Sterrekunde

Hoe help dit 'polêr uitlê' van 'n teleskoop met ekwatoriale berging?

Hoe help dit 'polêr uitlê' van 'n teleskoop met ekwatoriale berging?


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Wat is die ware doel van polêre belyning? Gisteraand kyk ek na Mars. Dit het vinnig beweeg. Ek moet steeds die RA-as verstel om die vinnig bewegende Mars op te spoor. Waarom het die teleskoop dit nie vanself opgespoor nie?


Daar is twee hoofkoördinaatstelsels wat in die sterrekunde gebruik word: ekwatoriaal en horisontaal. Die ekwatoriale stelsel stel 'n beeld voor rondom die aarde waarop sterre (vir ons doeleindes) vaste posisies inneem. (In werklikheid beweeg die sterre effens, maar nie met 'n spoed wat belangrik is vir gemaklike amateurwaarneming nie.) Die punt is dat hierdie stelsel goed werk vir voorwerpe (veral sterre) met 'n onbeduidende hoeveelheid beweging. Ons gebruik deklinasie en regs hemelvaart om posisies op die sfeer te beskryf, net soos ons breedte- en lengtegraad gebruik om 'n posisie op die aarde te beskryf. Die punt van polêre aanpassing van 'n ekwatoriale berg is om 'n gerieflike beginpunt te vind, dit is die Noordelike Hemelpaal: dit is hoe u teleskoop in lyn kom met hierdie rooster aan die hemel. Sodra u teleskoop 'weet' waar die paal is, kan u dit handmatig met behulp van gekalibreerde megamismes na 'n bepaalde posisie in RA en Desember verplaas. Die tweede koördinaatstelsel is die horisontale een, wat die waarnemer se posisie as vertrekpunt gebruik (dit is die plek -afhanklik), en meet voorwerpe met behulp van hoogte (vanaf die horison van die waarnemer) en azimut (ware weergawe van die posisie van die waarnemer). 'N Alt-az-teleskoopsteun kan links en regs op en af ​​beweeg. Soms het dit merke vir horisontale koördinate.

'N Ekwatoriale berg is nie ontwerp om planete op te spoor nie, maar wel. Die voordeel van die gebruik van 'n ekwatoriale berging is dat u die omvang fyn kan aanpas om rekening te hou met die beweging van die planeet gedurende die (beperkte) tyd wat u waarneem.

Waarom het die teleskoop dit nie vanself opgespoor nie?

Het u 'n GoTo-stelsel?


Met die rotasie van die aarde laat dit lyk of die sterre en planete weswaarts beweeg oor die okulêrveld van 'n stilstaande teleskoop teen ongeveer 900 boogsekondes per minuut. 'N Ekwatoriale berging kan dit teenwerk deur slegs teen 'n konstante tempo op sy poolas te beweeg. 'N Hoogte-azimut-berg moet teen albei asse teen wisselende snelhede beweeg om op te spoor.

Aan die begin van Oktober 2018 het dit gelyk of Mars ongeveer 1,1 boogsekondes per minuut ten opsigte van die sterre beweeg. In 'n ekwatoriaal-gemonteerde teleskoop, wat behoorlik in lyn gebring is en teen die syfersnelheid dop, sal dit ongeveer 13 minute neem om deur sy eie skynbare deursnee van 15 boogsekondes te beweeg. Sonder 'n opsporingsmotor moet u die RA-as met die hand beweeg, maar u kan die deklinasie-as 'n rukkie alleen laat.

As die houer 'n opsporingsmotor het wat ontwerp is om in albei die halfrond bruikbaar te wees, kan dit oorskakel na rigting. As die skakelaar in die verkeerde posisie is, blyk dit dat sterre tweemaal so vinnig weswaarts beweeg asof die motor afgeskakel is.

As 'n ekwatoriale berg verkeerd uitgestel is, lyk dit of sterre in deklinasie dryf, afhangende van hul posisie in die lug, tot 15 boogsekondes per minuut per graad van polêre belyningsfout. As u byvoorbeeld in die noordelike halfrond is en die pool-as van die berg 5 grade te oos is, lyk voorwerpe naby die meridiaan met 75 boogsekondes per minuut suidwaarts, terwyl voorwerpe wat 4 uur van die meridiaan af is, net die helfte van die vinnig. As die poolas meer as 30 grade van die hemelpool af is, kan dit net sowel 'n alt-az-berg wees.


Hoe om 'n teleskoopmontering gedurende daglig te polariseer

Vir diegene onder ons wat sterrekunde doen, hetsy visueel of vir astrofotografie, is polêre belyning 'n prosedure waarvan ons vertroud is en wat ons moet doen voor elke waarnemingsessie, tensy ons 'n permanente sterrewag het.

Daar is verskillende metodes om polêre belyning te doen, maar dit werk almal na donker. Of dit nou Polaris in 'n polêre omvang is, Celestron se All Star Polar Alignment (ASPA), QHY's PoleMaster, die meer akkurate, maar tydrowende Drift Alignment of DARV.

Aangesien ek die oopbron-Onstep-teleskoopbeheerder gebruik, gebruik ek die 6-ster-belyning, met plaatoplossing in KStars / Ekos, gevolg deur die OnStep RefinePA-funksie, wat behels dat 'n ster gesentreer word, en dit dan weer met behulp van die Alt- en Az-knoppies, ietwat soortgelyk aan Celestron se ASPA.

Al die bogenoemde metodes vertrou daarop dat sterre sigbaar is, wat slegs na donker gedoen kan word. Dit is minstens 30 minute na sononder.

Maar wat doen u as u polêre belyning gedurende daglig wil doen?


Ekwatoriale montering van die Polar sonder Polaris?

Ek wou vra of dit moontlik is om polêre belyning vir my EQ-berging te doen sonder om polarisse te sien? aangesien Polaris agter 'n muur geblokkeer is, is daar dus 'n manier om dit te omseil?

# 2 Brian Carter

U kan dryfbelyning doen (google dit), maar dit is 'n ware PITA en dit is nie die moeite werd nie, tensy u gaan fotografeer.

As u nie in fotografie belangstel nie, kan u goed genoeg polariseer vir 'n goeie opsporing en kans. Stel die houer op en maak seker dat dit gelyk is. Stel die hoogtehoek van die houer vir u Latitude in en kry 'n kompas om dit noord te wys. Gaan dan deur u hele belyningsterre en u is klaar. Dit moet goed genoeg wees om op te spoor en slegs hier en daar 'n paar klein regstellings.

Dit is eintlik hoe ek polariseer, selfs al is ek op 'n plek waar ek Polaris kan sien. Tensy u fotografie doen, is 'soort-naby' van polêre belyning heeltemal aanvaarbaar.

# 3 Maged

Kan u asseblief meer oor die hele belyningsterre verduidelik?

# 4 CharlesW

# 5 Brian Carter

Kan u asseblief meer oor sterretjies vir volledige belyning verduidelik?

Dankie

Jammer, belyningsterre is vir Goto. Ek neem aan dit uit u vraag dat u nie 'n kans op u omvang het nie. Rigsterre werk saam met die rekenaar vir luukse monteerders. Wanneer u opgestel is en dit aanskakel, vra dit u om na relatief helder sterre in verskillende dele van die hemel te wys. Nadat u dit gedoen het, weet die berg hoe dit gerig is, en u kan dit outomaties voorwerpe vir u vind.

Maar aangesien u dit nie het nie. U kan steeds dieselfde prosedure doen as wat ek uiteengesit het. Kry net 'n kompas en laat die berg na die beste van u vermoë noord wys, en pas die hoogte aan op u breedtegraad. Dit is baie polêr gerig vir 'n funksionele EQ-berging.

