MB 3/6/2008: From a clear hole to the gloomy gulfs of mystic shade, Or... how my HP15c helped me collimate my scope...

Marek Cichanski

Well, as the clouds slide over us, making 2008's Messier Marathon weekend rather uncertain for now, I can feel content that I was lucky enough to make the most of the weeknight observing opportunities. After spending Monday and Wednesday evenings at Montebello, I decided to go for the hat trick and head for MB again.

Yesterday's IR sat loop was rather unique, as it showed that we would spend the day under high clouds, but that a sharply-defined back edge to the cloud band was due to pass over us around sunset. That was a bet that I was quite willing to take. I thought hard about going to Coyote, so that I could bag some galaxies rising in the east, but in the end I opted for the easier drive and went up to MB again. Andrew Pierce had called in the permit, and my car was still packed from Wednesday, so I headed up the hill.

Clouds cleared off around sunset as promised, and it was a quite serviceable sky. The stars were fairly twinkly to the naked eye, but I ended up having some of the best views of the Trapezium that I've ever had. There were many moments of perfectly equant, round, non-spiky stars, as though there were virtually no atmosphere in the way, just the physics of the telecope's aperture. The E and F stars were really a delight to observe under those conditions.

There was a fair amount of extinction near the horizon most of the night, but conditions were pretty good up above about 30 degrees altitude. Seeing was generally sharp, and the sky background at least LOOKED good through the eyepiece. I forgot to take an SQM reading, but I'll bet it was the usual 19.75 or so. Sadly, though, mag 11-12 galaxies were still mostly DNFs in my 10" f/5 dob. It wasn't quite THAT good of a night at MB.

As is so often the case, the night started out with an equipment improv. I have two Orion laser collimators, one from several years ago, which seems to sit quite squarely in the focuser drawtube and which does quite a nice job, IMO. I also have a newer unit, which incorporates the 45-degree target reflector, so that you can crouch behind the scope and collimate the primary while looking at the collimator. Nice idea in practice, but the implementation leaves a lot to be desired. The lack of a disk that would project out beyond the edge of the drawtube and thus stabilize the unit in the focuser drawtube makes it almost impossible to get it to sit squarely. Plus, there's a chamfer on the barrel that makes things pretty hopeless. So... it was back to the old unit. But... the old unit's batteries were nearly dead.

Hmm... what to do?... this is where my new-found dangerous obsession with HP calculators comes in. I've recently undertaken a program of self-study in mathematics, endeavouring to re-learn the math that I took in high school and college. I'm currently back in eighth grade, working my way through an elementary algebra book, and I can't wait to claw my way back to calculus. I've made the astonishing discovery that calculators these days do symbolic math! Incredible what the HP48g that an ex-girlfriend gave me can do. I recently allowed myself to be consumed by the siren song of the classic HP15c, which is no longer made, and which occupies a place on eBay much like Rukl did before the new edition. It's as bad as going after Nagler eyepieces! If y'all TACos want to buy some new gear, pull your old HP calcs out of your desk drawers and put 'em on eBay. You'll have that T6 Nagler (or maybe even Ethos) without having to hurt your wallet, if you want.

(A colleague recently gave me a genuine HP35 from 1973. Words fail me, I am so grateful. Can't wait to build a new battery pack and see if this baby still works...)

http://www.hpmuseum.org/

http://hp15c.org/hp15c.php

So, back to our hero, on the Montebello ridge in twilight, looking for some new button batteries for his laser collimator... You guessed it, I popped open the battery door on my 15c, pulled out a couple of cells, stuck 'em in the laser, and tweaked the collimation. Then back into the calc. When I

checked the collimation with Orion's Cheshire-like eyepiece, it was bang-on accurate. (I attribute this to the general coolness of the 15c having rubbed off on the laser via the batteries. ;-)

I started out with a very nice view of the Double Cluster in deep twilight with the 24 Panoptic. Lessee, what's the magnification and FOV for that... you can guess how I'm calculating this... 52x and a 1.3 degree true field. I am still very pleased with how the views through this reincarnated 10" are stacking up against my 18". I'm seeing quite a lot of what I normally see through the big scope, and the 'bang for buck' factor of the 10" scope is turning out to be a real success.

Rather than going after a lot of objects in 'search and destroy' mode, I concentrated on looking at a few bright showpieces while listening to Rob Gendler's essays about them. I like these essays, they're full of fun facts to know and tell. So, I cranked up the iPod in 'Repeat - One' mode, and spent a very nice long time with M42, probably at least 20 minutes, maybe 30.

http://robgendlerastropics.com/M42text.html

I finally got my Theta-1 (Trapezium) names straight, so now I know which star is A, which one is B, etc... I was particularly impressed by the stats on Theta-1C. Wow, wotta star! The facts and figures about that star would make great star party fodder. Looking at the nebula and realizing that its fluorescence comes mostly from that one star's UV, is amazing. Plus the fact that so many other stars are hidden (at visible wavelengths) within the nebula. I'm finding it a little hard to grok that, but it's cool.

I also listened to some of Burnham's M42 essay, although it runs a full 29 minutes on my iPod, and I didn't get through all of it before Andrew arrived and I started happily jawboning with him. In the end, it was a nice long stare session with M42, and I was glad for it.

While listening to the Burnham essay, I couldn't help loving this line that Burnham quotes from Mary Proctor:

"...aisles of light and silvery streams, and gloomy gulfs of mystic shade."

I love it! Makes me feel like Dr. Strange is about to show up, sportin' the Eye of Agamotto. By the hoary hosts of Hoggoth!

