marked where the bolt would go through the block into the dovetail bar and also where I would need to glue the small channel pieces that would fit snugly into the two channels in the bar. I had cut them a little long just to give a bit more twist resistance in the channel.

Where the bolt would go through the block and screw into the dovetail bar, I countersank a 3/4” diameter hole about 3/16” deep, enough so the bolt head, with a 5/8” outer diameter - 1/4” inner diameter washer, would be flush or nearly flush with the surface, using a 3/4” Forstner bit. (3/4” because my wrench socket would fit in it so I could tighten the bolt.) You must do this before drilling the hole for the bolt so that the bit can center properly. It’s not essential to countersink the bolt head, but I thought it would be better than having it sticking out, and I recently got the Forstner bit set, so I’m eager to find reasons to use it! I then drilled a 1/4” hole all the way through the block, centered in the 3/4” countersunk hole.

I inserted the two little channel pieces into the channels and pushed them tight up against the screws in the bar channels. I inserted the bolt and tightened it to make sure the fit was good. Then I removed the bolt, put wood glue on the two channel pieces where they would join the block and bolted the block into place. Once the glue had dried for about 45 minutes, I removed the assembly and cleaned off some glue that got on the dovetail bar. It removes easily.

The dovetail shoe for the finder has four slots for screws. I screwed it into the top of the block with four 1-1/4” #6 wood screws. Everything looked good, so I took the shoe off the block assembly, painted the block assembly black, reattached the shoe, and attached the whole assembly to the dovetail bar. The shoe stays on the bar and the finderscope is removed for transport. This modification is also entirely reversible with no alteration to the telescope.

The finished mount. Note the four screws added to the channel bars. I found glue alone did not hold. Make sure you recess the screw heads into the wood with a countersink bit so they don't scrape the dovetail bar.

The finder is at a more comfortable, although still not optimum, location. I can also fit my head in there to use the red dot if necessary. The scope can rotate through the entire range of altitude motion without anything bumping or binding, but be careful when pointing above 50 degrees, as the additional weight of the finder will want to flip the tube backwards.

Packed up, the finder mount is out of the way and adds very little weight or volume to the overall package. Just loosen the two thumbscrews, slide the finderscope on, and tighten the thumbscrews. 

View from above when collapsed. The finderscope mount does not stick out beyond the round baseboard of the telescope mount. The dovetail shoe is mounted so that the thumbscrews point inward and are less likely to catch on a cover or other item.

Now I can use the RACI finder more easily and swap it between the two telescopes. It's still not an optimum viewing position especially at higher altitudes, although being able to rotate the diagonal on the finderscope helps. But for these collapsible telescopes, this makes a useful addition or alternative to the red dot finder.

Recording your observations

 

Jupiter-Venus conjunction, March 2023

 

July 3, 1990 (Miami, Florida)

Picked out major stars: Vega, Altair, Deneb, Arcturus, Spica, and Antares (near Moon). Found the “Teapot” and figured that was Saturn to the left (west) of it. Mosquitoes were fierce and it’s only July! Looked for M19- too washed out to spot it. Also M4. Traced out some of the constellations. Moon is gibbous—some good crater action on the “tan line”.

That was the first observation I ever recorded. I didn't even have celestial east and west sorted out yet. Not that I hadn't observed the sky with a variety of telescopes, binoculars, or the unaided eye before that. But this was my first year of "getting serious" with amateur astronomy.

But how serious are you about Sirius?

It's what you make it. It's a hobby. For some people it's a passion. But it's still a hobby. Most of your observations matter only to you, so consider that, when and if you record them. I do strongly suggest you keep some kind of observing log, for the following reasons:

• It will jog your memory to bring back specific nights and events
• You can compare observations made at different times, in different skies, through different instruments
• It's interesting to see your progress in the hobby, and your failures
• It will tell you if you've observed something before or if it's new to you
• You'll remember people (and critters) you would otherwise have forgotten

That's just a few, and it really varies depending upon the person.

