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Welcome to Houston Astronomical Society

Fostering the science and art of astronomy through programs that serve our membership and the community. Founded in 1955, Houston Astronomical Society is an active community of enthusiastic amateur and professional astronomers with over 60 years of history in the Houston area. Through education and outreach, our programs promote science literacy and astronomy awareness. We meet via Zoom the first Friday of each month for the General Membership Meeting and the first Thursday of the month for the Novice Meeting. Membership has a variety of benefits, including access to a secure dark site west of Houston, a telescope loaner program, and much more. Joining is simple; you can sign up online or by snail mail.

Membership Renewals and New Member Adds on Hold

Hello all,

We’re almost done with our website migration, so to make sure we transition everything over properly, we’re putting all membership renewals and new member processing on hold until January 9.  Please bear with us as we get through the migration.  We will announce when you may renew your membership when the migration is over.  Thank you very much for your cooperation.

Joe Khalaf
HAS President

by Steve Goldberg

Asterism: a grouping of stars that form a recognizable pattern.

Constellation: Pisces
Right Ascension:  23h 17m 00.0s
Declination: -01° 45' 00"
Magnitude: 8
Size: 22’ x 50’                    

In honor of the Artemis 1 mission, we feature an asterism that looks like a rocket ship. This asterism, sometimes labeled as an open cluster, is located in Pisces, near the border with Aquarius.

There are 3 stars that form a triangle, that make up the shape of the capsule on top of the rocket. With a single star further out to represent the capsule escape tower. And then 3 stars that form a short line represents the engine exhaust.

by Daniel M. Roy and Debbie Moran


These shielded LEDs in a restaurant garden in Las Cruces, NM are warmer and put light exactly where it is needed

Imagine an electricity generating company building an observatory, encouraging STEM education within the community as well as heightening the community’s interest in limiting light pollution.    This is what the Exelon Corporation (now Constellation Energy) did in 2016 by building an observatory in the Muddy Run Recreational Park in southeastern Pennsylvania at a goldilocks distance from Lancaster.   To quote from a 2020 edition of 50+ life, “This part of southern Lancaster County lies in truly dark skies, away from the light pollution of much of the surrounding area. But it is sufficiently close to Lancaster to attract a curious public.   It is by far one of the most innovative and well thought-out and technologically sophisticated projects of its type in Pennsylvania.”

The light pollution problem

Here in Houston you have to drive a couple of hours to find dark skies like in Muddy Run Park.  The International Dark-Sky Association founded in 1989 has been educating communities about lighting for three decades. They first coined the term “light pollution” to describe the adverse environmental effects not only on the night sky but also on the humans, animals and plants who live below. Of course, we need light at night to see and feel safe in cities and towns. But there is a way to do it without driving out our view of the stars.

The LED street light revolution is highly beneficial because LEDs consume a fraction of the energy of other lighting technologies. But Houston, like many other early adopters, is using them counter productively. What is the problem? LEDs are highly directional and pinpoint…a little goes a long way and it is easy to over light. The blue part of the spectrum that makes up 30% of their neutral white (4000K or Kelvin) color can cause a host of problems. The shorter wavelength is inherently higher glare for drivers and homeowners because it scatters worse in the atmosphere and your eye. The reason objects appear sharp under whiter light is that the eye’s pupil is shrunk down to the smallest possible opening. But this is also the same mechanism that destroys night vision, making nearby areas appear much darker. The shallow shielding on Houston’s lights still allows the bright LEDs to be seen from some distance causing some areas to disappear in the glare. We are using twice the brightness yet seeing only half the light.  

Seeing is believing. We have gathered some examples of excellent as well as poor lighting on the new website There you can find information on how to find good quality lighting. Shielded fixtures can be found using the key words “Dark Sky” but make sure they really do hide the bulb. For more information, also see and

And for more on light pollution please see

Five Principles for Responsible Outdoor Lighting – International Dark-Sky Association (

An inspirational project

The Ryan observatory construction began in 2016 in a truly dark skies part of southern Lancaster County, and the doors opened to the public in October 2017.  The speaker at the opening ceremony was no less than Princeton quantum physics scientist the late Freeman Dyson (1923-2020).

From 50+ life again: “The Rittenhouse Astronomical Society of Philadelphia is the primary amateur organization that runs the Observatory.  Monthly events are open to the public free of charge.  Local amateur astronomers play important supporting roles, providing telescopes and educators”.


Attendance at one of the public outreach events at the Ryan observatory

The observatory is named for the Ryan Family and their efforts to bring a STEAM facility to the community, while honoring their daughter Layla, a brilliant young student of cosmology who tragically, passed away from a long-term illness in 2006 at age 24. In  Layla’s honor, her parents established a scholarship at the University of Illinois for female astronomy students with a demonstrated history of “giving back” to the community.  This happened to be a value shared by Exelon  and Constellation, who have also supported the Layla S Ryan Scholarship. 

Picture3.pngLayla Ryan

I was fortunate to Email-interview her father, Mr. Al Ryan who led the effort to create the observatory in her name: 

  1. What kind of telescopes are housed in the two domes?

1.Under one of the observatory domes a Celestron Edge HD 14 with an E S 80mm refractor equipped with a  DS10C allowing the public to compare the eyepiece view in the 14” with the full color version from the refractor/camera combo that is piped to large flatscreen monitors on the walls.  


2.In our second dome, a PlaneWave  CDK14 telescope with a STXL 16200 camera that is primarily used for astrophotography.  We intend to offer classes in astrophotography and make the observatory available under special circumstances to astrophotography class graduates. The third observatory houses our newest instrument that will soon be available to the public.  This telescope is a binocular telescope and designed especially for use in public settings.  .  As far as we have been able to determine, with its 25 ½” mirrors, this is the largest binocular telescope designed for public use in existence.  



