Full moon, 1 Oct. 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: Total lunar eclipse on January 31, 2018

Man, only the second post in six months, and we’re back to another eclipse! Oh well, that’s how it goes sometimes.

This is also going to a short post. I have more photos from the eclipse, and I’m hoping to get them processed soon and put into a composite like I did for the October, 2014 (link), and April, 2015 (link), lunar eclipses. But those photos are still lurking in a raw state on my hard drive. You’re getting the only two I’ve processed so far: the above shot of the full moon at 12:20 AM, before the eclipse started, taken with a Nikon Coolpix 4500, and the below shot from the start of max eclipse, around 5:00 AM, taken with an iPhone 7. Both shots taken afocally through London’s XT4.5 dob and a 32mm Plossl.

Hope you got to see it. Stand by for more shots…at some point. Hopefully. What can I say? Fossil season came early this year…as I knew it eventually would.

Observing Reports: two perfect imperfect nights at the Salton Sea

The Saturday before last, November 14, I was at the Salton Sea with Terry Nakazono.

Terry was rolling with a new scope – a Meade Polaris 114. It’s an f/8.8 reflector – the 1000mm focal length makes it a bit longer than the 900mm, f/7.9 Orion XT4.5 (which London has). UPDATE Nov. 29: Terry writes, “It’s a standard 900mm FL, not 1000mm. A lot of the retailer ads have it wrong and says its 1000mm. I myself was intrigued when I first read about it, but later found out from looking at the PDF manual and those who bought it is that it is an F/7.9 of 900mm focal length.” So it’s not longer than London’s XT4.5, it’s essentially the same OTA.

This Meade is a pretty amazing deal. A lot of small intro reflectors have a short dovetail bar bolted to the side of the tube (like my old scope Shorty Fats), but this one has real tube rings and an EQ-2 mount. The three MA (Modified Achromat) eyepieces it comes with are nothing to write home about, but the focal lengths of 26mm, 9mm, and 6.3mm are at least useful and non-overlapping when doubled with the included Barlow. Terry shared a few views with me and I can confirm that it serves up a sharp, contrasty image, as you’d expect for a scope of this focal ratio. It would be a good deal at the list price of $170, but Amazon has it for $135 as of this writing, and according to Terry it can be found for even less if you look around.

I brought the Apex 127/SV50 combo – I’m sighting on the moon here, to align the finder with the scope – and the C80ED.

Here I am digiscoping the moon with the C80ED. I used the Apex 127 for tracking down some planetary nebulae and double stars, and the C80ED for photography and just messing around. It’s a crazy fun little scope. Unfortunately, none of my moon shots worked out this time.

The forecast called for clear skies most of the night, but clouds between 10:00 PM and 2:00 AM. We got set up before the sun set at 4:45, and pushed through until 10:40. Then it got too hazy to observe, so Terry and I sat and jawed about scopes, atlases, and observing projects until the sky cleared a bit at midnight. We got in about half an hour more before the sky clouded over completely about 12:40. We talked a bit more then turned in.

I got up at 4:00 AM to catch the morning planets – Jupiter, Mars, and Venus. I cannot get the iPhone to take a fast enough picture to capture any detail on Jupiter – it always comes out as a blank circle of light (with some glare from the iPhone, not the scope). But the moons show up nicely. I really need to get a better camera control app.

I was clouded out again at 5:15, and Terry and I sat up until 5:45 watching the approaching dawn. Then it started sprinkling! Weather Underground, the Clear Sky Chart, and my other weather app all missed that. We packed up quickly and drove out at 6:30. A hearty breakfast at the Coco’s in Indio put a cap on the expedition. Although the skies were less than perfect, we had a good time catching up, and we did see some nice things.

Back Again

As luck would have it, I was back at the sea just eight nights later. London and I hadn’t been to the Salton Sea since last November, and he has all this week off from school, so we went last night. He took his XT4.5, and I took my C80ED. The waxing gibbous moon was only three days short of full, so the skyglow was pretty bad. But the seeing was excellent, easily 8 or 9 out of 10. I could split the four main stars of Orion’s Trapezium wide open at 25x, and fleetingly at 19x with the 32mm Plossl.

