About that fake Mars night sky panorama

February 23, 2021

There’s a thing flying around Facebook, and probably other social media sites, that purports to show a panorama of a starry night sky over the Perseverance rover. There are a couple of problems with it.

For one, it’s a fake. The landscape around Perseverance is real, and the sky is real, but it’s an Earth sky, not a Mars sky, and the two have been composited together. How do we know?

  1. If it was dark enough to see all those stars, it would be waaaay too dark to see the ground in front of the rover.
  2. So I checked the NASA website and found the original photo (link): 

EDIT: to be perfectly clear, so there’s no confusion: the Martian landscape is a genuine photographic panorama from NASA, which is shown and linked below, and the night sky is a genuine photographic panorama taken from Earth, and the two have been misleadingly composited by a YouTuber, who I am not going to name or link to because I don’t want to promote his work. NASA didn’t fake anything here!

Not only is the composite a fake, it’s a particularly clumsy and hilarious fake. I realized that since the sky above the horizon at any one time is a hemisphere, there is a 50% chance that Mars would be in the sky in the panorama, and I thought that would be pretty hilarious. So I went looking, and I found it. Here’s the proof:

The ecliptic–the plane on which the sun, moon, and all of the planets appear to move across the sky as seen from Earth–goes right by Regulus. There is no bright star at the circled point, so it must be a planet. And I’m certain that the bright “star” in the image is Mars, because it’s red, and because Jupiter hasn’t been by there in a few years–it’s currently on the other side of the sky.

So the composite panorama has the amazing spectacle of Mars in the night sky above…Mars. That’s a pretty spectacular fail.

This composite thing is bogus and stupid. If it comes your way, don’t give it any likes, or any clicks. Put up a link to this post instead. It’s not like Mars isn’t amazing on its own! Reality doesn’t need any enhancement.


Listen to me yap about the Caldwells for 45 minutes

December 4, 2020

Briefly: I wrote an article about the 25th anniversary of the Caldwell Catalog for the December issue of Sky & Telescope, and Frank Timmes of the American Astronomical Society interviewed me about it for the AAS YouTube channel. It was a fun interview and I’m grateful to Frank for his interest and for a fun conversation.


Storing (and transporting) my meteorite collection

October 18, 2020

I finally got around to organizing my (small) meteorite collection. I don’t have the space for a display cabinet right now, and when the pandemic lifts I’d like to be able to easily transport everything to schools and club outreach events, so I got a couple of HDX storage cases from the toolbox section at Home Depardieu. I think these things are the bee’s knees. They’re big, sturdy, and dirt cheap–right now you can get two cases, which lock together with the side tabs, for ten bucks. Best deal going. I got a couple of sets for Vicki, to help organize her histology slides, and they’re working great for her, too. I’m tempted to buy a bunch of them just to have them on hand in case they ever stop making them or jack up the price.

I cut bubble wrap to fit and taped it into the lids, padded the little cubbies, put cards at the back of each cubby with info on each specimen, and every time I get silicone gel packets with anything I toss them in the front of the case.

I did the same for my impactites. At the meteorite show-and-tell at a PVAA general meeting a couple of years ago (described here), the sight of Ken Elchert’s monster tektite really fired my interest, and I went on a little tektite-collecting binge. 

Here are my indochinites, from an impact in Southeast Asia, about 780,000 years ago, that produced the Australasian strewn field (australites, indochinites, philippinites, rizalites).

And here are the rest. The philippinite is from the same impact as the indochinites, it just flew further. The australites flew the farthest of all, and as they re-entered Earth’s atmosphere (yeah!) their front edges melted and flowed to produce perfect little aerodynamic heat-shield shapes called ‘buttons’. Real ones are a little outta my price range right now, but I got a nice cast of one from Gary Fujihara on eBay (here’s his store). The bediasite is a personal favorite–it’s from the impact 35 million years ago that gouged out Chesapeake Bay. That tektite was sitting in east Texas for more than half of the Age of Mammals before someone recognized it and collected it.

Why am I so fascinated by tektites, in particular? I think it is the diversity of shapes. Tektites are travelers in space and time, a frozen snapshot from the moment that a giant rock from space slammed into our planet. Each one is unique, and its shape tells a story about its flight through the atmosphere and subsequent erosion. Tektites embody everything that interests me: space, time, astronomy, geology, aerodynamics, and the history of our planet.

Not a tektite: a 31g piece of nickel-iron shrapnel from the Sikhote-Alin airburst in 1947. See this post for more details, and photos of a bigger piece.

Parting shot: I have a question about storage. Right now I’m just using cotton balls for padding in my cases, because they were fast and cheap. Are there any downsides to using cotton balls over the long run? Should I spring for some Polyfil, or other artificial fiber? I live in a fairly dry climate and mold and mildew are generally not problems. Thanks in advance for any wisdom!


Dr. Phonelove, or: How I Learned to Stop Worrying and Love Astronomy Apps

October 6, 2020

Warning: long, navel-gazey confession inbound. To wit: I used to be a bit of a snot when it came to planetarium apps. When I put together my “Astronomy Wish List for Beginning Stargazers” post back in 2014, I wrote:

Yes, you can get a free app for your phone that will show you thousands of celestial objects. If you get one with a good night-vision mode AND turn the brightness way down on your phone, it might not destroy your night vision, but it will still only show you a small slice of the sky at one time. At best, you’ll be outside under the stars and still looking at a dadgummed screen. Here’s a thought: put all the devices away, get out a lawn chair or just lie down on the grass, grab a planisphere, and spend a quiet half hour picking out the constellations. One of the chief advantages of a planisphere over an app is that you can see essentially the whole visible sky displayed at once, so you can figure out how the constellations relate to each other. 

Ugh! That was written out of ignorance and prejudice, and I cringe to read it now. Especially the bit about how an app would supposedly only show “a small slice of the sky at one time”. I didn’t own a smartphone at the time and I hadn’t actually used a planetarium app, I’d only seen other people use them, so I didn’t know about using two fingers to zoom in and out, which by now has become such second nature that it’s like looking back and realizing I didn’t know how to turn a doorknob.