# 6 csrlice12

Brian het die reg daarvan. Ek gebruik net 'n kompas omdat ek nie AP doen nie, maar net visueel. dink ek het $ 4 vir die kompas by WalMart betaal.

# 7 Abhat

Ek het 'n soortgelyke metode gebruik wat Brian beskryf het toe ek my berg gedurende die dag gekyk het (Son, Venus, Jupiter, ens.). Ek bepaal die breedtegraad op grond van my ligging (40 grade). Google sal u die breedtegraad vir u poskode gee. Met behulp van 'n slimfoonkompas-app oriënteer ek die berg in die Noord-rigting. Maak seker dat daar geen metaalvoorwerpe naby is wat magnetiese interferensie kan veroorsaak nie.

Hierdie metode is benaderd en werk slegs goed vir visueel. Dit sal u toelaat om enkele minute op te spoor sonder enige probleme.

# 8 Hesiod

U mag die kompas vermy, mits u weet watter ster die naaste aan die Suide is tydens die opstel van u teleskoop (telefoon-"apps", planetêre sagteware en die goeie ou papierkaarte / efemeris kan hierdie vraag beantwoord).

Ek doen dit baie gereeld met my nie-goto-aangedrewe berg en dit kan redelik effektief wees vir visueel (veral as die son of die hoeke van die skakerings gebruik word om die S te raai).

Net om duidelik te wees: die berg moet noordwaarts geplaas word, presies soos dit deur die polarscoop gerig is.

# 9 dmgriff

Tweedens gebruik die kompas 'n magnetiese deklinasie of magnetiese variasie-offset (google as u nie die term ken nie).

Ek kan Polaris nie sien nie as gevolg van bome, en ek buig nie goed om 'n polêre belyning te gebruik nie.

Ek het die kompas gebruik vir eq1, eq3, eq5 juweelbelyning.

U mag verbaas wees oor hoe goed u 'n baan met 'n kompas-polêre juweel kan kry.

# 10 graslande

As u 'n kompas en die breedteskaal gebruik om u berg op te stel, help dit as u seker maak dat dit gelyk is. As die berg nie een het nie, kan u 'n goedkoop borrelvlak by 'n hardewarewinkel kry. Aangesien die breedteskaal nie altyd akkuraat is nie, kan dit help as u dit ten minste een keer êrens in lyn kan bring sodat u die noordster kan sien. Maak ook seker dat die berging op daardie stadium gelyk is. Dan hoef u nooit weer breedtegraad aan te pas nie, mits u dit altyd gelykmaak en u breedtegraad nie te veel verander nie!

# 11 Gemors

Baie dankie vir u baie nuttige antwoorde.

Ek gebruik eintlik die iPhone-kompas om my berg na die noorde te rig, wat 'n paar minute visuele waarneming bied sonder dat dit merkbaar dryf.

Maar toe ek my kamera aan die teleskoop heg, was dit so erg om te dryf. soos 'n blootstelling van orionnevel van 15 sekondes tot 'n baie slegte sterpaadjie, so ek probeer my bes om akkurate belyning te doen.

# 12 Brian Carter

# 13 mclewis1

Ek gebruik eintlik die iPhone-kompas om my berg na die noorde te rig, wat 'n paar minute visuele waarneming bied sonder dat dit merkbaar dryf.

Maar toe ek my kamera aan die teleskoop heg, was dit so erg om te dryf. soos 'n blootstelling van orionnevel van 15 sekondes tot 'n baie slegte sterpaadjie, so ek probeer my bes om akkurate belyning te doen.

Dit sal ons iets vertel van u verwagtinge en wat u redelikerwys kan verwag om te kan doen.

# 14 Maged

Ek het 'n 4 "-teleskoop met 'n brandpuntlengte van 900 mm

Ek het 'n canon 70D-kamera, die eerste fokus is aan die teleskoop geheg

tot nou toe kry ek nie foto's van baie slegte kwaliteit nie, en blootstelling langer as 4 sekondes is 'n ramp

# 15 Starman1

Hi,

Ek wou vra of dit moontlik is om polêre belyning vir my EQ-berging te doen sonder om polarisse te sien? aangesien Polaris agter 'n muur geblokkeer is, is daar dus 'n manier om dit te omseil?

Dankie

Stel eers die driepoot gelyk voordat u die berg installeer, en maak een poot ongeveer noord of suid, afhangende van waar u fyn azimutpaal op die berg geleë is.

Tweedens, stel u houer in om u die breedte op die sy-aanwyser te lees nadat u dit op die berg geïnstalleer het.

Derdens, soek die verrekening tussen magnetiese noord en geografiese noord vir u ligging. Magnetiese noord sal in die weste wees as u oos van Chicago is, en dit sal in die ooste van noord wees as u wes daarvandaan is.

Vierdens, gebruik 'n kompas om magnetiese noord te identifiseer, en draai die kompas totdat die naald na die ooste of wes van die N-punt wys met die aantal grade magnetiese verrekening. Maak seker dat die monteerpunte by die N-merk op die kompas wys, nie waar die naald wys nie.

Vyfdens, installeer die omvang en aansig. Die voorwerp sal meer as lank genoeg in die veld bly om dit visueel te aanskou.

Vir fotografie sal dit nie goed genoeg wees nie. Nadat u bogenoemde gedoen het, moet u dit byvoeg

Sesdens: Doen 'n prosedure vir wegdryfbelyning om die rigting van die berg in te skakel. U kan maklik kyk hoe u dit aanlyn kan doen. Daar is baie tutoriale.

# 16 Kendahl

Kyk u gereeld vanaf dieselfde plek? As dit die geval is, kry 'n goeie polêre belyning en merk die liggings van u driepootvoete. Ek gebruik towermerke op my betonoprit en klein stokkies op gras. Plaas die driepootvoet die volgende keer as u soontoe gaan. Vir visuele waarneming is dit goed genoeg. Vir fotografie sal u nog steeds 'n spoorlyn moet herhaal, maar u sal van naby begin.

# 17 SteveNH

Hallo Maged, moenie toelaat dat die klank van "drift alignment" u wegskrik nie, dit is regtig eenvoudig as u die stappe metodies volg, een vir een. Ek doen dit vir kort, onbegeleide fotosessies en vir smal veld planetêre fotografie, en dit hou die teiken binne 'n paar sekondes boog vir 'n paar minute, en beter as ek dit verfyn deur aanpassingsherhalings te verhoog. Dit sou u aanstootlike agterstand op 'n beeldskaal van 900 mm aansienlik verminder.

Stel eers u berg op soos Don, Brian en ander voorgestel het. Dit bring jou naby, soos jy gesien het.

Let op dat u bergkop fyn kan verstel op sy driepoot 1) van links na regs deur horisontaal te draai en 2) deur die helling van die poolas te verander met die fyn verstelskroef onder die suidelike rigting.

Soek eers Procyon (of 'n ander helder ster naby die ewenaar en naby die kruising van die meridiaan, dit wil sê in sy suidste posisie) en sentreer dit in 'n medium-hoë-okulêr met die aandrywing aan die gang. Dit is hier waar 'n 12 mm of 9 mm kruishaar okulêr handig te pas kom, maar u kan dit steeds doen sonder die dwarshaar. Let op watter kant jy die teleskoop in die verbuiging moet skuif om die ster sentraal te hou. As dit noord is, moet u die bergkop effens kloksgewys draai. As dit na die suide aanhou, draai die bergkop effens antikloksgewys (begin met ongeveer 1 tot 2 grade verstelling, minder as u nader kom om glad nie te hoef te skuif nie).