I could have held that split more easily with a better low-power eyepiece. I had not noticed it before last night, but my trusty Orion Sirius 32mm Plossl, my go-to widefield and finder eyepiece for many years, has some astigmatism. Not a lot – it was only noticeable immediately after switching from my 24mm ES 68. I tried both eyepieces with and without eyeglasses to confirm that the aberration was in the Plossl and not elsewhere in the optical train, my eyeballs included (I tried both). Another case of getting spoiled by premium eyepieces. It’s fine, though – since the 24mm ES 68 gives the same field of view, I only pull out the 32mm Plossl when I want to drop the magnification even lower, or when I’m doing outreach.

I spent a lot of time cruising the central part of Orion at 120x with the 5mm Meade MWA, which is now my preferred high-power eyepiece. Just three weeks ago I saw and sketched the multiple star Sigma Orionis for the first time. It’s funny – I’d been observing Orion regularly for eight years before that and I’d never seen it, but now I stop there every night I have a scope out. Even London’s little 60mm Meade refractor split the six main components wide open. But last night I saw a faint, seventh member that I’d previously missed.

I turned in relatively early, around midnight, figuring that I’d get up after the moon set and do a quick morning Messier hunt. And the sky was truly phenomenal after moonset. I was waking up about once an hour and having a quick look around, and it was a spectacularly clear, dark night. But the flesh was weak, and I overslept, only dragging myself out of my sleeping bag at 5:00. By that time the first glimmerings of dawn were lighting the eastern horizon, so I skipped the Messiers and went to Jupiter.

That planet above the scope is Venus, not Jupiter.

The view was jaw-dropping. The seeing was rock solid and I was able to Barlow the 5mm MWA up to 240x without the image breaking down. At that magnification I could detect at least three delicate brown belts north of the North Equatorial Belt, and the Galilean moons were little spheres, not just points of light. I tried taking some pictures but didn’t get any better results than I had the last time out, so I put the camera away and just stared. I must have spent 45 minutes just watching Jupiter drift across the field of view, mostly at 240x.

Last night I was definitely in aesthetic observing mode. I spent a little over two and a half hours at the eyepiece, entirely on four objects – the moon, Orion nebula and Trapezium, Sigma Orionis, and Jupiter. I had half-formed plans to look at other things, but I kept getting seduced into long sessions of fully immersed stargazing. And I’d do it again in a heartbeat.

So, neither night had perfect observing conditions. It was hazy the first night, and the moon was out during the convenient observing hours last night. But I had a great time both nights, saw some cool things, learned a little more about my gear, and enjoyed the good company of Terry and London. Couldn’t really ask for more.

Sunday night on Mount Baldy

Sunday night I went up Mount Baldy for a solo session. I was rolling with the C80ED, which has become my default grab-n-go rig.

One of my goals was to test a couple of new eyepieces. Several astro retailers had a big sale on Meade wide-angle eyepieces last month. I was torn between the 20mm and the 5mm Series 5000 Mega-Wide 100-degree EPs (man, is that a mouthful or what?). The 20mm would have been a great low-power, widefield scanner, which is something I’ve gotten progressively more interested in this fall. But for a long time I had been without an EP shorter than my 6mm Expanse, which is not without its problems, so I sprung for the 5mm instead.

In the meantime, thanks to this thread on Cloudy Nights I had become aware of the VITE eyepieces. These odd little birds come in only 3 focal lengths (at least so far): 23mm, 10mm, and 4mm. They are three-element EPs with one aspheric plastic element and plastic bodies. They’re about $17 apiece on Amazon, or $9 apiece on eBay. I ventured my nine bucks and got the 4mm from eBay, thinking it would make an interesting comparison with the 5mm Meade 100-degree. I had done a quick comparo late Saturday night from my driveway on the moon and the Orion Nebula – more about that in a bit.

Sunday evening on mount Baldy I cruised through the highlights in Lyra, Cygnus, and Sagitta. I did a quick, rough sketch in my notebook of the open cluster NGC 6823. It has a curl of stars wrapping up around it like a fiddlehead fern.

After that a couple of high school kids and their little brother drove up nearby, and I spent about an hour showing them around the sky – the Dumbbell Nebula (M27), the Double Cluster, Pleiades, Andromeda galaxy, Polaris, M15, 61 Cygni (aka Piazzi’s Flying Star), and finally the Messier open clusters in Auriga – M37, M36, and M38.

