Memories of Jupiter

Do you recall the largest planet of all?

Jupiter’s prime viewing season in 2017 has long past, but it should still be visible a little after sunset if you want to get a final glimpse of it this year in the evening sky.

Back in June, when Jupiter was high in the sky, I embarked to sketch the planet a few times, intermingled with on different nights opposite my digital photography of it.  Sketching at the telescope is an art for which I am barely a novice, but I am taking steps to improve my drawing skills in hopes of better future drawings for Jupiter, the Moon, and Mars.

I did mentioned in an earlier blog post or comment that I would post my sketches.  So better late than never, for better or worse, here they are, further below.  Note that I list the eyepiece filters used.  An objective I had this year was to determine which filters are best for seeing Jupiter’s details.  In my final sessions, as I was getting more comfortable making out the planet’s finer details, I decided to test each of my filters so that knew for years to come which filters will help my observations.

It is entirely possible that my filter opinions are just that, and yours may be different.  But if you are inclined to observe Jupiter someday at the telescope, here is my little guide on which filters I prefer.  The numbers, in case you are unfamiliar, as the standard Wratten numbers to denote filter color or type.

  • #12 Yellow – Very good, great band contrast
  • #23 Orange – Very good, can see band contrast
  • #25 Red – Bad, can only see the primary bands a little
  • #58 Green – Good-to-ok for band contrast
  • #80A Blue – N/A, filter was dirty, needed to clean
  • #80A Medium Blue – So-so (maybe results would have been better if Jupiter was higher in the sky?)
  • #96 Neutral – Very good, a little less bright but can see bands easily
  • Mars filter – Good, nice contrast and, in particular, the Great Red Spot really popped out

So I recommend #12 Yellow, #23 Orange, #96 Neutral, and Mars.  I have to recheck my #80A Blue filters next year.

And now, onto the Jupiter sketches…

Jupiter on June 1st, 2017.

Jupiter on June 2nd, 2017.

Jupiter on June 10th, 2017.

Jupiter on June 27th, 2017.

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My Hunt for Pluto, Part II: The False Star

Figure 2.1: My sketch of the area surrounding Pluto on September 14th, 2017.

“I really want to try to find Pluto again one more time this season…If I do get a chance, I will post a follow-up next month.” – Me, August 29th

With the Moon safely out of the way and a clear sky opportunity available, last week I resumed my quest to find Pluto.  Much of this post relies on information from my first attempt last month, and so I will be referring to that post frequently.

Recall that I leveraged the easily recognized “teapot” asterism in the constellation Sagittarius to star hop over to the approximate location of Pluto.  The main anchor star in the area of Pluto, both last month and now, is Albaldah.  Albaldah and a few nearby neighbors are the last stars I can see unaided.  So targeting Albaldah with my telescope was the first order of business.

The journey past Albaldah was guided with the help of both the Stellarium app on my tablet as well as my prior post.  I should note here that the “app” version of Stellarium is far less detailed than the PC version when investigating such faint objects in small spaces.  Further, based on my two observation sessions, I now believe there is an error in the PC Stellarium map, which I will explain in a moment.

Using the same 2″ Q70 eyepiece as last month, I quickly found HIP 94372, the 6.35 magnitude “mini-anchor” star near Pluto visible only with my telescope.  From HIP 94372 I located the 8th-magnitude star pattern I nicknamed k-lambda, assuring that I was in the correct vicinity.

At this point I was aggressively looking at the images from my prior blog post, the Stellarium app, and my telescope eyepiece.  I decided early on that it would be best to switch to a higher magnification than the 2″ eyepiece allowed, so I changed to my 1.25″ 14.5mm Planetary.  This eyepiece illuminated a much clearer view around HIP 94372.

Then I began sketching, referring to Stellarium only to assure that I was still in the location I wanted to be and drawing at the correct perspective size.  In my drawing above (Figure 2.1) it is difficult to see which stars are faint and which were really faint to the point that averted vision was necessary to see them.  The three stars I labeled as #1, #2, and #3 were the brightest, forming a triangle.  The three arcs were the approximate boundaries of the eyepiece.

