Lunar X Sidewalk Astronomy

This evening, I knew that my home astronomy club, the San Antonio Astronomical Association, was going to set up scopes at a bookstore to see the Lunar X. Just for something different, I decided to set my scope up on my driveway and see if I could attract some of my neighbors to see this sight.

The Lunar X is a pattern formed on the moon near the first quarter when sunlight just touches the top of several craters at the terminator. It is fun to find, because it is visible in the evening for only a few hours every other month.

In the image to the left, south is up and west is left. The lunar X is near the bottom of the photo and the V is near the top.

On this night, I knew that the right time to observe was from 515 PM to 830 PM local time in San Antonio. The sun did not set until the end of the window that was open for observation, so the operation in my front yard was more shade tree astronomy than a star party.

I was able to persuade 18 folks to come over and take a look through my scope in the three hours I was set up. I met several neighbors I had never had the opportunity of meeting. So the sidewalk astronomy was good for neighborhood friendliness too.

(As an aside, other members of the club, set up at the bookstore had over 300 visitors! They worked hard in the 104 degree heat. I napped and had relaxing conversations with my neighbors as they occasionally came by. Each place had its pluses and minuses.)

To prepare for the evening, I set up a table with a large scale map of the lunar surface and printed a photograph of the Lunar X. I used my 10mm Radian eyepiece for a 120X view of the moon.

I quickly discovered that the easy way to get people to look at the right place was to describe three nearby craters as "the two eyes and the open round mouth below them". Once the visitor had that in sight, looking just right of the rightmost eye located the X. As time went on, I also could see the Lunar V just above the X in my dobsonian scope.

As an experiment, I took several photographs through the eyepiece with my little Stylus camera. After cropping the picture, I have posted that cropped version with this entry. It is pleasantly blue colored, just like the image appeared in the late afternoon blue sky. I tweaked the contrast about 10 percent before uploading.

I also logged my sidewalk adventure in the night sky network to give my home club credit for the visitors I reached. Big Fun. Several of the neighbors told me to give them a call the next time I was out looking at objects in the sky. I think I will.

Garner State Park Star Party

Diane and I had a great time at Garner this weekend. Diane was especially popular with the crowds pointing out two different double stars. I think she got hoarse telling folks about the telescopic doubles. She was impressed at the reception she got from women who lined up to see the sky. Mothers with kids in their arms were especially appreciative of our club's efforts.

I had fun showing folks the moon in my binocular chair. I discovered that I could help them see the moon by having them sit down with their head back on the back of the chair and then bring the binocular down to their face so the white spots of light lined up with their eyes fairly well. This was the first time that I had successfully shown folks something with the chair.

The two of us closed up shop for the crowd about 1130 PM and I spent a while with Diane having her find several Messier objects. After the moon went down at midnight, I began to run the Astronomical League Deep Sky Binocular list. Since each entry requires a description, I logged descriptions of the objects with my voice recorder. After I got home, I listened to the recording and wrote up the entries.

For the binocular list, I logged 34 objects and still have 26 to go. All but one (which I inadvertently skipped) will need to wait for the fall, after the winter constellations rise.

I decided at 4 AM to make a start of the Hershel 400 list. I am using O'Meara's book, and I did a "single night" of observing - with five objects found. O'Meara's book is written up with about 5 nights of observing per month. The objects were dim, but not impossible. Unlike Messier objects, careful star hopping is required to find these little
smudges. Well that's one percent of the list, with only 395 more objects left to go. Sigh...

I think that given a good night, it will probably be possible to run a couple month's of objects in a long night of observing. Maybe that will be my project for our next trip to Garner.

Computerized Telescope

I have a love/hate relationship with computerized telescopes. For me, a computerized NexStar 4se Celestron was the best and the worst thing that happened when I got interested in telescopes again. To explain that, it might be good for the reader to know some of my history with astronomy.

I have had an interest in telescopes for a long time. As a youngster, I had a 2” refractor on a table-top mount. My dad got interested in astronomy for a time and he bought a 4 inch Newtonian reflector which we never really figured out how to use. (We probably had no idea how to collimate it.) I don’t remember seeing anything except the moon and Jupiter with those scopes.

Skip forward 15 years, and I was a father with young school children of my own. I decided that I really should show the sky to my kids. I bought an 8” Meade SCT scope (don’t worry about what that is for now – I’ll cover it in another chapter/blog). It was a great scope, but without any help to learn how to use it, I became frustrated trying to find anything except Halley’s Comet. I remember a particularly painful night twenty years ago. After laboriously orienting the scope, I finally found exactly one globular cluster. I still remember thinking that using this scope was too hard to be practical. If I did not have the patience to spend hours outside on a cold night to see one object, how could I expect them to? (It would have been very useful for me to have joined an astronomy club at that time – clubs are great at helping folks that are clueless to become experts. And my problem was that I was truly clueless.)