My favorite constellation: Cassiopeia.

In any case, no, every planetarium app I know of will show as much or as little of the sky as you want. And most offer a red-based night vision mode for preserving your dark adaptation, which combined with the native screen brightness controls and night vision modes on most smartphones mean that you can use the apps under dark skies without sacrificing all your dark adaptation. (Another easy solution: close your observing eye when using the phone, and ask any companions to look away.)

So what pried me out of my self-dug hole of stupidity regarding astro apps? Direct experience. In 2015 I got my first smartphone, and in 2016 I got the job of writing the ‘Binocular Highlight’ column for Sky & Telescope magazine. I decided it was time to drag my ass into the 21st century, and since I was finally in a situation in which stargazing was bringing in money instead of consuming it, I could afford a decent astro app. I went with SkySafari 5 Pro, and it didn’t take long for it to eclipse almost all of my other astronomy tools put together in terms of how often I referenced it and how much I relied on it. Four years later, I’m on to SkySafari 6 Pro, and I’m sure that when 7 is released I’ll trade up.

For the Binocular Highlight column, we plan for and illustrate a 5-degree circle, and the ability to zoom the SkySafari screen to show a 5-degree field is extremely useful for planning my observing and my writing.

Also, I started noticing at public outreach events and star parties that basically everyone else was using planetarium apps. For people just starting out, they offer a ton of functionality that a planisphere doesn’t. Allow me a metaphor. I firmly believe that Wikipedia is how encyclopedias are supposed to work, and that the beloved World Books and Encylopedia Britannicas that I grew up with were about the best possible implementations of that idea in paper, but hobbled by not having hyperlinks, not being available via wifi, not being continually updated, etc. Similarly, even thought I love planispheres, I can admit that they are basically physical planetarium apps that restrict you to one latitude, one magnification, and a tiny subset of stars and deep sky objects. The digital apps are more intuitive, period, and not just for beginners. Experienced folks use them all the time, too, and for the same reasons: faster, easier, more information. Nowadays I find myself hauling out my phone almost every observing session–to check the positions of Saturn’s moons, or the classification of the components of a double star, or, most often, simply to find the distance to a celestial object.

I’ve enjoyed chasing the moons of Saturn this summer, and SkySafari has been clutch for making identifications — only after I’ve made my own sketches, to avoid spurious detections.

My app use in the field took another jump when I got the NexStar 8SE. Before I got that scope, I was pretty darned proud of my knowledge of the sky. I didn’t quite know all the Messiers by heart, but I could find probably 3/4 of them without even checking an atlas. But the NexStar taught me a hard truth: I may know most of the constellations backwards and forwards, but I know very few stars by name. Caph? Nunki? Alpheratz? Might as well be Farsi, Swahili, and Linear B to this monolingual doofus. So when it comes time to find alignment stars, out comes the phone, because with a handful of exceptions–Polaris, the Summer Triangle, the Winter Hexagon, and a few favorite doubles–I don’t know what these darned things are called.

Oh, hey, there’s Nunki!

(Aside: in a way, this reminds me of what it was like when I first started stargazing in the fall of 2007. Every month, new stars and constellations were up in the eastern sky. I still remember vividly the first time I got up before dawn to see the spring constellations. I’ll get a taste of that in the coming year, as I have to keep familiarizing myself with new alignment stars.)

So to sum up, actually using planetarium apps myself, and seeing how much they opened up the sky to other people, forced me to belatedly pull the stick out of my butt.

The bright, popular double star Eta Cassiopeiae consists of a Sun-like yellow main sequence star and an orange dwarf, which lie only about 19.5 light years from Earth. I didn’t know that until the star party at the park last Saturday, when someone asked if the Eta Cass companion was a red dwarf, and I was able to look up the answer in SkySafari.

There’s another, larger point, which is that I think it’s stupid to criticize how anyone else enjoys the night sky. I’m glad I missed the GoTo wars of the 90s and early 2000s, and I have no time for the limited conflicts that are going on right now over Electronically Assisted Astronomy–essentially, looking at the night sky with night-vision googles, with or without a telescope–and smart telescopes like the Stellina and eVscope. It was always pretty selfish and short-sighted to worry about how anyone else was engaging with the night sky. It’s not like people who have different preferences regarding their gear or observing habits are hurting anyone. Surely we should be able to focus on what matters–our shared love of the cosmos, and getting out to enjoy it–and not whether anyone else is doing stargazing the “right” way. And that’s especially true now, in a year that sees the world shambling among catastrophes like a shell-shocked orphan. With all the horribleness going on, I just don’t have it in me to be upset at other people when they’re not hurting anyone else, especially over something as innocuous and ultimately positive as stargazing.

To the (near) future: the moon will visit Jupiter and Saturn on the evening of October 22.

So I say, bring on the technology. Cameras, electronic eyepieces, smart scopes, light enhancement devices, and the things that no-one has yet thought of. There is plenty of room out there in the dark for those things to coexist with traditional stargazing, and if they bring a few more folks into this wonderful pursuit, so much the better. If the expense bothers you, go look at what people spend on boats and motorcycles, let alone gambling and drugs, and also, check out what serious astrophotographers spend on the rigs that get their photos into Sky & Tel and Astronomy, and also, seriously, just mind your own beeswax. If dealing with the computerized gizmos isn’t your cup of tea, or you feel like using night-vision goggles is cheating, fine, I’m pretty sure no-one will ever force you to use them. I’m also pretty sure that no matter how fancy the hardware and software gets, there will be times that I feel like heading out with nothing but a manually-driven scope or some trusty old binos for “unplugged” observing. But I’m going to try to not close myself off to any more observing experiences a priori, without even trying the new things to see what they have to offer. That was dumb.