The kids left about 10:30. Since I was in the area I had a look at M1, and then cruised down to Orion. The constellation was slowly crawling over the ridgeline to the east, so I started visiting the bright stars, and in some cases splitting them. First up was Meissa, which was elongated at 68x and cleanly split at 120x in the 5mm MWA and 150x in the 4mm VITE.

Mintaka was an easy wide split at only 25x. Seeing was not good, but Eta Orionis appeared to be elongated east-west at 120x and 150x. The view in the VITE was kind of a mess, so I spent a few minutes just cruising around Orion’s belt and sword with the 5mm MWA. Alnitak and its dim companion were widely split. I turned south to Sigma Orionis. I’ll have to check my notes, but I don’t believe I’d ever split this star before. It’s pretty great, with a group of three fairly bright stars and a second group of three much dimmer ones. I backed down to 68x and all six stars were still nicely split, and frankly looked a bit sharper, although that might have been down to bad seeing.

So, here are my thoughts and observations on the 6mm Expanse, 5mm MWA, and 4mm VITE. These don’t count as an actual review, as I didn’t have equivalent focal lengths to compare, and I’ve only spent a couple of nights with the two newer eyepieces, observing only a handful of objects. Still, I tried them on a variety of things – the moon, globular and open clusters, the Orion Nebula, double stars – and the strengths and weaknesses were consistent. All of these observations are with the C80ED, so the chromatic aberration (CA) with certain EPs is particularly interesting.

6mm Expanse – Has a small but noticeable amount of CA on bright stars. Eye placement is a bit tricky – I get some kidney-bean and full-aperture blackouts until I get my eye placed just so. Comfortable enough once I get my eye in the zone, though. Halos on some bright objects.

5mm MWA – Sharp from edge to edge. No detectable CA, but the edge of the field does look blue until I get my eye centered. No detectable field curvature. Eye relief is pretty tight – when I move in close enough to see the entire field, my eyelashes brush the lens about half the time (I do have long lashes, but still). I have to move my head around to focus on objects in different parts of the field. Very immersive – I feel like I could climb through the eye lens and into space. The rubber eyecup is annoyingly loose – it frequently comes off with the dust cap.

4mm VITE – Can’t focus the whole field at once. Center of the field is sharp enough, but objects start getting blurry halfway to the edge of the field and are entirely defocused at the edges. ‘Sweet spot’ is pretty small. Considerable CA – makes an ED refractor perform like a short fast achromat! Strong internal reflections from bright objects on the edge of the field, or just out of the field. Almost impossible to focus on the lunar terminator if it’s centered – a big bright glow from the lit side of the moon fills the center of the field. Eye relief is tight – eyelashes scrape most of the time.

Verdict – The 5mm MWA is a keeper. The eye relief is short but tolerable, and totally worth it for the huge, flat, well-corrected field. As for the VITE, I’m glad I didn’t spend more than $9. I’ve read that these perform better in longer focal ratio instruments, but at f/7.5, the C80ED isn’t exactly fast. So how long does the light cone have to be for the VITE to perform well – f/10? f/15? At those focal ratios, it would take an exceptionally still night for a 4mm EP to be useful. I will try the thing in my Mak and probably in my C102 but I am not expecting much. People on CN seem pretty happy with the 23mm, so maybe there’s some variation within the line.

Back to the observing report. By midnight I was tired and my feet were cold. I had just resolved to pack up and head home when I saw that the hillside behind me was lit up by moonlight. The moon was coming up behind the ridgeline to the east. It had been a long time since I’d had a chance to shoot the moon rising behind trees, so I quickly set up the camera adapter and got to work. My best still shot is at the top of this post. And here’s a video:

I went for the sideways aspect ratio this time, but I didn’t quite get the camera square on to the view. Guess I’ll just have to try again next month.

Digiscoping with the GoSky universal cell phone adapter

As I mentioned in the moon video post, I recently got a GoSky universal cell phone/eyepiece adapter. So far I’ve tested it on some birds during the daytime, and on the moon after dark. Here’s a Northern mockingbird at 50x, about 125 feet away.

I did most of the digiscoping with my C80ED and a 12mm Plossl (50x). I tried other eyepieces but for my purposes the 12mm Plossl delivered the best balance of magnification, true field, and image brightness.

