--- Joe Bauman <bau@desnews.com> wrote:

Kurt, that's really helpful! I've printed it out. In past years I have downloaded tables from the National Observatory in Washington, and noted where the new moons are, to give myself a rough idea of good nights for astronomy. This is much better . . .

Joe, Your're welcome. The number of hours is approx to the nearest hour. I downloaded the USNO tables for astronomical twilight and moon-rise/set into a spreadsheet and then forced an estimate. But it's sufficient for quick planning purposes. I've uploaded a beefed-up table that includes average number and percent of cloudy and clear days per month. http://members.csolutions.net/fisherka/astronote/plan/2006SLCMoonlessHours.h... I wanted something simplier than the S&T annual sky calendar that I could throw in a briefcase and that would show me DSO dark sky frames at an glance - and still get me into bed at a reasonable hour. For example, in May, I can forget about DSOs until after May 20; Pioneer Day looks like a good astronomy vacation weekend; July 4 and Labor Day do not. For lunar observers, I've also prepared and uploaded an inverse table of hours of moonlight before midnight - http://members.csolutions.net/fisherka/astronote/plan/2006SLCLunarHours.html The lunar table is a prelminary version. In the next few months, I intend to throw together some lunar colongitude code and revise the table showing the selenographic longitude of the lunar terminator at 9:00pm on each good "lunar night." - Canopus56(Kurt) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

--- Joe Bauman <bau@desnews.com> wrote:

Thanks, Kurt. When it says 5 hours, do I double that to show (approximately) how many dark hours we'll have from twilight to twilight? Thanks, Joe

No, because of daily variations in the rising and setting time of the Moon. I decided to build the spreadsheet on a 24 hour day beginning and ending at midnight, instead of the sunset twilight to sunrise twilight across to two days. First, because the 24 hour day spreadsheet is much easier to build. Second, it was based on a conscious choice to limit my observing time in 2006 to more reasonable hours. There are some simple lunation patterns that indicate if the midnight to six a.m. time frame on the following day includes a Moon washed out sky. Consulting the Moonless hour table, for example, during Jan. 6 to Jan. 16 is 1st Qtr waxing, through the 3rd Qtr waning Moon. See the Lunar Observing table where the lunar phases are marked - E:\Daily\20060109 SunMoon Annual Planner\2006SLCLunarHours.html In the moonless hour table, On Jan. 17 to Jan. 29, where the number of hours pattern is 1,2,3,4 then 5,5,5,5,5,5,5 of darkness, is the waning Moon, ending in a new Moon on 1/29. Here, the Moon has transited and is setting in the west. During this waning period, the Moon is setting about an hour later each day between midnight and 6:00am. So, for the pattern of nine 5's in a row from Jan. 21 to New Moon on Jan. 29, the number of sunset-twilight to sunrise-twilight moonless darksky hours is: 5,5,5,5,5,5,5,5,5 24-hour-clock-darkness 5,6,7,8,9,10,11,12 sunset-to-sunrise twilight-hours - ending with the New Moon on 1/29. On Jan. 29 to Feb. 5, where the pattern of moonless hours is descending followed by steady 0's - 5,4,3,2,1,0,0,0,0,0 - is the waxing period between the New Moon (1/29) and 1st Qtr on Feb. 5. Here, the Moon is rising progressively later in the east, and almost the entire period between moonrise and twilight sunrise on the following day has bright Moon light. In summary, from the New Moon to 1st Qtr, where the pattern descends, - 5,4,3,2,1,0 - the most of the following night during midnight to 6:00am has Moon light because the waxing Moon is rising.

From the 1st Qtr to 3rd Qtr - where the pattern is 0,0,0,0,0,0,0 -the most or all of the following night during midnight to 6:00am has Moon light, because the Moon rising, transiting and then setting.

From the Third Qtr to New Moon, there are progressively more dark hours from midnight to 6:00am on the following night. This is where the pattern in the table for January ascends and stays steady, e.g. 0,1,2,3,4,5,5,5,5,5,5,5,5. The total number of hours of darkness sunset-twilight to sunrise-twilight approximately parallels that the ascending pattern, but totals - 0,1,2,3,4,5,6,7,8,9,10,11,12 - ending on the next New Moon.

In the moonless hours table for 2006, for Jan. through Sep., those ascending patterns generally fall between the 14th of the month and the 28th of the month. So where you see 0,1,2,3...., just write 0,1,2,3,4,5....12 in the column next to the series. That approximates the total sunrise-twilight to sunset-twilight hours. In June and July, truncate the numbering around 10 for the early summer sunrises. Because of these simple lunation patterns, I decided to leave coding the lunar phases off the moonless hours chart to keep things simple - and to keep my focus on a couple of reasonable after-work hours of observing. Maybe I made the chart too simple, if what readers really want is the total twilight-to-twilight hours. Although the lunation pattern is difficult to remember, as a practical matter as you reconnect to the physical night sky between Full Moons and daily life, the pattern is self-evident. To do the sunset-twilight-to-sunrise-twilight method right and with precision really involves solar and lunar longitude code that I have not prepared from Duffet-Smith's _Practical Astronomy on a Calculator_ book. The tables you see here are what I could do with a simple add-and-subtract method based on the pre-existing computations in the USNO tables. Thanks for taking an interest. Enjoy. - Canopus(Kurt) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

Thanks! I thought I probably was wrong about that. -- Joe

At last! I was able to download it and watch it with Quicktime. That's amazing, congratulations. If it had been almost any other day I would have gone too. But at least we can watch it on this great video. -- Joe

Thanks Kurt, Ed L --- Canopus56 <canopus56@yahoo.com> wrote:

--- Joe Bauman <bau@desnews.com> wrote:

...

Kurt, that's really helpful! I've printed it out. In past years I have downloaded tables from the National Observatory in Washington, and noted where the new moons are, to give myself a rough idea of good nights for astronomy. This is much better . . .

Joe,

Your're welcome. The number of hours is approx to the nearest hour. I downloaded the USNO tables for astronomical twilight and moon-rise/set into a spreadsheet and then forced an estimate. But it's sufficient for quick planning purposes.

I've uploaded a beefed-up table that includes average number and percent of cloudy and clear days per month.

http://members.csolutions.net/fisherka/astronote/plan/2006SLCMoonlessHours.h...

I wanted something simplier than the S&T annual sky calendar that I could throw in a briefcase and that would show me DSO dark sky frames at an glance - and still get me into bed at a reasonable hour. For example, in May, I can forget about DSOs until after May 20; Pioneer Day looks like a good astronomy vacation weekend; July 4 and Labor Day do not.

For lunar observers, I've also prepared and uploaded an inverse table of hours of moonlight before midnight -

http://members.csolutions.net/fisherka/astronote/plan/2006SLCLunarHours.html

The lunar table is a prelminary version. In the next few months, I intend to throw together some lunar colongitude code and revise the table showing the selenographic longitude of the lunar terminator at 9:00pm on each good "lunar night."

- Canopus56(Kurt)

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