Then it was on to M35/NGC 2158, listening to the Gendler essay for that one, too:

http://robgendlerastropics.com/M35text.html

It's neat to look at those clusters and think about the different ages, distances, and stellar populations. M35 has a classic "Sierra Nevada" age, about 95 Ma, that's pretty close to the age of a lot of the light-colored granitic rocks of the high Sierra. It's a very 'California' cluster, I guess you could say. And the light we see is 'Ancient Egypt' age. NGC 2158 is older, it's Mesoproterozoic or Neoproterozoic, with the light we see being 'last glacial maximum' age. Now that's an interesting thing to think about... what's the CLOSEST OLD object? Not a super-distant quasar at a long lookback time, but a nearby object that's really old?

I immediately think of a few things:

1) Globular clusters are kinda sorta nearby, and they're real old. Most of the age of the galaxy, IIRC.

2) There oughta be some really old red dwarfs nearby, but they're hard to see. I need to track down the ages of things like Proxima Centauri, Barnard's Star, Van Maanen's Star, Wolf 359, stuff like that.

3) The solar system itself is gonna be a little hard to beat. Look down, it's 4.5 b.y. old. Get a sunburn, and you got sunburned by a 4.5 b.y.-oldlamp. Find a chondritic meteorite, you're holding the oldest rock you'll ever see. Look at the moon, and it's the product of a giant impact back at 4.5 Ga.

I've searched for 'presolar' light from quasars, and seen it, but I'm interested in seeing presolar objects that are nearby. This will make for a fruitful hunt through the literature... if I ever have time for it. (The 'Prepare for Unfulfilled Promise' sign is now lit up and flashing.)

A close candidate is my next object: M67. While listening to the Gendler essay about it, I found out that it is ca. 4 b.y. old, and that's unusual for an OC. It sounds like it may have dodged various bullets by having an orbit that keeps it away from the galaxy's disk a lot of the time.

http://robgendlerastropics.com/M67text.html

I also had a great session with M46 and NGC 2438. There's another juxtaposition of ages, a 300 Ma cluster and a 1 Ga planetary nebula. It sounds like the cluster is young enough that there probably hasn't been time for its solar-mass stars to become pn's.

As you can see, I like to think of the geologic time scale when I look at astronomical objects. If you want a great visual reference for times in about the last 600 Ma, you can look at Ron Blakey's site at Northern Arizona University. He has some really neat paleogeographic maps in a variety of formats. Here are some links that show the earth, or parts of it, at various times:

300Ma: Formation of M46:

http://jan.ucc.nau.edu/~rcb7/namPP300.jpg

http://jan.ucc.nau.edu/~rcb7/300moll.jpg

http://jan.ucc.nau.edu/~rcb7/latecarbasia.jpg

http://jan.ucc.nau.edu/~rcb7/300NAt.jpg

95 Ma: Formation of M35:

http://jan.ucc.nau.edu/~rcb7/090NAt.jpg

http://jan.ucc.nau.edu/~rcb7/namK100.jpg

http://jan.ucc.nau.edu/~rcb7/crepaleo.html

Here's Dr. Blakey's main webpage:

http://jan.ucc.nau.edu/~rcb7/

Since I was spending so much time looking at M46, I also used the 9mm Nagler to examine NGC 2438 (the pn) in detail. (Yes, it's RPN time again... 139x and a 0.5 degree field.) I played around with trying to find the best 'aim point' for my gaze, to get the best results from averted vision. I found that if I picked a very close aim point, I maximized my results. NGC2438 looked quite annular, with what looked like a prominent central star. I had noticed that this 'close quarters' AV was also very useful on the Eskimo Nebula, too. If I got in real close, aiming at the outer edge of the 'parka ruff', I could get some of the 'face annulus' to show up quite nicely.

So, I think that AV is, of course, the way to go, but ease off on the 'A' a bit in order to get maximum results. I found myself calling this technique 'flirting with the fovea' or 'daredevil AV'. Ooh, I'm a rebel! I'm a bad boy! Cue the 'Top Gun' music...

Managed to bag 2346, a small planetary nebula. Had missed it on Monday and Wednesday, it's small and inconspicuous without fairly high mag; it's round and surrounds a prominent central star.

My last Gendler essay was the M95/96/105 group, the Leo 1 group. Now, this is a big 'ol piece of mind candy. It turns out that a big part of why the HST was launched was to be able to observe Cepheid variables in galaxies that were too distant for ground-based Cepheid studies. This was part of the great yearning in the 1970s and 1980s to nail down the Hubble parameter governing the redshift-distance relationship, and also to try and get a handle on the deceleration parameter of the universe. It turns out that Cepheids in the Leo 1 group allowed its distance to be nailed down quite precisely, and then, in 1998, the light from a Type 1a supernova in M96 allowed the Type 1a sn distance scale to be nailed down very well. This, it appears, was truly a watershed event, because it opened the door to the cosmological constant and the dark energy. Having the type 1a supernova distance scale in hand allowed observers - probably using HST a lot, I'd bet - to discover that the expansion of the universe had started accelerating several Ga ago. Whoa. This is today's BIG DEAL in cosmology, and it's neat to think that one of our standard Messier eye candy galaxy groups was part of what got the whole ball rolling. I wonder if the sn was visible to visual observers? If it was, I'll bet Steve saw it.

Shortly after that, I took a good look at Saturn - looked pretty nice, fairly steady - and packed up. Once again I really enjoyed the quick breakdown that the 10" gives me. Andrew and I rolled out around midnight. A nice night! I'm really glad that I took advantage of the 'clear hole' that was passing over us. It was nice to peer up through it at the Great Nebula in Orion, with its 'gloomy gulfs of mystic shade', and to contemplate the astronomical and geological time scales. Plus, I got to collimate my telescope with an HP 15c, so what's not to like?

Marek