After receiving my 43rd Observing Program certificate a month ago, I didn’t see any additional Observing Programs I wanted to start, until now. I just finished creating the web pages for the newest Bright Nebula Observing Program. Reading the requirements and looking at the Object List for the Program, I am excited to get started on this one and see what these nebulas look like in my telescope. Review the Introduction page and decide for yourself if this will be the next program you play with.

Members of the Astronomical League: we have Observing Programs that need new Coordinators.

These specific programs are on the list:
Asteroid Observing Program
Carbon Star Observing Program
Constellation Hunter Observing Program (Northern and Southern Skies)
Meteor Observing Program
Sky Puppies Observing Program
Solar System Observing Program
Urban Observing Program

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“What telescope should I buy?”

“How can I learn my way around the night sky?”

“What can I see with my telescope?”

Outreach is all about connecting with the public. The Astronomical League has developed a series of downloadable outreach materials that do just that. They help answer questions commonly posed by the public and help spark curiosity about our fascinating hobby. These materials can be displayed at club activities and astronomy events such as Astronomy Day, school sessions, star parties and amateur conventions, and club meetings.

Simply download the pdf files on a CD and take it to a local printing shop (e.g., Kinkos). Many shops will print the materials in black and white on 20 lb paper for as low as $0.75 per square foot. Color printing will likely cost substantially more, which is why most layouts are designed in black and white. At some shops, the maximum paper width is 36 inches with no restriction on length. Indeed, banner posters many feet long can be printed. If your home printer allows banners, they can be printed on banner or “doodle” paper found in craft stores (e.g., Michael’s).

The aspect ratio (width to height) is given in the description of each poster. Therefore, the printed size can be any proportion of that ratio with no unintentional cropping as long as the maximum width doesn’t exceed 36 inches. For instance, a poster with a 2:3 aspect ratio that is originally designed to be 20 inches by 30 inches can also be enlarged to 24 inches by 36 inches.

Foam project boards (20 x 30 inches or 24 x 36 inches) or tri-fold display boards (36 x 48 inches) can be used as the backing support for the posters. These inexpensive rigid backs can be found at craft stores or in the craft section of discount retail stores. The materials can be temporarily mounted using binder clips. This allows posters to be quickly and easily switched with other posters.

Some posters feature questions with multiple choice answers. The correct answers lie hidden under a liftable flap made from a stiff card taped to the poster.

The ABCs of Star Gazing

How would you describe to a friend the size of a sky object, its distance from a particular star, its brightness, or its location on the celestial dome?
The ABCs of stargazing allow you to do just that!

Download “The ABCs of Star Gazing” as banner size (19.28 x 29.28 inch) PDF format 450 Kbytes or as letter size (8.5 x 11 inch) PDF format 101 Kbytes (Revised April 15, 2016).

The Spring Sky

In a guided tour consisting of nine easy steps, the late April or early May sky is described. The poster features a large all-sky map showing the ecliptic, the Milky Way, and stars down to 4th magnitude.

Download “The Spring Sky” as poster size (PDF format 406 Kbytes) or as paper size (650 Kbtyes) 

The Need for Telescopes

Directly compares the apparent sizes of the moon, the bright planets, and a typical field of view of a low-powered telescope.

Download “The Need for Telescopes” as banner size (8.5×44 in.)  PDF 2.6 Mbytes) or as paper size (8.5×11 in.) PDF 987 Kbtyes 

Our Unnatural Night

Aspect ratio: 3:4

Original design size: 36 inches x 48 inches

Requires a lift able “Answer Flap” to conceal the answers to the nine questions posed. Simply tape (masking tape) the top edge of the flap to the top edge of the answer box.

Mounts to a 36 inch x 48 inch inexpensive tri-fold display board.

Describes how problem of light pollution affects us all.

Download in a poster format “Our Unnatural Night” (PDF Format 3.4 Mbytes) or as letter size trifold, 8.5 x 11 inch, front and back for two-sided printing.

The Autum Sky

Aspect ratio: 2:3

In a guided tour consisting of eight easy steps, the late September or early October sky is described. The poster features a large all-sky map showing the ecliptic, the Milky Way, and stars down to 4th magnitude.

Download “The Autumn Sky” as poster size (PDF format 408 Kbytes) or as paper size 8.5x11in (PDF format 668 KBtypes)

Is that a Planet or a Star?

