Sunday, June 14, 2020

 

#561: Fifteen Years After the Honeymoon or "The New Herschel Project: 1 Down, 399 to Go"


If you’ve been following the AstroBlog for a while, I don’t have to tell you who Charity Hope Valentine is. If you haven’t? She’s my little Meade ETX125PE Maksutov Cassegrain.  More than a few ETX fanciers—yes, there are still some out there in addition to your old Uncle Rod—have asked me how 15-year-old Charity is doing. The answer has been, “I don’t know, muchachos, I don’t know.” She hadn’t been out of her case in a couple of years. Could be three. Possibly four. At his advanced age, Unk’s months and years tend to fly by and get all jumbled up together. 2016, for example, seems like just yesterday. Nay, just hours ago.

My little girlfriend has, on balance, always been a Good Telescope. I’ll be the first to say she can be a slightly neurotic handful like her namesake, but she usually cooperates with your old Uncle. Charity has starred in more than a few AstroBlog articles, and if you’d like to learn more about her, click here, here, and here. But the above pretty much sums up our relationship over the years. 

Anyhow, it had been a while since I’d even thought much about the 5-inch Maksutov Cassegrain. But seeing as how I was looking around for something to do astronomy-wise with the New Herschel Project stopped in its tracks by clouds, I thought I’d get Charity out. I’d need to replace her battery, and would do any other maintenance she required. “Battery?” Yes, Charity is one of the last of the original breed of ETXes, the non-Ningbo Sunny ETXes if’n you know what I mean. She’s a PE, and she has an LNT.

“Wut?” The PE (Premier Edition) ETXes were different from earlier models in that they featured pretty—some would say garish—silk screened tubes and the aforementioned LNT finders. That stands for “Level North Technology.” A PE was like a GPS scope without the GPS. All you had to do was set the scope in a simple home position and turn it on. Charity and her sisters would then do a little dance, finding north and level, and would head to the first of two alignment stars, which you'd center. That was it. For it to be practical, of course, you had to have a real time clock battery to keep time/date current when the ETX was powered off.

The Girl Still has Her Good Looks
The system worked well. You didn’t even have to enter your position into the Autostar unless you moved at least 60-miles from your previous location. According to Meade, the LNT battery would be good for “five years.” That was awfully optimistic. One year or a bit more being as long as the scope’s 2032 button cell has ever lasted for me. That wouldn’t be so bad if Meade hadn’t made it so devilishly difficult to change the battery on the initial PEs. Not only is the battery down deep in the scope's red dot finder's guts, the finder uses a big plastic lens that's just begging to be snapped off in the process of replacing said battery.

Meade soon reworked the LNT finder, adding an easy (or at least easier) to access battery compartment and a lens for the red dot finder part of the LNT that would be less likely to be accidentally snapped off. Charity, however, is an original. Nevertheless, I’ve managed to keep Charity’s finder lens intact and battery changed out these 15 years. 

At any rate, I recalled replacing Charity’s RTC battery required disassembling the LNT finder, unscrewing a pair of bolts (the finder alignment bolts), and removing two associated springs, one of which is insanely difficult to replace when you are done. Naturally, these springs want nothing better than to fly off and hide on the floor. But maybe I wouldn’t have to do anything about the 2032. Maybe after “just” a couple of years of disuse, the battery would still be good. I was doubtful, however, and hunted up one of the button cells in the kitchen junk drawer where such things reside.

I pulled Charity from her case. Despite the passage of all the long years, she’s maintained her girlish good looks. I’ve always tried to take good care of my friend; she’s deserved that in thanks for the years of joy she’s brought me. But would she wake up when I turned her o-n/o-f-f switch to o-n? After who knew how many trips around the Sun?