Binocular Telescope, Moveable Shelter

We also make available a couple of 60mm Lunt solar telescopes, a C 9.25 Edge telescope, a 7” Questar and a few other smaller telescopes.

  1. Any notable observation made from the site?
    • Last year we were able to capture an occultation of a star by Hi’iaka, a moon of  Haumea (one of the Trans-Neptunian asteroids) which lies some 4 billion miles away. ).  For more on this, see our web page at  The data was reviewed and published.


  • One of our student interns worked with one of our imaging operators to help produce a narrowband image of Messier 27.  That will be posted to the website in the near future.


  1. Any anecdote to make my paper alive (construction/funding/ops headaches, fun facts and stories)?
    • I wouldn’t know where to start here.  We have always aimed high and that hasn’t always met the financial constraints.  But the site owner, Constellation Energy, has been magnificent and magnanimous in building all three facilities, retro-fitting the Visitors Center, providing staffing for public events and providing other non-descript support overall.  Some headaches and issues are ongoing, and range from lack of volunteers, insufficiently trained persons, reliance on one source for funds to expand programming, purchase new software and hardware, upgrading same, etc.  But the work we do has been extremely well received by the community.  Our latest hero is a kid who is almost continually in the hospital but manages to get out for each of our monthly open house events.  He is at most 8 years old but was thrilled when our primary astrophotography operator guided him through his very own capture of M13 with our equipment, which he and his family proudly displayed on Facebook.

A remarkable achievement

After a highly successful career in law, Mr. Ryan is even busier now with inspiring the next generation of scientists and engineers as well as the curious public.  We felt that this story was worth sharing at a time when “success” often consists in less honorable outcomes.   A beautiful anonymous quote (wrongly attributed to Ralph Waldo Emerson, 1803-1882) came to my mind:

"To laugh often and much; to win the respect of intelligent people and the affection of children; to earn the appreciation of honest critics and endure the betrayal of false friends; to appreciate beauty, to find the best in others; to live the world a bit better, whether by a healthy child, a garden patch or a redeemed social condition; to know even one life has breathed easier because you have lived. This is to have succeeded."

The Ryan observatory is a testimony to the partnership between visionaries in the electric distribution, amateur astronomers and ordinary citizens animated by the common good.


To learn more:

Web site: Ryan Observatory

Facebook page (7) Ryan Observatory at Muddy Run | Facebook

Night sky net Ryan Observatory at Muddy Run | Night Sky Network (

by David Prosper

Do you want to peer deeper into the night sky? Are you feeling the urge to buy a telescope? There are so many options for budding astronomers that choosing one can be overwhelming. A first telescope should be easy to use and provide good quality views while being affordable. As it turns out, those requirements make the first telescope of choice for many stargazers something unexpected: a good pair of binoculars!

Binoculars are an excellent first instrument because they are generally easy to use and more versatile than most telescopes. Binoculars can be used for activities like stargazing and birdwatching, and work great in the field at a star party, along the hiking trail, and anywhere else where you can see the sky. Binoculars also travel well, since they easily fit into carry-on luggage – a difficult feat for most telescopes! A good pair of binoculars, ranging in specifications from 7x35 to 10x50, will give you great views of the Moon, large open star clusters like the Pleiades (M45), and, from dark skies, larger bright galaxies like the Andromeda Galaxy (M31) and large nebulae like the Orion Nebula (M42). While you likely won’t be able to see Saturn’s rings, as you practice your observing skills you may be able to spot Jupiter's moons, along with some globular clusters and fainter nebulae from dark sites, too.

What do the numbers on those binocular specs actually mean? The first number is the magnification, while the second number is the size in millimeters (mm) of the lenses. So, a 7x35 pair of binoculars means that they will magnify 7 times using lenses 35 mm in diameter. It can be tempting to get the biggest binoculars you can find, but try not to get anything much more powerful than a 10x50 pair at first. Larger binoculars with more power often have narrower fields of vision and are heavier; while technically more powerful, they are also more difficult to hold steadily in your hands and "jiggle" quite a bit unless you buy much more expensive binoculars with image stabilization, or mount them to a tripod.

Would it surprise you that amazing views of some astronomical objects can be found not just from giant telescopes, but also from seemingly humble binoculars? Binoculars are able to show a much larger field of view of the sky compared to most telescopes. For example, most telescopes are unable to keep the entirety of the Pleiades or Andromeda Galaxy entirely inside the view of most eyepieces. Binoculars are also a great investment for more advanced observing, as later on they are useful for hunting down objects to then observe in more detail with a telescope.

If you are able to do so, real-world advice and experience is still the best for something you will be spending a lot of time with! Going to an in-person star party hosted by a local club is a great way to get familiar with telescopes and binoculars of all kinds – just ask permission before taking a closer look! You can find clubs and star parties near you on the Night Sky Network's Clubs & Events page at, and inspire your binocular stargazing sessions with NASA’s latest discoveries at


The two most popular types of binocular designs are shown here: roof-prism binoculars (left) and porro-prism binoculars (right). Roof prisms tend to be more compact, lighter, and a bit more portable, while porro-prisms tend to be heavier but often offer wider views and greater magnification. What should you choose? Many birders and frequent fliers often choose roof-prism models for their portability. Many observers who prefer to observe fainter deep-sky objects or who use a tripod with their observing choose larger porro-prism designs. There is no right answer, so if you can, try out both designs and see which works better for you.