I can only tell you how I log my observations. I don't always log details, especially for objects I've seen many times, unless I see something new in them. I like to keep it conversational and not too technical. I like to have fun. I don't like to be bothered recording the seeing, transparency, exact eyepieces and powers I was using, data from a sky quality meter, etc. for every observation. I'll note the sky conditions at the beginning of a session and if they change, as they often do. I keep it simple- who, what, where, and when. I already know the why. See my post on the Comet Shoemaker-Levy 9 impacts on Jupiter log entries to get an idea of what I put in there and how a log makes a great memento of a memorable observing session or event.

Two bins

My observing records end up in two bins: an observing log in narrative form, which includes notes taken while at the eyepiece that I then extract from the log and group together by object over time in a separate collection of notes files.

My actual observing log, as in the example above and at left, is a session by session narrative. I keep it in a series of Microsoft Word compatible documents, usually one document per year or half year, depending on how much observing I've done, and I'll add images from the internet for many of the objects. 

I note the situation, the people, animal sounds, big gusts of wind, spectacular lightning on the horizon—all those things that bring back the memory like it was yesterday. I'll also make notes at the eyepiece about specific objects. At the beginning of each session, I note the date, day of the week, location, and what equipment I'm observing with.

Periodically I'll extract the notes on specific objects, which I highlight in bold in the log to make them easier to find, and collect them in text files, which I call my observing notes. With this collection of notes, I can look up an object and compare what I'm currently seeing with what I have seen in the past from a variety of locations, in different sky conditions, and with different instruments. I aggregate the notes for each object into a single entry, as in the following example:

Veil Nebula (western portion), NGC 6960

Oct. 13-14, 1993, Chiefland Star Fest, Chiefland, FL

(4.5-inch) Quite bright- tried for dimmer side near the bright star in my scope- only a hint of its brightest part in 100x. Low power would be better if I had it.

Nov. 13-14, 1993, Lake Kissimmee State Park Star Party, FL

(10-inch) Nice view of the fainter section in the 10-inch SCT. Very bright with the nebula filter. Seems like there's a dark lane down the center of the nebulosity (this is the W section). E end visible with the filter.

Sep. 24-25, 2003, Skyline Drive, Shenandoah National Park

(4.5-inch) It's just such a nice transparent night I had to go for the Veil Nebula, and sure enough, it's pretty easy to see around 52 Cygni on both sides, not just the one brighter side, and I can see more than I usually can in those areas. I can see the other segment on the opposite side (NGC 6992) in the finderscope! It shows up nicely in 50x. I gotta say that's about as well as I've seen the Veil show up in this scope. I can trace the whole crescent shape of 6992 for at least 2 fields of view in 50x (almost 2 degrees).

...and so on.

Decades ago I wrote my notes at the eyepiece in pencil or pen. Then I used a handheld tape recorder. Then a digital recorder. Now I dictate in Google Keep using the voice typing feature, copy and paste into my log at a later date, and clean up the dictation errors. Google voice typing has particular difficulty with certain astronomical names, such as when I say "Ophiuchus," and it writes "all for you because," "ophelucas" (huh?), or the usual "off of Lucas." I'm used to correcting such phrases such as "and you see," for "NGC." A recent favorite is "IHOP address" for Saturn's moon Iapetus. 

Find a way to make it easy

Ideally, I would have a charting app at the telescope in which I could click on an object and it would bring up these observing notes for that object. Sky Safari falls short for me in that respect, in that it forces you to organize your notes by observing session, much like my observing log. But I want to see all my notes over the years for a single object in one place. I've tried to use one Sky Safari "session" to put all the observations for a single object in the comments, but the box has no scroll bar, there's no way to add images, and it's very clunky. 

I just wanted a simple app that I can update easily, add images, and most important, import and export through a standard format. 

I think I found just that in the Memento Database app. I started with an astro log template available through the app and modified it to include just two fields: notes and images. While it requires going between the Sky Safari and Memento apps, it's a pretty good second best solution. I use the app Twilight to dim and redden the screen while observing. iPhones do this natively.

I was able to export my notes from Sky Safari on the 1200+ objects I've recorded over the years, then import them to Memento, all via a .csv file. Cool beans. 

