My Review of Red LED with Holder (2-Pack)

Originally submitted at RadioShack

Use with digital clocks and remotes. Typical MCD is 0.8. This Red LED has a typical wavelength of 655nm.

Red LED with Holder (2-Pack)

Good for on-off indicator

By Beachastro from Hampton, New Hampshire on 2/7/2011

 

4out of 5

Pros: Pkg instr actually clear

Cons: Hole dia not specified

Best Uses: On off ind

Describe Yourself: Enthusiast

Primary use: Personal

Was this a gift?: No

Pkg reads: Power diss. 110 mW, Fwd. current: 40mA
Fwd voltage: 1.7V at 20mA
Luminous intensity: 0.8mcd at 10mA
Long lead is anode (+) connection

Unlike many of the other packages, this one had enough info to actually calculate the resistor required! Since my power supply was 12V I ended up using 2.2K ohms to get the dimmest light I could. A 1K resistor was just too bright, this will be used outdoors while observing with a telescope so dim is better. BTW, correct hole size is 15/64". :-)

(legalese)

Measuring the size of an asteroid

Asteroids are small and dim, but over time astronomers have managed to calculate the orbits of thousands of them. What is less well known, however, is their size and shape. They are just too far away for even the largest telescopes to get a good picture of any but the very largest ones.





However, once in a while, an asteroid will pass directly in front of a star (as visible from Earth) and for a brief few seconds the star will wink out, then reappear as it emerges from its eclipse. An event like this is called an "occultation" (because the asteroid temporarily occults, or blocks, the light from the star).





Timing the length of the occultation to a fraction of a second can actually give us an estimate of the size of the asteroid. Since we know its orbit and speed, knowing how long it occults a star makes it easy to calculate its size.





But what if the asteroid is oddly shaped, like say a peanut? Then an observer on earth who saw the fat part of the peanut occult the star might measure the star winking out for say 10 seconds, while an observer on earth a small distance away might see the star wink out for only 6 seconds, depending on whether the fat or the skinny part of the asteroid passed between their eye and the star. But if there were many observers, and they each had accurate clocks, you could actually use these observations to sketch an outline of the asteroid!





This is exactly what the members of the International Occultation Timing Association (known as IOTA) do. They coordinate their locations across the path of the asteroid's shadow on earth as well as along its "ground track" and send their data to the organizations central database. Over time, these observations build up and provide information about these objects size and shape. In addition, the actual times of arrival of the shadows lets astronomers improve their estimates of the orbit of the asteroid. All of this knowledge from a few frames on a video camera where a star disappears!





Well, this morning I made an attempt to add to this database by observing and recording the occultation of star TYC 5559-00693-1 (a very dim, 10th magnitude star) by the asteroid Hygiea from Hamton Beach State Park. This asteroid is pretty big, about 470 km across, so the occultation was expected to last about 10 seconds or so and cover a wide swath of ground across the Northeast. The occultation was scheduled to happen at 5:07am, so I set up my equipment (telescope and video camera) at 4am to record the event.

However, as I zoomed in on the area of the star that was going to be occulted, all the stars around it matched up with my sky map of the area except one. There was an extra, dim star very close to the target star, and this dim star did not appear on the star map. For a moment I wondered if I had mistakenly pointed my telescope at the wrong area of the sky. Then I realized with a rush of excitement that this "extra" star was actually the asteroid itself, on its way to pass in front of the target star. I actually saw the asteroid and the star close to each other!

Although I was now sure I had the target star clearly identified in my eyepiece, unfortunately a bank of clouds rolled in at 4:30 and by 5:00am not even bright Venus could be seen in the sky. Such is astronomy in the Northeast. So I hope my fellow IOTA enthusiasts who were spread out across Massachusetts and Connecticut had clearer skies.

There are hundreds of occultations each year, so I will try again soon.

Jupiter takes over from Saturn

It's with some sadness that we bid Saturn a temporary farewell in the evening sky. Earth's progress in its orbit has brought us around to the side of the Sun where Jupiter is currently travelling, leaving Saturn too low in the west to see it from the East coast. Interestingly, I just got back from a trip to California and out on the West coast Saturn is still high enough after sunset to get about an hour of viewing. We'll give Saturn a well-deserved rest, and when we see it next year those rings will be opened up a few more degrees and the view will be even better.

Meanwhile Jupiter has begun to dominate the evening sky, and in the past week literally hundreds of people have seen it (and its moons) from my usual outpost on the sidewalk in Hampton Beach. This has been one of the clearest weeks in recent memory, and the first time I can remember doing sidewalk astronomy four nights in a row without any interruption for cloudy weather.