A pair of good binoculars can show craters on the Moon around 6 miles (10 km) across and larger. How large is that? It would take you about two hours to hike across a similar-sized crater on Earth. The “Can You See the Flag On the Moon?” handout showcases the levels of detail that different instruments can typically observe on the Moon, available at image courtesy Jay Tanner

NSNRound150.pngThis article is distributed by NASA’s Night Sky Network (NSN). The NSN program supports astronomy clubs across the USA dedicated to astronomy outreach. Visit to find local clubs, events, and more!

by Will Sager

It’s that time of year again. The Halloween candy has been consumed, the turkey is gone, and the mall is playing Christmas carols (endlessly). Once again many people will think that purchasing a telescope as a Christmas gift for a budding astronomer would be the perfect thing. If you are in this group of well-meaning people, we are going to have a tough conversation here and my goal is to strip away the gauzy rose-colored filter from your blurred vision. There are myriad ways to mess this up and plenty of retailers who would love to take your money. But do not despair, I know many amateur astronomers in this very organization whose love of astronomy started in just this way (myself included)


An example of a high power telescope ad from 1952. Criterion actually made some good telescopes in the 1960s and 1970s, but this was probably not one of them.

I have started and restarted this article several times because it rapidly bogs down in telescope details. What makes a good telescope? How do you recognize one that is not? Let me start by repurposing an old saying: there are good telescopes and there are cheap telescopes, but there are no good cheap telescopes. Of course, this depends on your definition of “good” and “cheap”. Start this debate at a star party and it will provide amusement for hours. The motivation here is that nobody (except cheap telescope sellers) wants you to buy a “hobby killer”: a telescope so frustrating that it kills your neophyte’s interest before it can bloom. There are so many variables in this quest that it is difficult to give foolproof suggestions. I will try to give some perspectives based on many years of looking through telescopes, but your mileage may vary.

A Primer on Telescope Types

Before we can discuss telescopes, we need an understanding of telescope types. There are three broad categories: refractor, reflector, and catadioptric. All telescopes use an objective lens (or mirror) and an eyepiece lens. The objective gathers light and focuses it into an image. The eyepiece is a secondary lens (usually several lenses) that takes the objective image, enlarges it, and projects it into your eye. A refractor has an objective lens in the front that collects and focuses light rearward. A reflector telescope uses an objective mirror, located at the back of the scope, and focuses the light forward. In a Newtonian design, a secondary mirror redirects the light out the side where the eyepiece is located. A catadioptric telescope (“cat”) also uses an objective mirror, but usually has a figured secondary mirror and perhaps a “corrector plate” at the front. Often the light beam is sent to an eyepiece on the rear of the scope. 


Simplified diagrams of telescope types. From the Abrams Planetarium web site:

All objectives are defined by two measurements: diameter and focal length. The diameter controls how much light is gathered. By doubling the objective diameter, say 100 mm (3.9 in) to 200 mm (7.9 in), the amount of light gathered increases by 4 times. Focal length is the distance from the objective to the point at which the light is focused. If you take a lens or mirror and train it on a light bulb then put a sheet of paper at the focus, you will see a little image of the light bulb. The eyepiece also has a focal length, which is the distance from the center of the lenses to the point at which it is in focus.

Two more important numbers are f-ratio and magnification. The f-ratio is the focal length divided by the objective diameter. For example, a 152 mm (6 in.) objective with a 1219 mm (48 in.) focal length is f/8 (48/6 = 8). The lower the f-ratio, the brighter the image. Magnification (aka power) is the enlargement of the image. For example, 50x enlarges the image by 50 times. Magnification is calculated by dividing the focal length of the objective by the focal length of the eyepiece. On that 48 inch focal length scope, a 25 mm (1 in) focal length eyepiece produces 48x (=48/1). Obviously, the higher the magnification, the larger the image appears in your eye. But magnification also makes the image dimmer.

Since we are talking here about Christmas scopes and probably looking for the cheaper options, look again at the scope diagrams. The reflector has only one glass surface (the mirror) that must be precisely figured. The secondary is a flat mirror. This makes this type the least expensive to manufacture. The refractor objective lens is really not one lens as pictured because glass does not refract all wavelengths of light the same. Usually, the simplest objective is an achromat, which has two paired lenses together. With an achromat, there are four glass surfaces to be figured and they must be assembled into one paired unit. Better refractors have 3 lenses in the assembly. This makes refractors the most expensive of the telescopes. Cats have a primary, objective mirror and a secondary mirror and sometimes a corrector plate. They are more expensive than simple reflectors, but not as much as refractors. 

One final point about telescopes. The image is usually upside-down and sometimes also backwards. If you see this, your telescope is not broken. It is just optics. Look at the telescope diagrams and follow the straight lines that indicate the incoming light. Notice how on all telescope designs, the light that comes in on one side ends up coming out the eyepiece on the other side. To get correct images, as in binoculars, you need special prisms to twist the image back to normal.

A Bit About Mounts

All telescopes need a mount that allows the observer to move it easily to objects in the sky. Although there are many variations, most fall into two categories: alt-az and equatorial. Alt-az is short for altitude-azimuth, which describes the motions of this particular mount. It has two perpendicular axes, one that turns horizontally (azimuth) and another that turns the scope vertically (altitude). The equatorial mount also has two perpendicular axes. One (right ascension or RA) is pointed at the North Star (Polaris) to coincide with the Earth’s rotation axis. When aligned, the mount can follow the stars simply by turning on the RA axis. The other axis is declination and moves the scope either towards or away from the celestial equator. Because the alt-az mount is simpler (and therefore cheaper to make), it is the one most often found on inexpensive scopes. Although the equatorial mount makes tracking the moving stars easier, it must be aligned to Polaris (at least approximately) to work properly.