I downloaded images of the objects, resized them to keep the database small (the Memento cloud has 100MB free storage), and attached them to each file. Tedious, but fun and it helps me remember some of the objects I haven't observed in a while and should revisit. I like having images at the eyepiece to help determine if what I think I'm seeing is actually there.

Apps will come and go, so one of the keys is to be able to backup your notes and store them in a standard format like text or xml. I figure text is about as standard as you can get, so I stick to that.

Sometimes I just like to read through my old logs on my computer, and now the notes are portable so I can look them up at the eyepiece and even browse them while I'm waiting at the doctor's office. I did that today, reading my observing notes on the Comet Shoemaker-Levy 9 impacts on Jupiter, which were 30 years ago. I cherish the memories that I've preserved through my observing log and notes. How much would I remember without them?

Why does finding things easily have to be so hard?

In a previous post, I noted that I had gone over to the "Dark Side" and bought a 6-inch tabletop reflector with go-to, the ability to punch in an object and have the motor slew the telescope to it. This is a Sky-Watcher Virtuoso GTi 150P.

Well, so far I'm not impressed with the Dark Side. Like most tech gear, I have a love-hate relationship with it. I love it when it works. When it doesn't, which seems more and more of the time now, I hate it. I can't count the number of times just in the few weeks that I've had it that I wished I could just push the scope where I want it to go, like a manual dob. That always works. Always.

So what are the issues? For one thing, you need two suitable stars to do the initial alignment. These are selectable from a list. In a partly to mostly cloudy sky, which is common around here, two suitable stars may not both be visible at the same time. Understandably a limitation of the sky conditions. But if they are visible, the scope may slew many degrees away from the target star, so you need to choose only the brightest stars that are easiest to navigate to manually and recognize in the eyepiece as the correct star. 

Then there's the accuracy. Maybe because it's a cheaper mount (the scope retails for $470 and I paid even less on sale), but an initial alignment almost never lasts the whole observing session, which for me is usually between two and four hours. Sometimes, despite leveling, centering the alignment stars, and doing all the required tasks, the first object I punch in after alignment is still several degrees off. Occasionally it's right in the middle, but most of the time it's either on the edge if I'm lucky or somewhat outside a low power (30x) field of view. When it's several degrees off, I can starhop my way over to it with the help of the Sky Safari chart. Again, somewhat of a limitation of the technology.

Then there are the random take-offs. I'll have an object in view and then as I am watching, with the phone on the table, the scope suddenly decides it wants to look at something else and slews on its own. Hmm.

How about connection drop outs? This scope has WiFi, to which the Synscan app connects so you can control it with your phone. Synscan is very rudimentary in its interface for selecting objects (and the font for that function is inexplicably small). So I tried using Sky Safari to select and go-to the objects I want to look at. At first things were great, except that Synscan would drop the connection every 15 minutes unless it was in the foreground. Despite ensuring the Android settings would prevent this, it still did it. I could live with that. 

But then either Synscan or Sky Safari must have done an update (à la CrowdStrike), and Sky Safari would no longer connect: the Gray Screen of Death (GSOD) in the screenshot. So I used the apps separately, selecting an object in Sky Safari and pointing to it with Synscan, then going back and forth between apps to actually get it in the field. This is supposed to be the easy way of finding stuff? I later found that if I just move Synscan to the foreground and then back to Sky Safari, the latter will reconnect. But...really?

Lastly, I find that having to look down and press buttons on a cell phone when I'm observing is distracting and clunky. It also doesn't help with maintaining night vision, despite a "night mode" in the app, which is not well implemented. You can slew at different speeds, but it's aggravating to keep overshooting over and over. I tried the "tilt to slew" feature in Sky Safari, whereby you tilt your phone a little one way or the other and the scope slews in response. That is even more masochistic, no matter how slow I set it. Sometimes I give up, loosen the clamps on the axes, and just move it by hand. Always works. But that kind of defeats the purpose of go-to, doesn't it?

Well, by now you either think I'm a total crank, or maybe that go-to is not everything it's cracked up to be. In fact, I have come to the realization that both are true. 