With my sketch partially done, I had to make an assumption – that the small star close to HIP 94372, identified only by the Stellarium PC version, does not exist.  This probably threw me off last month, at least a bit, in determining if I truly had seen Pluto.  It is listed at magnitude 9.10, which should be easily visible, especially at the higher magnification I was now using with the 14.5mm eyepiece.  A 9.10 star should only be slightly dimmer than k-lambda, as well as the three stars forming the main triangle in my sketch.  And the few stars I drew around HIP 94372 are extremely faint, well past magnitude 9.  So either this star does not exist or its magnitude is incorrect in Stellarium.

Figure 2.2: Is this star really there?

Returning to the Pluto hunt, I knew it should be located within the three-star triangle I sketched.  In the figure below from Stellarium, I edited out the false star, as well as flipped the image to correspond to what I drew at the telescope that night.  Pluto is represented as a very, very tiny dot:

Figure 2.3: Pluto and surrounding stars as shown by Stellarium for September14th, 2017.

Remember, again, that most of these stars are very faint.  To help gauge where Pluto might be, I imaged a micro asterism forming a dipper or serpent, which starts at the star HIP 94338:

Figure 2.4: Identifying the serpent and “bright” stars.

I could see this dipper easily at the telescope so long as I knew where HIP 94372 was.  I also knew, then, that Pluto had to be just below (actually above, but the telescope reverses the image) this dipper and between HIP 94372 and HIP 94338.

Did I actually find Pluto?  I identified, at the telescope, three possible candidates, all hard to see without averting my eye a bit.  That night while still at the telescope, I drew an arrow pointing to the one I thought was most likely.  The other two candidates were to the right, the nearest dots above and below the one pointed to by my upward sketched “likely Pluto” arrow (see Figure 2.5).

Here is my sketch again, this time with the serpent/dipper lined, the three bright stars circled in orange, and the dot most likely to be Pluto, as determined afterward by comparing to both versions of Stellarium (iPad and PC):

Figure 2.5: My sketch with the most likely candidate for Pluto circled in yellow.

The best way I can confirm/reconfirm which dot was Pluto would be to sketch the area around HIP 94372 once Pluto has moved significantly.  Unfortunately by next month (after the next Full Moon passes), Sagittarius and Pluto may be too low in the sky for me to draw again, mostly due to the impacts of light pollution as they near the horizon.  And so, true final confirmation may have to wait a good seven to nine months, as the Earth and Pluto revolve around the Sun, beckoning the dwarf planet back into our East sky by late Spring 2018.

One More Name Change

For the last few weeks since I changed my display name, I noticed that it was too long to fit in many of the standard field sizes we are accustomed to.  I thought about shortening it by simply dropping “Backyard,” but that made the name too common.

So I came up with a slight variation that still has strong roots in the blog, and manages to be comfortably shorter.

As last time…same blog, same author, new author name!

My Hunt for Pluto!

On the evening of Friday, August 25th, 2017, I decided to take my homemade 10-inch Dobsonian out to my back deck.  The Moon was still young, so the sky would be fairly dark a few hours after sunset.  Paired with surprisingly cool August temperatures, it looked to have the makings of a great stargazing night.

It had been weeks since I last used the big “light cannon.”  A combination of summer temperatures and humidity, all sorts of nighttime bugs, and the pre-eclipse fervor put my normal telescope usage on hiatus.  I planned out what I wanted to see, leveraging Sky Map.  The star clusters in Sagittarius seemed like good targets, followed by other deep sky objects like the Ring Nebula.  And oh yeah, Pluto is in the sky, so for kicks I put it on the list as well.

I started around 10:40 p.m., after the Moon was fully set for the night.  I turned my attention first to the South and Sagittarius.  Its remaining time in the 2017 nighttime skies is fading, and it may not be practically viewable by next month from my location.  Unfortunately, I had no luck in pinpointing the several star clusters in the heart of this constellation, due to them being already low in the sky and overtaken by my local light pollution glow.