That big lens just begs to be snapped off.
I plugged in the Autostar, plugged up a jumpstart battery, flipped the switch and… Sweet Charity emitted the friendly beep that means, “Hi Rod! I missed you!” and displayed the good, old “Welcome to A U T O S T A R” on her red LED screen. I was at least relieved she awoken without complaint. But how about that battery? I mashed "Mode" a few times to get to time and date and…uh-oh. “07 July 2016.” Had it really been that long since I’d (ahem) turned on Charity Hope Valentine? It didn’t seem possible, but maybe. The time was, no surprise, off by hours.

So, there’d have to be a battery swap. I still have Charity’s manual, of course, and reviewed the instructions on that task. OK, remove the top adjustment bolt. Check. Remove the side adjustment bolt. Check. Gently lift the top of the LNT housing (there’s a wire connecting top to bottom). Check. Don’t lose the two springs associated with the bolts you just removed. Well, the horizontal spring was no problem, but, as I had feared, the vertical, smaller spring went flying to the floor of Unk’s (radio) shack. He spent the next 15-minutes crawling around on said floor with a Maglite before turning up the frickin-frackin thing.

“Well, alrighty then,” Unk said (actually he said some colorful words in the course of locating the spring and replacing it during reassembly). Next step was removing and replacing the button cell itself, which was no problem, it being held in the typical spring-type battery holder. What was a problem was reassembling the LNT. Lining up the vertical spring, passing the bolt through it, and tightening the bolt was not difficult; the other bolt and spring were where the problem lay and has always lain.

Alas, Meade’s instructions for replacing the horizontal spring were insane: “Tighten the vertical bolt until it is firm.” If you do that, there is very little space between the side of the bottom half of the LNT and the side of the top. You have to squeeze the spring between those sides, aligning it with the holes, and inserting and threading-in the horizonal bolt. It was clear that would never work. Not in a million years. What did work was threading the vertical bolt in just a few threads. That left enough space between bottom side and the top side for me to squeeze the spring into place. I managed to use a solder tool to nudge it around to get the holes lined up, and got that hellish bolt screwed in.

Surgery begun...
Next on the agenda would be recalibrating my girl’s sensors—one of the two requirements following a battery change, the other being “drive training.” Sensor alignment would require the star Polaris. There was no doubt in my (once) military mind that this would not be a Herschel Project night—I’d disassembled Mrs. Peel and moved her back inside to wait for a better stretch of weather. But maybe I could at least get Charity dialed in on the North Star?

It turned out I’d have to wait a while before I could even get the girl into the backyard. We had the perfect storm from an observer’s point of view: waxing moon, cloudy skies night after night, and, finally, Tropical Storm Cristóbal hit the coast dumping torrential rain on Unk’s vaunted backyard.

Anyhow, last Thursday dawned to drier and slightly cooler weather, which is common in the wake of a tropical storm. It looked so nice, almost fall-like, that I began to wonder if I should squander the night on “just” a 5-inch MCT and eyepieces. Alas, as the day wore on, those darned old white, fluffy things began to scud across the sky. I could scarcely believe it. Actually, that’s wrong. The way the weather’s been the last couple of years, that’s exactly what I have come to expect. I decided to stick with Charity and delay placing even her in the backyard until close to sundown.

And…the clouds just kept pouring in, flowing from (strangely for here) northeast to southwest. I had little hope, but at about 9 pm clouds had skittered off to the extent I thought I might get something done. The sky was still hazy, though, very hazy. While I could make out the Dipper/Plough, only the two “end” bowl stars of Ursa Minor were apparent. Whatever. At least I’d get the Calibrate Sensors business completed.

This is how the sky looked--until Sundown.
What that does is inform the mount’s computer of the difference between true north and magnetic north for the scope's current location. There’s really not much to it for the user. I put Charity in her home position (rotated counterclockwise to her hard stop), locked the azimuth lock, and started the procedure. The scope points to true north as best it can given the readings from its built-in electronic compass; then you are instructed (by the Autostar) to center Polaris and press Enter. Our magnetic deviation is small here, so just a little slewing put the North Star in the crosshairs and I was finished.