I am now experimenting with using the free progressive web app Astrohopper as my "push-to" way of finding things (see my initial review on Astrohopper here). It works well for that purpose and is more reliable than the go-to. I can still use the tracking once I find an object, and that's my main reason for getting the go-to version over the non-go-to. I can't use straight-through finders anymore due to physical limitations, otherwise I'd still be starhopping, which is the simplest, most reliable, and most rewarding way to navigate with a telescope.

By the way, the scope itself is great. It's the tech part that could use some refining, to say the least. The Synscan Pro app gets a 2.2 star rating on Google Play. The non-pro version only gets 1.7 stars. I may end up staying with Astrohopper as my finding tool, then turn on the tracking. That works. [9/21/2024 Update: I got fed up with the go-to, and Astrohopper seems to not be able to geolocate after browser updates, so I added an azimuth circle to the scope base and use that and my digital angle gauge to navigate now. I only use the tracking, and that is often out of whack, but it's nice when it works. Maybe I'll write up how I did the azimuth circle in a future post.]

Snarling dog image by Albert Leung via Flickr (CC 2.0).

New Binocular Space Walk audio guide available

I've added a new Binocular Space Walk audio guide. This one takes you through the Summer Southern Milky Way, as viewed from mid-latitudes in the northern hemisphere, looking at open clusters, globular clusters, a double star, and a few nebulae. It lasts about half an hour, but provides many opportunities to pause the recording to admire the objects and take breaks. Here's the link to the page, which is also available under Quick Hops on the right. Enjoy!

Binocular Space Walk - Summer Southern Milky Way

My favorite observing accessory

White duct tape. 

Okay, maybe not my favorite, but up there in the Top 10.

Why? Because it helps you find stuff at night. Not up there, down here. We worry about finding stuff in the sky, but when you drop something on the ground or walk into something in the dark, you’ll appreciate that being able to see stuff on Earth is almost as important as seeing stuff in the sky.

Few sites are so dark you won't see a piece of white duct tape more easily than something darker colored. I always keep a roll in the car.

Where to use it:

• On any equipment you don't want people bumping into in the dark, especially at public events with people unfamiliar with the size and shape of astro gear.
• Lens caps. Many lens caps are black. Drop one in the grass and you will need to turn a light on, not something you want to do unless you have to when you are observing. All my eyepiece caps and telescope covers have little squares of white duct tape on both sides so I can find them easily in the dark. Kudos to those companies that make the clear caps, but even they can benefit from a piece of white duct tape.
• Marking indicators. I have this thing about always forgetting to turn off red-dot finders. Always. So I put a couple of small pieces of white duct tape on the knob that turns it off. When they line up, it's off. Where to put the scope in the dovetail saddle? Mark it with white duct tape. Where does the telescope cap line up? Where do I grab something at night? White duct tape.
• At one site, we have a wooden fence gate that can be in various stages of open. I will invariably walk into it in the dark. Slap a piece of white duct tape on it.
• At another site, there was a big gopher hole. I stepped in it. You can be seriously injured by doing something like that. A stick with a piece of white duct tape on it kept me out of the hospital.
• Black telescope? Manufacturers love black telescopes, black binoculars, black cameras, black cases, black everything. A few strategically placed pieces of white duct tape will make it less likely to be stepped on, bumped, or run into at night, by you or someone else.
• Red LED flashlight. If it's dark colored, it's not going to do you much good if you can't find it in the dark. White duct tape.

And there's not much in the world you can't fix temporarily with duct tape, so it's always good to have it around.

I'm sure I've forgotten many other uses for it, and I'm sure you can come up with others.

30th Anniversary of the Comet Shoemaker-Levy 9 impacts on Jupiter

One of the great things about being an amateur astronomer is that you can take advantage of some really cool things that happen in space every once in a while that can only be seen in a telescope. Such was the case 30 years ago when, starting on July 16, 1994, pieces from Comet Shoemaker-Levy 9 (D/1993 F2), which had broken apart two years earlier, impacted Jupiter over the next week. This could be seen even in small backyard telescopes.

Image of Shoemaker-Levy 9 impacts on Jupiter by Hubble Space Telescope Comet Team and NASA.