Skip forward 25 years, and my youngest child was 19 on our last family vacation before he moved away to school and engagement and thinking of his own family. This was the summer of 2008, and we chose to do some hiking and relaxing at the Ft Davis State Park in the Big Bend portion of Texas. One of the bulletin board announcements in the lodge said that there would be a public star party at the McDonald Observatory on Friday evening – the next night. We went, saw Saturn in Leo, the ring nebula in Lyre, a couple globular clusters, the double double of epsilon Lyre, and generally had a blast.

I came home and decided that I had to get a telescope and had to find some places to see the dark skies of Texas. (Note, I was still pretty much clueless.)

I looked on the internet to try to get ideas and I went to a local telescope shop. I bought a used Celestron NexStar 4 which was about 5 years old. It had a thirty day “no questions asked” warranty from the shop. The scope had no tripod. I took it out into the countryside, about 20 minutes outside San Antonio. I had it sitting on a couple plastic bins. It was not a sturdy mount, but I was fascinated at the way it could figure out where objects were in the sky after I showed it where three stars were. But I knew I needed to get a tripod and some other things if I was going to be able to do much with it. The cost of a brand new NexStar was only $150 more than this used one, and it came with a tripod. So I returned the used scope and bought a new Celestron 4.5 inch NexStar.

The new version of the software was much better at finding itself in the sky. All I needed to do was to point it at three bright objects. I did not even need to know which ones they were. Once that process was complete – taking about 10 minutes or so, I was delighted to find out that the scope would point quickly at many objects that I could not see at all. Finally, I was able to access the many beauties in the night sky!

I remember one great evening of viewing in August. I was thrilled to see a dozen Messier objects in an hour and a half of observing. Really thrilled. I mean, completely overwhelmed and elated and amazed. This was FUN.

I could see Saturn and Jupiter and Messier objects and I began to see how all this might be more than a month’s diversion. It might take me a year or more to see everything in the sky. (Still clueless.)

There was a book written about using the Celestron NexStar telescopes. I devoured it. There was a website where people shared hints about the scopes and what they were doing with it. I discovered that there was a list of 50 objects which were good targets for the scope. Some of them were only visible from the southern hemisphere, but more than 40 of them could be seen from San Antonio, and there was an award for logging 40 of the objects. I set about the process of logging 40 and was able to complete the list by observing summer objects in the evening and as fall approached, to get up before dawn to see many more of the objects that were normally visible on winter evenings.

It was about this time that I found the local San Antonio Astronomical Association and joined its ranks. It had a Yahoo group, and I was able to share my successes and learn from sage comments by others. I could ask questions that had been bothering me for 30 years. I began to grow quickly in my understanding and appreciation of the sky.

That is the love part of my story. But there was a dark side of this relationship with the computer-aided scope. Somewhere along the way, I became aware that I had no real idea where the scope was pointing when it found all these pretty objects in the night sky. I strapped a laser to the scope so I could see where the scope was pointing. I tried to use the red dot finder to see where these objects were, but I realized that the red dot or the laser were pointing toward mostly empty and invisible things in the sky.

I felt a little like I was in a zoo, surrounded by pretty butterflies. I had a guide book that had pretty pictures of butterflies that were kept in the zoo. But I had no idea where all those pretty butterflies were hiding – since I could not see any of them when I looked around me.

The computerized scope had gifted me with the knowledge that there really were a great number of objects to be seen, and it had shown me what a galaxy and a globular cluster and an open cluster looked like. But I was still painfully clueless. I needed to know more about the sky.

Finding North in a Telescope

One of the Astronomical League observing programs I am working on is the double star club. It is not very difficult to find most of the stars, especially in a dark sky. And once the star is found, 120X is usually plenty to resolve the pair of stars. But the instructions for the observing program say that each double star needs to be sketched. The two points of light with relative distance and the celestial direction are the required elements for each drawing.

When I started thinking about how to find the celestial direction, I went through a long process of thinking about where the north south lines would be in the part of the sky I was looking at. These lines can be seen on planetarium programs if I set the program to show them. Then I needed to be able to remember how my scope turns the light upside down and backwards.

It was not really complicated, but I wanted to make sure I was doing this right before finding a hundred stars and drawing them. So I took the chicken way out. I posted a note on my local astronomy club and on an observing yahoo group and asked if I was going about this right.

I got a great set of answers back. Boy, am I glad that I asked the question.