Caveat Emptor

A big problem with the Christmas telescope is that inexperienced observers are prone to common misconceptions that all telescope manufacturers will exploit, but none worse than the unscrupulous cheap telescope makers. Do you see that fantastic photo of a nebula on the box? You won’t see that, even with a light bucket (a large reflector telescope). Human eyes can’t integrate light for extended periods like cameras can. You must adjust your expectations. That nebula may be well be visible in your scope, but you have to know how, when and where to look.  If you live in the city, you will need to take your scope away from the light pollution to see anything dimmer than the Sun (with a proper filter!!!), Moon, or bright planets. Even in a dark place, you will have to be satisfied with seeing a ghostly smudge that has traveled hundreds or thousands of light years to your eyeball. What is more, a cheap telescope will probably be the least likely to give you a good image. So don’t let unscrupulous sellers distort your expectations. Those same sellers will also try to catch you with POWER! They make unreasonable claims about how powerful their telescope is (see the section “Power Mad”).

Where to Start?

There are so many pitfalls that it is hard to give you foolproof instructions. I was going to say to stick with established manufacturers (Celestron, Meade, Explore Scientific, Skywatcher) or quality telescope sellers (Orion, OPT, Highland Scientific) and you will probably be OK. But even these folks market some cheap clunkers. I highly recommend a trip to our local telescope shop, Land Sea & Sky on Richmond. (I have no connection to this establishment nor am I compensated to mention them here.) You can actually see the telescopes and you can pose questions to people who know their stuff. They sell a lot of high end gear but they also have some beginner scopes. In fact, they have a glossy brochure “How to Buy a First Telescope” that they will give you. 

So what are the most important aspects of a good telescope? I will highlight two. Good optics and a solid mount. Good optics should be self-evident – the better the optics, the better the image that you see. Good is relative and many an astronomer with a good telescope is still lusting after some better glass. There is a basic level of performance that once you get beyond that level, the improvement in image quality is probably not appreciated by a beginner. So stay away from the cheap scope and you are probably OK. No matter how good the optics, an unsteady mount will ruin your view. The telescope will vibrate, shake, wiggle, and shimmy and whatever object you are viewing will do the same. Make sure whatever scope you get has a good, steady mount. It is worth it.

Making a Cheap Scope Cheap

Makers of cheap scopes have to cut corners. So what do they cut? They use cheap optics that can be manufactured easily but probably are not figured (shaped) well to give an optimal image. Some scopes don’t even use glass for lenses (they use plastic). The optics will be the simplest possible that will give you an image, so you don’t benefit from designs that are more expensive and better corrected for sharper images. Cheap scope makers cut the mount cost by using less parts and smaller parts. A good mount allows the observer to move the scope fluidly and easily stop on a target. A bad mount makes that difficult and the undersized parts make it rickety. Remember, you want solid. Another place to cut costs is metal. Cheap scopes often have plastic pieces for the focuser, eyepieces, finder scope, and some mount parts. Metal is better and more durable. Well-machined metal parts fit together better and work better. But they add to the cost.

Let’s take a look at the offerings from a well-known big box retailer specializing in low prices. These scopes are a sample of dozens that they offer online. A check of the Evil Empire of online commerce shows similar offerings.


These telescopes are on the website of a famous big box retailer. None are recommended.

The scope on the left is a Newtonian reflector and other three are refractor scopes. Where have these manufacturers gone cheap? The first obvious thing is the mount. The three refractors appear to be on cheap camera tripods. The reflector mount may be a bit more robust, (it is not clear from the photo) but it looks undersized. A camera tripod makes a poor mount because it is meant to be shifted and clamped to hold a camera steady – usually in one go. When you train your scope on an object, the object will move across the field because of the Earth’s rotation. So you have to keep moving the scope to keep up. This will not be easy with a camera tripod. Furthermore, the telescopes are much larger than a camera, so they will be unbalanced and hard to keep steady. The tripods also look undersized (and for this price, they are probably cheaply made). A rickety mount that is hard to adjust will be highly frustrating to use and nigh impossible to use with much magnification because the image will do a dizzying dance. It is hard to know about the optical performance of these scopes, but at this price point, the optics must be simple and cheap. My bet is that they are substandard. Refractor lenses must have two to three elements to bend all wavelengths of light to a sharp focus point. Cheap refractor lenses are probably poorly corrected, so you may see fringes on bright objects and sharp lines. This may not bother a neophyte, but will make experienced observers weep. In all cases the objective lens or mirror is small. The refractors all have 70 mm (2.8 in) objective lenses and the reflector has a 114 mm (4.5 in) mirror. The focal lengths are short at 400 mm (15.7 in) for the refractors and 500 m for the reflector, so it will be hard to coax high magnification. To their credit the ads don’t scream about high power (see the section Power Mad below). 

All ads all show a smartphone on the eyepiece. Astrophotography is difficult at best and will be extra difficult with these telescopes. The smartphone must be aligned with the eyepiece and held still. You can purchase a good smart phone adapter for about $50, but I wonder what they are giving you at this price point. At a minimum, this will be difficult because the phone will throw the scope out of balance and it will be hard to keep it in place. And with no tracking mount to follow the motion of the stars, the Moon is really the only target that will have enough light for a short exposure.

And one more thing. I checked the reviews because I was curious. These scopes have something like 400 excellent reviews and only a few that are less glowing. Call me skeptical. There should be a “bell curve” of reviews (i.e., some reviews that are less than glowing). The fact that this distribution is so skewed makes me suspicious. 