You may not have been around or into astronomy when this happened, so here I'm posting my observing log entries from those special nights when black marks appeared in the cloud tops of Jupiter. It was an exciting event and I hope this gives you some sense of that, or brings back memories if you observed it yourself.

Comet Shoemaker-Levy 9 Impacts - Observing log entries

Notes:

• Most observations were made with my Tasco 11TR 4.5 inch reflector from the parking lot of the apartment my brother, Paul, and I were sharing at the time in Bellevue, PA, on the north side of Pittsburgh (Bortle 8); some from our astronomy club's somewhat darker site in Freedom, PA, north of Pittsburgh. 
• I lost the sketches somehow, but if I find them, I'll add them.
• At the time, I was using a scale for seeing (steadiness of the air) and transparency ("clarity") of 1 to 5, 1 being the best.

SEB=South Equatorial Belt

NEB=North Equatorial Belt

STB=South Temperate Belt

NTB=North Temperate Belt

July 16-17, 1994 (Sat. night) Bellevue, PA

(4.5-inch) First day of Comet Shoemaker-Levy 9 colliding with Jupiter. Report on CNN said fragment A hit Jupiter this afternoon. Hubble Telescope imaged a plume and a spot. B scheduled to hit at 10:49 p.m. Observed Jupiter in 180x. Could see NEB, SEB. NEB very turbulent- almost joining the NTB. STB quite dark, but a light spot breaking it up- just about center, moving to the west as it rotates. Area to S of that, where impacts will occur is fairly uniformly medium dark.

Seeing about 3/5 but wavy. Clarity not particularly good- some cirrus, a lot of haze, but Jupiter shining through fine. Quite a large festoon extending S off the NEB into the equatorial zone- one of the largest I've ever seen, just a little past the meridian. NEB is very wide, with the tiniest gap between it and the NTB. Much wider gap between the SEB and the STB. All four moons symmetrically lined up on the east side of Jupiter two by two, dipping down toward the center. 10:42 p.m. Seven minutes until predicted impact of fragment B. Image still undulating like Jello, but not blurring too much. Seeing variable.

10:48 p.m. One minute to predicted impact. Jupiter is about 5 degrees NE of the Moon tonight (a little past first quarter). Quite a bit of thin cloud cover in the area.

Seeing improved to 2/5.

11:11 p.m. Moon hazed over. The white spot on the STB of Jupiter about 4/5 of the way to the western limb now. Looking like this may be an event for big scopes above the atmosphere only. Nothing seen so far. B impact site should be coming around into view. Nothing. Jupiter dimming from clouds.

11:19 p.m. Clouds becoming a problem- very murky. Paul got home at 11:36. Conditions deteriorating. Lights in the parking lot don't help either.

11:48 p.m. Jupiter's image brightening a little, but the seeing is terrible. Gave up at 11:51, no impact effects visible.

July 18-19, 1994 (Mon. night) Bellevue, PA

(4.5-inch) First look at the Comet Shoemaker-Levy 9 impact effects. Incredible! Two dark spots on Jupiter's SW quadrant, very prominent. Some other mottling along the same latitude. Beyond what we expected (Paul and I) to be able to see. We can't believe the spots are this prominent! Easier than the Red Spot's ever been. The two spots were heading for the limb- did a sketch.

9:17 p.m. darkest spot nearing the limb.

Did a second sketch. A third spot is now just past the meridian. Fainter than the other two, but still well defined. However, nowhere near as dark as Ganymede's shadow on the N hemisphere (coming up on the meridian). We both noticed that the N polar area seems quite dark. A couple white spots on the STB, just N and E of the third impact spot.

11:30 p.m. We had moved out to the grocery store parking lot around the corner and had some people stop by to take a look - Tom, Dan, a woman and two little girls. No more impact spots came around the limb. We were hoping the big one, G, would appear, but we're losing Jupiter in the hazy murk now. Packed it in at 11:40 p.m.

July 19-20, 1994 (Tue. night) Bellevue, PA 

(4.5-inch) Jupiter has two very big, very dark spots now in the impact zone. Amazingly large and dark- very prominent- most prominent features on Jupiter right now. We're still in twilight now. Clear but very hazy. Clarity only about 4/5.