It turns out that for a non-tracking scope like my dob, finding the celestial direction is very simple. After centering a star at a reasonable magnification like I mentioned above, all I need to do is to wait a minute or two and watch the direction the star tries to head out of my eyepiece. That direction is west. Of course it is. No matter where in the sky I am looking, the celestial globe rotates directly west all the time! Then to find north, all I need to do is to rotate counter-clockwise 90 degrees for my reversing telescope optics and that is north.

Now, I understand it is a little more complicated for a tracking telescope like a clock driven or a computerized scope. Turning off tracking is not all that practical when the plan is to observe a couple dozen stars in a night. Who wants to reset the tracking all those times? So for a wedge mounted scope, a practical method mentioned in the answers I got was to rock the fork slightly northward while watching in the eyepiece. If the tube is moved slightly northward, the star in the eyepiece moves southward. OK, so a direction is found. If the scope has a diagonal eyepiece holder, the view through the scope is probably right-side up and backwards. So if north is known, then west is 90 degrees counterclockwise from north.

For a computer driven go-to scope with alt-azimuth mounting, good luck. I think I’d go back to my complex way of looking through the scope and knowing which way north is to be found in that part of the sky where the star of interest is found.

I guess that is another good reason why a new amateur astronomer like me should be glad to have a manual dob as my primary scope.

Binoculars

In astronomy, it pays to go easy on equipment. Equipment makes it possible to see things that are impossible with the naked eyes, but it can also lead one away from the beauty of the sky. A good way to bridge toward fainter objects is to invest the time necessary to learn about the sky with a pair of binoculars.

I know the purists would like to say that the device I’m writing about is a binocular. Well, if it makes someone feel better, that is correct. It is just one thing, and it can be held with one hand. However, I’m not one to stand in the way of clear communication or to try to make someone feel insecure about their use of common language. I’ve always called ‘em binoculars, or a pair of binoculars. If you feel better about it that way, you have my official permission to keep calling them that too. (Yeah, I guess that kind of attitude is a little red neck of me – but you get what you get.)

What’s the big deal about binoculars? Why do they help a sky observer to see more? Well, it is a matter of physics. When I look up at the sky toward the Andromeda Galaxy from a dark sky site, what is entering my eye are photons that left that galaxy about 20 million years ago. Those photons cause chemical changes in my retina and my brain perceives it as light – a really dim light – that is spread out across an area larger than the size of the moon.

The cross section of the receiving area is the area of my cornea above my open iris in each eye. How big is that area? You may remember a little math from high school that says that the area of a circle is pi*r^2, or in words “pi r squared.” Pi is a constant that is about equal to 3.14. The radius of a pupil when it is dilated may be about 3mm. So the area of the pupil is 3.14*3*3 or about 28 square millimeters.
For two eyes, the area is about 56 square millimeters.

When I pick up a pair of astronomical binoculars, like the Orion Scenix 10x50 binoculars I bought on line for $100, those numbers mean that the binoculars magnify the image by 10 times and the lenses in the front are 50 mm across (almost two inches for the metrically challenged.) If the diameter is 50 mm, then the radius is 25mm and the area of the lens is 3.14*25*25, which is about 1963 square millimeters or 3925 mm^2 for the pair of lenses. That is about 70 times the area of my pupils.

The effect of this is to funnel 70 times as much light through my pupils from an area of the sky that has been magnified ten times. And the main effect of that is not so much seeing things bigger, as seeing more things! Stars that were not visible to my eyes are now easy to see. If the Pleiades are up, I can see six stars in the open cluster in good sky conditions. With a pair of binoculars, I can see more than fifty.

There only two real problems with binoculars for looking at sky objects.

First, some objects are not large enough to make out enough detail to make them interesting. That is especially true for objects in our solar system. Ten times magnification is not thrilling for the moon, Jupiter, or Saturn. It is about what Galileo had in 1609, and with it I can see the moons of Jupiter, the rings of Saturn, and craters on the Moon. This lack of magnification is not as much of a problem for many sky objects. In fact, many deep sky objects are beautiful at low magnification if you can get enough light into your eye to enjoy them. And that is what binoculars excel at doing.

The second problem is a real bother. Binoculars are really hard to hold still. If I try to see the moons of Jupiter with a pair of hand-held binoculars, all I see is a bright dot swimming in front of my eyes. To get the most out of all that optical power, I need to find a way to hold the binoculars still.

