Sky and Telescope, April 2013

After my previous little nostalgia trip into the glory days of astronomical magazine publishing, I decided that it might be cool to be able to read S&T on my iPad. Back when the iPad was announced there was a lot written about how it might save the magazine as a form by allowing for seamless and easy electronic delivery of the content. Sadly, this happy world has not come to pass because while magazines may know a lot about writing and organizing content the truth is that they simply do not understand electronic distribution.

When I am being more charitable I try to give them the benefit of the doubt. Here are a group of people who wrote their little articles and sent them to you and I in basically the same way for a hundred years. And then some asshole hipsters with their "computers" and "data networks" come along and mess everything up. Now they have to give away their words for free, and lay them out on "pages" that have no page boundaries at low resolution and with shitty typography. Any rational person would just throw up their hands and say "fuck this, I can't work like this" and just give up.

But then I go to the Sky and Telescope web site and stare at it in the light of day and my sense of charity evaporates faster than water on the surface of Mercury and is replaced by me wishing that they had just thrown up their hands and said "fuck this, I can't work this way."

To say that the user experience of subscribing to Sky and Telescope on their web site is "bad" is to insult the word "bad." Here is what happens:

1. You go through a standard sort of shitty checkout process. Their site does not use the Amazon payment engine (or the iTunes store), which means you will hate it.

2. After you are done, you get some e-mail confirming that you ordered something.

3. They give you a free login for the digital subscription! Excitedly, you go to you iPad and tediously punch in all the information.

4. The iPad says that you can't download the issue because you have no subscription.

Confused, you go back to the web site and note that you can read the current issue on a web-based piece of shit flash reader. You are depressed.

You navigate back to the main web site and try and figure out what you status is. You login with the information that the subscription engine sent you, but it does not work. Instead you are send to a page with this text on it:

Register now!

NOTE: Website registration is separate from registration at ShopatSky.com and from registration for your digital subscription.

I don't remember exactly how, but after reading this page, and doing some more surfing on their site I came to two conclusions:

1. First, I'm not sure who they paid to do their subscription payment system, but I hope they did not pay them much. After fighting through a page flow that is 10 times worse than the one Amazon launched with in 1994 all that system does is print your name on a small index card which is then passed to a standard magazine subscription office. There, some small group of septuagenarian paper pushers queue you up to get a copy of the print magazine in "4 to 6 weeks", at which time the digital subscription on your iPad will also kick in. I don't want to sound like I have anything against small offices full of septuagenarian paper pushers, but this is fucking insane.

2. Second, having spent all that money on the worthless payment system, they then built at least two more worthless payment/registration systems for al of the rest of their "services" (the web site, and the store). This gives you, the end user, the great pleasure and convenience of needing to keep track of three logins in order to interact with the media behemoth that is Sky and Telescope. Again, this is insane.

What the Sky and Telescope web site tells me about the company behind it is that it is Kodak. Recall that Kodak had a long standing business model for turning some specialized chemical processes into large piles of cash. Various people in the company saw the technology that would come and destroy this model, and they even worked to embrace and take advantage of it. But ultimately they could never let go of the old business and as it slowly sank into the muck it dragged the rest of Kodak down with it.

Magazine publishers are in a similar position now. They have collected and distributed their content the same way for the better part of more than a century. Ten or twenty years ago it became clear that this scheme was not going to survive for too much longer. It was even fairly clear how it was going to be replaced. But rather than take the bold (and risky) move of going all in on the new model, they are hedging. They want to keep their print business going while easing into the digital one. But all this means is that they will be incompetent at both.

The fundamental theorem of digital content is that it must be available immediately on any platform that I own where-ever I might be and however I paid you for it. There is no value gained by limiting access in any way. That just pisses your customer off. Your customer is now expecting to be able to buy and consume your product anywhere and any time she pleases. Furthermore, if you stand in the way of this expectation, she will just leave and find something else because she is carrying the entire library of everything ever published in her pocket.

There is not a single person at Sky and Telescope that truly understands this theorem. At least no one in a position of power. If there was, their digital services would not be as sad as they are.

I now hear you saying, "but Pete, Sky and Telescope is just a poor small publisher. Have some pity. It can't be easy to extract those tens of dollars from the few thousand 45-65 year old males who read this stuff."

In reply I will only tell you that the online experience at The New Yorker is no better than this same awful bullshit that you get at Sky and Telescope. And the reasons are exactly the same. Oh, the New Yorker thinks it's trying to play the game. It has the twitters and you can read some of their stuff in Flipboard and other new fangled channels on the iPad.

But do this:

1. Make a digital subscription with the iPad app but with your iTunes account and not their web site.

2. Now go to their web site and try to look at the digital archives, which are supposed to come with a digital sub.

Result? You can't. Why? Because they have separate subscriber databases for the iTunes in-app purchases and purchases from the web site. Why? Because they don't know what they are doing and they don't care enough about the right distribution model to fix it.