We also had a few nights where the waning gibbous moon rose early enough for some clear views.

I have started handing out 4x6 cards with some lists of local astronomy resources (club web sites, web sites for Stellarium and Cloudy Nights, etc.). On the back I put a reproduction of the page of Galileo's notebook in which he made the first sketches of Jupiter's moons in 1609/10. I may have to raise my estimates of how many people looked through the telescope, last night I gave out 30 of these cards in 2 hours, and that was mostly to kids. I think I have been underestimating how many people look through the scope, but I guess I'm having too much fun talking to people to count them!

Teaching depends on what other people think

An article in last Sunday's New York Times magazine about teaching how to teach contained this quote:

"Teaching depends on what other people think, not what you think."

The author of that quote was Deborah Ball, Dean of the School of Education at the University of Michigan.

I like teaching. Right now I mostly teach Astronomy. I don't claim any special knowlege of the subject over what an interested amateur can aquire in a few years of reading and observing.

I do, however, feel that I have a sense of what my students are thinking, what their mistakes are, how they make them, and how to lead them back to a proper understanding of a subject. Deborah Ball calls this the ability to step outside of your own head.

For me, it involves trying to have a trick, explanation, demonstration or other technique for correcting "wrong thinking" in a way that illuminates the problem and shows why another approach gives better results.

So preparing to teach Astronomy has required learning at two levels. First were the facts and theories themselves. Then came learning how to teach these concepts in ways that were fun, entertaining, and above all "sticky." Some of these techniques I have gotten from books, some from other Astronomy Club members, and some have been born of necessity during that moment of inspiration in front of a group when nothing you have tried has worked and you really need a new approach.

I find the development of the skills to teach the subject as much fun as I have found learning the subject itself. Actually teaching it - where the skills and knowledge come together in real time to make that "aha" moment for people - is more enjoyable still.

I feel I have always been sensitive - some have said perhaps too sensitive - to what other people think. Is it possible that this is a trait which might contribute to success in teaching?

Busy couple of weeks!

The last few weeks have been filled with wonderful activities and fun events. Members of my astronomy club, the New Hampshire Astronomical Society, joined me for an evening of sidewalk astronomy in Portsmouth. We had a wonderful time, lots of visitors of all ages. Mars, M42, the Pleiades, and first quarter moon all competed for attention. Then I gave a talk at the Rey Center in Waterville Valley, NH. Margaret and H.A. Rey were lifelong residents of Waterville Valley. Among their many accomplishments were the Curious George series of books, and a book called "The Stars - A New Way to See Them" in which they drew new outlines for the same starts in the constellations to form figures which matched their names more closely.

One of the demonstrations in that book included an umbrella to show why the Big Dipper appears in different orientations (sometimes holding water, sometimes on end, sometimes pouring water out onto the ground) at different seasons of the year. Several years ago I made one of these out of a large clear umbrella and I have used it in many classes. It was a real honor to "bring it home" to the Rey Center and use it in a demonstration where the Reys lived and worked.

NHAS sponsored a skywatch for the Alton School in Alton, NH. I spoke there on the life cycle of stars and various "What's Up Tonight" topics, then we all went outside for a few hours of observing. Some clouds marred the sky for the first hour, but then things cleared up and it was glorious for a couple more hours.

Finally, last night a friend and I spent a relaxing few hours in Portsmouth showing people Mars, M42 and eventually Saturn once it rose over a building. I put some stickers on the curb at the right distances for the planets and invited people to walk down Congress St. on the "Portsmouth Planet Walk" to see the relative distances of the planets. One mom responded, "Oh we know all about that. We parked near Jupiter!"

First light with XT10i

I picked up a used XT10i from a friend, and it is giving excellent views.

For the first time I was able to see surfact markings on Mars, at about 10:30 pm when Mars was nice and high. A 9mm EP with 2X Barlow gave 266X.

This morning I enjoyed views of Saturn (4 moons clearly visible, but rings are closing...sad). Also nice views of the moon at 3rd quartet. Lots of detail visible including lava flows along the floors of the plains.

Ted

Sidewalk Astronomy - Early Evening Jupiter

It's been clear and cold in the Northeast lately, so with some warm boots, long underwear and assorted

hand and head coverings I set up on the Portsmouth sidewalk in front of Starbucks for a couple of hours each evening for the past few nights.