Observing Report: PVAA at the park, October 4, 2020

October 4, 2020

My club, the Pomona Valley Amateur Astronomers (PVAA), is gradually adjusting to the pandemic. From March through June, we didn’t hold any club activities. In July we had our first board meeting since February, virtually of course, and we decided to dip our toes into holding virtual general meetings. We also wanted to give people a way to interact in person, but safely, and someone proposed having a socially-distanced get-together at a local park. We had our first one of those at the end of July. I was out of town, on a brief family vacation after the end of summer teaching, so I missed that one. We’ve been trying to hold another one ever since, but heat and poor air quality have bedeviled us. We finally held another “PVAA at the park” event last night.

It was a combination swap meet, star party, and social event. In the photo above, we were just setting up, but we ended up with five telescopes on the field, representing every major design:

  • our club Treasurer, Gary Thompson, brought the blue homebuilt 8″ Dobsonian reflector you can see at the left of the above photo;
  • board member Jay Zacks brought his Meade ETX 90, a Maksutov-Cassegrain;
  • I had my Celestron NexStar 8SE, a Schmidt-Cassegrain;
  • club member Karen Lenz brought a 60mm or 70mm Tasco refractor (I forgot to check the specs);
  • club members Thomas and Stephanie Chavez brought their Celestron FirstScope, another small Dobsonian reflector.

Karen Lenz had brought her refractor to donate to the club. By complete coincidence, we had a visitor in need of a scope: an enthusiastic and knowledgeable 6th-grader. So Karen passed on her scope, our visitor got his first serious telescope, and everyone was happy. Despite the reputation of small, “department store” refractors, this one was solidly mounted and optically sharp, and it got a lot of use throughout the evening.

I took the NexStar 8SE, and used it to show guests Jupiter and Saturn, and the double stars Polaris, Mizar & Alcor, and Eta Cassiopiae. I tried various deep-sky objects, but they all looked pretty yucky. The only one that looked good enough to show off was M11, the Wild Duck Cluster.

I was having too much fun bopping around among the various telescopes and chatting with visitors to be in gear-evaluation mode. I was aware that the FOV of the C8 was bigger with the new focal reducer attached, but I didn’t do any serious testing. That will have to wait for another evening.

Around 8:30 we decided to carry some of the scopes over to the west, in hopes of seeing Mars over the trees at the east edge of the park. We got good views of Mars in Gary’s 8″ Dob, and then we spotted a break in the trees to try and get the moon. Our young visitor brought over the Tasco refractor, and Thomas and Stephanie brought over their FirstScope, and we spent 10 or 15 minutes just enjoying the sight of the moon coming up through the leaves. I got the above photo through the refractor, and it reminded me of the fun I used to have catching the moon rising through distant trees up on Mount Baldy (here and here). I need to get back to that.

All in all, it was a great evening. We had a good turnout, conditions were nice, we had a nice variety of scopes set up, and I think everyone enjoyed themselves. I’m already looking forward to the next one.


Unboxing fest, part 2: Celestron f/6.3 focal reducer-corrector

October 3, 2020

Even before I had decided to get the NexStar 8SE, I knew that if I got a big SCT, I’d want a focal reducer-corrector for it. SCTs and Maks have secondary mirrors, which partially obstruct incoming light. This implies a necessary tradeoff: make the central obstruction small, which results in a long focal ratio–typically f/10 to f/15 for commercially-available SCTs and Maks–or get a shorter focal ratio by using a larger secondary mirror, which blocks more light and degrades the contrast.

There is a third solution, which is to use a focal reducer to make a steeper light cone and a shorter focal ratio. Astrophotographers use these all the time to making their scopes optically ‘faster’ so they can get brighter images with shorter exposure times. For SCTs they are useful because they bring the focal length of the scope down to something more reasonable, and increase the true field of view. As shipped, the Celestron C8 OTA has a focal length of 2032mm, so even a 32mm Plossl gives 63.5x, and the included 25mm Plossl gives 81x. The max true field of view with 1.25″ eyepieces is about 0.7 degrees, which can be a little claustrophobic. You can juuust fit the Double Cluster in a 32mm Plossl, as long as you don’t mind clipping the edges of both clusters. You can get M81 and M82 at the same time, as long as you don’t mind parking them on the extreme edges of the FOV.

The Celestron f/6.3 reducer-corrector turns the C8 from an f/10 to an f/6.3, with an effective focal length of 1280mm, which is pretty close to the mid-sized commercial Dobsonians–the XT6, XT8, and XT10 and equivalent models from other companies are all 1200mm scopes. That pushes the max true field to something like 1.2 or 1.3 degrees, which is a big jump over the native 0.7 or so. That’s enough to put some of the larger celestial objects, like the Pleiades and M44, back in a single field of view, although the Pleiades will be cutting it mighty fine (I will test this and report back!).

As the name implies, this unit is not just a focal reducer, it’s also a corrector, which makes the field flatter for better image correction across the entire field of view. In other words, stars at the edge of the field should still look round with this thing in, as opposed to oblong. This isn’t a factor for me–I don’t photograph stars, and the stars at the edge of the field in the C8 haven’t bothered me so far–but it’s nice to have if either of those things change.

Here’s the gizmo, out of its (unsealed) bag, with its custom dust caps. I got mine from Astronomics (here), and evidently it was one of the last they had, because the availability listing there says “More on the way”. Amazon has it, too (link), I just like supporting brick-and-mortar telescope stores and specialized astro-gear dealers whenever I can.

Why am I bothering to do an elaborate unboxing post for such a trivial piece of gear? Mostly because it took a lot of digging for me to figure out how one was used. What I wanted was a photo essay that showed how “this part goes here, that part goes there”. When I couldn’t find one, I decided to create my own.

Here’s how the NexStar 8SE OTA comes as shipped, with a 1.25″ visual back on the rear port. When I was first getting into this, it took me forever to understand what a “visual back” was. Did it mean anything other than the bit where you stick the eyepiece or diagonal? And if not, doesn’t every telescope have one?