Jupiter looks like a coconut with the two round dark spots on one end. Or maybe a bowling ball! The spots are definitely darker than the NEB or any other feature. The spot on the E side has an outer ring that's fainter than the inner area. The spots were so dark we could see them in Paul's little 60mm refractor with my 9mm eyepiece- fantastic! Tonight the spots are as dark as Ganymede's shadow was the other night, without sharply defined edges. Bob, from the astronomy club, is out at the [Freedom, PA] site tonight with some of the other guys (later reported the spots looked like two black eyes on Jupiter this night).

Seeing started out at about 4/5 and improved to 3/5. Jupiter a dark maize color due to the haze.

11:36 p.m. new spot coming around the E limb. First of the two dark spots going round the W limb.

10:55 p.m. packing it in- seeing worsened. The new spot is fainter and more diffuse than the other two big spots.

July 23-24, 1994 (Sat. night) Bellevue, PA

(4.5-inch) The last few nights all clouded up at sunset. Thought tonight might be different. Got a view of a big spot coming around Jupiter's limb- seeing very poor. Looks like there's a sprinkling of smaller spots along the zone, and they appear to be attenuating, forming more into a band. Started viewing at 9:10 p.m. The main spot is quite elongated, about the size of the Red Spot, but flatter and very dark- darker than any other feature on Jupiter. A large amount of activity on the S edge of the NEB, including one really big bump or festoon preceding the large impact spot in longitude. I'm continuing my series of sketches that I've done since the impacts started. A pronounced white spot visible on the STB. A little in front of the second spot visible (which is also elongated). May be my imagination, but there appears to be a dark band forming at the opposite latitude in the N hemisphere.

Clouds have pretty much stayed out of the way tonight.

Now it looks like there are actually two white spots close together on the STB.

Io is in shadow. Watched it reappear at 2203. Seeing improved for a while- best it's been since the comet impacts began. The darkest spot has a lighter center, with perhaps a detached portion more to the S. May even be a third white spot on the STB- smaller than the other two and following them around. The large impact spot now coming up on the meridian. Obviously more elongated now than three nights ago when these same three spots were visible. Almost cigar-shaped now, although a bit fatter. This is the same view as 7/18 (see sketches).

2155- Another spot came round the limb. Three teenage guys came by and took a quick look. I'm happy to report that Jupiter is rad.

Seems like the STB section just north of the darkest spot is correspondingly darker than the rest of the STB. Large festoon on the NEB makes it easy to identify this face of Jupiter. The darkest impact spot is slightly following (E) in longitude by 10 or 20 degrees.

Io reappearance from shadow was remarkably quick. It came up to full brightness in about a minute.

The Red Spot hasn't transited during any of my viewing times, so I don't know what it looks like now. I don't think I've seen it at all this viewing season.

2213- Another big impact spot "coming round the bend."

2251- Jupiter on the edge of a cloud bank. In and out of the clouds. Seeing deteriorated to about a 4 or 5. Call it 4.5. Two major spots still visible.

2315- Paul still not home from his temp job. Not much left to see with the clouds and altitude becoming a factor. Jupiter is only up about 20 degrees now. The second spot is a little larger than the first and not quite as elongated. Hard to see now. These spots are further apart than the ones on Tuesday night. The new one coming around the limb is massive.

2320- Seeing is 5. Jupiter rippling madly like it's in boiling water.

2338- Seeing improved a bit. Paul got home and got a halfway decent view. Another new spot is coming around the limb. Seeing worsened and we went in

July 25-26, 1994 (Mon. night) Bellevue, PA

(4.5-inch) Out looking at Jupiter again. Poor seeing=4. Started at 2225. At 2243 another large spot coming around the limb.

July 28-29, 1994 (Thu. night) Bellevue, PA

(4.5-inch) 2056  Continuing the "Jupiter Watch." Nice big spot approaching the meridian. Dim because the sky is very murky. Can make out the NEB, SEB, and the impact zone as a dark patch. Clarity=4.