Power Mad

Power is a common misconception about telescopes. You will almost never use high magnifications like 500x, even if your telescope could deliver it. Physics says that even good optics cannot give more than about 50x per inch of aperture. For example, let’s say that you get a telescope with an 80 mm diameter front objective (3.2 in.). This means that you can get about 160x from that telescope. You can push it beyond that, but you will not see more detail and the image will be dim and fuzzy. An even bigger limitation is something called “seeing”, i.e., the steadiness of the atmosphere. The atmosphere is like looking up through a swimming pool. If seeing is poor, high power just magnifies the squirming caused by air currents. To get detail at high power requires the atmosphere to be very still. Ask any experienced observer and they will tell you that they use their low power eyepieces a lot more than their high power eyepieces. Furthermore, the low-power view is brighter, clearer, and seems less wiggly. And another thing. When looking for an object in the sky, you always start with your low power eyepiece. As power increases, the width of your field of view decreases. High power is like looking through a narrow straw.

A Few Good Scopes?

Next I will take a look at some recommendations from respectable retailers that I have seen on various lists. There are dozens of possibilities and here I am exploring the lowest end of the price spectrum. I have not actually laid eyes or fingers on most of these scopes, so I can only comment on the specifications and photographs based on my experience. Other well meaning astronomers may disagree with some (if not all) points. The telescope photos come from web advertisements.


On the left is a small, tabletop reflector from Meade Instruments that retails for about $250. The scope has an aperture of 114 mm (4.5 in) and the focal length is 450 mm (17.7 in). Celestron makes something similar (FirstScope 76) with a 76 mm (3 in) mirror and a 300 mm focal length that sells for about $75. Zhumell sells the Z100, which has a 100 mm mirror with a 400 mm focal length and sells for $160. You probably detected a pattern here: the price depends strongly on mirror aperture – bigger is more expensive. These are small mirrors, so they will not collect much light. Remember also that reflector telescopes have a secondary mirror in the light path that blocks some of the light. For low f-ratio scopes like these, that blockage must be a little larger than for higher f-ratio scopes. This obstruction means that a 3-inch reflector does not collect as much light as a 3-inch refractor, which has no obstruction. The focal lengths of these scopes are short. This means that you will not be able to coax high magnification. The alt-az mounts all look similar with one upright that has the altitude axis connected to one side of the tube, so it is inherently unbalanced. But the tube will be light, so maybe that will work OK. It looks like a lot of plastic is used in the construction. There is only a unit-power finder, so you can only find bright objects. I doubt that this type of scope will be very inspiring. However, the main reason I can’t recommend this scope is the table-top mount. Unless you want to lie on the ground, you need a table to put the scope on. Are you going to drag a table everywhere you observe? Moreover, the table adds instability. Although the scope looks cute on a table top, I say no to this one in particular and to any table-top scope in general.

On the right is a little refractor from Celestron, the PowerSeeker EQ60 that sells for about $130 at a local big box electronics store. It has a 60 mm (2.4 in) objective lens with a focal length of 900 mm (35.4 in), making it f/15. It comes with two eyepieces, 20 mm and 4 mm, that give magnifications of 45x and 225x. You can also get a PowerSeeker EQ80, selling for about $200. That one has an 80 mm (3.2 in) objective and a 965 mm (38 in) focal length (f/12). The same two eyepieces give 48x and 241x. The mount is an equatorial mount and the knobs are slow motion controls (you turn the knob and it causes the scope to move slowly on that axis). This little scope does not appear outlandishly bad, but a lot depends on the details. The objective lens is on the small side, so it will do OK for the Moon, bright planets, and the Sun (remember the solar filter!!!), but does not have much light-gathering ability. If you can afford the 80 mm scope, you get 70% more light.  Because of the long focal length, the objective lens does not need to be well corrected to produce a decent image. The 225x claim is aspirational. Remember from the Power Mad section, you will find that a 60 mm scope can’t deliver that much power. Neither will the 80 mm scope give you 241x. Both are achieved using a 4-mm focal length eyepiece. This is very short focal length and hard for the beginner to see through. If you get this scope, pick up another eyepiece with a longer focal length, for example 10 mm (90x). The mount looks good, but a lot depends on how badly Celestron cut corners. It is probably somewhat undersized. Beware though, long refractors are very difficult to hold steady on a light mount because their length means the scope will shake when you focus it (this is true even for good mounts, but will be especially troublesome on a cheap mount). Here the devil is in the details - how good are the optics and mount? 


Here are a couple of small reflector telescopes from Orion telescopes that are on mounts that look reasonably robust. The one on the left is the SpaceProbe II and has a 76 mm (3 in) mirror with a 700 mm (28 in) focal length. It normally sells for about $99. The mount is an alt-az with the telescope in a fork. It comes with two eyepieces, 25 mm and 10 mm, which give 28x and 70x, respectively. It has a unit-power (red dot) finder. This scope has a rather small mirror. Because part of the field is blocked by the secondary mirror, it probably gathers about the same amount of light as the 60 mm refractor, mentioned above. The positive thing about this scope is that the mount looks solid. I don’t like the little rod on the mount fork – that is a locking mechanism, which means that the fork by itself won’t hold the scope tube in a fixed position. This is probably necessary with a small altitude bearing with no slip clutch. Another good thing about this scope is the f-ratio, which is f/9.2. At this ratio the mirror can have a simple, spherical curve that is easier to manufacture well. In addition, the 700 m focal length gives higher power for the same eyepiece.