Amazingly, it seemed like more people were interested in viewing through the scope than is typically the case in summer - almost 100% of people said sure and enjoyed the views. We looked at Jupiter on nights when I was out early, and Mars and the Pleiades for later events after Jupiter had set. I also took a peek at M42 when nobody was around, but due to the light-polluted sky it was less than impressive.

One of the Portsmouth parking meter readers (yes, the ones who give tickets) thanked me for giving back to the community, he has seen me many times in various spots around town. Jupiter's 4 moons were clearly visible, as was the jet stream blowing past the planet. Cloud bands were vaguely visible at moments when seeing steadied, but these moments were few and far between.

One other thing - it's exactly 400 years ago this week that Galileo recorded sketches of Jupiter's moons in his notebook, later publicized in his "Starry Messenger".

Lunar X Prize!

It's been a long time since I've posted, but tonight I am celebrating my first observation of the Lunar "X". This is an object visible only for one night a month. It is made up of the walls of several craters, and when the light is just right it makes a clear, bright "X". Here is a picture from Wikipedia showing the X, just as I saw it in the Celestron C6 refractor. You can see it on the left of the picture. Notice how the floors of the craters are dark but the walls make up the X by protruding into the sun's rays as they slant over the landscape. It is sunrise on the moon! Unfortunately the high winds we have had for a week have made the atmosphere very turbulent, so fine detail was hard to see.

I also looked at the double cluster in Perseus. This was less affected by the poor seeing, and the individual stars popped right out including the obvious red stars, both within and one special one between the two clusters.

The 16 degree temperature kept me from staying out too long, but it was fun while it lasted!

Sanborn School Star Party with NSAAC

Last night I made it to the NSAAC much-rescheduled star party at the Sanborn school in Andover, Mass. There were about 100 kids and parents, and seven scopes. I set up binoculars on a tripod so folks waiting in line for my scope could see the Pleiades, then showed them the double double in Lyra. Seeing was not very good, the individual doubles were just "barely" visible in the C8. Maybe it needs collimation, however star tests looked good. Quite a few of the kids could split the second doubles (young eyes!) and once in a while a parent could see it when the seeing steadied for a second. I think most folks were amazed that a star could be a double, much less a double double - I still am too!

Sidewalk Astronomy in Portsmouth

After a cloudy few days the sky cleared in time for some sidewalk astronomy in downtown Portsmouth. The town was packed with people enjoying a cool Saturday evening.

I set up the WO 80mm refractor on the iOptron Minitower and it tracked perfectly all evening as Jupiter swung from one side of Market Street to the other. The alignment couldn't have been better, I got about 90 minutes on the west side of the street and then another hour on the east side. At least 100 people looked at Jupiter, marvelled at its moons and took cell-phone pictures through the eyepiece, most with good success.

The most common question I got was, "Is this some kind of a special occurrence?" Using my (now coffee-stained) map of the solar system I explained how we saw different views at different times of the year, and how the planets move around the sun.

The second most common question was, "Why are the moons all in a line." I explained that if you could float *above* Jupiter, you would see the moons going around in circles, but since the Jovian system of moons is pretty much in the same plane as the rest of the Solar System, we see the orbits "edge-on" like looking at the edge of a piece of paper. Most folks understood right away.

Having some signs helped people understand what was going on. I use a whiteboard with some velcro on the back to sketch what people will see in the eyepiece.

It was a wonderful night of sharing!

A Dobsonian Handshake

I'm on a business trip to California, so last night with nothing special to do and a clear night sky, I set up my 80mm refractor in front of a local Safeway to spend the evening showing people Jupiter and the gibbous moon.

There was a lot of interest, but one lady in particular told me that over 20 years ago when her son was 4 years old, she took him to a San Francisco sidewalk star party and met a gentleman named John Dobson who, along with others, was showing people the night sky. She knew his whole story and her son still remembers that evening.

So while I haven't shaken John Dobson's hand personally, last night I shook the hand of someone who did.

Nebraska Star Party 1

It's hard to describe the experience of setting up under the darkest skies in the US, seeing the Milky Way become clearly visible before the sun has completely set, and then being treated to the most incredible display of starry wonder I've ever imagined.

This is the Nebraska Star Party, where I've spent the last two nights enjoying sights I've never seen before. NSP is held every year about 25 miles south of Valentine, NE, in the "sand hills" area of north central Nebraska. Skies are clear and there are no - repeat no - lights visible, other than the tiny light dome of Valentine in the north which we sometimes confuse with the lights of a car on the other side of the reservoir.