Soek nou 'n opkomende ster in die ooste naby die ewenaar, soos Denebola in Leo, en kyk hoe dit dryf soos hierbo. As u die deklinasie na die noorde moet skuif, wys u polêre as te hoog en moet dit verlaag word. As u suid skuif, is die poolas te laag en moet dit opgehef word. Probeer die kanteling ongeveer 1 graad op 'n slag verander, en verfyn dit soos u nader kom.

Moenie bekommerd wees oor die verskuiwing in die regte hemelvaart tydens polêre belyning nie - vergoed dit net soos nodig. Selfs nadat u perfek in lyn is, kan dit nodig wees om die RA-motorsnelheid aan te pas tydens opsporing.

Maak ook seker dat u buis (OTA) met 'n gemonteerde kamera goed gebalanseerd is op die afwykingsas (deur die buis op en af ​​te beweeg, indien nodig), en dat u teengewig die totale gewig van u OTA en kamera op die pool balanseer. as voordat die dryfbelyning gedoen word.


Tipes polêre belyning

Daar is verskillende tipes polêre belyning wat u kan gebruik, afhangende van die toerusting wat u het, of u 'n duidelike blik op 'n hemelpaal het. Die tipes wat ons gaan bespreek is:

  • Polêre omvangbelyning
  • Dryfbelyning
  • Polêre belyningskameras
  • Wysende modelbelyning

Polêre omvangbelyning

Hierdie belyningsmetode is redelik universeel, aangesien byna alle ekwatoriale dophouers dit in een of ander vorm het, van sky trackers soos die Sky-Watcher Star Adventurer tot 'n paar hoër-end monteerders soos die Astro-Physics AP1600GTO. Die poolomvang is 'n klein teleskoop binne die regteras-as van u berg (die as wat die rotasie van die aarde teenwerk). Polêre omvang het 'n klein draadkoord aan die binnekant, waarmee u u paalster (Polaris of Sigma Octantis) in die regte posisie kan plaas vir belyning.

Afhangend van die tyd van die nag, sal u Polaris êrens op die sirkel plaas met verstelknoppies om u polêre belyning te doen. Ons verkies om die app PSalign te gebruik om my die regte posisie te gee om Polaris te plaas. Nadat u die ster op die regte plek geplaas het, is dit goed om na beeldvorming te gaan. Daar is egter 'n paar dinge wat u in gedagte moet hou om die polêre omvang doeltreffender te gebruik. Hieronder is 'n video wat hierdie proses toon:

Om u polêre omvang so akkuraat as moontlik te maak, moet die optiese as daarvan presies in lyn wees met die regteras-as van die berg. Dit beteken dat as u die regteras-as van die berg draai, die middelpunt van die aansig vanaf die poolomvang op een plek moet bly. Polêre omvang word vanaf die fabriek gekollimeer, maar tydens versending of vervoer kan dinge afgeslaan word, dus dit is nie seer om na te gaan nie. U kan aan die kollimasie van die poolomvang dink, amper soos om die poolomvang op die berg uit te pas.

Die manier waarop u dit aanpas, is gedurende die dag, wys u polêre omvang op 'n veraf identifiseerbare voorwerp soos 'n ligpaal. Draai deur u polêre omvang en draai u berg se regterasas. As u polêre omvang gekollimeer word, sal die middelpunt van die poolomvang op dieselfde plek bly as wat u dit verlaat het voordat u dit draai. Indien nie, sal die middelpunt in die dwarshaar beweeg. Die kollimasieproses is nie te moeilik nie. Dit behels die vasdraai en losdraai van drie klein stelskroewe op die omvang. Kyk na hierdie bladsy vir meer wenke oor die kollimasieproses.

Polêre omvang is 'n maklike manier om 'n polêre belyning te doen. Dit is egter nie buitengewoon akkuraat nie (tensy u 'n AP-houer met 'n RAPAS gebruik). Dit moet gewoonlik volgens ander metodes aangepas word, soos dryfbelyning of die gebruik van 'n polêre belyningskamera.

Polêre belyningskamera's

Na ons mening is polêre belyningskamera's waarskynlik die beste ding om uit te vind sedert gesnyde brood. Polêre belyning op hierdie manier is ongelooflik vinnig en baie akkuraat, en dit neem gewoonlik minder as 5 minute om dit te voltooi. Dit is ook baie eenvoudig om te doen. Vir polêre belyningskamera's kan u waarskynlik aflei dat ons van die QHY Polemaster praat, maar 'n soortgelyke resultaat kan bereik word met Sharcap se polêre belyningsfunksie of PHD2 se statiese polêre belyningsfunksie.

Voordat ons nadink oor hoe die Polemaster werk, kan u die video van OPT kyk oor die gebruik van die Polemaster hieronder:

Die QHY PoleMaster is 'n soort 'elektroniese poolomvang', wat beteken dat dit 'n uitsig op die hemelpool nodig het om te werk. Om hierdie rede help dit om die berg ongeveer in lyn te bring met die hemelpaal voordat u die Polemaster-opstelprosedure volg. Die QHY PoleMaster werk deur twee dinge te bepaal:

  1. Die ligging van die sirkumpolêre sterre in die gesigsveld
  2. Die middelpunt van die rotasie van u berg in die gesigsveld

Die ligging van die sirkumpolêre sterre word bepaal deur op Polaris te klik en 'n skuifbalk te skuif totdat die sterre naby Polaris ooreenstem met 'n oortrek. Die rotasie-middelpunt van die berg word bepaal deur op 'n ster te klik, die berg in die regte hemelvaart te draai en weer op die ster te klik. Herhaal hierdie proses twee keer en die PoleMaster-sagteware kan die draaipunt van u houer vind.

Uit hierdie inligting weet die Polemaster-sagteware die ligging van die hemelpool in die gesigsveld. Al wat u hoef te doen is om die draaipunt van u berg bo-op die hemelpaal te skuif, en dan het u 'n baie akkurate polêre belyning. As u u Polemaster permanent aan u opstelling laat, hoef u die rotasiesentrum slegs een keer op te los, aangesien dit in u Polemaster-sagteware gestoor kan word. Dit maak die proses nog vinniger, aangesien die vind van die rotasiesentrum die langste deel van die Polemaster-proses is. Dit is nie selde dat u binne twee minute in 'n polêre rigting kom wanneer hierdie inligting gestoor word nie.

Die Sharpcap-polêre belyningsfunksie en die PHD2-statiese polêre belyningsfunksie funksioneer op dieselfde beginsel as die Polemaster, maar hulle gebruik u gidskamera in plaas van 'n aparte kamera. Daar is egter beperkings. Die sigkamergids van u gidskamera moet tussen 1 en 2,5 grade wees, en u moet binne 5 grade van die paal wees om die proses te begin. As u 'n gidsomvang gebruik en nie 'n OAG nie, is dit 'n proses wat u moet oorweeg, aangesien dit u geld sal bespaar. Aangesien ons gewoonlik 'n OAG gebruik, gebruik ons ​​'n Polemaster. Ons hou ook meer van die Polemaster-gebruikerskoppelvlak as die ander genoemde metodes.

As u 'n QHY Polemaster kry, moet u oorweeg hoe u dit op u stelsel gaan monteer. Daar is 'n baie algemene misvatting dat die Polemaster geleë moet wees waar u polêre omvang is, in die middel van die regterasas, om behoorlik te kan werk. Dit is vals. Die draaipunt van u houer kan vanaf enige punt gemeet word solank dit met die berg se regterasas beweeg. Dit beteken dat u, in plaas van u bekommerd te maak oor die verkryging van verskillende Polemaster-adapters, 'n universele ADM-adapter vir ADM kan kry om u Polemaster op die teleskoop te monteer. Dit beteken dat u u Polemaster maklik tussen mounts kan omruil en dit selfs as 'n klein elektroniese soeker kan gebruik as u besig is om te beeld.