2130  Still very dim through clouds. Gave up at 2139.

July 30-31, 1994 (Sat. night) Bellevue, PA

(4.5-inch) Seeing=2.5 to 3. Large sport coming around the limb followed by another fainter one, preceded by some straggly dark features in the impact belt. STB has darker segment past the meridian. A couple of bumps on the S side of the NEB.

Clouds came over Jupiter so I took a look at Albireo.

Jupiter came out again and I recognized the double-lobed spot as being the one from previous observations (7/23-24). Elongated more now, but not much. Hasn't changed much over the last week.

Seeing is very variable. NTB has gotten much less distinct lately- seems almost contiguous with the NEB now. Bright zone between the two doesn't seem to be as definite.

This major spot is the most interesting. Looks almost like there's a bright moon in front of it- a white "eye" in the middle, shifted up a little toward the S edge of the spot.

Packed it in at 2250.

July 31-Aug 1, 1994 (Sun. night) Bellevue, PA

(4.5-inch) Some of the larger spots visible. Possibly same view as on the night of 7/18-19. Spots are the darkest features on the planet, much more elongated now. Two major dark complexes visible now. Seeing=3 but very variable. Clarity=4. Viewed until 2207. Excellent view tonight!

Aug. 5-6, 1994 (Fri. night), Freedom, PA

(4.5-inch) A large elongated spot was just touching the W limb when I viewed it. Looked similar to the one I sketched on 8/1. Two moons were aligned N and S on the eastern side, presenting a nice overall effect.

Aug. 14-15, 1994 (Sun. night), Freedom, PA 

(4.5-inch) Spots from comet impact still surprisingly dark; elongated but not forming a complete belt. Europa reappearing shortly.

Sep. 5-6, 1994 (Mon. night), Bellevue, PA

(4.5-inch) Quite a bit of dark spotting at the impact zone, still darker than the SEB. No individual spots visible due to smearing. Surprising how dark the impact site is, and the south polar cap also appears quite dark. Seeing very poor- scope has only been out in the air about 10 minutes, but Jupiter is setting lower. Looks like impact zone is a dark mottled belt, surprisingly dark- about same darkness as the NEB.

Composite of Hubble images showing the comet fragments approaching Jupiter. Stereogram created with Owl3D and Paint.net.

NASA, ESA, H. Weaver and E. Smith (STScI) and J. Trauger and R. Evans (NASA's Jet Propulsion Laboratory)

Amateur astronomy humor

Amateur astronomy: it's not all just fun and games. Sometimes we get stupid. I've posted my original amateur astronomy cartoons here. 

Eyepiece cheat codes: Averted vision

Getting the most from your visual observations involves using a few "tricks of the trade," or cheat codes, as gamers might view them, at the eyepiece. I've picked up several over the 30 or so years I've been visually observing, but the most useful and well-known is the use of averted vision.

Averted Vision

One of the first things you hear about when you start observing is "averted vision," looking slightly away from a dim object to see it better. This uses the rods in your eyes to best effect. I would posit that there are several variations of averted vision (AV), what I call close, medium, and extreme. 

In all three variations, which are really just part of a continuum, you are usually not keeping your eye fixed on one spot, but moving it around slightly to find the sweet spot where you can get a fleeting glimpse every now and then of the object or detail. When logging my observations, I'll sometimes refer to the percentage of time I can actually get glimpses of an object to indicate how dim it was. For example, I may see a brighter or larger galaxy 50% of the time, but a tiny dim one only 10%, sometimes even less. 

Consciously trying to determine this number is a fun way of determining how difficult the observation is for you and how it compares to others. You might be surprised how infrequently you are getting glimpses of an object, despite being absolutely certain you're seeing it. This gives more meaning to terms such as "bright," "difficult," or "extremely dim."

Medium AV

Medium-sized objects such as some galaxies, globular clusters, more compact open star clusters, and some double stars respond well to what I would call medium averted vision. This is the most common variation I use as an observing "generalist." In medium AV, with the object centered, you are usually looking about 1/5 to 1/3 of the way from the object to the edge of the field of view (FOV) to see it best. Depending on your own eyesight and equipment, you may find looking in one particular location consistently yields the best results, but more often it just pops out randomly as you move your eye around the periphery of the object. Be aware that your eye has a blind spot, but by moving your eye around, you will likely not notice it.