The answer is that not everyone sticks an eyepiece or diagonal at the back of a scope. Some people put a camera, or a spectrograph, or who knows what else. So if you are going to use the scope visually, you need a doohickey that holds the eyepiece or diagonal, and that’s the “visual back”. It was just new to me because non-SCTs aren’t generally described as having a “visual back” (some high-end astrograph refractors excluded), they just have focusers.

ANYWAY, the focal reducer-corrector threads onto the rear port of the scope, after the visual back has been removed.

Then the visual back screws into the focal reducer.

Then you put eyepieces or diagonals into the visual back, as usual. Everything is just scooted back 3/4 of an inch or so by having the focal reducer interposed between the scope and the visual back.

Incidentally, this is something to keep an eye on for NexStar users: when the scope is pointing high, the diagonal already comes pretty close to the base of the mount, depending on how far forward the OTA is scooted in the dovetail clamp. I’ll have to mess around with the system, but I might have to start mounting the scope a smidge farther forward to make sure the diagonal clears the mount when observing up high.

And here’s where the last post and this post come together: the Baader Hyperion 8-24mm clickstop zoom eyepiece, riding in an Astro-Tech dielectric diagonal, inserted in the stock 1.25″ visual back that came with the C8, screwed into the f/6.3 focal reducer-corrector. All saddled up and ready to go (er, minus the finders). Now all I need is for night to fall.

I have one more piece of gear to write about, but it hasn’t come in yet, so the next post might be an observing report–hopefully, a first-light report on the focal reducer and the Baader zoom. Stay tuned.


Unboxing fest, part 1: Baader Hyperion 8-24mm clickstop zoom eyepiece

October 3, 2020

It has been a long, long time since I got a new eyepiece. Three and a half years since I got my Edmund 28mm RKE, and just under five years since I got my Meade 5mm MWA, which was the last “premium” eyepiece I picked up (the 28mm RKE is one of my all-time favorites and most-used eyepieces, but at $85 I don’t think it counts as “premium”–for however much or little that is worth!).

I have been wanting to try this Baader zoom for years and years. It has an almost unbelievably positive reputation on Cloudy Nights, where at least some observers report selling off a lot of their premium fixed-focal-length eyepieces after acquiring the Baader zoom.

Does it really live up to the hype? Thanks to a bolt of consulting money coming in last week, I’m about to find out.

I found it in stock at Woodland Hills Camera and Telescope, and one arrived on my doorstep a couple of days later, extremely well-packed. Since I ordered mine, Woodland Hills seems to have run out of the standalone eyepiece, although they still offer it bundled with the matching 2.25x Baader barlow, which I skipped, for a little more dough (here). Amazon has it in stock, but for a little more than most other outlets–$325 right now, versus $289 or so most other places (here).

There’s no instruction book inside the box–the box itself is the parts inventory and instruction manual. I really dig this. I think every other eyepiece I’ve ever owned has come in an unadorned box, some of them quite fancy and nice enough to repurpose as gift boxes for birthdays and holidays (looking at you, Explore Scientific). This box is functional. Every surface is illustrated, and most of the sides show you how to use the eyepiece in various situations.

Even when you open the box, there are more instructions on the newly-revealed surface! Who does that? As a catalog-junkie who likes looking a photos of gear, this box ticks all my, er, boxes.

Now this is kinda awesome, and kinda hilarious. Instead of coming in a bolt case, like my two Bresser eyepieces; or clamshell foam, like all of my Explore Scientifics; or a sturdy plastic can with a screw-on lid, like the Celestron 8-24mm zoom; or just dust caps inside the cardboard box, like all of my Orion eyepieces, the Baader Hyperion 8-24mm clickstop zoom comes in a rugged nylon pouch with a velcro closure and–as you can see in the inventory photo on the side of the box–a belt strap. And it’s high-visability yellow so you won’t lose it.

This is pretty cool, and definitely functional, and also amuses the heck out of me. This is the kind of case I expect for a multi-tool, or a handheld GPS unit, or some other thing you might take hiking, not a telescope eyepiece. I guess if you ever wanted to bushwhack across Utah or Patagonia with a high-end telescope eyepiece on your hip, or clipped to the side of your pack, now you are prepared. I imagine I’ll keep mine in my eyepiece case, like any normal person.

Here are the eyepiece and the extra bits, out of their respective bags. The four things in the extra bag are (clockwise from top) the winged rubber eyecup, the fold-down eyecup, the spotting scope adapter, and the dust cap that goes with the fold-down eyecup. The eyepiece itself comes in the bag with the larger dust cap on top of the adjustable eyecup, which rotates up and down, and with the 2″ adapter and its dustcap on the bottom end.

I should mention right here that both plastic bags were open, not sealed, which is good, because it prevents dew formation. The one for the accessories had one of the little silica gel packs, which I always steal to throw in with my meteorites. (Note to self: blog about new meteorite storage system soon.)

Pull the dustcap off the 2″ adapter and you find inside the smaller dustcap on the 1.25″ adapter. You could use the eyepiece in a 2″ focuser or diagonal with both the 1.25″ and 2″ adapters in place, and I’m not sure if there’s any benefit to taking the 1.25″ adapter off.

Here’s the adjustable eyecup in the down position…

…and twisted up. I’m a fan of these things–I notice that civilians are much less likely to stab the eye lens with a greasy finger* if there’s something in the way. Plus it’s nice to be able to signal to people where they should put their eyes, something that can be surprisingly tricky with eyepieces that have long eye relief.

* I’m not mocking n00bs or people who come to public star parties. To astronomical optical surfaces, all fingers are greasy.

Here’s the Baader compared to my Celestron 8-24mm zoom. The Celestron has been in service for a few years and eventually the knurled rubber wrap around the middle of the eyepiece split and fell off, which doesn’t impact the function whatsoever.