Of course, if you get a print subscription, through the same small office of septuagenarian paper pushers that Sky and Telescope uses, it will probably all work peachy. So, the New Yorker is also Kodak.

I would not be so enraged about this if there were not obvious examples of how to do this right staring me (and them) right in the face. Again the jocks are doing better than the nerds here because ESPN, Bill Simmons and their collective web site: grantland.com is a template for content delivery in the modern age. This is not surprising since 20 years ago Simmons looked at the Boston Globe on the one hand and the Internet on the other and realized that he had a better shot on the network than getting a job writing columns at the Globe. He started writing online, then got a gig at ESPN and now runs one of the largest and best online content publishing businesses in the world. Their template?

1. The content is intelligent (for sports and pop culture), long form, not laden with a lot of online SEO bullshit, and most important it is always available.

2. They get some money from ads.

3. They also get some money from special print projects that reprint the online content in a nicer more premium form.

I would bet that if they wanted they could do some kind of subscription service. I would also bet that if they did this it would not take 4 to 6 weeks for the content to start appearing on your iPad.

This is content delivery done right. And this is nothing like what Sky and Telescope or The New Yorker manage to do.

Anyway, as enraging as all of this is, I only have myself to blame. I should have known that nothing good could come of getting a print subscription from an aging dinosaur of a magazine in the vain hope getting a usable iPad experience. I was doomed to fail from the start. What I'm hoping is that they actually do have some bright young mind in their midst who will show them how to do this right and that they'll get there fast enough to not share the same fate as Kodak, drowning in the muck as the rest of the world passes them by.

How to Polar Align Your Mount, A Survey

Polar Alignment is where you carefully make sure that the right ascension axis of your mount is exactly parallel with the rotational axis of the Earth. When you get this right, your mount can track any star in the sky just by rotating around its RA axis. If you get it wrong, stars slowly drift off of your field of view and the field will slowly rotate as you track from east to west. The amount of tracking error you get will be proportional to how far off you are. Finally, for various reasons, while an auto-guider and compensate for drift, it cannot compensate for the rotation.

Getting the polar alignment right is ultimately a problem of geometry. You want to measure the geometry of your mount with respect to the Earth's rotational axis. To understand how all of the various methods work you need to be able to visualize in your mind how deviations from the correct geometry will affect the tracking of the star. Sadly, I lack the graphical skills to really draw this out for you. But, because we have the Internet you can go and look at the excellent diagrams in this article by Frank Barrett and it will teach you everything you need to know. With those pictures as a basis, here are some ways to get polar aligned.

0. Preliminaries

Some terms you need to know. The meridian is an imaginary circle splits the night sky into east and west halves. In my yard in Pittsburgh it runs through the north pole and around to the southern part of the sky. If your yard is in New Zealand, then it runs from the south pole up and around to the north.

The celestial equator is the circle in the sky that has a declination value of zero. If you had a globe of the universe it would be the line that splits the sky into north and south halves.

The North celestial pole is what you polar align to in the Northern hemisphere. If you live in the southern part of the world, then you want the south pole. Everything still works the same way, it's just upside down.

Finally, you align your mount using mechanical adjustments on the base of the mount head. The mount have knobs that let you raise and lower the altitude of the RA axis and also spin the axis in azimuth. These are the controls you use to polar align the mount.

1. Polar Scope

Most equatorial mounts that are used these days are of the so-call German design. GEMs are characterized by having the telescope ride on top of the declination (north to south) axis with a counterweight on the other side. The RA axis sits perpendicular to this arrangement.

Most GEMs also have a hollow RA axis. In the Northern hemisphere, this means you can usually get a rough polar alignment by sighting through the RA axis and putting Polaris in there. This will get you close enough for a lot of work, but it's not good enough for taking pictures.

Some mounts have a small telescope that sits in the RA axis with a picture of some sort in it. The Losmandy style polar scopes have a little diagram with Polaris, Ursa Minor, Ursa Major and Cassiopeia in it. The idea is that if you can wiggle the mount until Polaris and two other stars are in the right holes, you'll be even closer than you were before. This works OK for some people, but I never had much luck.

The Takahashi (and now Astrophysics and iOptron) mounts have a reticle that looks like a clock in them. You run some software that tells you where on the clock face Polaris should be and you stick it there. If the polar scope is well calibrated with the RA axis, you are polar aligned. If it's off, you'll still be off.

The Tak mounts have the scope installed in the factory and are very well calibrated. The Astrophysics scope requires that you install and calibrate it yourself, so mine is a bit off. I could work harder to get it closer, but I lack the mechanical fortitude to get it really accurate.

2. Pointing Model Alignment

This is what most computerized mounts use for helping you polar align. The computer or hand box connected to the mount will ask you to center multiple "alignment stars" one at a time. As you do each one, the mount makes a note of the pointing error and builds a simple linear model of the relationship between where it thinks it should go and where things actually are. This model compensates for various sorts of errors that make pointing less accurate.