So I scratched the South star clusters off my list and decided to try Pluto next, since it was in the vicinity of Sagittarius.  I held little hope of finding Pluto, but felt the need to try anyway, as I have been wanting to for a while.  Locating a 1,400-mile long object over three billion miles away is not easy, to put it mildly.  This would be unexplored territory for me, requiring all my rudimentary stargazing experience to date as well as the power of my 10-inch reflector.

I started by locating the “teapot handle” in Sagittarius.  It is barely visible from my yard, but leveraging the brightest star in the area, Nunki, makes for finding the handle quickly.  Nunki’s apparent magnitude is 2.05, a little less than Polaris’s, to it is still within easy viewing at my location.

As of mid-2017, Pluto is above the Sagittarius teapot asterism when looking from Northern locations on Earth.  The closet bright star to Pluto is Albaldah, with an apparent magnitude of 2.89, so still easy to find.  Albaldah is directly above the teapot, as shown in Figure 1:

Figure 1: The Sagittarius “teapot handle” including star Nunki, with the Pluto guide star Albaldah above it.

Albaldah is more officially known as Pi-Sagittarii, and it forms a triangle with two other “Sgr” stars in the area, Omicron-Sagittarii and Epsilon-Sagittarii.  This triangle provides a visual cue to where Pluto should be in the August 2017 sky, to the left of the triangle, as shown in Figure 2:

Figure 2: The three Sagittarii stars and the approximate location of Pluto, circled in orange. Click to enlarge.

Assuming you are looking at the full image, you should see one brighter star within the orange circle along with two dimmer stars.  This brighter star is called HIP 94372, and with an apparent magnitude of 6.35, it is not visible to the eye.  So here is the leap from naked eye observing of the three Sagittarii stars to telescope viewing of HIP 94372.  Figure 3 below gives the Stellarium details on HIP 94372 along with an even closer view, now showing Pluto’s location on the evening of August 25th:

Figure 3: HIP 94372 with nearby stars, and Pluto on 08/25/2017. These are visible only with a telescope.

At this point in the observation session, I was heavily consulting Stellarium on my iPad, as there was no way to see the following-discussed stars unaided.  I leveraged my best-quality two-inch eyepiece, the 32mm Orion Q70 Wide-Field.  I post the name and link here not as an ad for Orion, but so you get a sense of the equipment used for this difficult exercise.  The Q70 is better than average as I have found that it significantly reduces the coma effect (blurriness around the edges) common in many 2″ eyepieces.  In hindsight and for next time, I should also have had at-the-ready a high-powered 1.25″ eyepiece.

To get a sense of the field-of-view through the Q70, I was able to see both Albaldah and Omicron-Stagittarii at the same time in the same eyepiece field, with each star near the edge on opposite sides.

It is important to note here that we are discussing the limits of common star map apps.  We are getting down to 10th and 14th magnitude objects, so the overall accuracy of the maps may start to get fuzzy.  I am not saying Sky Map or Stellarium are wrong, only that this exercise approaches the limits of their usefulness.  Because as I discovered, it becomes very difficult at these magnitudes to align the computer map with what you see in your telescope.

HIP 94372, at 6.35 apparent magnitude, is easily seen through a 10-inch reflector telescope.  The second-brightest star in this area is unnamed with an apparent magnitude of 9.80 (see Figure 4).  This was still very visible via the telescope but much fainter than HIP 94372.

Figure 4: Stars near Pluto, August 2017.

And so we come to the task of actually identifying Pluto.  At an apparent magnitude of over 14, is it visible at all from my Western Chicago suburban skies?  I could see, near HIP 94372, the ever-so-tiniest dot, which I assumed to be Pluto!  “Assumed to be” is key here as I cannot say for sure.  When you look at the Moon, Venus, Jupiter, Saturn, or Mars, you can say with 100% confidence what you are looking at.  But with Pluto, I am relying on approximations of a nearby bright star (Albaldah) to make even more approximations of faint star patterns seen only with a telescope.

Figure 5: Pluto’s location and details in Stellarium, August 2017.