The reflector on the right is the Orion Observer 114. It has a 114 mm (4.4 in) mirror with a 500 mm (19.7 in) focal length. It comes with the same 25 mm and 10 mm eyepieces, which give magnifications of 25x and 50x. Because of the shorter focal length and wider aperture, the f-ratio is f/4.4. This gives a brighter image than the smaller reflector, but at this f-ratio, the mirror must have a parabolic curve, which is harder to manufacture cheaply. With the low f/ratio, it will probably suffer from coma at the edges of the field of view that cause stars not to be pinpoints (this happens on all low-f-number reflectors). It is on a decent-looking equatorial mount with slow motion knobs that will allow the observer to move the telescope more easily. This bundle, which costs $280, includes a solar filter (larger circular object in the photo), which is necessary to look at the Sun. It also comes with a Moon filter, which fits on the eyepiece and cuts down the glare of the bright Moon. This seems like a reasonably nice small telescope, depending on how well the manufacturer did on the scope optics, fittings, and mount. I suspect that many people would be disappointed with the low magnification. You will probably want to purchase a barlow lens, which multiplies (most commonly doubles) the power of a given eyepiece.


Next, let’s look at a couple of “computerized” scopes. The scope on the left is the Celestron StarSense Explorer LT 80AZ. It is a small refractor with an 80 mm objective lens with a focal length of 900 mm (f/11.2). The mount is alt-az with a stabilization rod to lock the altitude axis. A typical “bundle” comes with 25 mm and 10 mm eyepieces, which give 36x and 90x and a 2x barlow lens that multiplies the magnification by two (i.e., 72x and 180x). The thing that makes this scope “computerized” is the contraption on top, which is a cell phone mount with a mirror so the phone camera can see the sky. The phone is placed in the cradle on top and a Celestron StarSense app captures a picture of the stars and calculates the telescope location and orientation. StarSense shows a sky map and when a user wants to go to an object, the app tells the user how much to push the scope in azimuth and altitude until the object is in the field of view. This app sounds cool, but it is new and I have not heard from anyone who has used it. If it works well, it could be a boon for inexperienced observers. I have concerns, though. Most people today live in places with severe light pollution that hides most stars. I don’t know how many stars StarSense needs to get a lock or whether nearby sources of light (e.g., streetlights) will throw it off. This particular scope sells for about $240. Celestron also sells a 114 mm reflector with a StarSense phone holder on a similar mount for about the same price. I was able to examine one of these at Land Sea & Sky. It seems like a budget telescope with lots of plastic parts and the mount does not seem very rigid. Nonetheless, it will probably be serviceable for a first scope.

The scope on the right, the Celestron 4SE, is truly computerized. The scope itself is a small cat with a 102 mm (4 in) objective and a focal length of 1325 mm (f/13). It comes with one eyepiece only, 25 mm, which gives 53x. The mount is alt-az. The computer is in the hand controller (the thing with buttons), which is shown mounted on the side of the mount (its stowed position). The controller contains a small computer that controls motors on the azimuth and altitude axes. The user must align the scope with some stars and the computer figures out the orientation. From there, the user can choose objects from a large database and the scope will move itself to put the object in the field of view. You can get optional modules that make the alignment process automatic (basically, the computer checks the stars in a camera). The tripod and mount on this scope are very solid and with the short scope tube, there is little image shake. But you pay a price to go computerized. This scope is about $600. Frankly, a 4-inch f/13 cat doesn’t gather a lot of light. You can get larger aperture cats on similar mounts for more. One of the most popular scopes around is an 8-in computerized cat, sold by both Celestron and Meade, which sells for about $2,000. The 8-incher has kept many an amateur observer happy for years.


That was a lot of scope stuff, but what recommendations can I leave you with? 

1. The best telescope is the one you will use. Of all considerations, the telescope has to be one that gets pulled out of the closet and put to use. You have to decide where the scope will be stored (best in a climate controlled space) and how it will get to the observing site. If you live in the country, maybe all you have to do is put it out in the yard. But if you live in the city, you are probably transporting it to a location where the sky is darker. And this also brings up an important point – telescopes don’t use themselves. If you are giving the telescope to a child, you will want to encourage learning about the sky. Get a planisphere (a time-adjustable star map) to learn the constellations. Get a simple set of star maps like the Sky and Telescope Pocket Sky Atlas. Since this is the HAS newsletter, you already have a good start because you joined a club with a lot of in-house knowledge and resources. Take the telescope someplace dark (like the club dark site) and make an adventure of it with your kids. Talk to other amateurs – they are usually quite chatty.

2. Stay out of the bargain basement. The most suspect telescopes are the ones that are ultra-cheap online from manufacturers having no obvious track records (use Google). You could get lucky, but probably not.

3. Go simple. Simple scopes are cheaper

4. Buy as much aperture and as sturdy a mount as you can afford. On the low-price end of things, manufacturers have cut corners with cheap optics, small optics, and rickety mounts. Of the two, I recommend the solid mount over the bigger aperture. No matter how good your optics, you will be frustrated if your image dances around too much. 

5. Refractor or reflector? Refractors are more expensive per inch of aperture, so you can get a bigger scope for less money with a reflector. Reflectors require occasional collimation. This means adjusting the optics into alignment. To collimate a reflector, the user turns screws on the mirror mount that move it until the mirror optical axis goes straight into the eyepiece. This is not very hard, but a scope out of collimation gives poor images (and may not focus properly).

6. Phone or not? Yes, I know, you probably want your kid to get off the phone. This is the 21st century and that is unlikely. Suppose the phone could be something that gets your kid interested in astronomy? Well, OK then. As I said above, I have no idea how well the StarSense app works, but I think Celestron may have come up with something to interest youngsters in observing the sky. On the other hand, a bright cell phone screen at a dark site (and specifically at the HAS dark site) is about as welcome as car headlights. It will blind you and everyone else around. At minimum, you will need to set the screen to be dim and colored red (get a red transparent cover), so it doesn’t mess up your dark vision.

Which scopes to buy?