If you haven’t seen one of these cell phone adapters, it has a diamond-shaped, padded clamp that screws down around the eyepiece, and another padded clamp to hold the phone. The bracket for the phone can slide up and down and rotate relative to the eyepiece clamp, so you can get the phone’s camera centered over the exit pupil of the eyepiece. As you can see here, the phone bracket is wide enough to hold an iPhone 5 with a heavy Otterbox case. I prefer to leave the case on while shooting – it’s rubber, so I can crank down the adapter bracket and make sure the phone is truly secure. Plus, it’s one less thing to do during setup and teardown.

You may be wondering why I have earbuds hooked up to the phone. It’s because of a very nice feature with the iPhone 5 and 6 (don’t know about other iPhone models or other brands of smartphones) – the volume buttons work as shutter release buttons, which is often handier than trying to press the button on the screen, AND this functionality extends to plug-in volume buttons like those on the earbud cords. So you can plug in your came-with Apple earbuds and use the volume control there as a remote shutter release for hands-free, no-shake photography.

That mockingbird again, fluffing its tail feathers.

Here’s one of the moon. The seeing was punk last night so I know the system was not performing anywhere near its limits. I’ve done far better holding the phone by hand on nights with better seeing, but only by dumb luck, taking loads of pictures, and throwing away all but the best. Using the adapter I get much more consistent results, even if the seeing makes them all consistently lousy on a given night.

The biggest problem with this setup so far is that the lens of the iPhone camera is bit fish-eyed and that introduces some kind spherical distortion (I believe it is positive or pincushion distortion – feel free to educate me in the comments) in the image. It’s not so bad in this cropped picture:

But check out the diverging power lines – which are parallel in real life – in the unmodified original:

These are European starlings at 50x, again with the 12mm Plossl, from about 250 feet.

I did lots of back-and-forthing between camera and the various eyepieces to confirm that the distortion was in the camera and not in the telescope or eyepieces. It’s a fairly minor annoyance for me – I’m not expecting world-class results out of my smartphone camera. Just something to be aware of.

I tried going up to 100x with the 6mm Expanse on this starling. It caused a lot of vignetting – even in this severely cropped photo, you can see that the corners are dark. I’ve had this problem with using too much magnification with handheld afocal photography as well. I think that as magnification goes up and the exit pupil goes down, it’s progressively harder to fully illuminate the camera’s CCD.

This may seem like a lot of caveats and complaints – distortion, vignetting, etc. – but they’re all problems that come along with doing afocal photography with a phone. The adapter itself is dandy. It holds the phone and eyepiece securely and without stressing either one or leaving a mark, it’s easy to put on or remove, and it adjusts easily. I wish now I’d gotten one a lot sooner. There are lots of interchangeable brands on these things – if you want the GoSky verison, it’s here.

Sinus Iridium

Taken at 7:43 PM PDT last night, from the top of the parking garage in downtown Claremont, using a handheld iPhone 5c shooting afocally through an Orion Apex 127 Mak and a 12.5mm Plossl eyepiece.

In other news, no, I’m not dead. Just been busy with teaching. But I have some exciting astronomy news coming up later this fall (finally revealed here!), and in the meantime, I’m looking forward to the total lunar eclipse this coming Sunday evening, September 27.

Observing Report: Total lunar eclipse on April 4, 2015

I stayed up late Friday night to catch the beginning of the lunar eclipse early Saturday morning. The penumbral eclipse started at 3:16 AM local time, and it was still going on when the sun rose. The umbral or ‘total’ eclipse was very brief, just five minutes between 4:58 and 5:03. Just like last October, I got London up to see it. He was kind enough to loan me his 60mm Meade refractor for the event, and he used his XT4.5. The little Meade refractor made photography easier by cutting down the light level without sacrificing contrast. I took all of these photos with my iPhone 5C shooting through a Celestron 8-24mm zoom eyepiece. As usual, I processed and composited the photos in GIMP.

I’m particularly happy with this shot of the full moon. I really need to do a composite image with all of my best full moon shots. One of these days.

