Week 13 Exercise: Galactic Locations of Deep Sky Objects

Week 13 Exercise:  Galactic Locations of Deep Sky Objects
Astronomy 25 Section 61795
April 7, 2020


Purpose(s) of Lab:  
To visualize the location of various Deep Sky Objects in relation to the Galactic Plane we will graph sets of different kinds of Messier and similar objects on a map referenced to the plane of the Milky Way, or Galacto-centric Coordinates.  You will comment on the distribution of each kid of object to determine if their locations on the sky can be use to determine their origin or properties.

Apparatus used in the Exercise:

We will use materials provided in the lab as well as colored pens or pencils you will need to use at home (four different colored pens/pencils would be best). The results of the lab will be due in one week for grading.

You can work in groups during the Exercise.  BUT THE MATERIAL WRITTEN IN THIS WRITE-UP TO BE HANDED IN FOR GRADING NEEDS TO BE UNIQUE TO YOU. 
Background:  A useful way to visualized the sky is the same way we visualize locations on the Earth, i.e., with a globe or a two dimensional ‘projection’ of the Earth’s three dimensional surface on to a ‘map’.  There are many projections possible starting with the common ‘Mercator’ projection.

A more useful projection for comparing the size of areas is the Mollweide or ‘equal areas’ projection as in this map of the Earth’s surface


 We will use a similar mapping of the sky BUT we will not use the ‘Celestial Equator’ – the projection of the Earth’s equator onto the sky – but use the shape of the Milky Way Galaxy we reside in as out ‘Equator’.  The resulting ‘latitude and longitude’ system is now called ‘Galactic Latitude and Longitude’.  In this frame of reference, the plane of the Milky Way is the ‘Equator’ on the ‘globe’ of the sky.


Galactic Longitude starts at 0 degrees in the Constellation Sagittarius (actually toward the Center of the Milky) and goes to 360 degrees as it returns back to the Center direction.  Latitude is like on the Earth going from 0 at the equator to +90 at the ‘North Pole’ and -90 at the ‘South’ Pole (there are no North and South’s in space  )

There are four maps to be made in this Exercise.  After each map you will be asked to write a paragraph describing your ‘observations’ of the distributions of each kind of object you see on the map.  For example, are the objects near the Galactic Equator?  Are they distributed all across the map?  Are they clustered in any particular area of the map?  Do this for each map you create.  Use the back of each map to describe what you observe on the map on the front of each map.

Task 1:  Map Galaxies

Map the objects on Table 1, left group.  Use a colored pen or pencil and place an ‘S’ at the location.  There is no need to label the object as ‘M95’, etc.

Task 2:  Map Open Clusters

Map the objects on Table 1, middle group.  Use a colored pen or pencil and place an ‘O’ at the location.  There is no need to label the object as ‘M35’, etc.

Task 3: Map Globular Clusters

Map the objects on Table 1, right group.  Use a colored pen or pencil and place an ‘G’ at the location.  There is no need to label the object as ‘M5’, etc.

Task 4:  Map ‘Odd Ball’ Messier Objects

Map the objects on Table 2.  Use a colored pen or pencil and write the name of the object at the location. 

 Do you notice any clustering of these objects?