Andromeda easily visible to the naked eye. Sagittarius filled with open and globular clusters to the extent that every binocular field of view shows some other breathtaking object, which glow against the black background with the true 'diamonds on black velvet' experience. And just the sight of the Milky Way, our own galaxy, arching overhead from horizon to horizon, showing so many stars that finding Cygnus or Casseiopeia becomes an exercise in patience.

Luckily, my friends John and Pat from Denver were interested in joining me, so I sent my C8 and iOptron minitower to them via FedEx Ground (arrived perfectly and still in collimation) and they brought it with them on their drive. I flew to Omaha and drove to meet them in Valentine.

I don't do astro photography, but I will try to get a few pics of the milky way tonight. Tonight we will eat dinner at the NSP site, then open to the public at 9pm for outreach to say thanks to the residents of Valentine for hosting this Star Party for more than fifteen years.

Ted

Outreach on Star Island

On Wed., June 24th, I took my first-ever trip to Star Island in the Isles of Shoals aboard the M/V Uncle Oscar out of Rye Harbor to present an evening talk on Astronomy to the attendees (called "conferees") at the 2009 Natural History Conference being held at the Oceanic Hotel on Star. This group of adult Natural History devotees has been gathering for a week of lectures, workshops, reading, writing and exploring the island every summer for more than thirty years, and some have attended every conference.

I started by showing the first 5 minutes of the famous Charles & Ray Eames film "Powers of 10" which I'm sure most of you have seen. It pulls the camera back by 10 times the previous distance each 10 seconds, and you go from a picnic on the short of Lake Michigan to out beyond the Virgo Galaxy cluster in about 5 minutes.

From there I talked about the local neighborhood, Moon and Solar System, what some of the "stars that aren't stars" might be (clusters, binaries, nebulae, etc.), the Cassini mission including the Huygens descent movies (always a big hit), why the moon shows phases, and a few other things before wrapping it up some highlights from Saturn. We tried to do some observing but were completely shut in by clouds, so we had to settle for eating ice cream and talking.

The high point of the trip for me was getting to meet an elderly conferee who, in the 1960s, worked at MIT packaging electronics for the Apollo moon missions. Her hands were the last human hands to touch some of the equipment before it went to the moon. I thanked her on behalf of all of us for that dedicated work, and after shaking her hand I am now just one handshake away from touching the original Apollo spacecraft.

A gentleman named Al Doolittle, who had been a member of their conference for many years before passing away, used to bring a home-made 8" dob to every conference. His wife donated it to Star Island, and it now resides in the Natural History Lab building, along with a Bausch & Lomb 8" f/10 SCT (like a Criterion) with wedge and 110V motor drive, and a 3" refractor by Celestron on an alt-az mount with wooden legs. There are 4 eyepieces as well. The equipment is available for anyone to use, just check with the staff during the day if you ever overnight on the island. I left brochures and handouts for NHAS along with documents with links to our website and other web information.

Astronomy Day!

NHAS (the NH Astronomical Society) sponsored a big exhibit at the McAuliffe-Shepard Discovery Center on May 2. For the first time NHAS also offered an indoor session in addition to the outdoor display that we always sponsor (well, this is my first year participating!)

Indoors we did a lot of "educating" of the young ones, while outdoors some real demos, explanations, solar scopes, magnification demonstrations, and other hands-on activities really got folks interested.

Great day!

















It was a lot of fun, both inside and out. The pictures tell the story best!

Moon and Saturn on the Sidewalk in Portsmouth, NH

Wednesday evening was a beautiful, clear, calm and fairly warm night so I decided to try something new - set up two telescopes myself for some sidewalk astronomy - one for the Moon and one for Saturn.

Normally this would be difficult because I'd have to be bouncing back and forth between scopes, but I recently purchased (at NEAF, the North East Astro Fest) the Vixen SkyPod. The SkyPod is a neat little alt-az mount with tracking and it's own built-in computer, the Vixen Starbook-S.

Over the weeks since NEAF I worked a bit with the SkyPod and its manual, and got the basic functions down. I also tightened up the backlash on both axes using instructions from Mike Fowler at Vixen Optics. This reduced the play in the azimuth axis quite a bit.

How did it work on the sidewalk? Just great! I put a William Optics 80mm refractor on it, aligned it to the moon and did an "align" operation, then it kept the moon in the field of view pretty much all night, almost three hours. I tweaked it a bit about once an hour, or moved it to focus on a new part of the terminator, but it was a very helpful piece of gear. I could just point people to it and say 'take a look at the moon' while I operated the 8" Orion XT dobsonian and kept it pointed at Saturn. (I have a platform for the XT8 but I was too lazy to set it up.)