Previous lunar eclipse reports:

• February 20, 2008
• October 8, 2014

Previous full moons:

• January 29, 2010
• September 22, 2010
• November 21, 2010
• August 1, 2012
• October 8, 2013

 

PVAA outreach at Oakmont Elementary School

Our local club, the Pomona Valley Amateur Astronomers, had a public outreach at London’s elementary school this evening. London brought his 60mm Meade refractor, and I brought my C80ED.

Our little scopes were quite literally overshadowed by Jeff Schroder’s 11-inch refractor, which is mounted to the top of his car. Jeff built this scope by hand, even ground the lenses himself. It’s entirely fitting that he’s the outreach coordinator for the PVAA – not only does he have the coolest scope, he was one of the founding members of the club back in the day.

Jeff also had a 10-inch Dob along, and Ron Hoekwater brought his Skywatcher 10-inch collapsible Dob. We showed people the moon, Jupiter, Venus, and the Orion Nebula. I got this moon shot with my iPhone with much less futzing around than usual. I don’t really understand how that happened, but I’m not complaining.

The lunar ‘Cheshire Cat’ revisited, and problems of contrast

Just a quick post before I head off to work. London has the telescope bug and he has a birthday coming up, so we were looking at various scopes on Amazon and other places. He wasn’t clear on the distinction between the three main telescope designs, so we hauled out the DK Universe book and looked at the ray diagrams the three kinds (refracting, reflecting, and catadioptric). He was familiar with refractors, like his 60mm Meade, and reflectors, like his Astroscan, but was less familiar with catadioptric scopes, which is not super-surprising since I’ve used my Maks hardly at all in the last year and a half, other than last year’s All-Arizona Star Party. The sky was clear and the moon was high, so we popped outside and set up my 90mm SkyWatcher Mak for a quick look at the moon. Astonishingly, I had not had this scope out in more than two years, since July of 2012.

Here’s my best iPhone photo of the moon from last night. Up near the top of the terminator you can see two glowing dots like eyes peering over the limb of the moon. If you click through to the full-size version, you’ll see that the eyes have a wide mouth below them and that one nostril is showing. Yep, that’s the lunar “Cheshire Cat”, which I first identified back in November, 2010. It was nice to see it again.

While I was processing that photo I noticed something alarming: a circle of glare around the moon that was bright enough to make the eyepiece field stop visible. It’s more apparent in this over-brightened version:

I was shooting through the Celestron 8-24mm zoom, just like Saturday night. Since I had a comparable shot with the same eyepiece through the C80ED from that evening, I dug out the raw photo and tried brightening it up to see how much glare would appear.

The answer is “almost none”. I used the same tool in GIMP (‘Curves’), and I brightened the image way beyond what I did with last night’s shot through the Mak, and the space around the moon is still pretty black in the C80ED shot. Not grey, as in the Mak shot. And this was only with tweaking the brights up, and not moving the darks down, which would be cheating since it would mask the problem.

It’s tempting to read this as a refractor-vs-Mak thing, but it might not be so straightforward. In this case the refractor has very good optics and coatings, so it’s near the upper end of what refractors are capable of in terms of control of stray light. But the Mak does not have fully multi-coated optics–this SkyWatcher version only has ‘coated’ optics, which means possibly as little as one coat of MgF2 on only the outer surface of the corrector. I have heard from someone (Doug or Terry, maybe?) that this particular model of SkyWatcher 90mm Mak has poorer contrast than the comparable but fully multi-coated Celestron C90–irritatingly I cannot find that post or comment at the moment, but I’ll post it if it turns up. Also, the C80ED has a long-ish dew shield which helps control stray light entering the objective, whereas the Mak does not; you can buy or fashion such things for Maks, but I haven’t taken either of those steps. Finally, I’ve seen some threads on CN about glare from the baffle tube in Maks and SCTs, so that’s another possible culprit here.

An informative test would be to pit the C102 against the Apex 127 on the moon, with a homemade foam or cardboard dew shield on the Apex to eliminate that variable. If I get time this evening or next, I may just try that.

A visit to the Griffith Observatory

Yesterday London and I went to the Griffith Observatory for the first time in a while. We used to go fairly frequently between 2010 and 2012, but this was our first visit in 2014 and might have been our first visit since 2012.

It had been rainy earlier in the day but the skies opened up nicely in the late afternoon, and the waxing gibbous moon was bright overhead.

