ASTRO-PHYSICS Mach2GTO, Руководство пользователя

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APPENDIX H: SUGGESTED STARS FOR THE GTO QUICK STAR
DRIFT METHOD
The following list of stars is intended to make the GTO Quick Star Drift Method much quicker and easier. Since hunting
through a star atlas for suitable stars can take as long as performing the actual method itself, we put together this list of sug-
gested stars to give you a big head start in most situations. The paired columns suggest pairs of stars that are found in the
keypad’s database for the northern and southern hemispheres. The stars in each row are very close in Right Ascension, but
differ substantially in Declination. Use the pairings for the azimuth portion of this method. Since the rows are all relatively
close in RA, you usually have the option of choosing a replacement star if one of the suggested stars is obstructed in some
way. Stars on the list that are near the celestial equator are good choices for the altitude iterations.
Two additional partial columns of stars were added in the middle to increase your number of choices. Stars were added here if
we felt that a gap needed filling in a particular RA row, or if one of the polar stars was very close to the pole, and therefore not
suitable for a non-orthogonal system. There are, unfortunately, some parts of the sky where suitable stars are simply not to be
found.
For the altitude portion of the adjustment, most people will find that the ideal star will be in the column for the other hemi -
sphere’s non-polar side. In other words, people in the north may find the best choice in the southern hemisphere’s “NORTH”
column, and those in the south will find good choices in the northern hemisphere’s “SOUTH” column. These will tend to be
stars that are not too far from the celestial equator, but are also somewhat overhead. If there is a star listed in the “Optional
Additional Star” column, it may also be an excellent choice for the altitude adjustment. Choose a star that is slightly south of
your zenith if you are in the northern hemisphere, and north of your zenith if you are down under. This is to protect your instru-
ment from hitting the pier when you flip sides.
For the azimuth portion, make sure that BOTH stars are on the same side of the meridian. For example, in the southern
hemisphere, if the LST is at 06:30, do not choose Canopus at RA 06:23 and Alhena at RA 06:37. Choose a pairing one or two
rows above or below them in the list. Alternatively, you could wait a few minutes until the LST has gone past the higher RA, or
you could activate the meridian delay feature to put both stars on the same side of the meridian. Also, keep in mind that you
can be several hours east or west of the meridian with your azimuth pairs. The main advantage to being relatively close to the
meridian is that you won’t be as likely to lose stars in the atmospheric soup.
Remember also that any given RA value is equivalent to that same value plus or minus 12. What this means is that people in
far northern or far southern latitudes can often substitute a circumpolar star 12 hours different in RA for one of the suggested
stars. No matter what time of day or year, you should have available stars within one or two hours of the meridian. For exam-
ple: assume you are at a latitude of +50 deg, and the LST is 02:30. You would choose the row with Eta Persei that has RA val-
ues near 02:50. Eta Persei, however, might be fine for someone at a latitude of 30 degrees, but at a latitude of 50, it is almost
directly overhead. For the northern star in the azimuth routine, you could substitute Kochab which will have an equivalent RA
of 14:50 and will be much lower in the north. Likewise, a person using this method from the southern tip of New Zealand when
the LST is at 06:30 might decide that Canopus at RA 06:23 is much too straight overhead and choose Zeta Pavonis at R.A.
18:43 as the southern star instead in the azimuth routine.
Please note: The stars below that are listed by their Bayer designation must be accessed through the 1=Objects => 8=Tour
=> 1=Stars/Constell. menu system. The stars listed with common names are accessed through 1=Objects => 5=Strs.
SUGGESTED STARS FOR GTO QUICK STAR DRIFT METHOD
Northern Hemisphere Southern Hemisphere
Azimuth Pairs Azimuth Pairs
North South North South
(Southern
Optional Additional Stars
(Northern
Hemisphere Hemisphere
Altitude) North South Altitude)
Star: Caph Iot Cet Bet 2 Tuc Algenib Bet Hyi
RA: 00:09:11 00:19:25 00:31:33 00:13:14 00:25:45
Dec: +59*09:00 -08*49:00 -62*57:00 +15*11:01 -77*15:00
Star: Tet Cas Eta Cet Eps Psc Zet Phe
RA: 01:11:06 01:08:35 01:02:56 01:08:23
Dec: +55*09:00 -10*10:00 +07*53:00 -55*14:00
Star: Eps Cas Baten Kaitos Alrescha Sheratan Alf Hyi
RA: 01:54:23 01:51:28 02:02:03 01:54:38 01:58:46
Dec: +63*40:00 -10*20:05 +02*45:49 +20*48:28 -61*34:00