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Main
Date: 07 Dec 2006 19:45:22
From: canopus56
Subject: Ann: Spreadsheet to make annual dark sky calendar
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This is to announce a website the distributes an Excel spreadsheet for
Windows that prepares an annual dark sky calendar and a lunar observing
calendar.
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/AnnualDarkSkyTable.html
Example 2007 calendars for my op at N41 Lat and W111 long can be viewed
here -
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007SLCDarkSkyHours.html
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007SLCLunarObsHours.html
The spreadsheet is configured to prepare calendars based on the
observer's latitude and longitude and their preference for a starting
24 hour UTC time. Observers typically want dark sky calendars that tell
them the number of dark sky hours between sunrise and sunset. A civil
24 hour day rarely corresponds to dinural darkness. At northern
latitudes there can be about 7 hours of darkness between local sunset
and local midnight. The observer can configure the spreadsheet to the
best annual local sunset time. For example, at my observing site at N41
Lat, W111 Lon, about 5 pm Mountain Standard Time - which is equal to
midnight or "zero" hours Universal Time Coordinated - is the best
division between hours of light and dark for an entire year. This
provides a better division between hours of darkness and daylight for
an entire year. The spreadsheet examines the start of each of the 24
hours in a day for one year - or the next 8760 hours - to determine the
local horizon altitude of the Sun and the Moon. Based on this, an hour
is declared a "dark sky" or "lunar observing" hour, and is summed for
the calendars. Entering the UTC for your local midnight prepares a
darksky annual calendar based on civil days.
The observer can configure the spreadsheet criteria applied to
determining whether an hour is a quality dark sky hour and a quality
lunar observing period.
This spreadsheet can also be used as a deep sky and lunar target
planner. Using Microsoft Excel's "Data filter" feature, the next dark
sky date that an specific right ascension will be transit your meridian
for the next year can be found. Similarly, the next dates and UTC hours
that the Moon will be observable when the terminator is at a specific
colongitude can be identified over the course of a year.
Regretably, I have not been able to get the VBA macro code in the
spreadsheet to run under MS Excel for Macintosh.
Clear Skies - Canopus56
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Date: 08 Dec 2006 12:19:11
From: canopus56
Subject: Re: Ann: Spreadsheet to make annual dark sky calendar
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canopus56 wrote:
<snip all >
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/AnnualDarkSkyTable.html
Regretably, I discovered an error in the main calendar worksheet. It
has been corrected. Anyone who downloaded local copies of the
spreadsheet or sample calendars on 12/7/2006 will need to redownload.
My apologies for the inconvenience.
An annual calendar feature for a table of local sidereal times and an
annual table of facing lunar colongitudes (based on a favored UTC
observing hour) was added.
Example 2007 calendars can be viewed here -
Annual local sidereal time calendar based on observer's longitude and
defined UTC hour
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007SLC_LST_UTC4.html
Annual number of dark sky hours calendar based on observer's op and
defined UTC hour that "breaks" a day
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007SLCDarkSkyHours.html
Annual number of lunar observing hours calendar based on observer's op
and defined UTC hour that "breaks" a day
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007SLCLunarObsHours.html
Annual lunar facing colongitude calendar based on favored observing UTC
hour
http://members.csolutions.net/fisherka/astronote/plan/anndarksky/html/2007LunarCoLongUTC4.html
Clear Skies - Canopus56
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