Among other things, this model can compute how much of the pointing error is caused by polar alignment error. So, after building the model typically what you do is point at a star and the software will displace the mount according to the error it computed. You then center this star in the telescope my mechanically adjusting the altitude or azimuth of the polar axis, and you are done. I've used the Celestron version of a scheme like this and it works very well.

3. Drift Alignment

Drift alignment is the classic astrophotographer's tool. If you read the pdf at the beginning of this article you'll already know how this works. Here is what you do. First put a high power retical eyepiece in your telescope and rotate it so that the lines correspond to north/south and east/west motions of the mount. Now point at a star near the intersection of the celestial equator and the meridian. Center the star carefully in a high power eyepiece. Now watch the star move in the eyepiece. if the star drifts north or south, you adjust the azimuth east and west respectively to fix the drift. Keep adjusting until there is no drift after a few minutes (or up to several minutes if you want to be really picky).

Next point the telescope at a star fairly far to the east or west and also on the celestial equator. Do the same observation in the eyepiece but now if the star drifts north adjust the altitude higher, and if it drifts south lower the altitude.

If you study the diagrams in the pdf and think about the geometry, its pretty clear why these are the right moves.

There are two annoying things about drift alignment. First, it seems complicated. Second, it involves a lot of staring at small stars in high power eyepieces. Since its likely that you are going through all of this to take pictures with a CCD camera, the obvious thing to do it to use the camera to do it.

4. Drift Alignment with a CCD Camera

This works exactly the same way as the scheme above but you use computers to make it easier. First, since your mount can point itself, you use the pointing computer to find the stars. Second, you use your CCD and computer to watch the star for drift. Finally, if you want to get fancy, you use a third piece of software to analyze the drift and tell you how to adjust the mount.

This is super convenient. You plop your mount outside, point it roughly at Polaris and then set up your camera (which you'd have done anyway). Then you let the computer stare at the star for a few minutes and when it's all done you are polar aligned. I've been using this scheme with a piece of software called PEMPro and it's great.

Another scheme that does not require extra software is outlined here: http://www.observatory.digital-sf.com/Polar_Alignment_CCDv1-1.pdf.

5. Plate Solving

Recall that a plate solver analyzes the image that you took and calibrates the stars in the image with known catalog stars. It can then use the positions of those stars to compute the actual coordinates of the center of the picture. Plate solving is fantastically useful for various things involving pointing your telescope. It requires a computer and a large star catalog to work, so it is not used as much as it could be. But there are now free Internet plate solvers, and the software fits into even cheap computers, so I think people will start using it more.

Anyway, you can use a plate solver to compute polar alignment error. The idea is that instead of waiting for your mount to track to measure the drift, you take two pictures, one at the initial point of the reference star and one offset by some fixed amount of RA. After taking each picture you use a plate solver to find out where you are really pointing. You then compare the difference in position to what see if the declination drifted. At this point you can work out how to adjust the mount to improve the alignment. There are a few different software packages that do this automatically.

What this scheme is really doing is shortcutting the drift alignment by moving the mount ahead all at once and then using the plate solver to compute the drift. People will quibble over whether this is as accurate as actually measuring the drift. It probably does not matter most of the time.

6. "Quick Drift" Alignment

The Astro-Physics mounts have the following clever polar alignment scheme. It uses a feature of the mount control that lets you flip the mount over the meridian whenever you want to check alignment. All you need is a finder scope with a retical eyepiece that you can rotate. You want to rotate the retical so that one line is always on the E/W axis one is on the N/S.

Now, pick a star near the meridian and near zenith and have the mount point your finder scope at it. Center the star and hit "recalibrate". Now shift the meridian either East or West by one hour depending on which side of the meridian you are on to make the mount flip over. If you are well aligned, the star will still be centered in the finder. Any shift East/West is the finder scope not being quite aligned with the mount. Any shift North/South is the mount not being quite aligned in altitude. Use the altitude adjustment to get rid of half the North/South error. Use the adjustment on your finder scope to get rid of half of the East/West error. Use the keypad to center the star the rest of the way. Flip the mount again. Iterate this process until the star stays centered.

Now pick a second star that is at also near the meridian and at least 30 degrees away of the first star. Point the telescope there. If you are polar aligned, the star will again be centered in your finder. Any shift is a result of azimuth error, so with the azimuth adjuster to remove it. Now point back at the zenith star. If it is off center, center it with the keypad, hit recalibrate, and slew back to the second star. Adjust the azimuth again. Repeat this until the star stays centered as you slew back and forth. You are done.

Again, if you think about the geometry of the problem as described in the pdf that I linked to, you'll sort of see how this works. The meridian flip simulates the E/W movement of drift alignment, and so if the star moves N/S after the flip you know the altitude is off. The second stage is similar to other iterative alignment schemes, the idea being that the pointing error on the second star is all accounted for by polar misalignment. Since you know the altitude is already right, you only have to move azimuth.

7. Notes

There really was not any point in my writing all this down. The following pages actually can summarize all of this better than I can, so here you go.

A General Survey

Measuring Alignment Error

Drift Alignment Math

Star Offset Positioning