Drift Alignment

Drifbelyning is 'n baie vervelige en stadige manier om u omvang te polariseer. Drifbelyning is 'n polêre belyningsmetode wat staatmaak op u outoguider om foute vir polêre belyning te meet. Dit beteken dat dit gewoonlik ook binne PHD2 se dryfbelyningstoerusting uitgevoer word.

Die meganisme waaraan dryfbelyning werk, is die feit dat 'n ster se dryfsnelheid direk verband hou met u polêre belyningsfout. As u byvoorbeeld 'n ster met 'n perfek uitlynlyn hou, sal daar geen drywing wees nie. As u 'n ster met die slegste moontlike poolbelyning (wat op die ander hemelpool in die grond wys) wys, het u 'n dryfsnelheid van twee keer die syfersnelheid. Met behulp van hierdie feit kan PHD2 die dryfsnelheid van 'n ster meet en dit direk in verband bring met 'n polêre belyningsfout. Hierdie hoeveelheid aanpassing wat nodig is om die fout op te los, word as 'n magenta sirkel vertoon en u moet die ster eenvoudig na die magenta sirkel skuif. U sal hierdie proses met twee sterre doen, een vir hoogte-aanpassing en een vir aanpassing van azimut in verskillende dele van die lug. Lees hierdie gedetailleerde verwysing om die dryfbelyning in PHD2 te doen.

Dryfbelyning is 'n baie akkurate manier om belyning te doen, en as dit reg gedoen word, sal dit verseker dat u goeie opsporing en goeie beelde het. Die rede waarom dit so akkuraat is, is dat dit die ding waaraan ons die meeste aandag gee, direk meet, hoe vinnig die sterre in ons beeld dryf. Een sterk voordeel van hierdie metode is dat dit nie 'n duidelike siening van Polaris benodig om behoorlik te doen nie. Dit vereis egter 'n duidelike oorsig van 'n lae deklinasiegebied rondom die meridiaan en 'n duidelike Oost- of Wes-horison. Die probleem is dat hierdie proses verskeie kere gedoen moet word om 'n goeie belyning te kry, en hoe nader u aan perfekte belyning kom, hoe langer neem dit om die ster se dryfsnelheid te meet, want dit sal stadiger beweeg. U kan maklik verwag dat hierdie proses 15 of 20 minute sal neem om reg te kom. Om hierdie rede het dit grotendeels in onguns verval vir nuwer, vinniger belyningsmetodes.

Polêre belyning verkeerde opvattings

'N Misvatting van die polêre belyning wat ons baie gereeld sien, is die uitstel van driepote. Nivellering van driepote het geen impak op u polêre belyning of opsporing akkuraatheid nie (solank u driepoot nie so ver buite vlak is dat u omvang val nie). Die skoonheid van ekwatoriale monteerders is dat hulle op die ekwatoriale verwysingsraamwerk funksioneer, wat beteken dat die enigste belyning wat relevant is vir hul prestasie, hul polêre belyning is. U kan 'n EQ6 sywaarts aan 'n muur monteer, en solank dit polêr is, sal dit goed werk. Die enigste keer dat ons dit oorweeg om 'n driepoot te nivelleer, is dat die omvang van die omvang gevaar kan wees, wat feitlik nooit is nie, aangesien u in die meeste gevalle op 'n plat grond moet beeld. Gaan dus voort en bespaar jouself 'n paar minute elke keer as jy êrens plat opstel en die nivellering oorslaan.

Wys modelbelyning

Vir diegene wat hoër-monteerders gebruik met 'n beter wys akkuraatheid, tesame met meer gevorderde sagteware, kan u polêre belyning gebruik met 'n wysmodel. 'N Wysingsmodel is 'n kaart wat die wysfout van 'n teleskoop na verskillende dele van die lug beskryf. Wysfout is altyd wanneer die berg êrens uitslaan, en dit is 'n bietjie af van waar dit eintlik sou gedood word. Die rigtingmodel is gebou deur u kamera op verskillende dele van die lug op te los en te meet waar u teleskoop eintlik gerig is teenoor waar dit volgens al hierdie gebiede gerig is. Uit hierdie inligting kan u baie fisiese modellering van u teleskoopstelsel doen, insluitend die meet van die polêre belyningsfout. As u polêre belyning 'n mate afgeskakel is, sal dit in die aanwysingsmodel by elke versamelpunt weerspieël word. Hoe meer modelleringspunte, hoe akkurater sal u die polêre belyningsfout meet.

Hierdie aanwysingsmodel-vermoë is goed geïntegreer in TheSkyX, wat saam met baie verskillende soorte houers gebruik kan word, maar dit word hoofsaaklik met Paramount gebruik. Dit word ook hoofsaaklik met permanente teleskoopopstellings gebruik.

Hierdie metode hou wel enkele voordele in. Dit is redelik akkuraat en benodig nie 'n direkte aansig op die hemelpool nie. As u egter 'n goeie maatstaf van die polêre belyningsfout wil kry, moet u dalk 'n redelike aantal punte insamel wat 'n tydjie neem om te voltooi. Vir 'n permanente observatorium op afstand is dit regtig nie 'n probleem nie en is dit die beste sin vir belyning. Die meeste observatoriums op afstand gebruik Paramount's wat TheSkyX bestuur, dus dit is 'n betroubare metode wat niks ekstra benodig nie.


Dryf 'n ekwatoriale berg in lyn

Polêre aanpassing van 'n ekwatoriale houer vir astrofotografiedoeleindes is nie so maklik soos om die berg na Polaris te wys en 'n beeldsessie te begin nie. Vir astrofotografiedoeleindes is goeie polêre belyning absoluut noodsaaklik! Die gevolge van slegte polêre belyning is veldrotasie en beelde wat lyk asof dit regs buite die gesigsveld van u kameras dryf. Albei is baie frustrerend en baie maklik om te ervaar as 'n mens nie die tyd spandeer het om die berg goed te pas nie.

Daar is verskillende maniere om die belyningsproses te bewerkstellig, maar my gunsteling is die dryfbelyningsmetode. Ek het agtergekom dat hierdie metode uiters akkuraat is nadat 'n mens dit onder die knie kry, en dat jy eintlik kan sien hoe goed die bevestiging in regte tyd in lyn is. Enige en alle foute is duidelik sigbaar op u rekenaarskerm. Ek voer drifbelyning met my CCD-kamera met die grootste fokus uit, en gebruik K3CCDTools3 en sy retikule-funksie om die drift van die berg te monitor.

Ek het geleer hoe om my berg op 'n boodskap van Charlie Hein in die cloudynights-forum te dryf. Ek sou kon probeer om dit wat ek daar gelees het, te laat herleef, maar ek haal sy boodskap eerder in sy geheel aan, aangesien sy verduideliking van die wegrigting so in die kol is. Hier is dit:

Lawrie, dryfbelyning is nie naastenby so hard soos dit klink nie (alhoewel dit redelik skrikwekkend klink) & # 8211 Ek het juis om daardie rede vermy om te veel te leer hoe om dit te doen.

Die belangrikste is om te verstaan ​​wat u probeer doen. Hopelik kan ek dit op 'n eenvoudig verstaanbare manier verduidelik. Om die waarheid te sê, kan ek dit vir u vereenvoudig net omdat ek geen idee het wat u ervaringsvlak kan wees nie. As gevolg hiervan, moet u nie dink dat ek met u praat as my verduidelikings te eenvoudig lyk nie. Ek wil net seker maak dat ek dit op 'n maklik verstaanbare manier aanbied. Aan die ander kant, voel asseblief vry om enige gedeelte van die volgende aan te dui wat u nie optel nie, en ek sal my bes doen om dit vir u duidelik te maak.

