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.
- Course sessions on Fridays: March 27, April 10, April 17, May 1 and May 8.
- Course time: 7:45 – 10:00pm formally with priority given to observing when clear sky
- Note: Donations can be receipted as charitable . Donations can be made online to Mississippi Valley Conservation via canadaHelps Choose Night Sky Conservation fund
- References used in this course:https://millstonenews.com/2014/05/references-to-use-for-night-sky-activities.html
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:
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.
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). The yellow(giant) Aldeberan was about 10 degrees from Venus. We used manual gauges (a closed hand's width) to determine that. 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
Observe Western Sky before the Target Sinks Below the Horizon (or gets ‘tangled’ in the Trees)
- 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.
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)
2000mm/20 = 100X
To help relate what you will be seeing to your star chart. Check the following:
- Location (at least altitude and azimuth)
- Apparent Size
- Visual Brightness
- 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
- 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
- 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