I wanted to confirm my finding as best as I could, so I started hunting for noticeable star patterns in the area of HIP 94372 that I could recognize with the help of Stellarium.  Below and to the East I found one small set (see Figure 6).  But the “Rosetta Stone” was the pattern a little farther to the East still.  It is easily seen as a faint pattern in the telescope.  I call it “k-lambda” as I imagine it is the fusion of the letter k and Greek letter lambda in a Star Trek transporter accident. 🙂

Figure 6: Recognizable star patterns very close to Pluto in August 2017,

All of the stars in k-lambda are in the apparent magnitude range of 8.2-8.3, which make them faint but still easily seen in my telescope.  Figure 7 shows the details of one of these stars, called HIP 94784:

Figure 7: The stars of my k-lamba asterism.

Finding these stars seems easy with the hindsight of a few days.  It involved a lot of “feeling around” past Albalduh to get my bearings at the scope.  Even moderately bright stars are easy through a telescope, but going past that 6-7 apparent magnitude threshold was like walking through a forest at night with little-to-no light.

So by leveraging these two small and faint star patterns, mapped towards the “bright” faint star HIP 94372 and anchored to the naked-eye star Albaldah, I can safely say that I found the location of Pluto that evening, even if I cannot say for 100% certain that I saw Pluto itself.  See Figure 8 below for Albaldah, Pluto, and my k-lamba all in the same Stellarium image.

Figure 8: Click to enlarge.

I really want to try to find Pluto again one more time this season with the experience I now have.  Unfortunately the Moon is growing towards Full each night, which will make the evening sky too bright for such fine work over the next week and more.  I estimate the Moon should be out of the way again around September 13th.  By then, Pluto will have nudged a bit towards the West, as shown below in Figure 9.  If I do get a chance to try for Pluto one more time this year, I will post a follow-up next month.

Figure 9: Pluto’s location from Earth on September 13th, 2017.

Thanks for reading to the end!

(And yes, I did find the Ring Nebula after my Pluto trek.)

Starlight and Einstein and Solar Eclipses

Much talk is in the media these recent days about the upcoming North America solar eclipse.  Anyone following the world of astronomy for the past year at least has been aware of it, but suddenly the mass population is waking up to the pending reality of the event too.  Their focus is on traffic jams and hotel rooms and possibly defective solar glasses.

Having prepared for August 21st months ago, I am now waiting just like most of you, and watching the weather forecasts with an interest usually not provided to the television personalities.  I will not be using glasses, in part because I enjoy doing things differently than most.  So while millions will gaze up with open mouths at the Moon and Sun with their 3D-esque eyewear, I will be leveraging my telescopes along with simple cardboard holdouts to measure the event.

This waiting time is a good time to reflect on the eclipse and what it means beyond the covering of the Sun.  The eclipse will bring darkness and with darkness comes stars.  I am in the 88% coverage range and have no idea what it will look like, though I assume at least bright Venus towards the West will be visible.

Those in the path of totality will have a special treat as the sky should go dark to the point stars appear.  It was this phenomena that helped prove Albert Einstein’s General Theory of Relativity true, or at least as a superior theory to explain the universe over Isaac Newton’s gravitational theories.  If you want to read the details of how it was done, do an Internet search for the 1919 solar eclipse to find many articles.  Here is one from space.com that summarizes it nicely.

I am neither astrophysicist nor physicist, just a backyard astronomer.  But I feel I know enough to explain the 1919 solar eclipse experiment in the simplest terms.  Consider first a typical clear evening on the planet Earth, with stars shining and the Sun well out of the way on the other side of the globe.

Figure 1 (not to scale)

With no large cosmological objects in the way, starlight in aggregate gets to Earth mostly on a straight line.  Whether Einstein was correct or not was not crucial for this part.  There is a path of light from a star to here, and we can assume a straight line for this path.

Now consider what happens during a solar eclipse.  The Sun (and Moon) have gotten into the path of some of that starlight, but for other stars their light will skirt past the Sun and still reach Earth.  Einstein asked, “will the gravity of our massive Sun alter course of light from those stars?”  His theories said yes, and the 1919 eclipse was used to prove him and his theories correct.