I like the Celestron a lot. It’s been one of my most-used eyepieces, and along with a 32mm Plossl it is hands down the eyepiece that I’ve recommended the most. Long-time readers may recall that when I flew to Texas in 2017 for the Three Rivers Messier Marathon, the only eyepieces I took were the 28mm RKE and this Celestron zoom, and they proved to be all the eyepieces I needed.

In fact, it was my positive experiences with the Celestron zoom that convinced me to venture the money for the Baader zoom. I rarely splurge like that for a piece of gear in a class I’ve never tried. In normal times, the Celestron zoom runs $65-$75. With the temporary shortage of astronomy gear because of increased demand during the pandemic, the price has spiked a bit, at least at some retailers. I see it going for just over $90 at Amazon (link).

If I have one knock on the Celestron zoom, it’s that it is ever-so-slightly less sharp than the best of my fixed-focal-length eyepieces. The difference is subtle–I would not have been able to spot it in my first 3-4 years of observing, and even now it takes a determined effort for me to see it–but it’s there. (As always, your eyes, your experience level, and your sample of this piece of equipment might vary from mine, and probably do.) Which is another reason I wanted to try the Baader, with its sterling reputation for clarity and sharpness. If it lives up to that, I will be using it a lot.

I haven’t pulled out a ruler, but the eye lenses of the two zooms look about the same size.

My kitchen scale says the Baader zoom weighs 10.4 oz, or 296 grams.

And the Celestron zoom weighs about 3/4 as much, 7.7 oz or 218 grams. I was pleasantly surprised by the lightness of the Baader; at least to me, it looks like it might weigh a little more.

With any luck, I’ll have a first-light report along soon. And there’s more unboxing coming soon–stay tuned!


Full moon, 1 Oct. 2020

October 2, 2020

My first decent moon shot in ages. Handheld iPhone 7, shooting through a Celestron NexStar 8SE and an Orion 32mm Plossl, contrast punched up using curves in SnapSeed.


Observing Report: the Smoky-Tex Star Party

September 26, 2020

In the recent post on my new NexStar 8SE, I promised to explain why I was moving quickly trying to get the scope and the mount checked out. It’s because I knew I was bound for darker skies.

This is Black Mesa, at the extreme northwestern corner of the Oklahoma panhandle. The mesa is named for the thick cap of black basalt, the product of sporadic volcanism in northeastern New Mexico over the last 20 million years or so. The basalt is capping a sequence of sedimentary rocks in which portions of the entire Mesozoic are represented, including Cretaceous sandstones, Late Jurassic limestones, clays, and mudstones, Early Jurassic aeolian sands, and Triassic sands, shales, and muds. That’s what normally takes me to Black Mesa: digging dinosaurs.

The extant vertebrates aren’t bad, either. I took this photo on my very first visit out there, in 2016. I’ve been back to dig almost every year since.

Black Mesa draws visitors for another reason: inky-dark skies. On this light pollution map, I’ve highlighted Utah and Oklahoma in white, and circled the field areas of my digs in pink. It’s not just paleontologists that are drawn to such remote areas. The Okie-Tex Star Party is held each year just outside the tiny town of Kenton, less than five miles from our dinosaur quarry.

I’ve been wanting to go to Okie-Tex for ages, but every year before this one I was too busy teaching at this time of year. This year my schedule would have allowed me to attend, but of course the star party was cancelled because of the damned pandemic (correctly, I might add). I had planned to meet up at Okie-Tex with my friend Reggie Whitten, one of the founders of the Whitten-Newman Foundation that supports our dinosaur dig out there. The WNF has a cabin near Black Mesa, and when Reggie heard that Okie-Tex was cancelled, he said to me, “Hell, Matt, come on out and we’ll have our own star party”. I knew this was coming from a couple of months out, and that’s why I was scrambling to get the new NexStar 8SE up and running: I wanted it to be my star party scope.

I started the drive out two Wednesdays ago, on September 16. It’s 1070 miles from my driveway to Black Mesa. The first day, I made it as far as Santa Fe, New Mexico. At home, I’d been stuck under groady, smoky, ashy skies since the Mount Baldy run at the start of the month, and even though I’d been on the road for 12 hours, I was craving starlight. So I drove out west of town, past the airport, found a deserted dirt road, and spent half an hour cruising around the sky with the SkyScanner 100, shown above, and 7×50 binoculars. The skies weren’t crazy dark–the light dome from Santa Fe reacted with the humidity in the air to wipe out everything from the nose of Pegasus to Cassiopeia–but I still had fun looking south and west. I caught Jupiter, Saturn, M11, M57, M56, Albireo, Alpha Vulpeculae, Brocchi’s Coathanger, M71, M27, the heart asterism around Sadr, M29, and M39. I hit the gas giants again at the end of the session, checked in on Mars, and called it a night.

The next day I mostly counted pronghorn while I drove. I love these goofy critters, and there are a lot of them in northeastern New Mexico. Between Santa Fe and the Oklahoma border I counted at least 110, in 17 groups. Not many people know that pronghorn are so ridiculously fast–60 to 65 mph–because they evolved to outrun the now-extinct American cheetah, Miracinonyx, which was probably not a true cheetah but a convergently-evolved offshoot of the North American mountain lion or cougar. Pronghorn are not only fast, they also have a preternatural ability to tell when I’m about to take a picture, at which point they bolt. So I have a lot of photos, like the one above, that show pronghorn butts as they run away.

NB: not a pronghorn.

I got in Thursday afternoon and started unpacking scopes. I’d brought four: the NexStar 8SE as my main ride and big gun, at least for this trip; the C80ED as the next-nicest backup scope in case conditions were too windy for the big C8 (that would be prophetic); the Bresser AR102S for rich-field observing; and the SkyScanner 100 because I wanted a reflector along so I could demonstrate the three main types of telescopes, and because why the heck not.

That first night was the best. It got cool, down in the 50s, but there was no appreciable wind, and the seeing and transparency were both phenomenal. On the planets and bright deep sky objects like the Ring Nebula, I just kept throwing shorter eyepieces into the C8 until I hit the 5mm MWA, which is currently my shortest decent non-Barlowed EP. I only realized the next day that the 5mm was giving 406x in the 2032mm C8, which is a heck of a lot of magnification. Here in SoCal I find there are only a handful of nights each year that I can go past about 350x–and, frankly, for the stuff I observe I rarely need any more juice than that.

