ASTRO-PHYSICS GTO KEYPAD 부록 - 페이지 8

{카테고리_이름} ASTRO-PHYSICS GTO KEYPAD에 대한 부록을 온라인으로 검색하거나 PDF를 다운로드하세요. ASTRO-PHYSICS GTO KEYPAD 10 페이지. Plus supplemental information for customers outside of north america and the revised gto quick star drift method of polar alignment

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6.● Make azimuth adjustments:

a)● Pick a second star that is at least 40 degrees

away from the first star, and that is away

from the pole. ●●Choose●a●star●that●is●in●the●

south,●east,●or●west,●if●you●are●in●the●northern●

hemisphere;●in●the●north,●east●or●west●if●you●are●

in●the●southern●hemisphere.●●●You●can●choose●

this●star●from●the●table●in●Appendix●I●if●you●wish.● ● ● ●

If●you●have●not●eliminated●all●of●the●orthogonality●

error,●make●sure●that●your●second●star●is●on●the●

same●side●of●the●meridian●as●the●first●star●from●

the●altitude●adjustment●portion●of●the●proce-

dure.●●●●●You●do●not●want●the●telescope●to●swap●

sides●and●introduce●any●remaining●orthogonality●

issues●into●the●azimuth●adjustment.

b)● Use the GOTO to slew to the second star.

c)● Make THE ENTIRE centering correction with

the azimuth adjuster.●●Note●that●this●movement●

could●be●along●either●crosshair,●or●from●a●point●

in●between●depending●on●where●in●the●sky●you●

chose●your●second●star.●●●As●the●Horizon●Circle●

d)● No need to Re-calibrate since you have NOT used the direction buttons to do any final centering.●●●If●you●do●

end●up●tweaking●with●the●direction●buttons,●then●go●ahead●

and●re-calibrate,●but●you●should●not●really●need●to●do●this.

e)● Slew back to the first star (Altitude Adjustment Star).●●●●

Since●it●is●almost●directly●overhead,●it●should●be●virtually●

centered●in●the●crosshair.●●●●This●is●because●the●azimuth●

adjustment●you●made●is●mostly●rotating●the●mount●around●

an●imaginary●axis●that●would●go●straight●up●through●this●

star.●●●

f)● If needed, center with the direction buttons only, and

then re-calibrate. ●●

g)● Repeat as needed. ●●●Slew●back●and●forth●between●the●

altitude●star●and●second●star,●making●the●adjustment●de-

scribed●in●6-c●above●on●the●second●star●each●time.●●

7.● When●these●two●adjustments●are●finished,●you●will●be●very●accurately●polar-aligned.●If●you●wish,●you●can●refine●this●

further●by●using●a●crosshair●eyepiece●in●your●main●instrument●and●repeating●the●procedure.●●●The●higher●magnification●

of●the●main●instrument●will●allow●greater●precision●than●the●finderscope.●●●However,●the●finderscope●had●its●orthogonal-

ity●error●removed●during●the●altitude●portion●of●the●alignment.●●●If●you●move●to●the●main●instrument,●you●will●see●the●

effects●of●any●orthogonality●error●in●your●main●instrument●assembly,●and●you●can't●simply●remove●this●error●by●turning●

adjustment●screws.●●●The●accuracy●when●using●your●main●instrument●also●depends●on●how●well●your●telescope●holds●its●

orthogonality.●Any●mirror●shifting●or●diagonal●misalignment●(that●applies●to●refractor●diagonals●as●well)●will●not●only●com-

promise●the●polar●alignment,●but●also●the●ability●to●accurately●center●objects●when●slewing●from●one●to●another.●Please●

refer●to●the●Orthogonality●section●for●further●discussion.

diagram●at●left●shows,●

stars●that●are●in●the●east●

or●west●will●result●in●

azimuth●adjustments●

that●are●N-S.●●●●A●star●along●the●meridian●in●the●south●(or●in●the●north●if●you●are●in●the●

southern●hemisphere)●will●result●in●azimuth●adjustments●that●are●E-W.●●●●A●star●chosen●

between●the●cardinal●compass●points●will●not●parallel●either●crosshair●as●it●is●adjusted.●●●

Wherever●you●land●after●the●GoTo●slew,●however,●the●azimuth●adjustment●will●take●you●

toward●the●center●of●the●crosshairs.●●●●(Ignore●any●small●perpendicular●displacement●as●your●

azimuth●adjustment●brings●you●to●the●center●of●the●eyepiece●crosshairs,●especially●if●your●

second●star●is●near●the●horizon,●as●it●will●likely●be●from●atmospheric●refraction.)●●●●●●