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.

Third Quarter Starlight

Last night was an opportunity to enjoy a perfectly clear evening without moon or clouds. It was my last real practice before Messier Marathon weekend for those sunset objects. Diane and I took off for Hill Country State Natural Area, near Bandera Texas.

Before leaving for the observing session, my wife and I had watched the Space Shuttle blast-off at about 6:40 local time. A fellow amateur, Brian, from the San Antonio Astronomical Association, had sent out an email reminding us that we would probably be able to see the Shuttle at the end of its first orbit from the San Antonio area. (Brian is el presidente of the club.)

At sunset, I was setting up the scope at Hill Country. I had my satellite spotter (Diane) with me and she had first view of the Shuttle at about 815 almost due north about 30 degrees high. 45 minutes later, another bright satellite passed just below Orion's belt, just above M42, also traveling SW to NE. Space Station? We saw a dozen satellites, and several shooting stars. One dim satellite passed reasonably slowly (high altitude I'd guess) through Andromeda galaxy about 845 when I was finally able to see M32 and M110.

I got a good practice on M74 and M77 two weeks before the marathon. M74 sure is hard, though I believe I was able to see it with averted vision.

With the rain of the end of last week, the ground was wet and the dew was early and heavy. I ended up having to cover my Telrad and eyepiece with a piece of cloth between observations to keep them warm enough to not fog. By 945 when I was done for the night, the outside of the tube was covered heavily with dew.

The open clusters of Gemini and Auriga were bright and easy with binoculars with the limiting magnitude of 6 - normal from Hill Country.

I had to pull the plug at about 9:45 because of work the next day. The deer on the way home were numerous and we even saw deer along Bandera Highway. I had previously seen a lot of deer on Park Road, but not on Bandera. Total deer seen on the way home... about 18. None actually ran onto the road in front of me, though a couple thought about it as they listened to my sudden braking.

Selling Short our Children's Future Dark Sky

I remember looking up at the sky from my suburban home and seeing the Milky Way shining like a silvery belt across the moonless night. I remember being spellbound by the thousands of stars and asking my father how many there were. After years passed, I remember the pride I had two years ago when I moved into Helotes, Texas and found out that the City Council had passed a plan to bring the dark sky back to my neighborhood.

Unfortunately, I am now deeply disappointment in the city where I live. This pain began when I found out that the City Council had quietly passed a new lighting ordinance last month which guts the 2006 measure and eliminates the hope that we will again be able to see the Milky Way from our Helotes back yards.

The July 2006 lighting ordinance had programmed a generous schedule during which businesses and home owners had years to replace their outdoor lights so that glare would not be directed upward into the sky (and into each other's back yards). The city had grandfathered existing lights, only requiring that they be replaced with lights that comply with the ordinance by 2012 - six years from date of enactment.

As of 2009, the only lights affected had been fixtures on new commercial construction. Only those who had installed new outdoor lights since 2006 were required to meet the standards - essentially a standard which said that the light would not have a direct beam of light shining uselessly into the sky. Unfortunately, there have been a number of new construction projects erected along Bandera highway the last two years which did not meet the standard. But, instead of enforcing the standard, our Council chose to replace the ordinance with one where ALL existing lights are grandfathered FOREVER.

The new ordinance does not simply "clarify and simplify outdoor lighting requirements" as stated in the draft minutes of the last meeting of the City Council. The new regulation abandons all effort to achieve dark skies in Helotes. The new ordinance does NOT "continue dark sky compliance" as reflected in the minutes. It eviscerates the ordinance in a way that dark sky compliance can never be achieved.

Helotes occupies important space between the light sensitive neighborhoods surrounding Camp Bullis and the Government Canyon State Natural Area. The protected habitat of these areas is adversely affected by urban light pollution. Why would City Council choose to take steps backwards away from light control at the very time that surrounding areas are trying to discourage light pollution? This makes no sense.

2009 is the International Year of Astronomy, for heaven's sake! I am a member of the San Antonio Astronomical Association, the Astronomical League, and the International Dark Sky Association. One of the reasons I live in Helotes has been our stance to protect the night sky. I have been proud to hold up Helotes as a model city attempting to bring its lights into compliance with the goal of every lighting fixture being a full cutoff light. However, I now find that all mention of private homes has been eliminated from the new lighting ordinance. No longer are Helotes residents encouraged by the ordinance to have full cut-off lighting. I am outraged at this abandoning of example and responsibility.

