How Deep-Sky Catalogs Work

November 23, 2022November 23, 2022 / Emma / 14 Comments

Meet the Veil Nebula, one of my favorite deep-sky objects.

The Veil is one of the more common star party requests I get from more experienced participants. Unfortunately, it requires a very powerful telescope. My 11-inch Schmidt-Cassegrain–pretty advanced, as far as intermediate amateur telescopes go–can barely manage it with a nebula filter.

The Veil has several different segments and can’t be viewed all at once. Seriously–the entire Veil Nebula covers an area six times the diameter of the full moon! If it were bright enough to see with the naked eye, it would be a very visible object.

Together, the segments of the veil make up the Cygnus Loop: a ring-shaped phenomenon that is a supernova remnant, formed roughly 10,000 years ago. That’s actually not that long ago, in astronomical terms. But other supernova remnants, such as the Crab Nebula, are much younger.

Those segments have all been observed separately over time and ended up with separate designations in star catalogs, too. The Veil’s components within the NGC star catalog are NGC 6960, NGC 6992, NGC 6995, and IC 1340. It is also known in the Caldwell catalog by Caldwell 34 and 33.

Fainter “knots” of nebulosity that you might not immediately realize are part of a broad, wispy loop are noted as NGC 6974 and NGC 6979.

Different portions of the supernova remnant have also been named the “Witch’s Broom” and “Pickering’s Triangle.” In particular, the Witch’s Broom refers to the same segment as the picture shown above–the Western Veil.

For this post, I thought tell you a bit about how star catalogs work–and share an interesting story about the NGCs!

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The Hubble Space Telescope

October 13, 2017November 23, 2022 / Emma / 4 Comments

The Hubble Space Telescope is one of the most famous telescopes in the world.

Oops, excuse me—one of the most famous telescopes built.

Hubble, after all, is certainly not in this world. Unless you call the universe the “world,” it’s about as far from being in this world as you can get. It’s in space.

Hubble isn’t that different from an ordinary, ground telescope. It’s only as big as a bus. There are bigger optical telescopes. Its mirror is 2.4 m across—hardly an achievement by modern-day standards.

Palomar Observatory, which was the biggest telescope in the world when it was built, has better optics than Hubble, meaning its images are a bit crisper.

But that doesn’t keep astronomers from continuing to use Hubble. In fact, if you want to use Hubble, you have to get in line—it hardly has time to complete all the projects astronomers ask of it, even observing the night sky 24/7.

So why is Hubble so useful?

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Telescope Imaging Systems

October 8, 2017November 23, 2022 / Emma / Leave a comment

Have you ever seen an image like this?

Okay, maybe you have…online. What with the spread of the internet these days, I’m guessing that at one point you have seen something like this on a page of image search results.

That’s the thing, though. You’ve seen this incredible phenomenon on a computer screen. But have you ever seen it through a telescope?

Don’t worry—if you haven’t had an opportunity to look through a telescope, you’re not missing out. You’re not going to see the Sombrero Galaxy above in all its photographed glory just from looking through the eyepiece of a telescope.

So…how do we get an image like this, then?

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Interferometry

October 7, 2017November 23, 2022 / Emma / 6 Comments

Imagine you have an image like this. This object is faint and faraway, so you can’t make out much more detail. You know that other stars like it—closer, brighter stars—have looked like this and turned out to be two stars, nestled very close together.

How do you figure out what you’re looking at? How do you increase the resolving power on your telescope so that you can make out more detail?

A telescope’s resolving power is limited by its size. Bigger telescopes can make out more detail on faraway objects—that’s because they can gather more light. But now, we can make telescopes that are so big their size doesn’t limit their resolving power anymore.

The atmosphere does.

We obviously can’t change the atmosphere. So how do we get around this particular predicament?

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A Telescope Tour

October 6, 2017November 23, 2022 / Emma / 15 Comments

For the past few days, I’ve done a lot of talking about differences between types of telescopes and mounting systems. On occasion, I’ve mentioned some of their parts, though I haven’t focused on that.

Today, I will.

This post is meant to be a brief overview of differences between telescopes and their parts. If you want some more in-depth explanations, I’ll link back to those I’ve already written.

In the image above, you see just a few different examples of telescopes. And just in this image, they range far and wide. Most stand on tripods, but some don’t. I can see two different telescope shapes. Some have the eyepiece in different places.

There are more variations of telescopes than are shown here.

So climb on board…I’m about to take you on a telescope tour!

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Improved Telescope Mounting

October 5, 2017November 23, 2022 / Emma / Leave a comment

So, any idea what this handy-dandy thing is?

Okay, so maybe I sort of gave it away in the post title…

I know what you’re about to say next. Why are we looking at a mount? What’s so special about a mount—isn’t the telescope itself more important?

And the fact is…I know where you’re going with that. The telescope is important, and without it, the mount would have no purpose. But without the mount, the telescope would be lost—it would have power, but nothing to do.

How’s that work?

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Improved Telescope Mirrors

October 4, 2017November 23, 2022 / Emma / Leave a comment

When it comes to telescopes, bigger is always better.

Bigger means more light-gathering power and better resolution. And a longer telescope—meaning, a longer focal length—can actually do wonders for your magnification power.

Light-gathering power, by the way, just means how much light a telescope can gather—and it works the same way as rain in a bucket. The bigger the bucket, the more rain you can collect.

And resolution means how much detail you can see in an image. It goes hand in hand with light-gathering power—more light means more detail.

So bigger, for serious astronomers, is the way to go. Until your mirror starts sagging.

Yeah…that’s a bit of a problem. But nowadays, we can fix it.

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Improved Reflecting Telescopes

October 3, 2017November 23, 2022 / Emma / Leave a comment

Can you tell the difference between these two telescopes?

I’ll give you a hint. They are both reflectors. I know I wrote before that you’ll normally find the eyepiece (the little bit tacked onto the telescope tube) on the side with reflectors, but as you can see here, this isn’t always the case.

Here’s another hint. The mounting setup isn’t the difference I’m talking about. I realize the most obvious difference is probably that one is on a “fork mount” (right) and the other is on an equatorial mount (left), but I’m thinking of something related to the optics.

Don’t worry, we’ll talk about these two mounting systems in a later post.

So, can anyone venture a guess and tell me what’s different about these two telescopes?

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Light Pollution

October 2, 2017November 23, 2022 / Emma / Leave a comment

This photo was taken at night.

Seriously. At night.

But…it looks too bright for the night. I’ll bet I wouldn’t even have to shine a flashlight to see my way around here.

Need proof? Here’s New York City during the day.

The lighting comes from the sun. Not the billboards and flashing advertisements.

Who needs that many adverts in their life, anyway?

But I’m not interested in judging New York City…all I want is to make a protest against light pollution.

What is light pollution, anyway?

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Telescope Powers

October 1, 2017November 23, 2022 / Emma / Leave a comment

Have you seen one of these guys before?

You probably have, even if you don’t recognize this brand-new innovation. This is the European Extremely Large Telescope, or the E-ELT. I know, imaginative name, huh? Anyway, it’s not all that different from one of those white observatory domes you’re used to seeing.

Astronomers keep building new observatories. They keep putting new telescopes into space—Hubble, Spitzer, and James Webb, to name a few. But the common goal of all the telescopes they build is to make telescopes that are as big as possibly possible.

Why? I mean, are astronomers just huge braggarts that like to impress us all with their big toys?

Well…I’ll admit that we astronomers have a lot of fun with our toys. But we need huge telescopes for a much better reason than bragging.

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