Dit gesê, laat ons begin. Ek is nie seker watter soort berg jy het nie, maar ek sal uittree en raai dat u nie 'n vurkhouer op 'n ekwatoriale wig het nie, maar eerder 'n GEM (soos 'n CG5, SkyViewPro , LXD-55 of 75, of 'n soortgelyke montering). As dit nie die geval is nie, laat my dan weet, alhoewel dit regtig nie te veel verander nie.

Dit is belangrik om daarop te let dat alhoewel dit nie juis noodsaaklik is om 'n rowwe polêre belyning op u berg te doen nie, dit u * baie * tyd in die proses sal bespaar, want hoe nader u aan reg is, hoe minder jy moet jou berg skuif om dit reg te kry. Deur net te raai oor waar Noord is en hoe hoog Polaris is, kan dit u verder buite die lyn bring as wat die monteurs van u berg kan vergoed, wat u sal dwing om die berg fisies te skuif om dit & # 8220 in die sone te kry & # 8221.

Dit sal baie pynlik wees om 15 minute of selfs langer in die proses te ontdek, dus sal ek * sterk * ​​aanbeveel dat u Polaris ten minste gelyk maak aan Polaris deur die polêre omvang (of die gat waarheen u sou gaan) voordat u begin. Dit sal u van hier af baie tyd bespaar!

As u Polaris nie kan sien nie, rig dan die berg na die noorde en stel u breedtegraad so na as moontlik. Dit is ver van 'n akkurate manier om dit te doen, maar dit is beter as om net te raai. Probeer ook op hierdie stadium seker maak dat u Oos- en # 8211-Wes (regs-links) verstelboute (aan weerskante van die houer teenoor die voor- en agterkant van die houer, wat op en af ​​verstel) so ingestel is dat daar genoeg reis in albei rigtings is & # 8211 dit baie pynlik sou wees om uit te vind dat u nie die berg meer in 'n rigting kon skuif nie, want u het te ver na die een of die ander kant begin! Ek sê dit, want hoe verder u buite perfekte belyning is, hoe meer reis sal u nodig hê om daarheen te kom, dus dit is regtig die moeite werd om dit in gedagte te hou.

Terwyl ons praat oor hoe u besig is om op te stel, kom ons raak ook aan waar u opstel en u moet 'n duidelike uitsig hê reguit oor u kop en na die suide (agter die berg), en U moet ook na die Ooste of die Weste kyk wat so laag tot by die horison is as wat u dit kan kry om die dryflyn te laat werk.

Stel u kamera nou in die teleskoop en fokus dit. Begin watter program u ook al het (u het K3CCDtools genoem, en ek gaan van die veronderstelling uit dat u dit het) en bring u voorskouvenster na vore.

Soek 'n ster. Enige ster sal dit doen om die kamera gefokus te kry, maar op hierdie stadium kan u net sowel die eerste ster kies wat u benodig vir u wegrigting en dit is tydbesparend. Hier is 'n maklike manier om uit te vind waar in die lug hierdie ster is.

Beweeg eers u houer sodat die teengewigte parallel met die grond is en u omvang reguit na bo wys. Dit sal u omvang op die meridiaan plaas ('n denkbeeldige lyn wat van noord na suid reguit oor u kop loop).

Kyk nou na die liggaam van u berg, skuif die omvang in DEC na die suide (die agterkant van die berg) sodat u omvang en die berg lyk soos 'n & # 8220T & # 8221 wat op sy sy lê (as u kyk na die omvang en monteer van die kant af). Dit wys u omvang ongeveer op die hemelse ewenaar.

Kyk na hierdie lugruim en kies 'n ster wat êrens in hierdie algemene omgewing is & # 8211 dit hoef nie presies daar te wees nie, net in die omgewing. Die belangrike dele wat u moet oorweeg, is dat u nie te ver hiervandaan afdwaal nie, en dat die ster maklik sigbaar is op u voorskouskerm. Gebruik hierdie ster om u kamera te fokus & # 8211 dit hoef nie noodwendig 'n kritieke fokus te wees nie, maar hoe skerper dit is, hoe beter.

Nou moet ons die kamera opstel en uitvind in watter rigting die beeld gerig is. Bring die regterkantskerm in K3 na vore. Draai die teleskoop nou sodat die ster in 'n linker-regs (of regs-links) rigting beweeg, en let op hoe goed die ster die horisontale lyn van die reghoek volg. U moet die kamera in u fokuser draai sodat die ster die horisontale lyn van die reghoek so noukeurig volg as wat u dit kan kry. Wees voorbereid om 'n bietjie tyd te spandeer om hierdie stap te doen, maar as u dit eers agterkom, sal dit minder en minder tyd neem om te bereik.

Sodra die ster presies volg met die horisontale lyn van die reghoek, dan is u kamera se oriëntasie ingestel. Nou moet u uitvind watter rigting Noord, Suid, Oos en Wes u beskou. Dit is maklik om te doen. Om Noord-Suid te vind, druk net die suidekant van u omvang (aan die einde van die lig in) na die Noorde terwyl u na die uitstalling kyk. Druk net genoeg om die ster in u skerm te sien beweeg. Your star will appear to move to the South. Now you know the North-South axis. You can use a similar routine for East-West – lightly pushing on the West side of your scope towards the East makes the star appear to move West.

Whew! All that to get to here! Now we’re ready to actually look at the East-West drift of the mount. As counter-intuitive as this sounds, we look for this East-West misalignment by watching for a North-South drift of the star in our display. Slew the scope so that the star you’ve just used to focus and orient your camera with is placed exactly on the line of the recticle that runs East-West. Try to place it as exactly on the line as you can. We want to bisect the star with this line (cut the star in half).

Now we watch for the star to drift off the East-West line in one direction or the other, and we move the mount using the East-West (side to side) adjustments to correct this drift. The rules for this are pretty simple at this point:

Step 1 – Correcting East-West misalignment

If the star drifts South, the polar axis is pointing too far East.
If the star drifts North, the polar axis is pointing too far West.

Depending on how far out of perfect alignment you are, the star may start to drift immediately. You can make adjustments as soon as you can positively detect the direction it’s drifting in, using the above rules. At first, you will probably want to make a fairly large correction. Watch that you do not lose your drifting star off the edge of the screen while making your adjustments – if it looks like that is going to happen then center the star and then continue to move the mount if you need to. As you get closer to nailing the alignment, make smaller and smaller moves. I find that sometimes it’s advisable to adjust past where you think the perfect point is so that you get a sense of what you are accomplishing by moving the scope. The bottom line here is that you are aiming for having the star stay perfectly bisected by the East-West line of your recticle for a longer period of time than you would want to expose for without guiding – a good time frame is five minutes with no drift – the longer it can stay right on the line the better your alignment is. I’ve had the star stay perfectly bisected for over a half hour (I lose track of time chatting with folks while it drifts), which is a very good alignment.

Now that you have drifted out the East West misalignment, you need to do the same for the North-South axis. Leaving your DEC axis exactly where it is, unlock your RA axis and move it either to the East or West, whichever direction gets you closest to the horizon. Find a star in the general vicinity, just like you did earlier. Your camera should still be focused and correctly oriented, so all you need to do at this point is figure out where North-South and East-West are again, using the same trick you used earlier. Once that’s settled, you’re ready to go.

Once again, bisect the star on the East-West line of the recticle, and watch for drift in the North-South direction. However, this time we’re checking to see if the mount is too high or too low, and we use the adjustments at the front and rear of the mount to move the mount up or down. An added wrinkle here is that the rules are different depending on if you are looking at the Eastern horizon or the Western horizon:

Step 2a – Correcting North-South misalignment (using Eastern horizon)

If the star drifts South, the polar axis is pointing too low.
If the star drifts North, the polar axis is pointing too high.