Happily there were still some clouds to the west and north, which made for a fantastic sunset.

One of my favorite displays is the replica of Galileo’s ‘Old Discoverer’ in the Hall of the Eye. It is still amazing to me that Galileo saw and learned so much with a 1-inch objective mounted in a paper tube. London is blocking the objective end here, but I had to pose him there for a reason.

Here’s the same shot, five years earlier. London was not quite five years old, and he was very excited about being at the “Griffick Ugzerbatory”. I didn’t realize until I checked the dates on the photos that that first visit was not approximately five years earlier, it was exactly five years earlier, on the first of November, 2009.

Farther down the same hall, there is this miniature architectural model of the observatory. The three domes all house different things. The one on the west end of the roof, nearest the camera in this shot, holds the triple beam coelostat for live viewing of the sun. The huge middle dome holds the planetarium, and the dome on the east end holds the big 12-inch Zeiss refractor–you can even see a translucent miniature version of the scope in the model dome.

And here’s the 12-inch Zeiss itself. There are actually five scopes on the mount currently: the big Zeiss, f/16.7, at the center, a 9.5-inch f/14.8 Zeiss refractor piggybacked on top, a 2- or 3-inch finderscope on the lower left, and two 8-inch Celestron SCTs on either side.

Originally the mount only held the 12-inch and the finderscope–you can see photos of it mounted that way on this page, which has a very interesting history of the scope and its uses. The 9.5-inch was added in 1955. The double refractors allowed one scope to be used for visual observation while the image from the second was sent to a closed-circuit TV. That job is now farmed out to one of the Celestron SCTs, which are much more recent additions.

Here’s another view. The total moving mass of the rig is 9000 lbs, or 4.5 tons.

We have gotten to look through the big Zeiss a couple of times, but we didn’t do so last night. There is usually a line with a wait time of about an hour. The way to beat the system is to be on the roof and near the east end at the moment that they open the dome and the line first forms–we have been lucky to be in that position once before. But last night we were in the middle of a planetarium show when the dome opened at 7:00, and we didn’t fancy standing around in the cold for an hour. Especially because there was a public star party on the lawn in front of the observatory, with about half a dozen scopes set up. There were long lines for the big scopes, but one guy had a 90mm Mak on an EQ mount that everyone seemed to be ignoring. London and I got razor-sharp views of the moon through that little scope with no waiting at all.

At home I hauled out the C80ED and the 8-24x zoom eyepiece for a quick look myself, and to make another photographic attempt with the iPhone. The two biggest challenges are getting the camera the right distance from the eyepiece, and getting the sensor fully illuminated without being overexposed. Through much trial and error I found that if I left the eyepiece cup up and stripped off only the outer layer of my 3-layer Otterbox phone case, I could rest the second layer of the phone case on the rubber eyepiece cup and have the phone at just the right distance. But that only worked perfectly with the zoom set to 18mm (33x), which is how I took this shot. There is some CA, but I’m pretty sure that was mostly from the eyepiece. If it’s clear tonight, I’ll try again with the ES eyepieces to see if I can isolate the cause of the CA.

One thing I desperately need to do is get one of the iPhone apps that lets you control the ISO and shutter speed of the camera. As it is, I’m just using the camera as-is, so I’m constantly fighting with its auto-exposure and auto-shutter. There’s a delicate balance–if I don’t magnify the moon (or the filtered sun) enough, all I get is a featureless white spot. But if I magnify the subject enough to spread out the light and give the camera’s internal processes some detail to bite on, then it’s hard to get the object fully illuminated–I get vignetting, or kidney-bean blackouts, or both at once. Eric Teske has a nice list of iPhone astro apps on his (ridiculously entertaining) blog–past time I started using them.

Still, for a shot through an 80mm refractor with the came-bundled camera driver on my phone, I’m pretty happy. One thing I really like about the iPhone is the number and utility of photo-editing apps. The first moon image here is the raw shot, only reversed left-to-right to match the moon’s orientation in the sky. The one immediately above I processed in Snapseed: sharpened, contrast enhanced (using the ‘Ambiance’ tool), and desaturated to take out the CA. Given the relatively small number of GIMP features that I actually use, Snapseed is a fast and easy alternative. I’m going to keep messing with it and see how far I can go.