Above: Image of M22 by StudentAstronomyGroupUoC, CC BY 4.0, via Wikimedia Commons. Edited to simulate eyepiece view with annotations.

A good example of using medium AV is observing the line-of-sight "double" star 55 Cygni. This one has a 4.9 magnitude primary component and an 11.1 magnitude secondary, with a separation of 22.7 arc seconds at position angle 174. Close doubles with a big difference in magnitudes are a fun challenge. At first glance it's not easy to spot the secondary in my 6-inch reflector from my light-polluted Redneck Observatory. But it's not particularly hard if I use medium averted vision at around 150x. It pops into view if I look about 1/5 of the way to the edge of the FOV with the pair centered, but blinks out when I look directly at the primary. Give it a try or a similar one that is a good fit for your telescope.

Close AV

Close averted vision is useful for observations of tiny objects like Saturn's dimmer moons or detail in the core of a galaxy. When viewing Saturn, I notice that the brighter moons require a bit more distance (medium AV) and the dimmer moons often require I look right next to them (close AV), sometimes seeing them if I look directly at Saturn itself, which also helps keep my orientation fixed. I recommend a free app called Moons of Jupiter and Saturn. There is also a paid app for iOS called SaturnsMoons, although I have no experience with that. Apps like Sky Safari also will show the positions of planet moons. Just zoom in on the chart.

Above: Image of Saturn and its moons by Kevin M. Gill, CC BY 2.0, via Wikimedia Commons. Edited to simulate eyepiece view with annotations.

Close AV is also useful for seeing more detail in larger or brighter galaxies. For example, the other night I was observing NGC 5907, a striking 10th magnitude edge-on galaxy in Draco about 11 x 2 arcminutes in size. I can pretty easily see the ghostly slash-shaped galaxy in medium powers in my 10-inch in a Bortle 4.5 sky, with a hint that the center is slightly brighter. This core area pops out a little better if I use close AV, looking right next to it. 

Above: Image of NGC 5907 by By Kết Nối, Việt Nam, Public Domain, via Flickr. Edited to simulate eyepiece view with annotations.

M82 in Ursa Major is another good galaxy to practice AV on. It will likely yield more detail in close AV. You might even be able to pull out a brighter core or some mottling in dimmer and smaller galaxies with this technique.

Left: Image of M82 by David Warrington from England, CC BY 2.0, via Wikimedia Commons. Edited to simulate eyepiece view with annotations.

Extreme AV

I call it extreme, because in this case you're really trying not to look directly at anything in the eyepiece. Instead you're trying to take in the whole FOV at once rather than focusing on a particular spot. Just think of relaxing your vision and letting the entire view wash into your brain. Your eye is moving around trying to soak up every photon to make some sense out of the scene. It's almost like you're trying to pull your eye back into your head a bit to get the widest field possible to register.

This is useful for extended objects or dimmer objects such as a dim but rich star cluster. A good example is NGC 6645 in Sagittarius. It's a beautiful and interesting cluster for a darker sky, but often ignored because of all the other flashy stuff nearby (M8, M20, M17, etc.). 

Left: Image of NGC 6645 by Mike Durkin from Forest Hills, NY, derivative work: Winiar, CC BY-SA 2.0, via Wikimedia Commons. Edited to simulate eyepiece view with annotations.

Extreme AV is pretty much essential for most nebulae other than planetaries. Coupled with a nebula filter (I use an NPB narrowband filter), this can often yield great results where you can see the shape of the brighter portions of nebulae. 

Left: Image of NGC 2174, the "Monkey Head Nebula" by Nigel Hoult, CC BY 2.0, via Flickr. Edited to simulate eyepiece view with annotations.

Sometimes even a small object that's extremely faint can benefit from extreme AV when you're trying to get any hint at all that something is slightly brighter than the surrounding sky. You just have to experiment, as everyone's situation can be different.