Brunson 771 - Horizontal Collimation Calibration

Model 771, 75, and 76-RH190 Transits 44
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Forbestresultsduringthistest,leavetheverticaltan‐
gentclamplooseandthemicrometerdrumpointing
upordown.Makesurethemicrometerdrumissetto
zero.
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Forthistest,wewanttosetuptwoscalesonopposite
sidesofthetransit(Figure4.4).Eachofthescales
shouldbe17feetfromthetransit.Thescalesshould
nominallybeonalevelsightlinefromthetelescope.
Thesescaleswillallowustocomparethelineofsight
establishedinthe“forward”positionofthetransit
withalineofsightwhichisestablishedinthe
“reverse”position.Wewillbeverifyingthatnoan‐
gularerrorexistsbetweenthelinesofsightinthese
twopositions.
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1.Roughlevelthetransit.
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2.Pointthetelescopetowardoneofthescales,andaligntheverti‐
calreticlewirewithsomearbitrarypositiononthescale(e.g.,the
fiveinchtargetposition).Makesurethehorizontaltangentclamp
islocked.
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3.Plungethetransitʹstelescope180°tosightattheotherscale.Do
notturntheentiretransit—turnonlythetelescopearounditshori‐
zontalaxis.Thetransitwillbepointingatsomerandomlocationon
Description:Determineifthelineof
sightisperpendiculartothehori‐
zontalaxis.
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Tolerance:±1arcsecond.
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Affectedparameters:Reticleorienta‐
tion.
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Requiredequipment:
Opticalmicrometer,instrument
standandtwoscales.
HorizontalCollimation
Figure4.4
Again,wechoosetoputthe
scales17feetawaybecause
atthisdistance,0.001”
equals1arcsecond.