I’ve tried holding binoculars against a tree, against the back of a chair, and I’ve tried to hold my breath to hold them still. None of this works very well. When I was out at the Texas Star Party in April 2009, I came across a device for holding binoculars called the Couch Potato Telescope. Designed by SIM PICHELOUP, this is a rotating platform that holds a beach chair and an adjustable frame to which the binoculars clamp. While I was out at the TSP, I bought a kit from Sim and built it when I got back to San Antonio. It makes binocular observing a dream! (If you want your own Couch Potato Telescope, Google the term and write to Sim.)

There are a number of special observing lists devoted to binocular observing. They are all worth spending the time to find the objects on that list. So Far, I have gotten the TSP binocular list done, and the Binocular Messier list of the Astronomical League. I am hoping to do the AL Deep Space Binocular list this summer and fall.

Maybe I will invest in a larger pair of binoculars for the Messier Marathon this coming spring. A friend of mine was able to see over a hundred of the Messier objects with a pair of 80 mm binoculars across a wonderful night of observing. Of course those 80 mm lenses are bigger than mine and collect a lot more light. 3.14*40*40*2 is 10 square centimeters or two and a half times more light than my binoculars gather. Sounds like a nice Christmas present, Diane.

Star Party at the Hog Plum Ranch

I've been able to participate in a number of public star parties sponsored by the San Antonio Astronomical Association this summer. This is a simple way to spread the love of the skies with the next generation. The outreach events I have been in on have included schools, parks, and this last Saturday evening a summer family outing sponsored by a couple SW San Antonio school districts.

For a change, this star party was held at a great dark sky site, far from street lights. The Hog Plum Ranch is outside of Karnes City, TX. It was very nice to be able to see a range of Messier objects as well as the standard views of Saturn, double stars. A walk through the constellations was easier with so many stars to see.

Some of our club members had not seen omega Centauri before, and it was nice to show it on the southern horizon, as well as the ring nebula of Lyra and the great globulars in Scorpius.

For the main part of the star party, it works best to have each scope focused on one object, with no two scopes showing the same object. That keeps the kids from getting bored as they go from scope to scope. But after the crowds began to thin (there were 83 visitors at this star party and 8 telescopes) then it became possible to do a little more wandering around the sky.

After the visitors left, the astronomers began to thin out too. But I had the opportunity to spend the night at a dark sky site for my own observing program. Whoo Boy! There were others who thought of staying, but I ended up being the only observer left at midnight. It was me and the dog and a couple kittens.

There were bands of clouds that rolled in through the night, and I took advantage of those times to get an hour's worth of sleep. But there was enough time with clear skies to draw 37 double stars for the AL double star list. That pretty much catches me up until late summer or early fall, when I can get in the rest of that list.

I left at about 450 AM and drove an hour home to drop into bed for a good Father's Day morning sleep. My wife was pleasantly surprised that I was not trying to get her up before breakfast. So it was a good time for all.

Thanks to Matt R. for the photos!

Summer Solstice Telescope Project

I have spent some time over the last week trying to figure out how to find some of the magic plastic laminates that make dobs azimuth bearing work better.

I have a 10 inch Orion XT10.

I looked around for the black magic laminate called ebony star - the "-50" version - but found no laminate at all in the local HD and Lowes.

When I was nosing around in the new Lowes out on I-10 at 1604 this morning, I was able to find the next best thing, a sheet of FRP - fiber reinforced plastic. I bought a 4x8 sheet for $32. (Ebony star when it used to be available cost upwards of $80 for a sheet.)

I also picked up a can of contact cement and a few chip brushes.

The first thing I did was to replace the LP record bearing in my "Helotescope". The FRP with stick on furniture glides worked so much better than the record!

Next project was a little bigger. I decided to apply a ring of the FRP to the underside of the round board on my 10 incher's bearing.

I took the central bolt off and cleaned up the under-surface of the board and the teflon like bearings. I used the bottom board to trace a circle on the FRP and then cut the circle out with a jigsaw.

The bottom of the board has several bolt like hardware pieces that I may want to take out someday, so I cut the center of the circle out with the jig saw. In addition, they stick out of the bottom of that board by a fraction of an inch and covering them would be difficult.

Afterward, I figured out that I could have cut the outside and then the inside circles with my router and made an even neater job of it. All that would have required was building a little circle cutting jig - plans available on the internet. Well, I used the jig saw and especially the inside edge is not very pretty.

I applied contact cement to both the circle I had cut and the baseboard where the two pieces needed to be joined. I allowed the glue to dry for 5 minutes in our 100 degree heat and glued them together. Maybe next time I will put two layers of glue on the pieces. That works a little better. After the glue had set well, I used my router to give a smoother outside surface to the white ring.

The results are promising. I set up the scope this evening in my back yard and Saturn was much easier to follow at high power by hand. This is a technique I will probably use when I build my next scope.