I had over fifty visitors in the three hours, including a little girl of about 4 years just recently adopted from Russia, who spoke no English but could certainly understand that beautiful view of the moon. I will never forget her big eyes when she saw it.

To top the night off, my first visitor came back with some Pizza just as I was packing up. That made a nice snack on the way home.

Getting ready for some observing on Nantucket

Tonight I got the 8" dob carefully collimated just to see how Saturn looked in it since the clouds have finally cleared out. It was beautiful as usual. At 180X I could easily see the gap between the rings and the planet even thought the ring tilt is only a few degrees. I put in a 9mm UO with 2X barlow which gave 266X and the view was spectacular, including cloud belts and at least four pinpoint moons. The Hyperions are great, but when you look at the moons, the Orthoscopic EP is clearly the winner, even over the WO Super Planetary.

This weekend is a work weekend in Nantucket, but I have an 8" dob down there and hope to do some observing during the new moon night on Saturday - right after I put in the new tile in Little Pines...

Saturn on the Sidewalk

Tonight I had some books to return to B&N so I set up the 4" refractor on the sidewalk outside the store in Newington. About 30 people came by in 90 minutes to see Saturn and Titan. Naturally I told everyone what I have just learned about Titan and the Huygens probe in 2007. I need to get some pictures of what Huygens saw. People were really happy to see both Saturn and Titan. In fact the manager of the store came out for a look, and then sent all his employees out for a peek.

Talking about Cassini

Last Friday night I had the honor and pleasure to give a talk on the Cassini-Huygens mission at the newly dedicated McAuliffe-Shepard Discovery Center in Concord.

I was not expecting this, but at the last minute our Astronomy club (New Hampshire Astronomical Society) got a call that the original speaker could not make it, and could we cover the talk.

The club's Educational Outreach Committee (which is fairly new, having met only about four times) came together in the clutch. One member set up web conferences so we could work on the presentation together. Another contacted Jane Houston Jones, JPL Outreach Senior Coordinator for the Cassini mission, who provided us with endless material. On Wednesday I put together an outline of the talk and that evening members of the committee signed up for various sections. Then each person combed through all the JPL presentations looking for the slide or video that best described each item, from launch through the Huygens probe landing on Titan, to the icy moons, Saturn itself, its rings, and finally the Equinox extended mission plans.

Three of us met at Panera's in Concord at 5pm on Friday and went over the talk, had a quick bowl of soup and then headed over to the Discovery Center. We had about 30 people attending including a troop of Boy Scouts who asked the most (and best) questions. We ended the evening with two NHAS members outside operating three scopes so all the kids and parents could see Saturn for real. It was a great ending to a really enjoyable evening.

Shuttle Discovery Launch from Rye, NH, and ISS pass

The shuttle launched tonight from Florida, and my son Jason called me to tell me he'd seen it go up (he lives in Orlando). Sure enough, about 8 minutes later we saw it from the beach in Rye, in the distant southeast, and watched it until it disappeared in the northeast.

Then about 30 minutes later, along came the International Space station, which Discovery will rendezvous with in 2 days. Here's a picture (60 second exposure) of the ISS going past Orion's belt. The exposure ended by lucky chance just as the ISS had reached the belt. Notice the small brightening along the streak - must be a glint from a window or a solar panel. If you look carefully you can see how the stars, normally pinpoints of light, have become streaks due to the earth's rotation. The camera was mounted on a photo tripod which did not make any counter-motion to the rotation of the earth as a telsecopic mount might do. Several families happened to be there so we made it a sidewalk astronomy night too!

Outreach at the McAuliffe-Shepard Discovery Center

The NH Astronomical Society has a long-standing relationship with the Christa McAuliffe Planetarium, where we provide public skywatches on the first Friday of every month.

Last Friday was extra special, because it was the grand opening and dedication of the new McAuliffe-Shepard Discovery Center, which includes the original planetarium and much more including an observation dome with a 14" Celestron Schmidt-Cassegrain telescope.

Although there were some clouds, we had a mostly clear night with around one hundred visitors between 6pm and 10pm. Four members of the NHAS had scopes set up, ranging in size from 4" refractors to 12" reflectors. Since the famlies were attending the opening of the Discovery Center, this was a very science-literate group and many of the kids knew a lot about the planets and moon already. We showed them Venus and explained why it was showing as a crescent, the lunar terminator and why craters were more clearly visible near sunrise on the moon, Saturn's rings, several star clusters, and a few other objects.