Figure 2 (not to scale)

Figure 2 shows a few things happening.  First, the Moon is between the Sun and Earth, hence blocking the Sun’s light.  The Sun of course is enormous in size compared to the Earth and Moon, but the Moon’s proximity to us and the Sun’s distance make them approximately the same apparent size in the sky.  If one were to make an argument that the ancient gods set up the universe so that their sizes looked the same, you would probably have difficultly coming up with a sound rebuttal for why this is so, beyond coincidence.

Next, the Sun blocks some, a very small amount, of starlight that is directly behind it.  I suppose you could say that the Earth, Moon, Sun, and any stars hidden behind the Sun will be in conjunction on August 21st.

Lastly, there is starlight with paths that will approach the Sun.  As proven in 1919, the Sun’s gravity will effects this starlight as it travels past the Sun, altering the starlight’s course.  This is happening all the time in the daylight, but we cannot observe it due to that -27 magnitude star close by.

When the masses of millions look at Monday’s eclipse, few will be thinking about Einstein.  But some yearning, bright individuals will.  Perhaps the next Einstein will be among them, awaiting the inspiration to change our fundamental understanding of the cosmos once again.

Saturn in July 2017

July 16th, 2017, 11:10 p.m. local time

All the recent rain and generally miserable humid summer weather almost made me forget that there was a brief pocket of pleasant evening clearness just this past Sunday.  It was a great opportunity to move my 10″ Dobsonian to my back deck for taking in the evening’s astronomical wonders.

I started with imaging Saturn, my primary objective.  I had great difficulty locating Saturn that night and it was almost 20 minutes before I locked on.  Keep in mind this is all a manual process.  My homemade Dobsonian is a Newtonian reflector on a simple alt-az swivel mount.  Even by turning my exposures all the way up, I still had problems finding it.  The lesson here is that it may be next to impossible to attempt imagining of Uranus in a few months with my meager equipment.

Returning to the present though with Saturn, I think this may be my best yet.  When I image the planets, I always take a few sets of videos with different refocusing.  It is really, really hard to get the exact focus right, and the digital camera’s view screen can only get you approximately there, hence the need to take a few sets so that hopefully at least one of them is good.

This night, I took two sets, and it was the first group of videos that allowed me to create the above image.  I also used my Neodymium filter, which I prefer for Saturn as it brings out a nice color contrast among planet’s cloud bands and ring levels.

After my Saturn session was complete, I put a 17mm eyepiece on the scope just to look around on that clear no-Moon night.  Of note was the Hercules Globular Cluster (Messier 13) which I saw clearer than I ever had.  Wow!  I could make out many bright stars in the foreground of the cluster.  I don’t have the proper equipment to image it, but I hope to have the skills to properly draw it by next year.

Also of note was that I am starting to see Cassiopeia earlier and earlier in the Northeast.  It’s the great pointer to the Andromeda Galaxy.  My view to the East is mostly blocked, so I have to wait some before the galaxy is visible via telescope and binoculars from my backyard, but it is comforting to know my favorite gray smudge will be back soon!

Merging the Telescope World with the Real World

From left to right: Moon, Callisto, Io, Europa, Jupiter, Ganymede. Click to see the full-sized image.

As mentioned previously, I took several different types of photographs the night of Sunday, May 7th, when the Moon and Jupiter were close.  One of these perspectives was by mounting my digital camera on a tripod to get a wide-field view of the Moon and Jupiter together.  I took many images with different exposures and ISO settings.  Here is one such raw image:

Click to enlarge.

Here, you see an overexposed Moon along with Jupiter.  This shows the distance between the two at 05/07/2017 21:20 Central Time, approximately.

The important aspect of this picture is that it captures all of Jupiter’s Galilean moons.  If you click on the image, you will easily see three of them – Io, Europa, and Ganymede.  Callisto is there, or at least, is there in the raw TIFF image.  You will have to take my word for it that Callisto is there, just very faint.

How do I know which moons are which?  The easy way I follow is to use this Jupiter moon tracker, plugging in times and dates when I take my pictures.  If you enter the time stamp I wrote above, you will get this:

Now while my original source image is nice, I knew I could improve upon it with other images taken that same night at my telescope.  After accentuating Callisto’s brightness a little so we can see it, I used Photoshop Elements to carefully cut out Jupiter and its four moons.  I then overlayed these into a properly-exposed wide-field Moon image.