You already saw that I find plenty to dislike with low cost scopes. If I were trying to stay around $100, the Celestron 60 mm refractor and Orion 76 mm reflector would be decent bets. Jumping up to just above $200, consider the Orion 114 mm reflector or the 80 mm refractor. The Orion scopes look like they have good mounts. I’m concerned about the StarSense telescopes because the mounts are not very sturdy – and I don’t know whether the StarSense app is good or gimmick. 

If you want to jump up to the next level and prices near $500 don’t deter you (maybe you have a giftee who has a demonstrated interest in astronomy), consider the scopes in the picture below. These are SkyWatcher Dobsonian reflectors. Dobsonian has become a term for reflector telescopes on inexpensive alt-az mounts. The scope on the left has a 6 inch mirror with a focal length of 1200 mm (47.2 in), which gives f/7.8. This is enough aperture to start seeing faint fuzzy things (in a dark sky). The focal length will give decent magnification. In the middle and on the left are Dobsonians with 8-inch mirrors. This is a scope that will satisfy for many years. The one on the right is “collapsible”, meaning that the ring with the focuser can be pushed down to make the tube shorter for storage. The prices are about $450 for the 6 incher, $550 for the 8 incher, and $750 for the collapsible version. These scopes have real finder scopes (rather than red-dot finders) and have mostly metal parts and reasonably good focusers. Orion also makes similar Dobsonians at similar prices (in fact, I think they are made in the same factory in China).


Three Skywatcher Dobsonian reflectors at Land Sea & Sky. Left, 6 inch; middle, 8 inch, and right, 8 inch collapsible. (author photo)

Online resources

“Telescopes Explained”, Cosmic Pursuits

“Choosing a telescope”, Sky and Telescope Magazine

“Buying a Telescope”, OPT Corp.

“Best Telescopes Under $500 for 2022”, Popular Science

“Best Beginner Telescopes”,

“17 Best Scopes for Astronomy Beginners”, Sky at Night Magazine

“Best Telescopes for Beginners”, New York Times

Orion Telescopes

OPT Corp (Ocean Pacific Telescope)

High Point Scientific

Anacortes Telescopes


This is an online selling forum mostly inhabited by amateurs turning over gear. To be useful, you need to pay a $15 subscription. If you know what you are looking for, you may be able to find it at a discount here. But of course, you are at the mercy of the seller and may have no recourse if unhappy with your purchase.


Polar Alignment

By Don Selle

A picture containing textDescription automatically generatedAfter a brief hiatus (life seems to intrude on my astronomy) this installment of Astrophotography Corner concerns one of the two important mechanical requirements for getting good image data, polar alignment. Next to autoguiding (which we cover in the next installment), getting your mount well polar aligned is essential.

So what exactly is polar alignment? Simply put, it is the process whereby one of the two axes of your mount is aligned as closely as possible to be parallel with the Earth’s axis of rotation. The term polar alignment comes from the fact that this axis, by definition, runs through the Earth’s north and south poles. The axis of rotation also points at the locations in the sky that (also by definition) are known as the North and South Celestial poles (NCP &  SCP).

For polar aligned observers in the Northern Hemisphere, this means the line which runs through the center of rotation of your mount axis, and which is perpendicular to the plane of its rotation, will point at the NCP. For a  German Equatorial Mount (GEM) this is typically known as the RA axis. For an alt-az mounted scope such as an SCT mounted on an equatorial wedge, it is the azimuth axis which is aligned with the NCP. While the concept is pretty simple, the why’s and how’s take a little more explaining.

We polar align so that only one axis of our mount needs to track at “sidereal rate*” to keep our object of interest in the same spot on our imaging chip. Ok, but why all the fuss? An alt-az mount that is well leveled can do this too. It does so by making continuous adjustments in both the altitude and azimuth axes. Tracking and keeping an object centered is only half the problem though. Field rotation is the other half.

The image in the scope using an alt-az mount, while staying centered, will rotate over time** (see figure below) due to the geometry of the mount and the movement of the night sky. Field rotation is not acceptable for a camera taking long exposures, as the rotation of the object will lead to smearing of the image.

So how closely polar aligned does your mount need to be? If you are doing visual observing, a rough polar alignment is just fine. The built-in “All-Star” polar alignment routines on many GoTo mounts will get you close enough to keep the object in your eyepiece, but it is unlikely to be accurate enough for imaging. Don’t fall in the trap of using this polar alignment routine and wondering why your stars aren’t pinpoint! A picture containing text, outdoor, night, starDescription automatically generated Autoguiding is also not a reliable substitute for an accurate polar alignment. If you are autoguiding, you can be well out from polar aligned and still keep a star on the imaging chip for exposures of 5mins or longer. You can still, however, get oval stars and blurred images due to field rotation.

While it is possible to calculate*** how accurately you need to be polar aligned to keep field rotation from rotating 1 pixel width or less, keep in mind that blurring due to seeing conditions will also mask the effects of field rotation, so the results of the calculation will be conservative.

In general, polar alignment of less than 5 arcminutes error will be adequate for most imaging. Longer exposure times, higher focal lengths, and to a lesser extent, smaller camera pixels will require more accurate polar alignment.

So what is the best way to polar align? There are several general methods all of which require that your mount, OTA and camera have a clear line of sight to Polaris. These are:

  1. Use an accurate polar alignment scope that is installed in the center of the RA axis or with the polar scope mounted on a separate bracket and aligned parallel with the mount’s polar axis.
  2. Iterative polar alignment
  3. Polar alignment camera and software combination

Only the drift alignment method can be done without Polaris being visible.

Using a polar alignment scope. A polar alignment scope has a special reticle which is designed so when the reticle is rotated to the correct angle to match the date and time, placing Polaris in the designated position completes your polar alignment. In order to be more accurate, the scope must be collimated with the RA axis.