Aspect ratio: 2:3

The visual differences between a planet and a star are noted along with a description of where the different bright planets can appear in the sky. The ecliptic is presented.

Download  “Is that a Planet or a Star?” as poster size 19.487 x 29.443 inch PDF format 296 Kbytes) or as letter size 8.5 x 11 inch 1,879 KBytes. 

Seasons Change, Stars Change

Aspect ratio: 2:3
Diagrams illustrate why different stars come into view as the Earth orbits the sun which causes the seasons to change.

Download “Seasons Change, Stars Change” (PDF format 444 Kbytes)

What is the best telescope for me?

Aspect ratio: 2:3
Newcomers to the hobby are often confused as to what telescope they should buy. This guide gives them suggestions on what to consider and what is important.

Download “What is the best telescope for me?” as banner size (PDF format 428 Kbytes) or as page size (8.5×11 in.) PDF (1,8 Mbytes)

You are here

Aspect ratio: 2:3
Our location in the Milky Way Galaxy is illustrated. The barred spiral galaxy NGC 1365 is used as a model for the Milky Way.

Download “You are here” (PDF format 2.19 Mbytes)

How is your knowledge of astronomy and stargazing?

Aspect ratio: 3 x 4

The public will enjoy answering the questions posed on this 36 x 48 inch poster which fits nicely on a try-fold display board. Requires three liftable cardboard answer flaps. Use masking tape to tape the top edge of each cardboard flap to the top of the respective answer box.

Downoload “How is your knowledge of astronomy and stargazing?” (PDF format  5.4 Mbytes)  – Updated Oct 28, 2011
 

First Telescopic Observation Certificate

Certificate: landscape

This 8 1/2 x 11 inch certificate can be awarded at public events for people who have never looked through a telescope. Simple fill in their names, dates of observations, the public events where the observations took place, and the objects they observed.

Download “First Telescopic Observation” Certificate” (PDF format 2.5 MBytes)

How do you find celestial objects?

By Bill Pellerin
Houston Astronomical Society
GuideStar Editor

Just after midnight (Central Daylight Time) on June 21, summer began officially. You would be forgiven (in some parts of the country) if you thought that summer was here prior to that date, with some especially hot days. June 21 was the summer solstice, the day on which the Sun is the highest in the sky and the longest sunlit day in the year. At the solstice the Sun is at its northernmost excursion.

I live in Houston, Tx, where the latitude is 29.8 degrees north. Does the Sun ever get directly overhead here? No, it doesn’t. That is, the Sun does not reach the zenith. You’re probably aware of two lines on the world map called the ‘Tropic of Cancer’ and the ‘Tropic of Capricorn’. These two lines represent the northernmost and southernmost positions of the Sun at summer solstice and winter solstice. Does the Sun get to the zenith at any point in the continental United States. Again the answer is no.

The northernmost position of the Sun this year is 23 degrees, 26 minutes. So, in my hometown, the Sun was about 6 degrees south of the zenith on June 21 as it crossed the meridian, and close to M35 at the foot of Gemini. How about other locations? Brownsville, Tx has a latitude of 25.9 degrees; still too far north. Even the southernmost location in the continental United States Ballast Key, Florida at 24.5 degrees north is just about one degree too far north. The southernmost point of the entire United States is at Ka Lae, Hawaii at 18.9 degrees north, so clearly the Sun will reach the zenith at this location and at other places on the big island just north of this site.

The good news about the summer solstice, of course, is that the amount of darkness per day increases from now until December 21, so we’ll have a bit more dark time every day. How much more dark time? Well, the velocity at which the Sun moves south in the sky varies over that time, but, on average, Houston gets about 1.6 minutes more of darkness every day between now and December 21. This is based on astronomical twilight, which is when the sky gets as dark as it’s going to get (not considering moon phase). On June 21, we got just over 6 hours of darkness and on December 21 we’ll get almost 11 hours of darkness. We’ll have two and a half hours extra of darkness in the evening and two and a half extra hours of darkness in the morning. I’m not taking into account the changes in clock time associated with daylight saving time.

If you live north of Houston, the change in dark-time between summer and winter is even higher.