Next, I wanted to get a good Jupiter into the picture, since the planet itself is overexposed in all my tripod images.  I created the following image from stacked video at my 10″ Dobsonian:

I will shrink this good Jupiter to overlay into the main picture were the bright overexposed Jupiter resides.  But I also wanted to get the planet’s angle right relative to the moons.  So I imported as a temporary layer this other picture I took on Sunday that I previously wrote about:

This “moon” image is the perfect gauge, first to align with the native orientation of Io and Europa in the main image, and then to align the good Jupiter with the moon image Jupiter.  With the proper angle, I then overlayed this good Jupiter on top of the overexposed Jupiter, shrinking it a bit to compensate for the over-brightness of the original.

The final result is the image at the top of this post.

As a final perspective, I used the telescope Moon image I posted earlier and overlayed it in, and then moved the Jupiter system next to the Moon.  This gives you an idea of how wide an area Jupiter and the Galilean moons take up in reference to our Moon:

Click to enlarge.

That’s all for now. I am hoping with the Moon waning over the next week that I will be able to take more constellation pictures, and possibly a few deep sky objects.

Grinding a Telescope Mirror: The Non-DIY Project

johndobson2002

John Dobson

I did not know John Dobson, nor do I know someone who knew him, but I feel like I did from all the testimonials I have read.  At the least, my telescope build is an extremely distant branch of his legacy.

Mr. Dobson is the namesake for what is commonly referred to as the Dobsonian telescope.  He did not invent this type of telescope, but instead ingeniously brought together a number of amateur telescoping making (ATM) techniques.  This compilation is a method with general designs for how to build your own Newtonian reflector on an altazimuth (up/down left/right) swivel mount.  Sometimes you see references to only the mount as the Dobsonian part, but a true Dobsonian refers to the complete package, from the mount to the tube to even hand grinding the primary mirror.

This latter part, concerning the primary mirror, is what I stumbled on conceptually at the beginning of my telescope build journey.  When you start any type of project, and especially when you undertake what we call DIY projects today, you will have many “make or buy” decisions.  How much of the project will you, personally, create from raw materials, and how much will you rely on pre-built/pre-manufactured components?

Platonically speaking, there is no such thing as a true DIY project.  I am not going to grow my own forest to harvest trees for wood, nor start a lumber company to secure the requisite labor and machinery for my platonic lumber mill.  Nor would I obtain raw silicon to fabricate my own nano logic gates for a homemade CPU.  Still, there is a generally accepted boundary for raw materials – products that are not a specific end to themselves but are intended to be reshaped and combined with other raw materials into some form of finished component.

The primary mirror of a Newtonian reflector is indeed the main component of the telescope.  Its aperture determines everything else about the telescope’s dimensions and how “powerful” the final instrument will be.  The creation of primary mirrors is a deep step into the peculiar world of optics.  Remember the Hubble Telescope’s original blunder of having the wrong curve on its mirror?  That’s optics.  Whether we are talking big or small mirrors and lenses, the universe of optics and optical creations are not really an end-consumer endeavor.  There is a level of precision required unique to that industry.

If you follow any guide on John Dobson’s telescope build strategy, you will quickly learn that construction of the primary mirror was the core task of his method.  Below is what I assume was an old VHS era documentary on Mr. Dobson’s step-by-step approach, and most of it (a little over half) is about grinding and finishing the primary mirror.

If you watch this, or follow another guide on the Internet for grinding your primary mirror, it seems to be truly a daunting task.  It is beyond hard work and effort and closer to a stint in a hard labor camp.  Why would anyone do this to themselves?

I am in no way criticizing the method John Dobson laid out.  Too often, we judge the past by our perspectives grounded in our present.  60 years ago, the nature of amateur telescope making was very different.  There were no online guides, no easily searchable list of vendors to purchase obscure products from.  If you wanted a big telescope, I’m guessing the overall costs were too prohibitive for anyone except established institutions.  If you wanted to build a nice big telescope of your own to see the universe, you had to build your own, even scavenging for your raw materials at times.  This, I surmise, was the world of John Dobson and the source motivation for what would become the Dobsonian design.

