Uppsala General Catalogue

A man made a big list of space groups.

These groups are far away in the sky. The list shows over twelve thousand of them. It was first made in 1973. The man used old blue prints for data. The list tells us how they look. It also tells us where they are. It shows how wide they are. Some groups are very small. A new list adds more groups to it. It is a great way to find them.

Scientists made a big list of galaxies. We call this the Uppsala General Catalogue. It is also known as the UGC. This list has 12,921 galaxies in it. You can see these galaxies from the northern part of Earth.

Peter Nilson edited the list. He was a researcher at Uppsala. He first published the list in 1973. He used blue prints to find the data. These prints came from the Palomar Observatory Sky Survey.

The list tells us how galaxies look. It shows their size and their shape. It also shows where they are. Some galaxies are very small. The list includes those small ones if they are bright.

There is also a second, smaller list. We call this the UGCA. This addendum has 444 more galaxies. It helps us learn even more about space. The list helps us study the sky. It is a very helpful tool for science.

The Uppsala General Catalogue is a big list of galaxies. Scientists call this list the UGC. It helps us know what is in our sky. This list covers galaxies in the northern hemisphere. It includes 12,921 different galaxies.

These galaxies are very far away. This list is a vital tool for space study.

Finding these galaxies was a careful job. The team used blue prints from a special survey. This was the Palomar Observatory Sky Survey, or POSS. They looked for galaxies north of a specific line. This line is called declination -02°30′. They looked for galaxies with a certain brightness. They also looked for a specific size.

This way, the list stayed very organized.

Peter Nilson edited this large catalogue. He was a researcher at Uppsala. He was also a Doctor of Astronomy. He first published the work in 1973. Nilson had written about the history of science before. Later, he became a full-time writer and novelist.

He still wrote about space and humans in his books.

The UGC contains many specific details. It lists the diameter of each galaxy. It also gives a description of their shape. The list uses system classifications for these shapes. For flat galaxies, it shows the position angle. It also notes the area around each galaxy.

Some small galaxies come from the CGCG list. These must be brighter than 14.5 magnitude. This helps make the list very accurate.

You can think of this like a giant map. A map shows you where things are located. The UGC shows where galaxies are in the sky. It also shows what they look like.

There is even a smaller list called the UGCA. This addendum adds 444 more galaxies. It works like an extra page in a book. This helps scientists see even more of the universe.

The Uppsala General Catalogue of Galaxies, known as the UGC, is a massive astronomical record. It catalogs 12,921 galaxies that are visible from the northern hemisphere. This collection serves as a vital map for astronomers studying the deep universe. By organizing these distant objects, the catalogue helps scientists understand the structure of our sky. It provides a standardized way to identify and study galaxies across a specific region of space.

To build this catalogue, researchers relied on specific data sources and strict rules. The primary data came from the blue prints of the Palomar Observatory Sky Survey, or POSS. The catalogue focuses on galaxies located north of a declination of −02°30′. Declination is a coordinate used to measure how far north or south an object is. The list includes galaxies with a diameter of at least 1.0 arcminute. It also includes galaxies up to a limiting apparent magnitude of 14.5. Apparent magnitude is a scale used to measure how bright an object looks from Earth.

The catalogue also includes special entries from another source. It incorporates smaller galaxies that are less than 1.0 arcminute in diameter. However, these specific galaxies must be brighter than 14.5 magnitude. These entries were taken from the Catalogue of Galaxies and of Clusters of Galaxies, or the CGCG. This ensures that the UGC captures both large and bright small objects. This combination makes the catalogue a more complete resource for researchers.

Each entry in the UGC provides detailed physical descriptions. The catalogue lists the diameter of each galaxy to show its size. It uses conventional system classifications to describe the shapes of the galaxies. For galaxies that appear flattened, the catalogue provides the position angle. The position angle helps astronomers understand how a galaxy is tilted in the sky. The descriptions are written to be as accurate as the survey prints allow. The catalogue even describes the areas surrounding each galaxy.

Peter Nilson was the editor responsible for this significant work. At the time, he was a researcher at Uppsala and a Doctor of Astronomy. He first published the catalogue in 1973. Nilson was already known for writing essays about the history of science. A few years after the catalogue was released, he changed his career path. He became a full-time writer, novelist, and essayist. Even in his fiction, he often explored themes of cosmology and the history of science.

The accuracy of the UGC is tailored to its specific purpose. The coordinates provided are accurate enough for identification purposes. This means a scientist can use the numbers to find the exact galaxy in the sky. The catalogue is so useful that an addendum was later created. This addendum is called the Uppsala General Catalogue Addendum, or the UGCA. The UGCA adds another 444 galaxies to the original collection.

Understanding the UGC helps us see how astronomical catalogues function. These lists are essential for organizing the vast amount of information in space. The UGC connects the work of the Palomar Observatory to the research conducted at Uppsala. It shows how different surveys and catalogues, like the CGCG, can work together. By combining data, astronomers create a clearer picture of the northern sky. This organized data allows for better study of galaxy shapes, sizes, and positions.