The north to south (summer to winter) movement of the Sun from our viewpoint is a manifestation of the tilt of the axis of Earth. On the first day of summer, the southward velocity of the Sun is near zero. At the autumnal equinox on or near September 21, the southward velocity is a maximum, at the winter solstice the north-south velocity of the Sun is near 0 and it’s a maximum south to north velocity at the vernal equinox on or near March 21. I calculated the change in hours of darkness (based on USNO data) over the year and plotted the result. As you might expect the result looks like a familiar sine wave. There would be some variance from a sine curve because the orbit of Earth around the Sun is slightly elliptical, not circular.

The US Naval Observatory has a web site that shows hours of darkness or daylight for various cities in the U.S. and around the world. The numbers in their calculations don’t match mine because I’m using astronomical twilight time and they’re using (essentially) sunset time. (Search for “USNO hours of darkness” and you’ll find the web site.)

By Bill Pellerin
Houston Astronomical Society
GuideStar Editor

If you have a world globe in your house it may include a strange figure 8 pattern, called the Analemma, with some dates on it. Without going into great detail, this shows the north/south position of the Sun in the sky for the year. Because the orbit of Earth around the Sun is elliptical, the Sun is not always on the meridian at mid-day. In fact, the Sun is only on the meridian at mid day on the two equinox days and on the two solstice days. To keep ourselves going to meetings our time clocks show the average length of the day as 24 hours. Close enough. On some days the Sun is east of the meridian at noon and on some days it’s west of the meridian at noon (always ‘standard’ time). The Analemma shows you how this goes.

So for the next 6 months, revel in the notion that you’re getting more dark sky every day. Take advantage of it.

ALCon 2013 Flyer.

ALCon 2013 Flyer with white background for printing

Library lending telescope flyer

Registration form

By Bill Pellerin, Houston Astronomical Society

GuideStar Editor

If you’ve been outside on a dark night, looking up you’ve probably seen a number of satellites move across the sky. I see them in my eyepiece from time to time too; it’s a fairly common occurrence. They zip by in a hurry and I haven’t made an effort to figure out which one I saw. If you’re an imager you likely don’t want a satellite to be recorded on your camera. It happens, though, and there are image processing techniques to fix those problems.

But, what if you want to see a satellite? If you want to see a satellite, such as the International Space Station, go by it’s not difficult. You need to know where in the sky to look and when. The simplest way to find out, go to www.heavens-above.com. Once there you can register (no cost), and save your location, or you can simply pick your location, pick the ISS and get a report of visible passes in the next 10 days. The visible passes show where the satellite will first show up in the sky (altitude and azimuth), how high it will get in the sky, and when and where it will be when it disappears from view. You can look at a sky map for the event, too.

Satellites are visible to us in the night sky because they can be in sunlight while the observer is in darkness. If the satellite is 300 miles above Earth it will be sunlit later in the evening than we will, with our eyes just a few feet above Earth. This means, that for many of the satellites you will only be able to see them for the few hours after sunset or the few hours before sunrise. Think about this. If you are outdoors and it’s just getting dark after sunset the Sun is below your western horizon. A satellite moving (conveniently) west to east would be illuminated by the Sun and reflect some of that sunlight to your eyes. As the satellite moves east it likely will move into the shadow of Earth before it gets to the horizon.

There are satellites at various altitudes above Earth. Many of them are LEO (Low Earth Orbiting) satellites. The Space Station is at about 230 miles above Earth and would be considered a LEO satellite. If you use the common size for Earth (8000 mile diameter) and scale that down to the size of a desktop globe, say 12”, the Space Station is about 1/3” above the surface of the planet.

That said, a LEO satellite, being closer to an Earth-based observer will (all things being equal) be considerably brighter than another satellite at very high altitudes. How bright any satellite appears to you will depend on the size of the satellite and the reflectivity of the satellite as well.

How about geosynchronous satellites? Those are the ones whose orbital period is equal to the (sidereal) period of rotation of Earth. That is, they must be high enough so that the period of one orbit equals 23 hours, 56 minutes, and 4 seconds. It turns out that if you do the math, the satellite must be placed in orbit just over 22,000 miles above Earth to be geosynchronous. This is commonly done for satellite radio satellites and communication satellites of various types. For our 12” Earth globe, these satellites would be roughly three Earth diameters away.

