Accuracy Notes
All calculations rely on on the Date/Time properties
reported by your operating system. For high-accuracy set your system
to the correct time, time-zone, and daylight-savings (summer time) status
for your location. Public domain National Institute
of Standards and Technology Software that can synchronize your
computer with the atomic clock is available. Follow the above link
and select the software for your computer. (That document also
contains a technical discussion of time data format that is not required
to run the software.)
Usage Notes
Take Astro Pal© with you to the observing site by using the
File/Save As feature on the Microsoft Internet Explorer browser.
This will create an HTML file and an accompanying subdirectory based on
page title. You can move the file and directory to a laptop or other machine and
get all the functionality of Astro Pal© without logging on.
Note that Netscape 4.08 can not save the page properly to do this.
Another possibility is to generate print-outs of
this page at various dates/times and places of interest. Internet Explorer
can limit printing to highlighted selections.
Sections
The Observer Time and Place section reports your local
time/date, Coordinated Universal Time (UTC)/date, and Local Mean Sidereal
Time for your Longitude. (Netscape users can click in the text boxes
and view the complete record using arrow and [Home]/[End] keys). For
first-time users the displayed longitude is that of your time-zone
meridian. As such the sidereal time reported can be off by a
half-hour. This can be corrected through the Modify Data Control
Panel described below.
Due to time-zone differences the UTC on an
event happens at differing local dates and times around the world.
Use the data in this section to confirm your UTC date and time of
observation. Local sidereal time indicates what meridian of Right
Ascension is currently above your observing location. This can
be used for star map orientation. The longitude, in decimal form,
indicates the terrestrial meridian the calculated values are valid for.
Objects Near Meridian lists objects
approaching or just past their highest point in the sky. Listed are
setting circle calibration stars -- a list of bright easy-to-find
stars used to confirm your telescopes positioning accuracy. (First
polar align your telescope according to the manual.) To calibrate manual
telescope setting circles just point at one of these stars and then dial
the RA circle to
the listed coordinates. Point at the other stars and confirm their
positions. Hint: some telescopes have inner and outer (north and
south hemisphere) RA scales; this exercise will help you sort out which
scale to use if you are new to this.
A short list of some of the most easy-to-see
Messier Objects near the meridian is included. This is a nice
feature for beginners just learning the sky. Where possible
"show-case" objects are featured that are suitably impressive enough for
viewing by non-amateurs. Show them these targets while you wait for your scope to cool-down
before your serious observing session.
The Modify Data Control
Panel is highlight in
blue. Customize the data displayed in the prior sections
through this. Enter your correct Longitude in degrees,
minutes, and east/west of the prime meridian. You can enter decimal
values for minutes to account for seconds, i.e., 5.1667 minutes is 5'
10". Similarly enter local time and date in the indicated
places. Do not enter negative signs, non-numeric values, and numbers
that exceed the indicated range. Negative will be treated in the
absolute value while the rest will be ignored. Press the [Save]
button to recalculate and display the new circumstances. Note that a
cookie with the entered longitude will be placed on your
computer. This is to avoid having to set your longitude each time
your return to Astro Pal.
Comments
Send comments
concerning Astro Pal. What features would you like to see?
Did you get an error? or have a layout problems?
Related Links
These links will open pages with related content. Note that the listed Astro
Utilities pages are the static demo HTML version and will not
carry-out live calculations. Also visit the Astro
Computing section of this website.
Terms of Use
The SOFTWARE PRODUCT was designed for hobby, educational, and
entertainment purposes only. It should not be used for mission critical or
commercial applications. The user accepts the responsibility to
investigate the suitability and adaptability of this SOFTWARE PRODUCT for
their own purposes. This SOFTWARE PRODUCT is not warrant to be error free.
In no event shall the author of this SOFTWARE PRODUCT be liable to you for
any consequential, special, incidental or indirect damages of any kind
arising out of the delivery, performance or use of the software, even if
the author has been advised of the possibility of such damages. The
information in this SOFTWARE PRODUCT and any accompanying documents is
subject to revision without notice, and represents no commitment to you
the user.