The next day, conditions took a turn for the worse. First, there was wind, which is normal for Black Mesa, we’d just gotten lucky the night before. My first solution was to roll with the C80ED instead of the NexStar, but the wind was so strong that even that small, solid scope on a very competent mount was bouncing around like crazy at anything over the very lowest magnifications. The next night, I had the better idea to repark the truck perpendicular to the wind, and put the NexStar in its lee, and that worked great.

The less welcome development was the arrival of, yep, smoke from wildfires. Here’s a shot of Black Mesa looking northwest from Robber’s Roost, scaled down a bit but otherwise unretouched–compare to the photo on a cloudy day at the top of this post, which was taken from essentially the same spot. I felt a little deflated to have crossed about a third of the US for exactly one clear night. This smoke was from fires in southern Colorado, and fortunately conditions got better quickly. We had one bad night of smoke, and then things got clearer every subsequent night.

For the entirety of my stay, I was the sole astronomer in a small and ever-changing group of civilians. Almost every time out, there was at least one person who hadn’t been with us the previous evening, and consequently I spent a lot of time showing people the best and brightest objects: the Ring, the Dumbbell, M13, the Double Cluster, Andromeda, and so on. And of course, Jupiter and Saturn and Mars. Not that I’m complaining! Those crowd-pleasing objects look good from home in small scopes. Under Bortle 1 skies with 8 inches of aperture, they looked phenomenal, and I would have spent most of my time observing them even if I’d been completely alone. The Double Cluster just fits in the field of a view of a 32mm Plossl or 24mm ES 68. You could spend a long time gazing into the depths of those two clusters, and many of my companions did. Different people had different favorites: the Double Cluster, the Ring Nebula, Andromeda, but the winner for most was Saturn. Which is entirely reasonable–even after all these years of stargazing, it’s a kick in the brainpan. Every single time I look at Saturn through a telescope, I am forcibly confronted with the reality that while I’ve been dealing with meetings and oil changes and dentist appointments and grocery shopping, it’s been out there for billions of years, vast, majestic, and serene, supremely untroubled by all the traffic jams and mass extinctions and whatnot transpiring on this wee little rock far across the solar system.

One morning I got up at 4:00 to go on dawn patrol. Several folks had indicated that they might join me, but the only one who actually did was Rachelle Whitten-Newman, Reggie’s spouse. We spent an hour and a half rocking through Orion, Taurus, Monoceros, Gemini, and Auriga. The Orion Nebula looked about as good as I’ve ever seen it, and M37 looked like diamonds on black velvet.

Ad Astra: the official wine of our star party.

Allow me to impress upon you just how darned dark it is out there. In the whole valley between Kenton and Black Mesa, there are about two porchlights on at night. The headlights of a car coming over the local horizon, 3 or 4 miles away–which does not happen very often–look like spotlights. The closest towns are Boise City, Oklahoma, population about 1200, which is 38 miles east, and Clayton, New Mexico, population about 2900, 45 miles to the southwest. You could draw a circle with a radius of 50 miles around Black Mesa and probably sweep up fewer than 6000 souls (the same circle around my house in Claremont would get 10 or 15 million). There are no light domes on the horizon. The major sources of light pollution are the planets themselves.

One night after packing away the telescopes I was sitting on a folding chair outside my tent, just taking in the night sky, when I realized that the entire landscape was very dimly illuminated. I can hardly stress enough how faint was this illumination–it was to the light of a bright moon what moonlight is to sunlight–but it was enough to cast pools of jet-black shadow under the cedars, the vehicles, and the awnings of the tents and buildings. I looked up to see the source of the light and the only possible culprit was Mars, soaring high overhead in the middle of the night. That’s right: out there, Mars casts shadows.

The NexStar 8SE performed like a champ. I started every evening with a 2-star align, usually on Mirfak (Alpha Persei) and Nunki–the latter is the star in the handle of the Sagittarius teapot that is closest to Jupiter. After that, the scope was good to point all over the sky, and to track for longer than I ever needed it to. I felt a little spoiled. One night I was out by myself for a bit so I decided to rock through the Messiers in the western sky. Scorpius was getting low, but I caught all of the M-objects in the “steam from the teapot” in Sagittarius and Scutum, as well as all of the globular clusters in Ophiuchus and Hercules, in about half an hour. After spending 13 years finding objects myself, and nudging the scope along, it felt a little like cheating, but I also realized that I’d never done a careful comparison between, say, M10 and M92, because I’d never gotten to observe them within 30 seconds of each other. That’s an epiphany I would never have had if I’d never used a GoTo scope. So I am looking forward to exploring the full ramifications of how this new tool will affect my observing.

My C8 meets its biggest sibling: a C14 EdgeHD.

Oh! I almost forgot to mention the Talentcell battery pack. MAN this thing just keeps going. I charged it to full on the day that it came in. Here’s what it’s been up to since then:

  • Sept. 9: 4.75 hours of tracking, in the garage, down to 4 out of 5 charge indicator lights by the end
  • Sept. 17: 3 hours of slewing and tracking
  • Sept. 19: 1.5 hours of slewing and tracking, down to 3 out of 5 charge indicator lights by the end
  • Sept. 20: 1.5 hours of slewing and tracking
  • Sept. 21: 3 hours of slewing and tracking, still showing 3 out of 5 charge indicator lights

I haven’t had a chance to run it since I got home, but so far it looks like it will run the scope for 4-5 hours per charge light, so possibly 20-25 hours of scope operation on a single charge. Very, very happy with this thing. Now that I know that it works and the mount works, I need to velcro them together so I can stop moving the battery pack around on the eyepiece rack while the telescope is slewing, to keep the scope from unplugging itself. Here’s that model again if you’re wanting one (link). I couldn’t be happier with mine.