Can you see these? Yes, you can but because these are dime seeing these will require a telescope and a precise understanding of where these objects are on the sky. Since they’re moving at a sidereal rate, a telescope that tracks the stars will also track these satellites.

Commonly, amateur observers who aren’t primarily satellite observers like to see the Space Station, the Hubble Space Telescope, and missions to and from the Space Station. These are easy to do on dark nights without any optical aid. I recall seeing the Space Station go over with the Space Shuttle trailing along behind it (some years ago, of course). The Shuttle was leaving the Station on its way back home.

The other very cool thing to see is an Iridum flare. These sound more exotic than they are. These communication satellites have large solar panels, and when the orientation is just right there’s a very bright reflection of sunlight from the solar panels to your observing position. I’ve seen a bunch of these and it’s definitely worth your time to step outside and see one. The heavens-above web site can predict when one will be available for you to see.

There is also software you can install on your personal computer or on your mobile device. Some astronomy software has satellite tracking capabilities built in.  I use TheSky for my astronomy work, and it will track satellites across the sky. I have GoSatWatch on my iPhone; it’s a paid application. GoSatWatch allows me to pick the satellites that I want to view (ISS, HST, etc.) and it will alert me when a visible pass is coming. It also estimates the magnitude (brightness) of the satellite, and shows an all-sky view of the pass. Once the pass starts, the software shows the position of the satellite in the sky in real-time. Many of these satellites are quite bright so you can see them from an urban observing location.

If you want to try to see a satellite through your telescope (or take its picture) you need some special software to drive your telescope at the satellite rate. Satellites move across the sky quickly. Join the Yahoo Group ‘satellitetracker’ to learn about doing this. (Go to groups.yahoo.com.) I’ve seen some really nice images of the Space Station taken by amateurs. I also have seen an image if the ISS transiting the Sun.

Want to talk to an astronaut aboard the ISS or communicate through an earth-orbiting satellite? You can do this by amateur (ham) radio. To get your license go to www.arrl.org/get-on-the-air and find out how. To find out more about amateur radio satellites go to www.amsat.org. To communicate to the ISS or through a satellite you’ll need to point your antenna directly toward the satellite. If you have a telescope mount that can be driven at the satellite rate it may be possible to attach the antenna to the telescope mount and let the mount do the real-time pointing for you. There are also alt/az antenna rotators you can use to point your antenna at satellites.

The Astronomical League has a program called Earth Orbiting Satellite Observing. It is created by the Colorado Springs Astronomical Society and it will introduce you to the process of observing satellites. Check this out on the Astronomical League web site.

By Bill Pellerin

Houston Astronomical Society

There are a variety of amateur observers – those who go to the darkest of sites with the largest of telescopes to see the dimmest of objects, and there are those who (like me), believe that the universe reveals itself in every object we see, including the bright ones. The poet William Blake talked about seeing the world in a grain of sand. If Blake can see the world in a grain of sand surely we can see the universe in a single star.

I write a monthly article for our club’s newsletter in which I provide the information needed to find a star or other bright object in the sky. Then I attempt to tell the reader why that object is interesting. The newsletters are available at: www.astronomyhouston.org.

So, let’s look at a bright star that’s easy to see with any telescope and which comes with a good story.

La Superba (Y CVn) is at RA: 12h, 45m, 08s / DEC: 45 deg, 26 m, 25 s in the constellation Canes Venatici. It is especially well placed for viewing in the spring and it’s easy to see. As this is written, in April, 2013, Y CVn is shining at about magnitude 5.0 (you can see a plot of magnitude versus time at www.aavso.org). The designation Y CVn tells you that it’s a variable star; its brightness range is from 4.8 to 6.3 with a period of about 160 days. It’s also a carbon star (see the Astronomical League Carbon Star observing program on this web site). Other parameters:

Distance: 710 light years

Variable type: SRb (Semi-regular)

Temperature: One of the coolest stars you can see at 2200 Kelvin

Mass: 3 solar masses

Size: Radius of about 2 AU or about 430 times the radius of the Sun

Composition: Significant concentration of Carbon-13

So, what’s a carbon star and why is it red? The answer to this question is what makes this star interesting. Mid-life stars are said to be on the main sequence, and main sequence stars fuse hydrogen (the most abundant element in the universe) to helium. The Sun is doing this now.

When the hydrogen supply runs low, and the star gets hotter it begins fusing helium to carbon at the core of the star. So there’s carbon at the core (the byproduct of helium fusion), with shells of helium and hydrogen surrounding the core. The energy of the star is generated at the core and that energy moves to the outside of the star mostly by convection, a process very similar to what happens in a boiling pot of water. You may have seen images of the Sun that show a granular pattern, most visible in the chromosphere; these granules are the result of convection in the Sun.

In the case of a carbon star, the core carbon is ‘dredged up’ from the center of the star and carried to the outside of the star. For this reason, when we look at the star we’re seeing some of this carbon.

The carbon-based compounds in the outer layers of the star absorb much of the radiation at shorter, bluer wavelengths enhancing the visual redness of the star. The star radiates much of its energy in the infrared (heat) that is invisible to our eyes.

This carbon at the ‘surface’ of the star acts as a blanket around the star causing it to get hotter. As it does, some of the carbon is burned off, the star gets brighter, and a new exterior carbon layer starts to form. This accounts for the variability in brightness that we see.

Carbon Stars are literally off the chart in color. The traditional color designations (OBAFGKM) for stars do not apply to carbon stars, so a special color category for carbon stars was created — ‘C’. This star falls into that category.

This is a low mass star and its final fate will be to become a white dwarf, cool off to a black dwarf,  and disappear from view forever. On its way it may produce a planetary nebula, visible for only about 60,000 years.

The name 'La Superba' was attached to this star by Father Angelo Secchi, an Italian astronomer at the Pontifical Gregorian University in the mid 1800's.

Take a look at this star and check out the Carbon Star Observing Program here on the Astronomical League web site. My Observing Stellar Evolution program goes into more detail about how stars are formed and evolve, and ultimately die.

By Bill Pellerin

Houston Astronomical Society

GuideStar editor

If you look at the population of stars by color you will find that as you go from blue to white to yellow to orange to red the stars go from rare to plentiful. You probably know that star colors are given letters as follows OBAFGKM from blue to red. Does this make sense? No, not if star colors are your primary interest. Originally the classification of stars by letter was based on the strength of the hydrogen absorption line in the spectrum of the star. With that in mind the A star has a strong hydrogen line, a B star had a less-strong hydrogen line, and so on.

We’re stuck with this color scheme, and if you look at a HR (Hertzsprung – Russell) diagram you’ll see these designations (or the equivalent temperatures) along the horizontal axis. Color and temperature are the same thing. The hotter the star, the bluer; the cooler the star, the redder. A HR diagram plots color versus luminosity and it will surprise nobody that more massive stars are hotter and more luminous.

Anyway, only one in three million stars (.00003%) is an O star whereas 77% of the stars are M (red) stars. This means that for every O star there are 2,310,000 M stars. So, it’s a challenge to find an O star on the sky. If you want to see one, you won’t do better than Plaskett’s Star (SAO114146), a bright steely-blue star high in the northern sky, in the constellation Monoceros.

It’s the brightest star in a field of stars and shines like a diamond in the sky. Its sky coordinates are: RA 06 h 37 m 24 s, and DEC 06 deg 08 min 07 sec, and it shines at magnitude 6.1 so it’s easy to see in even the smallest of telescopes. Plaskett’s Star is estimated to be about 100 solar masses, one of the more massive stars in the sky. The star that you see is really a double-star, but they are so close together that you will not be able to separate the pair in an amateur telescope. According to stellar researcher Jim Kaler, while the system totals 100 solar masses the two components are 51 and 43 solar masses each, making the total system mass near the 100 solar mass estimate. The space between the stars is estimated to be about 50 million miles. The uncertainty in the total mass of the system and the distance between the components of the system is associated with the uncertainty of the distance to the system. It’s simply too far away to determine the distance using parallax measurements, so other, less accurate methods are used.

The end-of-life of stars is difficult to predict with certainty, but these are very high mass stars destined to become neutron stars or supernovae. What we can’t know is which one will reach its demise first and when it does what will happen with the other star. Perhaps nothing unusual will happen and we’ll end up with a binary black hole system.

It was discovered to be a spectroscopic binary star by John Stanley Plaskett in 1922 when he was working as director of the Dominion Astrophysical Observatory in British Columbia, Canada.