Additional accuracy can be gained if you make an adjustment from Standard Time (ST) on your watch to the Local Apparent (LAT) time of you location and use the LAT time to match the date and time of the polar alignment scope. Since 15 degrees of Earth’s rotation equates to 1 hour of ST, each degree of longitude difference is 4 minutes difference in LAT. If you are east of a ST meridian, correction is added to ST, if you are West, it is subtracted. For Houston, the difference between is about -20 minutes from ST as 90 deg W is the time zone meridian for Houston while about 95 deg W is the actual longitude.

The polar scope on the Takahashi mount I have been using for 15 years has an adjustment built into it that accounts for this adjustment to Standard Time. With this polar scope I routinely am able to align the mount better than 5 arcminutes from the NCP in about 5 minutes.

If your polar scope does not have this function built in, do not despair. There’s an app (actually several) for that! I typically use Polar Finder on my phone in order to polar align my camera tracker. It finds my position from the phone and then recreates the reticle in my finder scope and simulates where Polaris needs to be place. Works well every time.

Iterative Polar Alignment. Back when I was first starting in astrophotography, I was using a fork mounted SCT on an equatorial wedge. The only two ways I could get polar aligned was to use this method or the drift method. Iterative polar alignment took me less time to complete so I got pretty good at it.

You can use this method with today’s GoTo  GEMs. The steps are as follows:

  1. Complete a rough polar alignment of your scope. An “All-Star” polar alignment qualifies for this.
  2. Do a one star alignment to establish your pointing model
  3. Find a reasonably bright star (mag 3 or brighter) rising in the east that is about 40 degrees above the horizon and which is north of but nearby the Celestial Equator (ie Dec is + single digits up to may +20 degrees)
  4. Slew to this star, center it in your camera and synch the mount to the position of this star.
  5. Slew the mount to Polaris. Center Polaris in your camera using the Altitude and Azimuth adjustments for the mount. (DO NOT SYNCH)
  6. Repeat steps 3, 4, and 5 for 3 or 4 iterations. You will see the amount of distance you need to move the mount on both stars decrease significantly. When the distance is small you are polar aligned.

Polar alignment camera and software combination. These days high sensitivity cameras are relatively inexpensive, and imaging software has evolved so much that plate solving (ie analyzing an Astro-image and comparing the stars in it to match them with the known position of stars in a database) to find where the camera is pointing have become commonplace. These technologies can be combined into a slick way to dial in your mounts polar alignment.

Accessories like the QHY PoleMaster or the Ioptron iPolar can be mounted on the polar axis of your mount and act like electronic polar alignment scopes. They take and plate solve images and annotate them to show you where to place particular stars in the field by moving the mounts altitude and azimuth adjustments, in order to have the camera pointing at the Celestial Pole. These work great in the northern hemisphere but are ideally suite for the southern hemisphere where there are few bright stars near the SCP.

There are also imaging oriented programs like SharpCap and PHD2 which have built in functions to assist you in polar aligning your mount by using your guide camera instead of a dedicated “electronic” polar scope type camera. Once you get the hang of how these devices and software work, polar alignment can be done quickly and with relatively good accuracy.

Drift Alignment.**** All of the above require that you are able to see Polaris with your polar scope, or your OTA and camera. What can you do to polar align if your northern horizon is blocked? Do a drift alignment.

Drift alignment is an age-old approach to getting your mount polar aligned. It is based on the fact that if your scope is out of polar alignment, stars tend to drift in Declination – either north or or south depending on where they are in the sky. Adjustments to the mount’s azimuth and altitude until this drift is minimized or practically eliminated.

  1. Roughly polar align your mount.
  2. Find a fairly bright star on or close to the meridian and as close to the celestial equator as possible.
  3. Using a reticle eyepiece or your camera watch the star drift for at least 5 minutes or more. If the star drifts South the telescope’s polar axis is pointing too far East.  If the star drifts North, the telescope’s polar axis is pointing too far West. Adjust the mounts azimuth accordingly.


Repeat this process for the same duration and make adjustments until very little or no drift is seen.


  1. Now switch to a star rising in the east which is at least 20 degrees above the horizon and on or near the celestial equator.
  2. Using a reticle eyepiece or your camera watch the star drift for at least 5 minutes or more. If the star drifts South the telescope’s polar axis is pointing too low.  If the star drifts North, the telescope’s polar axis is pointing too high. Adjust the mounts azimuth accordingly.

Repeat this process for the same duration and make adjustments until very little or no drift is seen.

  1. Now go back and repeat steps 2 through 5 to ensure that any azimuth adjustment has not changed the altitude and vice versa.

I would suggest that you learn one or more of the polar alignment techniques and practice them during evenings when sky conditions do not favor good images. With a little work and practice, you will soon be able to get your mount well polar aligned quickly and efficiently without wasting too much of your precious dark time!

Want to learn more about Astro-imaging or have a specific question? Contact me at: [email protected]. If you would like to share your experience with others by submitting an article for the AP Corner by all means let me know!

* You would think that sidereal tracking rate would equal 1 revolution per 24 hour day, since our clock time is based on one full rotation of the Earth per 24 hour day. In fact, the sidereal rate is slightly faster than this. Since the Earth moves slightly in its orbit each day it, the stars return to their same positions after 23 hours, 56 mins and 4 secs or about 3 mins and 54 seconds earlier each day. That’s why the sky changes from month to month and season to season.

** It is possible to add a “field rotator” to an alt-az mounted OTA to counter this effect, however this adds more complexity (3 axes to coordinate precisely etc.). This is done on some professional telescopes. It was also tried on amateur scopes over a decade ago, but did not catch on.

*** Here is a calculator you can uses

**** You can find a more detailed procedure here: