September 2016

Tony Martinez

                                    Tony Martinez

Each month I will describe sights of interest in the night skies of South Carolina. These sights will be broken down into four sections: what you can see with the naked eye, with binoculars, with a small refracting telescope and with a Dobsonian reflector. The best time to view the night sky is at and around the times when the Moon is not visible, what is known as a New Moon; which will occur this month on September 1st and September 30th. For September, your best viewing nights will be from September 1st to the 7th and the 21st to the 30th. The Star chart below is set for Florence, SC on September 15th at 9 pm. Note: A table of contents for earlier columns is located in the February 2016 column.

wholeskychart1

The August Perseids Meteor Shower Update:
As I mentioned last month, some astronomers were predicting a possible great Perseids meteor shower with counts ranging from 100 to 150 meteors per hour. My personal count from the west Florence suburbs was only 30 meteors per hour.

Clear Sky Chart:
The weather report says clear night tonight, so maybe you can spot that Messier galaxy you have yet to see. A clear night weather report doesn’t always mean a clear night for astronomy. Many other factors affect our ability to see objects clearly through our telescopes.

However, there is a weather site designed for astronomers, this site is called “The Clear Sky Chart,” and it has viewing forecasts for 5277 locations, covering the entire United States (except Hawaii), all of Canada, parts of Mexico, and the Bahamas. The location closest to Florence is the Francis Marion University Clear Sky Chart; http://www.cleardarksky.com/c/FMUObSCkey.html?1. When you go the site to check out the viewing forecast, you may be perplexed. You won’t see any maps or radar, etc.; instead you see only a bunch of small colored squares, as shown below.

Clear Sky Chart

The Chart reports data for a 45-hour period. Next notice the times listed on the site use a 24-hour clock. Then, notice that in the far left, the vertical bands tell you that the top four lines of little squares refer to sky conditions, and the bottom three lines of squares refer to ground conditions. These bottom three lines, wind, humidity, and temperature, are there primarily there to tell you what clothing, etc. that you might need that evening. Therefore, the top four lines of squares (sky conditions) are where you focus your attention.

For all sky conditions, dark blue squares are great, and white squares are bad. Next, notice that the fourth row of squares, from the top, is for darkness. This information gives an overview of the Moon phase situation. All black squares for a new Moon and blue and lighter blue squares as the Moon interferes with viewing.

The first row denotes cloud cover: dark blue, no clouds; white, total cloud cover; and pale blue, partly cloudy. The next two rows supply you with the information that no other weather site will give you. The “transparency” row refers to the amount of moisture in the atmosphere. Excessive moisture in the atmosphere will definitely affect your viewing. The “seeing” row refers to atmospheric turbulence due to temperature differences. Therefore, you can have a cloudless night with low atmospheric moisture, and still not be able to resolve the cloud bands on Jupiter because of poor seeing. So, go to the Francis Marion Clear Sky chart, check the time of night that has all dark blue squares in the first three rows, and go outside and enjoy the stars.

Besides “Clear sky Chart” basics, there is other interesting information available. If you are a visual type person, you can click on any small square and it will show you the visual map that refers to that information. Also note that you can animate the map if desired. The image below came from clicking on the cloud cover square at midnight on September 30th; note that the faint crosshairs denotes the Chart’s location.

Clear Sky Map

Next, look to the right side of the main page of the Clear Sky Chart at a green box labeled “Other Charts.” In this box you can go to all the Clear Sky charts in South Carolina, or those nearby Francis Marion University. In addition, you can click on “All,” which will direct you to all 5277 locations. Now notice that you have a choice of “List” or “Map.” If you click on South Carolina List, you will go to the image shown below.

Clear Sky List

This is an interesting page. It gives a list of all the Clear sky charts in South Carolina, along with comments and links for most sites. Next, under the heading, “Preview,” is a column of the actual first two rows of every site. This allows you to quickly determine the best viewing site in South Carolina on that particular date.

Before leaving this page, note that there is a vertical column of colored squares in the center of this page, under a heading of light pollution. Click on the heading, and you will see an explanation of the colored squares. Note that black means no light pollution at all, and white means too much light (cities, etc.). You will also notice that no site in South Carolina is better than a green square, with Florence having only a yellow square.

CSC 4a

Finally, return to the Green Box on the main page, and click on South Carolina “Map.” Now you have a map of South Carolina with all the Clear sky Chart locations represented as a “push pin” matching the color of the light pollution for every site in our state.

Clear Sky Map2

Naked Eye Sights: You may get a glimpse of Venus in the west.

Binocular Sights (7 to 10 power): The Summer Milky way area is still the best region to scan.

Telescope Sights (60-100mm: Last chance for an easy view of Saturn.

Dobsonian telescope (6 -8 inch): Last chance for Saturn.

See you next month!

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