I asked myself, “could I grind my own primary mirror?”  My weak answer was…maybe.  I have completed DIY projects before, but the grinding of a primary mirror seemed beyond my need to satisfactorily say that I could build my own telescope.  There is so much more to it than just the primary mirror – the tube, the many proper measurements, the mount wood cutting, the secondary mirror’s spider, the swivel construction, to name a few.  I decided that acquisition of the primary mirror, and all the optics in general, would be a firm “buy” decision for my telescope project.

There are other reasons to refrain from a homemade primary mirror as well.  I concluded, after all the investigations I did into the task, that there is no such thing as a true homemade primary mirror.  A DIY build means you can run to your local hardware store, buy the parts, and then construct what you need in your garage or other appropriate home venue.  Construction of a primary mirror requires, as a final step, the aluminization of the mirror’s surface.  This critical step is not a home DIY task.  You would need to find an industrial optics company willing to perform the aluminization for you.  You can spend weeks of your life grinding the mirror, then be lost because you cannot find an aluminizer.  Unless you know someone, you are going to be left having to ship your precious near-finished glass to an unknown company, somewhere and at great cost, hoping it will eventually be returned as the desired finished product.  I’m not saying it couldn’t be done, but I safely believe it is too much of a risk of both effort and money, especially when you can buy a finished primary mirror relatively easily today.

I say “relatively” easily to buy a primary mirror, because even that was a challenge, although nowhere near as hard as grinding one yourself.  For what I call consumer high-range optics, it can be very hard to find a supplier for this type of work.  Only a few online merchants offer shopping-cart style access for primary mirrors, and their supplies are limited.  Many companies post that they will make custom mirrors, but usually at a high cost, or only make very large custom mirrors, like 16″ and above.

We live in a much different world today from when John Dobson started building telescopes.  The bottom line is that, unlike most DIY projects, it is going to cost you more to build your own Dobsonian, regardless of make-vs-buy for the primary mirror, over purchasing a commercial Dobsonian or general reflector from one of the big established merchants.  So from the DIY perspective, your best route is to find one of the vendors or re-sellers of the commercial primary mirrors supplied to the Meades, Celestrons, and Orions of the market.

Who should attempt to grind their own primary mirror?  For one, masochists, and I mean this in all seriousness.  Another group that could reasonably give it a shot are those involved with any type of materials shop, from wood to metal, where building anything is just part of your routine.  And those connected to building components for the optics industry could certainly do this as well.

For the rest of us, if you really enjoy a challenge, then grinding a mirror is for you.  But for nearly all stargazers contemplating building their own telescope, I recommend purchasing all your optics, including the primary and secondary mirrors, focuser, eyepieces, and finder scopes.  Your homemade telescope will be so much more than a few specific components.  It is the journey, the knowledge you will gain, and the final satisfaction garnered from creating something far greater than the sum of its individual parts.

Which Deep Sky Objects are Good to View Right Now?

m37-02

Last week, when viewing conditions where still great and just before I got a bad cold, I was perusing the skies with my big (10-inch Dob) telescope.  It had been a while since I was outside with the heavy equipment just browsing for new stuff above.  So after taking a good look at all things Orion and the Pleiades, I used my Sky Map app to see if any DSOs might be worth viewing.

Since they were around Zenith (and still are) at my best night viewing time, I decided to look for three open clusters, Messier objects M36, M37, and M38.  They are in the constellation Auriga, above Orion and Taurus.  All three clusters are nice, but I found M37 in particular to be amazing.  Even from my light-polluted suburban skies I could see dozens of concentrated stars, if not more.  It had been a while since I had an awe-inspiring find, and this was finally it.  I am hoping, if weather conditions improve this coming weekend, to try sketching M37.

We are in the middle of Winter and looking towards Spring.  Are there any deep sky objects you enjoy viewing at this time of year?