His interests included measuring the radial velocities of stars and other objects by measuring the red or blue shift in the spectral lines of the light from the object. In binary stars the spectral lines move in a periodic way that reveals the movement of the components of the star system. Plaskett died in 1941.

Compare this star with the white star in Albireo (you’ll have to wait until summer) – the white star here is a B star, slightly redder than Plaskett’s Star, and a lot more common. The other star in Albireo is a K star, noticeably orange and very common.

Bill Pellerin

Houston Astronomical Society

GuideStar Editor

My observing log is looking a bit empty these days. It’s accurate to say that I don’t live in a part of the world known for its clear skies (the gulf coast). I suspect that only a few of us are fortunate to live in places with a large number of clear nights.

What to do? What can we do when we are visited by cloudy nights? Quite a lot, actually. Let me suggest a few things.

Schedule an observation on a remote telescope. There are several telescope systems online on which you can purchase time. You can point them where you want, take the images you want and download those images to your personal computer. Generally, these systems are quite good, using telescopes, mounts, and filters, that are quite costly. Maybe you have a comparable system in your backyard, but I don’t. You can operate these telescopes in real-time, schedule observations, script observation runs on these telescopes and pick up the data (images) in a day or so. I’ve made numerous observations this way, and, although I’d rather use my own system, these systems allow me to pursue my amateur astronomy interest without leaving home. Want to do something fun? Take an image of a moving object over a period of time and stitch the images together to show the movement. I did this with Vesta in 2010. The downside of using these systems is that, depending on what you’re doing, they can be expensive.

Read your equipment manuals. Have you ever done this? If not, you may be missing out on features of your telescope, mount, or camera that will make your observing process easier and more fun. It’s easy for us to find ourselves doing what we’ve done before because that’s the way we’ve always done it. My mount has a capability of significantly improving its polar alignment built into its controller. It took some time for me to understand the process, but now that I do I use this capability to improve the mount’s tracking.

Plan your next observing session. The amount of time we actually get to spend under a dark, starry sky is often limited. Optimize your time by planning your observing. There are several computer programs that can help with this. This software allows you to create an observing list based on, say, an Astronomical League observing program. Some observers have created these lists and made them available for download. Then, the software will tell you which objects are available to you to observe on that night. If you don’t want to have a computer on the observing field with you, print the list before you go out.

If you’re imaging you’ll need to decide which filters you want to use for your object of interest, assuming a monochrome imager. You need to determine your exposure time for each filter and have in mind how you are going to process the images following the imaging session.

Read a book, or one of those magazines you’ve been stacking up. Make a serious effort to read through the astronomy magazines or an astronomy book that you’ve been hoarding for a while. If you don’t have a book you’re eager to read, get one – buy it or visit your local library to borrow it. My library even has e-books available for loan. It’s easy to get behind on your reading, so don’t let it happen. Make an effort to keep up.

Take an online class or view an online lecture or presentation. There is a lot of astronomy related material online these days. Some of it is in the form of podcasts, both audio and video. Many colleges are putting their class lectures online for all to see. There are college level courses available via audio (CDs or download) and video (same). There are audio books that you can listen to. Check those out. I have listened to an audio book on the history of astronomy several times. I can even quote some passages from the book. Still, it seems that I hear something new every time.

Process your imaging data. Do you have any images that you haven’t processed yet? Have you learned any new techniques for processing those images? Cloudy nights are a good time to work on these images, develop some new skills, and produce a ‘keeper’ picture for the wall.

Rationalize your equipment inventory. Admit it. You (and I) probably have too much equipment sitting around. What about that old, but still usable, telescope that’s been sitting in the closet for a few years. A friend of mine has a personal ‘policy’ that if he hasn’t used something in a year he gets rid of it. I’m planning on taking a telescope that I rarely use to a star party. I’ll use it for the event and offer it for sale at the end. I hope that someone else will take it home.

There are web sites that list equipment for sale, often at no cost to the buyer or seller. I’ve bought and sold on these sites with outstanding results. It’s a bit of work to photograph your equipment, create the listing, monitor the sale, and finally pack and ship the equipment to its new owner but it often a true win-win situation. You’re getting rid of something you are not using, you are getting a bit of cash, and the buyer is getting equipment he or she will use at a good price.

Wishing you clear skies.