Step 2b – Correcting North-South misalignment (using Western horizon)

If the star drifts South, the polar axis is pointing too high.
If the star drifts North, the polar axis is pointing too low.
As before, we’re looking to keep the star bisected on the East-West line for as long as we can stand to watch it – at least five minutes is a good rule of thumb, longer is always better. Once you have this down, you might want to go back to check the East-West just in case you accidentally messed something up along the line – that’s your call.

No question about it – this procedure takes time – time to learn (repetition and familiarity make it faster), and time to perform (repetition and familiarity make it faster). It taxes your patience, but it is definitely worth the trouble!

I had no clue on how to properly align my equatorial mount until I read the above explanation by Charlie. I now keep a print out of the directions on me every time I go out to image. The picture to the right is a perfect example of how an image will look like if your equatorial mount is poorly aligned. The night I took this image I was in a hurry to align the mount so I could get going imaging M51. Can you blame me? You will probably have to click on the picture to enlarge it, but in it you will see streaks that go from top right to bottom left as well as stars that look elongated. These streaks are actually hot pixels which decided to make their presence felt between my regular dark frame acquisition sessions which I do between light imaging session. Actually, this image was one of the reasons why I decided to Peltier cool my DSI Pro!

At any rate, the downward direction of the streaks shows that my mount was poorly aligned.

I hope that the information here will help some out there as much as it has helped me. Drift alignment of your equatorial mount is an important concept to master as an astrophotographer. Good luck and clear skies.


A Lifetime of Amateur Astronomy


The above diagram indicates the general layout of the mechanics of the night sky. If you projected a line through the Earth from the south pole to the north pole, and on into space, that line would appear to point directly at Polaris, or as we commonly call it, the north star.

All of the stars in the northern hemisphere rotate around Polaris during the course of the evening due to the Earth's rotation. To counteract this, one needs only line the Right Ascension axis of the equatorial mount at this magical center point, and all movements can be counteracted by turning the telescope on one axis. The Right Ascension axis is the one that is connected to the tripod. The one that is connected to the telescope and the counterweight shaft is the Declination axis. Every object in the sky has a co-ordinate given in hours, minutes and seconds of Right Ascension, and degrees, minutes, and seconds of Declination. Objects above the celestial equator have positive degrees of Declination and objects below have minus degrees of Declination. You go from 0 to 90, and 0 to -90 degrees going north of the celestial equator and then south of the celestial equator respectively. There are 24 hours of Right Ascension in a full circle.

You can do a simple alignment of your astronomical telescope's mount by placing the mount with the counterweight down, tube up. Now rotate the telescope until the tube is exactly in line with the Right Ascension, or polar, shaft of the mount. You can turn the base of the telescope in azimuth until it is in line with Polaris, and then finally, adjust the latitude setting on the equatorial head until the telescope is directly aimed at Polaris. This is the most simple method of polar aligning a telescope, and is sometimes called the home position on GoTo equatorial mounts.
Once you have roughly aligned the scope, you can use the hand controller to pick two stars, center them in the field of view, and hit enter to tell the electronics that you are pointed at them. Aligning a GoTo mount is really this easy, and once you've done it once, you can remember how to do it time and time over.

Another far more precise method uses the declination drift method, where you choose stars near the celestial equator both at the meridian, and at the eastern horizon. I first discovered this method in a 1977 Sky and Telescope article by Robert Provin on doing precision astrophotography. It has never let me down. You need a reticle eyepiece to do this, and you only move the telescope in Right Ascension to do this. The longer you can keep the star from drifting, the more precisely aligned your telescope will be. This method works great in an observatory, even when you can't see Polaris.

First, choose your star near where the celestial equator (i.e. at or about 0º in declination) and the meridian meet. The star should be approximately 1/2 hour of right ascension from the meridian and within about five degrees in declination of the celestial equator. Center the star in the field of your telescope and monitor the drift in declination.
•If the star drifts south, the polar axis is too far east.
•If the star drifts north, the polar axis is too far west.
Using the telescope's azimuth adjustment knobs, make the appropriate adjustments to the polar axis to eliminate any drift. Once you have eliminated all the drift, move to the star near the eastern horizon. The star should be 15 to 20 degrees above the horizon and within five degrees of the celestial equator.
•If the star drifts south, the polar axis is too low.
•If the star drifts north, the polar axis is too high.
The closer those stars are to the celestial equator, the more accurately your mount can be aligned. For long term use in an observatory, I will let it drift for 90 minutes, but you can speed this process up a lot by using a barlow lens because it really amplifies the drift. Remember to only make corrections in Right Ascension while doing this.

Some people like Dobsonian mounts. I have only ever used equatorial mounts, first without tracking, then with tracking, and finally with GoTo, which I absolutely love. Doing this simple procedure can let you see thousands of objects without frustration, and let you focus on enjoying your scope, rather than tracking it around the sky. I don't find an equatorial mount confusing in the least, either to operate or find objects with. Merely using one can teach you how objects appear to move in the night sky, much like the drawing above depicts. So before you go out and buy that big yard cannon that everyone recommends to newcomers, you might consider the convenience of having and using an equatorial mount. If you are going to do any kind of astrophotography, it is the only way to go. My blog's record is proof of that. If an 8 year old can use one without tracking, you can learn too. It really can deliver you a lifetime of amateur astronomy.


  • Telescope (do not put your telescope on at this stage)
  • A degree in astrophysics
  • Clouds

1. Placement and rough alignment

Things don’t happen all fully automagically. There are some elements that require you to think for yourself! This bit can be done during the day though.

  1. First, pick your spot where you’ll be going back to night after night if you don’t have the luxury of something more permanent. You’ll need to have an idea of what you can and cannot see from that location. And you’ll need to be able to see Polaris. There are some astro-ninjas on here that seem to navigate using in-built magnets, but for the rest of us – do not make life hard for yourself and make sure you will be able to spot and see Polaris. Use something like Stellarium on your phone for a rough guide of where it is in the sky.
  2. Get yourself a compass and stand out in your garden and rotate yourself until you are pointing North. The North Celestial Pole (NCP) that you really will be aligning to is irrelevant at this stage – it’s slightly off to the right from North. If this is the daytime, make sure you can see high above, in front of you – quite a bit above the roofs or trees – that’s where Polaris will be.
  3. Now rotate your mount so that the mount itself is pointing North too. This generally means the weights/weight shaft are the things in direction of North (providing your mount is at the start position if you loosened the clutch and let the weights swing down – this will be your home position. The mount puck is pointing South and up, the weights and bar will be pointing down and North). Some mounts have a handy N on the front leg to help with this part. The EQ5 legs have an N on the front leg, that should point North. The EQ6 legs as shown below, for example, has that leg pointing South instead.
  4. There, you’re done for this bit. This is your spot for your tripod and mount. We’re not completely finished, but we’re not adjusting anything to get any precise settings at this point either.

2. Levelling

I read questions about whether or not the mount should be level or not. What is strange, I reckon that they spend more time writing out that question and waiting for an answer than actually just bothering to level the mount. Just level it!

Some mounts have a little spirit level in-built. I find that more than adequate. Else get a spirit level onto the tripod and just make sure it is level. It’s a simple as that. Adjust the legs until you’re happy.

3. Wait until its dark

Astrophotography (and astronomy) is not for the impatient. This is the hardest part – waiting to try something out. If you’re in the UK, I reckon you have a 1 in 365 chance of it being a cloud-free day. But you’ve got this far and technically you only need the patch of sky around Polaris to be cloud-free to do the next bit.

4. Polar Alignment using a QHYCCD Polemaster

Note these steps are specifically for the Northern Hemisphere and Polaris. Adjust as necessary for you Southerners!