Next up, I figured I’d better do some Drive Training, the purpose of which is to let the ETX computer know the magnitude of backlash in the mount's gears. That is vital for good goto pointing. After years of experience, what I’ve determined is it’s better, for some reason, to use a terrestrial object like a distant streetlight than a star. You’d think Polaris would be just the thing, but it doesn’t seem to be. Unfortunately, there's not a good terrestrial target visible from my backyard, so I just used Polaris, which worked OK.

As with Calibrate Sensors, there’s not much to Drive Training. The Autostar tells you to center your target, you do that and press “Enter,” it slews away from target target and tells you to re-center it (the Autostar even shows you which direction key to mash) and you do that and press Enter again. Repeat the procedure for both azimuth and altitude and you are done. In my experience, drive training needs to be accomplished periodically. So, when Charity begins missing targets, I immediately do a quick re-train.

Note, as with some other goto systems, certain targets are just hard for Charity's Autostar--mostly those directly or near directly overhead. Because of the construction of the ETX's fork, it's hard to access the focus knob when the scope is pointed near zenith, anyway. So, all things considered, as with big Dobs, it's best just to avoid Dobson's Hole with an ETX.

The sky really was looking yucky now. Not so much cloudy anymore as just very hazy. However, I thought if I could get an object or two in the can, so to speak, that would put me ahead of the game. I also wanted to see if Charity was still her old self after so long a layoff.

In her salad days.
Yes, the haze was bad, the seeing was bad, and clouds were still scudding through. But that is exactly what I used to call a “Sweet Charity night.” Her good contrast despite a rather sizable central obstruction (do NOT tell her I said that) gives her a leg up under conditions like these.  I’ve often been surprised at what the girl can pull out of some fairly nasty conditions.

On this night? Not so much. Messier 3 looked OK—at 150x a fair number of stars were resolved around its periphery—but just OK. Not even really “fair.”  “Well, let’s knock off one Herschel 400 object, anyhow. M82 oughta show something.”

Indeed, Ursa Major’s Cigar Galaxy did show something; just not much. When Charity stopped slewing and the weasels-with-tuberculosis sounds that accompany that stopped, I wondered if she’s missed the Cigar. However, a little bit of staring and reducing power to 75x showed a filmy something centered in the field. A little more looking with averted vision turned up the galaxy. I could cross M82 off the list, but that’s all I could do. There were no dark lanes visible, and even the basic shape of this “disturbed” galaxy came and went.

Also, the bugs were biting. When I’d masked up and visited Publix the previous Tuesday, they didn’t have any of the replacement candles and repellent pads for the Off mosquito lantern I use to keep the biters at bay (much less Thermacell refills). So, I thought the best course was to throw the big switch, cover Miss Valentine, and perhaps devote one more night to her.

Friday was supposed to be better, but, like Thursday, while it started out clear and crisp and beautiful, as soon as darkness came the sky flooded with clouds. So that was that. I disassembled Miss Valentine and returned her to her case--I hope for a shorter stay than last time. I didn’t feel like I could devote any more of our increasingly few observing hours to my ETX girlfriend no matter how much I love her. Next up will be my Edge 800 and Mallincam and we’ll see if we can really knock off some New Herschel objects.

Nota Bene:  Friends, while Charity was mostly in good shape after all that downtime, I noticed the insulation on her Autostar hand control cable is gone in several places. I’ll definitely need to replace it before our next outing. Unfortunately, a bit of googling hasn’t turned up a source for a good replacement. Can any of y’all help?

Book Plug Department

I’m gobsmacked at a new book that’s just crossed my desk, Thomas Fowler’s The View Through Your Telescope. It is subtitled And How to Make it Better. And that is just what it can do, muchachos. I haven’t had time to really dig into it yet, but I can tell you already this is just the sort of book a lot of us, and especially imagers (but not just imagers), have been looking for. It is somewhat technical in places, but that’s also just what many of us have been looking for. Go get it, muchachos. Expect a full review soon.

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