I feel deeply wounded and ill at what our Helotes leadership has decided to throw away. From correspondence with Benjamin Jones, the young man who worked so hard for years to have the 2006 lighting ordinance passed, I know that he is sick at heart to hear what the Council did when they abandoned our future.

I have published this critique in my Astronomy Blog, highlighting the irresponsible action taken by our city of Helotes during this Year of Astronomy. Instead of increasing protection of our dark sky, we now embrace fresh light pollution. I intend to bring the city's action to regional and national attention. I will be transmitting this critique to National Geographic magazine which had a recent cover story on Dark Skies. I will be contacting the Discovery Channel to make them aware of the new stance of the Helotes City Council on Dark Skies. I will let the International Dark Sky Association know of the new Lighting Ordinance and how the City Council believes this new ordinance "continues dark sky compliance." I will contact the Sierra Club and the Nature Conservancy regarding Helotes' stance and the effect on threatened bird species. I expect that the San Antonio print and television news groups will continue their interest in Helotes dark skies.

I grew up believing that "The truth will set us free." I also grew up knowing that good never came from pretending. This action by the City Council will see the light of day.

What can be done? I encourage the City Council of Helotes, Texas, to reinstate the July 2006 lighting ordinance and begin to educate builders in our city how they can comply with that ordinance. I encourage the city leadership to help people understand how they can improve our sky and why that matters.

The way forward is not to abandon good effort to make our sky dark once again - it is to make the requirements of the ordinance easily understood. Train us. Don't abandon the cause as hopeless. Help us all achieve the goal! Don't tell us that our only path is the path of failure.

I dream that one day our children will once again look up at the Helotes sky in awe. The Milky Way will be clearly visible. The children will be looking at thousands of stars instead of a couple dozen when they ask their parents how many stars there are out there.

School Star Party

When I pulled up outside the elementary school on the west side of San Antonio, there were large groups of kids milling around with "Young Astronaut" printed on their school tee shirts. It looked like a rainbow because each school had their own individual uniform, and there must have been a couple dozen schools represented.

I found that my friends in the San Antonio Astronomical Association were set up behind the elementary school. We had six scopes between us and about 8 or 9 volunteers. I learned that the kids, who were going through a number of activities that evening would come out to our astronomy field in groups of about 100, and we would have about 7 groups. Each group would try to get through all six scopes in the fifteen minutes they had, before a whistle sounded and we got a new group.

I was there with the Helotescope, a home-made, wood-box scope that the reader may have read about in these pages. The 30x scope was pointed at Orion's great nebula - M42. I usually had 5-10 kids or parents lined up waiting to take a little look at this wonder all evening.

My jingle ran about like this, "What you are looking at is the Great Orion Nebula. If you see the three stars of Orion's belt, the telescope is looking at the tip of the sword that is hanging from the left side of his belt. When you look through the eyepiece, you will see a group of three stars - and here I held my hand up so that the palm was cupped toward the ground - in a shape about like my left hand. If you look really close at the star that would be here, at the base of my thumb on the left side, you will see that it is actually a group of four stars. They are in a cloudy bit of dust that makes them look misty. What you are seeing is an area where stars are being born. If you can see those four stars, it is a little like looking into a basket with four newborn little puppies in it."

I repeated my monologue about 4 times per group of students, and the students changed out four times an hour. I also told the kids and their teachers/parents that their club could build a telescope about like this little one.

About nine out of ten of the students saw what I was talking about and I frequently got "wow!" as the comment. A few kids struggled to see the image through the eyepiece. A few of the kids were much more interested in being outside in the dark than in seeing through the scope. They were kids, after all.

It gave me a little warm feeling in my heart to have been out there showing a lot of kids that had never before looked through a telescope what a star nursery looks like. Other members of the SAAA were pointing out open clusters, the crescent Moon, crescent Venus, and later on - Comet Lulin.

This is the sort of activity that I would have never figured out how to organize on my own. As it turns out, a couple of our members are wonderfully talented at getting into schools to show them the sky. It takes marketing, persistence, dedication, and organization. Certainly I would not be able to get out occasionally if Don And Keith were not working the issue all year long. This is one of the great parts of being a member of a local club.

While this sort of activity does little to increase my understanding of the sky, I think it is useful in the long run in molding young people who have known the importance of the sky since they were kids. I may need them to vote for a space telescope one day, or to get the parking lot lights turned off at the neighborhood McDonalds. Kids that know something about the sky are good kids.

Anyway, it made me feel a little better about life to know that I had done just a little to help some school children be exposed to the sky. After all, someone who calls themselves a "young astronaut" should have a memory of looking up and seeing the stars.