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Old 18-02-2009, 12:12 PM
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gary is offline
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,474
Messier Marathon with your Argo Navis

Originally Posted by erick View Post
Haven't thought this all the way through as yet but what's the easy (non-thinking!) way to undertake a Messier Marathon with the Argo Navis?
Hi Erick,

Great to hear you want to perform a Messier Marathon.

As mentioned by other respondents, an optimal way to observe them is
in ascending RA order.

As you will be aware, with the rotation of the Earth, just as the sun and the stars
rise in the East and set in the West, so do lines of Right Ascension. For this
reason, RA is measured in units of time and at any given fixed Azimuth and elevation,
RA sweeps by at a sidereal rate.

With this in mind, you might want to grab an Argo Navis User Catalog with
the Messier objects sorted in RA order. You can find a user contributed
copy of such a catalog on the Argo Navis User's Group under the name
jk_messier marathon_cap.txt which can be found in this folder here -

Load the User Catalog as per the instructions starting on page 163 of the
Argo Navis User's Manual.

To use the catalog, you need to determine the starting point. On the night
in question, perform a star alignment. Then point the scope due west and
IN ANY CONSTEL. Argo Navis should then identify the Messier object that
is closest to where the telescope is pointing.

Now, if you then press EXIT and DIAL up MODE CATALOG, USER OBJECTS
and press ENTER, the object that you last identified will be the default object
displayed. Press ENTER in the usual way a few times until the GUIDE
mode display appears and GUIDE to it.

To go to the next object in the User Catalog, you then use a special feature of
MODE CATALOG which is that whilst in GUIDE mode, if you spin the DIAL
clockwise one detent click, you go to the next object in the catalog, which
by definition, will be slightly further East than the one you just observed.
Continue this way for the rest of the night.

For casual touring of Messier objects at any other time of the year, you can
simply push the scope toward the zenith and DIAL up MODE TOUR,
and Argo Navis will take you on a tour of all Messier objects currently
above your local horizon. Use the DIAL to advance through the tour by
spinning it clockwise or backtrack through the tour by spinning the DIAL

You can depart the tour, say to look at other objects of opportunity and then
rejoin it at any time. To do this, simply press EXIT whilst in MODE TOUR.
You then might use MODE CATALOG to view some other object. When
you want to continue the tour, DIAL up MODE TOUR, REJOIN LAST TOUR.

Good luck on your Marathon and I hope you get clear weather on the night!

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
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