Honestly, life’s too short. I know seasoned veterans can polar align with their eyes closed during the daytime, but this is about how to enable beginners quickly in the field of astrophotography – and if one of these gems of equipment is a Polemaster, then so be it.

What the Polemaster does is be that polar aligning ninja for you and your mount. It walks you through the adjustments of the alt-azimuth bolts of your mount so that the mount then points to the North Celestial Pole courtesy of knowing where Polaris is. You only use it during this phase of your astrophotography outing – before you set your scope up. Once you’ve aligned your mount, you can technically turn off that software – it doesn’t do any magic adjustments during your guiding, or do any participation of auto-guiding. I think that’s a perception people have with the Polemaster. It does one job: it helps you with the fine adjustments for getting accurate polar aligning.

At a high-level – these are the steps:

  • Get Polaris and surrounding stars in view
  • Align the template to match Polaris and surrounding stars
  • Perform an RA (Right Ascension) rotation exercise (basically rotates the camera around Polaris)
  • Compare to the template again to see if anything has moved so it has an idea of where things are placed
  • You then use the live-view to adjust the alt-azimuth bolts on your mount to align Polaris over a target
  • Then finally fine tune using a closer view

  1. You’ve added your Polemaster to the front of your mount, you’ve connected it to your laptop and you’ve downloaded the software. Fire it up and you get a blank screen.
  2. Click on connect and you get to adjust the gain and exposure time depending on your light pollution levels etc. For me, the lowest settings are fine.
  3. It asks you to identify where Polaris is by double-clicking on it.
  4. It then asks you to rotate the template around Polaris to line up the surrounding stars.
  5. You then acknowledge it’s lined up. Once done it asks you to do a rotation of your mount. What you’re doing here is identifying and selecting one of the surrounding stars and watch that rotate around the arc – which is the RA rotation – the rotation that your scope will be doing when following the night sky. So choose a star and keep an eye on it while you’re rotating. Rotate it about (at least)

Congratulations! You’re polar aligned ready for a night of fun under the stars.


How to track the planets with an Eq mount?

Pardon the illiterate amateur for asking something that silly? I have a newtonian telescope on an eq mount with a motor on the RA. Is it possible to align it so that it can track a planet? I can align the telescope with Polaris, but how can I track objects on the Ecliptic that for now lies on the Southern side of my sky?

#2 Tapio

#3 james7ca

If you are reasonably close to the correct polar alignment (meaning you don't have any issues with tracking simple stars) then an equatorial mount will track pretty accurately to the planets. In that case, you should do fine with the standard sidereal rate of tracking for your mount (which moves the mount in Right Ascension).

However, the moon is a different story and that's why most (some?) mounts have a lunar tracking rate (and perhaps a solar rate). But, lunar tracking rates are only approximate since the moon moves in both Right Ascension (RA) and Declination (DEC) and most mounts don't provide tracking corrections for Declination. Also, the moon's rate varies from night to night, so just any one tracking rate won't work equally well over an entire lunar cycle.

Planets also move in RA and DEC but the changes in DEC are so slow that they can basically be ignored (unless you are trying to track a planet for many hours or days).

Edited by james7ca, 06 August 2018 - 04:44 AM.

#4 zanxion72

After aligning the telescope as close possible with Polaris, Should I just turn it the other way towards the South in a horizontal (relative to my location) motion? I have ensured that the mount is placed on a leveled tripod.

#5 james7ca

If you are properly aligned to Polaris then you should be able to re-point the telescope (using the movable RA and DEC axes) anywhere that you wish. I don't know what kind of mount you have but you should be able to either use the motor controls to slew to a new location or you should be able to loosen the clutches on one or the other axes and manually move the scope to point at your object. Just make certain that the telescope is balanced so that it doesn't "flop" to one side or the other when you loosen the clutches. After you are pointed near to the object just tighten the clutches so that the mount will continue to track on RA.

#6 sg6

Thank you so much both!

After aligning the telescope as close possible with Polaris, Should I just turn it the other way towards the South in a horizontal (relative to my location) motion? I have ensured that the mount is placed on a leveled tripod.

That is a bit ambiguous. You polar align the mount but swing the scope around to the planets. The text reads that you might be thinking of polar aligning then picking the whole mount up and aiming it South. Not a good idea but people have done it - and worse.

Post reads "after aligning the telescope as close as possible with polaris".

You do not align the telescope. You align the equitorial mount.

Think along the lines that you can polar align a mount without a scope on it. The telescope is not part of the alignment process.

As the initial reply says the planets move at what is very close to the rate that the stars do, so just leave it at sidereal. You cannot actually do much else as if you think about it each planet moves at a slightly different rate.

Think the Sun is likely the "fastest" at non-sidereal rate and the sun will remain in view for an hour without much problem.

#7 Sky Muse

You unlock the RA and DEC axes, then swing the telescope towards the south.

You do not move the mount itself once it's aligned to Polaris just the telescope.

#8 Napp

Take your scope and mount to an astronomy club outreach event or star party. Club members can help you polar align the mount and show you how to point the scope at targets including planets. This is a great way to learn a lot in a hurry and really advance your observing.

#9 zanxion72

Thank you all. It is now clear how to do this. Apparently I had a false impression of how the EQ mount wokrs!

@Sky_Muse, Thank you so much for the video.

@Napp, It is in my immediate plans. I will do so in the next month as here in Greece everyone dissapears in August.

#10 Napp

Thank you all. It is now clear how to do this. Apparently I had a false impression of how the EQ mount wokrs!

@Sky_Muse, Thank you so much for the video.

@Napp, It is in my immediate plans. I will do so in the next month as here in Greece everyone dissapears in August.

Don't feel bad. EQ mounts are not intuitively obvious.

#11 Sky Muse

Thank you all. It is now clear how to do this. Apparently I had a false impression of how the EQ mount wokrs!

@Sky_Muse, Thank you so much for the video.

@Napp, It is in my immediate plans. I will do so in the next month as here in Greece everyone dissapears in August.

You're very welcome. Did you know that you can motorise the RA-axis, and for automatic and hands-free tracking of any object.

Your kit is also sold with the motor-drive included, so you may already have it. I do not know.

#12 zanxion72

You're very welcome. Did you know that you can motorise the RA-axis, and for automatic and hands-free tracking of any object.

https://www.teleskop. G3--mounts.html

Your kit is also sold with the motor-drive included, so you may already have it. I do not know.

It is exactly the mount I have! I own a Celestron Astromaster 130 on an equatorial mount with a motor on the RA axis. It was very difficult for me though to understand how I could track the planets.

#13 gnowellsct

the law of the equatorial mount:

#14 gnowellsct

It is exactly the mount I have! I own a Celestron Astromaster 130 on an equatorial mount with a motor on the RA axis. It was very difficult for me though to understand how I could track the planets.

Well first off, it counteracts the movement of the earth. For planets and stars and galaxies that's good enough. For the moon and sun your higher end scopes have special speeds (lunar, solar) to track those, since relative to the earth their movements are a bit different.

There is an extremely slight difference between the movement of planets and stars, so slight it's hard even to watch in software I just plotted a movement of 4 arc minutes over the course of two hours, which would not take it out of a high power eyepiece.

So anyhow for planets and stars the basic deal is a simple counteraction of the earth's rotation. We are always moving to the east and so stars appear to move west. The motor constantly turns towards the west as objects appear to track west. In the 1960s they used extremely simple standard kitchen clock motors for this job. No complex calculations required. Everything is in the gearing.

The rotation speed of the mount is 15 degrees an hour which only looks like movement if you sit there and watch it for a while. But it's surprisingly speedy when you become an astronomer and are looking through the eyepiece. That's why it's good to have the tracking.


