Lecture 3 – Night Sky April 17 2015

MVNSC: Mississippi Valley Night Sky Conservation:
Observing the Night Sky Around Us’:stellariumApril17

Our Night Sky as it appears April 17 2015 around 9pm – courtesy Stellarium
Program developed by:

  • Mississippi Valley Conservation Authority
    • Royal Astronomical Society of Canada
    • Ottawa Astronomy Friends
      • Instructor: Pat Browne
      • Assistant: Bob Hillier
  • Sessions are given at the Mill of Kintail Visitor Center or with special arrangements, the Fred Lossing Observatory.

The Visible Night Sky Around us – All Stars, Star Systems, Diffuse Nebula, Open Clusters and Globular Clusters are located within our own Milky Way Galaxy

April is the beginning of the amateur astronomy ‘pilgrimages’ into the Night Sky. As Fred Schaaf wrote in the April 2015 Sky and Telescope, (column: The Pilgrim’s Way”)…

    After winter’s cold has kept us indoors, April is the time to seek the special pilgrimage around the entire sky:

  • The setting bright stars in the West
  • The Open Galactic Clusters in the Milky Way
  • The more distant globular clusters located in a spherical halo around the Milky Way
  • Finally, extragalactic pilgrimage to the galaxies beyond our own galaxy

The very same night that our class made our voyage into the Night Sky, a fellow member Michael Watson (RASCals online observing group) made his way to Torrence Barrens:

mWatsonOrionSet

This past weekend Venus passed close to the Pleiades, just as the sky cleared over southern Ontario.
After spending Saturday at our family cottage near Huntsville, I drove down to the Torrance Barrens Dark-Sky Preserve 30 km west of Gravenhurst for a session of astrophotography.
Finally winter seemed to be over as the temperature sat at zero degrees C. all night, although the wolves still seem to be in hibernation - they were quiet all night.
Here is a small album of astrophotos from Saturday night. There is a detailed description below each photo. My favourite is the 7th image, which is a 200 mm close-up of Venus near the Pleiades."
See: April 11 2015 astrophotos - Michael Watson

April pilgrimage – The Western Winter Sky

The planets known as 'wanderers' lie along the plane of the ecliptic: The path of the planets within our Solar System. 
Planets appear in different constellations when they are visible. 
mWatsonFavourite
Venus, in the Constellation Taurus and setting in the West, is close to the Pleiades Open Cluster. 
It has already crossed the Meridian (our imaginary North/South line,looking due South). 
mWatsonVenusPleiades
The yellow(giant) Aldeberan was about 10 degrees from Venus. We used manual gauges (a closed hand's width) to determine that. measuring-the-sky_2_285x190
We say the object "culminates" when it reaches its highest point on the meridian. 
This April, Jupiter is transiting the meridian (near Leo, it is actually still in Cancer)  
Jupiter and Venus are the brightest objects visible, and next comes the brightest star of winter, Sirius .

The planets known as ‘wanderers’ lie along the plane of the ecliptic – the path of the planets within our Solar System. Planets appear in different constellations when they are visible See: Jupiter traversing through the Constellations

mWatsonJupiterLeo


 

Observe Western Sky before the Target Sinks Below the Horizon (or gets ‘tangled’ in the Trees)

Align on Sirius and aim at deep sky objects in Taurus, Auriga and Orion observingLog

    • Constellation of Taurus the Bull
  •  M1 – Supernova Remnant: The Crab Nebula 6300 Light Years distance

All information below taken from the SEDS Messier Database: http://messier.seds.org/

	Distance 	6300 light years
Visual Brightness 	8.4 (mag)
Apparent Dimension 	6x4 (arc min)

 

  • M45 Pleaides : Open Cluster – The 7 Sisters visible Naked Eye. Nebulousity around stars seen in the eyepiece.

 

       Distance 	440  ly
Visual Brightness 	1.6 (mag)
Apparent Dimension 	110.0 (arc min)

 

  • Constellation Auriga
  • M37 Rich Open Cluster
Distance	 	4400 ly
Visual Brightness 	6.2 (mag)
Apparent Dimension 	24.0 (arc min)

 

  • Gemini the Twins- Bright Stars Castor and Pollux
  • M35 – Open Cluster is also a rich cluster at roughly the closer than the open clusters and nearby a much further cluster NGC 2158 can be viewed in the periphery of a low power eyepiece

 

Distance 		2800 ly
Visual Brightness 	5.3 (mag)
Apparent Dimension 	28.0 (arc min)

Observing Celestial Objects:  Things that are Good to know about your starfield and eyepiece ‘Field of View ‘To be certain to find the object,  we have to know what to expect when we look through the Eyepiece

  • To be able to find an object we need to use the lowest eyepiece that will allow us to pick up the object and center it.
  • To be able to recognize the object for what it is and what it should look like, we need to be familiar with the
    • Size of the object  and  therefore the magnification of the image,
    • the expected brightness and the surrounding star field.

Field of View

 The circle of sky that you see when you look through a telescope or binoculars. Generally, the lower the magnification, the wider the field of view.

FieldOfView

When looking through an eyepiece, it is useful to know how wide or narrow a view you are seeing. Typically a low magnification eyepiece will provide about a 1/2 degree field. The way to test your eyepiece is to allow a bright star to drift across your field of view. For a low power eyepiece it might take 2 minutes . Since the earth rotation is 4 minutes per degree – that’s a 1/2 degree field of view – much like a Full Moon. So if the Full Moon fills your Field of View you have a 1/2 degree field. It is probably a lower power eyepiece . The power of the magnification is:

Focal Length (telescope) / Focal Length (eyepiece)

like

2000mm/20 = 100X

See https://millstonenews.com/2014/04/night-sky-observing-tips.html

To help relate  what you will be seeing to your star chart. Check the following:

  1. Location (at least altitude and azimuth)
  2. Apparent Size
  3. Visual Brightness
  4. Know your Magnification:Last week we learned how to find objects in the separate ‘finder’ telescope which has lower magnification but a wider field of view. When using the FLO telescope, we have two eyepiece ports, and the large one is used to help align the scope. We use the large ‘bomb-site’ as the finder. However in the second eyepiece port, we used a fairly high magnification . It is 19mm, and the Focal Length of the telescope is 2 meters or 2000 mm. The magnification of 100 X is often too high to observe large clusters.

Other useful pieces of information: Type of Object and Properties of the Object

  • Distance
  • Star – colour, brightness, binary
  • Type of Nebula:  Star, Supernova Remnant, Stellar Nursury, Dead Star (“Planetary Nebula”)
  • Star Asterism
  • Type of Cluster (Open/Globular)

Spring Southern Meridian – Globular Clusters and External Galaxies

stellariumApril17

  • Globular Star Clusters
  • External Galaxy and Galaxy Groups
The general view of the Southern Meridian contains fewer bright stars. 
This characterizes the Spring Sky as our line of sight rotates 90 degrees away and out of the plane of the Milky Way. 
Open Clusters are scarce in this area which is dominated by globular clusters and other (faint) and far away Galaxies.
Observe the Spring Night Sky 
nscLec1_planisphere

Let’s look more detail at What we Observed around us…

Starlight in our Milky Way Galaxy

Stars and Star Clusters in our Milky Way