Yes, that’s the Bresser Messier AR102S riding on the table-top mount from the SkyScanner 100, which is itself riding on the Bogen-Manfrotto tripod. Believe it or not, at that moment that was the most capable rig I could assemble in a hurry!

All too soon, my time in Oklahoma was over. I saw even more pronghorn on the way home, at least 119 in 14 groups between Black Mesa and Santa Fe. At one point, while checking out a group of four that resolutely refused to run away, I set up a scope, and got my best-yet photo of one of these beautiful and bizarre creatures:

I’ve seen a lot more deer than pronghorn over the years, more often, and usually up closer, and I’m always struck by how different pronghorn look from deer. Their bodies are more compact and their legs even skinnier, like furry bullets on sticks. You can tell at a glance that they are built for a completely different level of speed. Marvelous animals. Long may they reign.

Later that day I made an ugly discovery, after sunset when I was barreling down I-40 west of Flagstaff: smoke from the California wildfires. It made a distinct layer in the air, visible from many miles away, as you can see in the above photo. As I-40 plunges off the western edge of the Mogollon Plateau it was like submerging in gunk. Up top, I’d been able to see for dozens of miles; I first saw the San Francisco Peaks rearing above Flagstaff before I even got to Winslow, Arizona, 60 miles to the east. When I came down into the low desert, visibility shrank to just a few miles, and I realized that the smoky air was lapping at the edges of the high country like water at a rocky shore. Yuck.

As it turns out, my astronomical adventure was not quite over. I made it as far as Kingman, Arizona, before I decided to call it and find a place to spend the night. I pulled into the Maverick station off Andy Devine Blvd, just north of I-40, and got a wrap and some yogurt for a late dinner. I walked around as I ate, to stretch my legs, and I discovered a big empty lot south and east of the store, crisscrossed with tire tracks. The moon was out, and at first quarter it looked like it had been chopped in half with a katana. I drove the truck out onto the dirt, set up the Bresser AR102S on the hood, and had a look at the moon, Jupiter, and Saturn. I didn’t spend long, only 15 minutes or so, but it was a nice coda to the trip.

What now? I’m back in SoCal, patiently waiting for the wildfires to subside, for the air to clear, and for it to get cool enough for London and I to go camping. I’m going to really enjoy having an 8-inch scope that doesn’t take up the entire back of the truck or require me to move 30-50 pounds at once. I’m going to enjoy having a scope that will track objects so I can sketch them. Who knows, I might actually get back to the Herschel 400.

And I’m going to miss Oklahoma. We had a pretty darned good run out there, despite the wind and the smoke. Reggie and Rachelle and company are already talking about turning our private star party into a yearly event, and I’m all for it. Many thanks to the two of them, to Jeff Hargrave, to Diane, Becky, James, Melissa, and Robert Newman, and to Noah Roberts for a fantastic visit. Clear skies, y’all, and keep looking up.


Why I prefer RACI finders to straight-through finders and red-dot finders

September 26, 2020

My Orion 9×50 RACI finder mounted on my son’s XT4.5, at the Salton Sea.


A commenter on the last post asked why I hated red-dot finders. I wrote a short comment by way of explanation, but I realized that I had a lot to say on this issue, so I’m coming at it again with a full post.

Right off the bat we need to get something straight, and that is the difference between facts, on one hand, and preferences or opinions on the other. If I say that red-dot finders tend to be smaller and lighter than magnifying finders, or that straight-through and red-dot finders require users to put their heads lower than right-angle finders, those are statements of fact. I may be right or wrong about them, and if I’m wrong, I expect to be corrected. If I say that I don’t mind the extra weight and bulk of a magnifying finder, or that I hate crouching to look through a finder, those are my preferences. I can’t be wrong about them, any more than I can be wrong about liking egg salad and long solo drives. If you have different preferences, great! You can’t be wrong about them, either. It’s a big world, and there’s room for all kinds of preferences. Where we often get into trouble is when we (a) mistake preferences for facts, and (b) expect others to fall into line with our preferences. Maybe egg salad and RACI finders just aren’t your cup of tea. That’s fine, I can’t tell you that you are wrong.

So I will try to be as clear as possible in this post between the objective facts and my subjective preferences, and I expect to be called out if I get any facts wrong, or get any of those facts and preferences on the wrong side of the line.

With all that in mind, here are some issues that arise when we consider finders:

  1. Straight-through versus right-angle viewing
  2. Magnification
  3. Size and hassle
  4. Longevity

1. Straight-through versus right-angle viewing

The main difference in preference here seems to come down to just a handful of things: with a straight-through finder, whether magnifying or non-magnifying, you’re looking in the same direction as the telescope tube is pointed, which some people find more intuitive, and if you want you can use both eyes and overlap the image through the finder with the image through the other eye, whereas with a right-angle finder you’re looking in the same direction as the telescope eyepiece, which typically requires less head and body movement, and less crouching to get your head down behind the finder.

Sighting down the tube of my Apex 127 to get the finder aligned, using the top of a palm tree as a target.

One criticism that might be leveled at right-angle finders is that people using manual mounts often end up sighting down the tube anyway to get the scope in the right neighborhood, and as long as you are down there with your face against the tube, you haven’t actually saved yourself any ergonomic benefit over looking through a straight-through finder. My counter is that I’ve gotten good enough at “shooting from the hip”, just aiming the scope up at the patch of sky I want without sighting down the tube, that I can almost always put the target somewhere in the field of view of a 9×50 RACI finder. So I hardly ever sight down the tube. I realize that’s a personal experience and preference, not a universal one. (You can also get away from sighting down the tube by using a laser pointer as a finder, as discussed below.)

I prefer to sit when I observe, and I often observe things when they are high in the sky, and there’s no getting around the fact that if you do those two things, using a straight-through finder means crouching or kneeling on the ground. The only ways I know of to get around that are (1) putting the scope higher, which means either standing or using a really tall observing chair, (2) not observing near the zenith, which means giving up the darkest part of the sky, or (3) using go-to, where you only need to use the finder at all during setup, assuming the alignment is good and the pointing is accurate.