Intermediate Method

This is suitable for mounts with setting circles or polar-alignment scopes, such as bore- scopes. A bore-scope is a small telescope, usually with an illuminated reticle, inside the polar axis of a German equatorial mount. Some other mounts have detachable sighting scopes. For all these, follow the manufacturer's instructions, as the exact method of set-up will be specific to the mount and the alignment scope. The general principle of these alignment scopes is the same: they are exactly parallel to the polar axis and are sighted onto Polaris. The scope either has rotatable reticle or is itself rotatable, and has a marker which is aligned with a sidereal time scale (or local mean time and date scales) on a bezel. Polaris is then centred in the appropriate place in the reticle.

For mounts without alignment scopes, but with setting circles, the method is an enhancement of the Rough Method:

  • Level the base of the mount.
  • Adjust the altitude of the polar axis so that its angle to the horizontal is equal to your latitude. A plumb-line (or level) and protractor is useful for this if there are no suitable markings on the mount.
  • Set up the mount so that the polar axis is pointing as nearly north as you can judge.
  • Using the setting circles, set the telescopes to the RA and Dec of Polaris.
  • Sight through the telescope, adjusting the altitude and azimuth of the polar axis until Polaris is centred in the eyepiece. Ensure that the base of the mount remains level.
  • Once Polaris is sighted, offset to ¾º in the direction of Kochab (beta UMi). If you know the field of view of your eyepiece, this ¾º should be relatively easy to judge accurately.

If you do this carefully, this method should allow long periods of visual observing and will be sufficiently precise for piggy-back photography for up to exposures at least as long as 30 minutes with lenses up to 200mm focal length. It will also allow the setting circles to be used to find objects.


Another homemade telescope mount slewing video

I've put the DIY homemade GEM telescope mount back together after improving the mounting of the motor output shaft and done another indoor GOTO slewing video.

The mount is run from a Meade Autostar DS motor kit. These motors are designed to run a much smaller telescope, but can be adapted to run a much larger telescope mount because the Autostar controller lets you program in the ratio of the worm gears.

A consequence of this means the slewing is very slow - but it gets to the target in a few minutes, and I can wait a few minutes as I normally only image one or two targets a night.

The noise is still pretty dire, but sounds much more healthy than my previous video due to the better mounting.

Tomorrow, if it says clear, I will take the mount outside for some real GOTO and PEC tests. If the PEC looks acceptable then I am on the home run - I just need to make some covers and other weatherproofing bits and bobs . Then we can move the new mount into the observatory shed.


How exactly 'polar aligning' a Telescope with equatorial mount helps? - Sterrekunde


You may have learned that for taking good astrophotos, you need a polar aligned mount preferably a german equatorial mount. But with new high quality Alt-Az mounts, this is no longer true. New technologies introduced in Alt-Az mounts mean they can deliver precise equatorial tracking while maintaining the basic advantages of the Alt-Az mount (read more about these advantages and a comparison to Polar aligned mount here).

Tracking needed for precise astrophotography

One of the first challenges when taking astrophotos is to achieve good tracking. Without good tracking of the object imaged, the rest doesn’t matter. Top quality optics, super sensitive low noise camera, everything collimated and aligned perfectly – all this will not help you if the tracking is bad.

M31 – 5 hours exposure, TEC140 APO, Canon 5D, TTS-160 Panther Mount w/rOTAtor

Tracking the sky means that the telescope must continually be pointing at the exact same point in the sky. The stars rise in east and set in west and the telescope mount must have a movement pattern following them all the way.
The polar aligned parallactic mount handles most of this in the setup process. After carefully aligning the polar axis to be parallel with the Earth rotation axis, it is possible to track the sky by rotating the Polar axis at the correct constant speed. A solution that made it possible in the old days to have a mechanical clock running the mount. And the alignment of the polar axis also secures that no field rotation (explained below) takes place. But leveling and polar aligning the mount takes time and is not always easy.

The Alt-Az mount calculates the movement pattern in the alignment process. The mount can be setup without any leveling of any kind. When powered up, the mount is aligned on two known objects creating the information needed for precise tracking of the sky. Based on that information, a basic Alt-Az mount can track a single object across the sky with great precision. The movement pattern of the basic Alt-Az mount will on the other hand result in field rotation. Setting up and aligning an alt-Az mount is very simple to do – a lot easier than polar aligning a GEM.

Field rotation

Field rotation principle.

If you watch the half moon rise in east, you will typically see the moon terminator at an angle not being vertical. If you look again later when the moon has reached south (or north), you will notice that the terminator now is vertical. When the moon reaches the western horizon, the terminator is again angled to the horizon and in the opposite direction to when it rised in east. This phenomenon where the sky changes its angle to the horizon is called Field rotation.
The Alt-Az telescope mount moves around a vertical and a horizontal axis. Therefore, a camera placed on an Alt-Az mount will keep it’s angle in relation to the horizon and terrestrial objects. But if you point the camera at the moon and takes 3 images: in east, south and west the moon will have different angles on the pictures even though the mount has tracked perfectly and kept the moon centered in the pictures.
In a coming articles the details of Field Rotation will be covered in details.

Long exposure astrophotography with Alt-Az mounts

With modern technology it is very easy to eliminate field rotation and achieve true equatorial tracking with Alt-AZ mounts. And with the fast technological development within astronomy equipment this is continuously getting even easier. To eliminate the field rotation two solutions are available today.

Alt-Az telescope with camera rotator (Planwave CDK700)

The first solution is the introduction of a camera rotator. It is a device installed on the telescope allowing for automatic rotation of the camera around the optical axis. When tracking the sky this rotator will track the field rotation exactly as the mount tracks the azimuth and altitude. This is the solution used on all larger professional telescopes and some larger amateur telescopes. Using the camera rotator also adds the advantage that the framing of objects and picking of guide stars can be done remotely/automatic. When using a camera rotator guiding must be done off axis through the imaging telescope. Several companies are offering camera rotators.

Optech Pyxis 3″ rotator

Moonlite Night Crawler focuser/rotator

Telescope rOTAtor (Track The Stars)

The second solution to eliminate field rotation is the Telescope rOTAtor. It is an invention I made for the Panther mount from Track The Stars. The idea is to rotate the entire telescope OTA on the mount including any piggyback mounted equipment. The basic functionality is the same as the camera rotator – when the mount tracks an object the Telecope rOTAtor tracks the field rotation.
The main difference from the camera rotator is that a piggybacked guide telescope can be used for guiding and a piggybacked DSLR camera will also track the sky equatorially. For a transportable setup, this can be a great advantage.

Alt-Az mount with rOTAtor

The Telescope rOTAtor has a certain rotation angle and must be reset every 1-3 hours depending on where in the sky the object is located. It is possible to take single subs as long as you normally want (up to 1 hour or more). For a large total integration time, the rOTAtor must be reset as needed.

The quick and easy way of stacking short subs

If you are new to astroimaging or just want to have the easiest solution at the telescope, stacking of multiple short exposures might be the way to go. All you have to do is setup and align your mount. Then focus and frame your target. Now, you can start taking short subs. If you keep the subs short, no guiding is needed and field rotation will not show up on the individual subs (more on this in a future post). Typically, you can have subs up to 30 seconds without any visible field rotation and if you image in east and west your subs can be much longer. Of course, the unguided tracking accuracy of your mount must be

NGC891 800x10sec TEC140 f/7 refractor, ZWO ASI224 camera, Panther Alt-Az mount, no rotator, no guiding

taken into account too. To get the best resolution, you can guide the mount to get the most precise tracking.
The subs will of course show field rotation between the frames, but most of the stacking software programs available will handle this and align the images perfectly. With the new low noise cameras, very impressive results can be made using this simple principle.

In the coming posts, I will go into more details with these different astrophotography techniques. Stay tuned.


Kyk die video: Как открыть веб-студию (November 2022).