2. Magnification

Some people prefer magnifying finders, and others don’t. I prefer them, for a few reasons. First, a magnifying finder offers an intermediate step between naked-eye and ‘main telescope’ viewing, which I find especially useful for star-hopping. Particularly in dark areas of the sky, or under light-polluted conditions where big areas of the sky have all the naked-eye stars wiped out of visibility, I often need something between my eyes and the scope to help me get on target, even with the aforementioned sharp-shooting. Not everyone does, so that counts as a preference.

The Apex 127 with a little SV50 mounted as a luxo-finder and mini-RDF. The wide-field, low-power views in the little refractor complement the narrow-field, high-power views in the larger Mak.

I have also come to appreciate using a magnifying finder as an observing instrument in its own right. The finder offers a larger true field for big objects that might not fit in the FOV of the scope, and under sufficiently dark skies the finder serves as a miniature rich-field scope. From the Salton Sea, Anza-Borrego, and dark places out in the Mojave, Utah, and the Oklahoma panhandle, I’ve seen virtually all of the Messier objects in a 9×50 finder. As an enthusiastic binocular observer, I think of a 9×50 finder as a 9×50 monocular that I can park, and which I don’t have to worry about holding steady. I also find a magnifying finder useful for educating newcomers—I can have them compare the views in the finder and the main scope to learn about the tradeoffs of light gathering, magnification, and field of view.

3. Size and hassle

Here the point goes to the red-dot finder, and in fact most non-magnifying illuminated dot or ring finders. Even Telrads are voluminous but not heavy. So if size and weight are considerations, the RDFs come out ahead.

Also, dot- and ring-finders can typically be aligned with just two or three adjustment knobs. The spring-loaded finder brackets used for a lot of magnifying finders these days are equally easy to adjust, but the older two-rings-with-three-screws-each setups can be pretty tricky by comparison. They’re not exactly hard, especially once you get used to them, but they have a slightly steeper learning curve over the very simple alt-knob-plus-az-knob alignment of most red-dot finders.

I’ll say this for RDFs, they are much less hassle when you’re trying to balance a scope.

4. Longevity

Red-dot finders require batteries. So do illuminated magnifying finders, but non-illuminated magnifying finders don’t, so that’s a slight convenience win for them. More seriously, in my experience red-dot finders are the component of a modern scope with the shortest lifespan; in fact, they’re the only component that usually wears out at all (although reflectors eventually need their mirrors recoated). We use Orion StarBlast 4.5 scopes in the Claremont Library Telescope Program, which has been running so long now and with so many scopes that I have about 20 cumulative telescope-years of experience with that model. The RDFs always fail early in the lives of the scopes. After a couple of years of trying to fix or replace them, I started pulling the batteries and rewrote the instruction manuals to direct people to use them as peep-sights, and that has solved the problem to everyone’s satisfaction. So at a base level, I don’t trust RDFs because I expect them to eventually fail, and that’s not something I feel about any other piece of kit that I own or work with.

I see you, red-dot finder, but I don’t trust you.

The third way: what about laser pointers as finders?

I have to admit, I use a green laser pointer a lot as an auxiliary finder. Several manufacturers make GLP mounts that can be precisely aligned with the main scope. I tend to just pull my GLP out of my pocket and slap it alongside any straight edge on the telescope, mount, finder base, or focuser, and that’s good enough to get the 9×50 RACI on target–or the whole scope on target, in the case of the SkyScanner, which I modified with a bespoke wooden trough to hold a GLP. On my other scopes, I can do without a mount for the GLP precisely because I use a magnifying finder, which takes over where the rough laser alignment leaves off. I can certainly understand, though, why some people prefer permanently-mounted GLPs as finders, and if I didn’t like using mine freehand so much—or if I was willing to buy a second one—I’d be awfully tempted to do the same. I wouldn’t give up a magnifying finder, though, so I’d have to dual-mount.

Cheap GLP in the wooden trough I built for my SkyScanner 100. I got the idea from fellow PVAA member Ken Crowder, who had done something similar for his 8-inch SCT!


In summary, I don’t like the ergonomics of any straight-through finders, red-dot or otherwise; I don’t trust the longevity of the cheap came-with red-dot finders, and I’m unwilling to invest in better ones because of the ergonomic issues; I strongly prefer to have a magnifying finder as a second telescope mounted alongside the first; and I don’t mind the extra size, weight, and hassle that comes along with 50mm finders in particular. In fact, if 70mm and 80mm finders were cheaper, I’d probably have them sprouting from my telescopes like mushrooms. A 9×50 RACI finder was the very first add-on I got for my first telescope back in 2007. I’ve moved it around as needed to almost every other scope I’ve owned, so I’ve been using one for so long now that if I don’t have one on a scope, it feels like I have a limb missing. (The SkyScanner 100 gets a pass here, because with a 32mm Plossl in the focuser, the scope itself serves as a 12.5×100 right-angle finder, albeit with an inverted image, and the same goes for other super-widefield scopes like the Bresser AR102S.)

Every one of those things is a preference, not a fact. Obviously many other folks have other preferences—just witness the devotion to Telrads, which IMHO are about 10 times as large as they should be to do what they do. And using my new NexStar 8SE is gradually eroding my hate for RDFs. I have to grudgingly admit that the RDF is a handy tool for the initial 2-star alignment, especially because I tend to select alignment stars near opposite horizons, so I don’t have to crouch too much to use the RDF. I still do the first round of centering using the Celestron illuminated 9×50 RACI that I bought from Doug Rennie, and I check the finder on about half the targets just to see what they look like in the smaller instrument. But the RDF is clawing for a place in my kit, and possibly when I’ve used one as much as I’ve used a 9×50 RACI, my preferences will have changed.

What do you roll with, and why? The comment field is open.