en:ost:telescope:setup

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en:ost:telescope:setup [2021/05/29 16:29] – [Kollimation] rhainichen:ost:telescope:setup [2024/07/11 07:45] (current) – [Refining the alignment] rhainich
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-FIXME <fs xx-large><fc #ff0000>This page is currently under revision.</fc></fs> 
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 ====== Telescope setup and maintenance ====== ====== Telescope setup and maintenance ======
    
-===== Setup of the mount =====+===== Setup of the GM4000 HPS II mount =====
  
-==== Using the mount directly ====+==== Using the mount directly via the handheld terminal ====
 === Alignment === === Alignment ===
  
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     * to improve the accuracy all stars should be spread across the whole sky     * to improve the accuracy all stars should be spread across the whole sky
  
-There are further methods to change/improve the alignment that are documented in the manual of the GM 4000 QCI, which can be found in room 2.009.+There are further methods to change/improve the alignment that are documented in the manual of the GM 4000 HPS II, which can be found in room 2.009.
  
  
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 <WRAP twothirds column> <WRAP twothirds column>
  
-The advantage of setting up the mount via the OMS is that a much more precise pointing model can be created, since not only a few stars are used, but up to 100 star fields distributed over the whole sky can be utilized. The exact position of these star fields is determined automatically with the help of the so-called [[https://en.wikipedia.org/wiki/Astrometric_solving | Plate Solving]].  +The advantage of setting up the mount via the OMS is that a much more precise pointing model can be created, since not only a few stars are used, but up to 100 star fields distributed over the whole sky can be utilized. The exact position of these star fields is determined automatically with the help of the so-called [[https://en.wikipedia.org/wiki/Astrometric_solving | Plate Solving]]. We use the software //ModelCreator//.
- +
-We use the software //ModelCreator//.+
  
-The most important settings in the **Equipment** tab such as **Camera**, **Mount**, **Solver** and **Dome** should already be preset. These settings are stored as profiles. The predefined profiles can be selected from the **Profile** drop-down menu. By clicking on **Profiles** the profiles can be edited and also new ones can be created. By clicking on the ''Connect'' buttons at **Camera**, **Mount** and **Dome** the corresponding devices can be connected to the //ModelCreator//. In the case of the camera, it must be ensured that the camera is connected beforehand to //MaxIm DL// because //ModelCreator// fetches the data from there.+The most important settings in the **Equipment** tab such as **Camera**, **Mount**, **Solver**, and **Dome** should already be preset. These settings are stored as profiles. The predefined profiles can be selected from the **Profile** drop-down menu. By clicking on **Profiles** the profiles can be edited and also new ones can be created. By clicking on the ''Connect'' buttons at **Camera**, **Mount**, and **Dome** the corresponding devices can be connected to the //ModelCreator//. In the case of the camera, it must be ensured that the camera is connected beforehand to //MaxIm DL// because //ModelCreator// fetches the data from there.
  
-Next you should set the points where //ModelCreator// will create images of the sky. You should set a minimum height above the horizon (''Min Alt''), because points too close to the horizon do not make sense due to the long way the light travels through the atmosphere. It has been proven that at least a minimum altitude of 15° is necessary. Furthermore, it has turned out to be useful to activate the option ''Equal az spacing'' in order to achieve an optimized distribution of the points. If you also activate the option ''Show number'' the order in which the points are processed is also displayed. Afterwards you can click on **Generate** to generate the points. After that you can click on **Sort-EW** to sort the points from east to west. This significantly reduces the overall slewing time required by the mount. For our final pointing model we usually use up to 100 points. For this we usually set ''Points per row'' and ''Rows'' to 10 each. Additionally 3 base points can be selected. Click on the corresponding points with the mouse. +Next you should set the points where //ModelCreator// will create images of the sky. You should set a minimum height above the horizon (''Min Alt''), because points too close to the horizon do not make sense due to the long way the light travels through the atmosphere. It has been proven that at least a minimum altitude of 15° is necessary. Furthermore, it has turned out to be useful to activate the option ''Equal az spacing'' in order to achieve an optimized distribution of the points. If you also activate the option ''Show number'', the order in which the points are processed will also displayed. Afterwards you can click on **Generate** to generate the points. After that you can click on **Sort-EW** to sort the points from east to west. This significantly reduces the overall slewing time required by the mount. For our final pointing model we usually use up to 100 points. For this we usually set ''Points per row'' and ''Rows'' to 10 each. Additionally 3 base points can be selected. Click on the corresponding points with the mouse. 
  
 It has proven useful to increase the exposure time for points close to the horizon, because there the air mass increases significantly. Otherwise not enough objects can be identified. For points in the Milky Way, on the other hand, it can happen that no solution can be achieved by plate solving, because there seem to be too many stars in this area. In this case, it might be helpful to reduce the exposure time. The exposure time can be adjusted via the **Control** tab. Here you should also set a ''Slew settle time'' of 3s and the focal length of the telescope (''Focal Length'').  It has proven useful to increase the exposure time for points close to the horizon, because there the air mass increases significantly. Otherwise not enough objects can be identified. For points in the Milky Way, on the other hand, it can happen that no solution can be achieved by plate solving, because there seem to be too many stars in this area. In this case, it might be helpful to reduce the exposure time. The exposure time can be adjusted via the **Control** tab. Here you should also set a ''Slew settle time'' of 3s and the focal length of the telescope (''Focal Length''). 
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 </WRAP> </WRAP>
 <WRAP third column> <WRAP third column>
-[{{ :ost:software:platesolve_5.png | Recorded star field - Red crosses: detected stars, Turquoise crosses: catalog stars, Yellow circles: identified stars}}]+[{{ :ost:software:platesolve_5.png | Image of the star field - Red crosses: detected stars, Turquoise crosses: catalog stars, Yellow circles: identified stars}}]
 </WRAP> </WRAP>
 </WRAP> </WRAP>
  
-//PlateSolve// identifies the stars in the respective star field and compares their position with star catalogs. Starting from the coordinates provided by the telescope, a spiral outward search is performed. In the example in the center below, the first step of the iteration was already successful and the star field was successfully identified. If the pointing model is not yet as good as in this example, which is usually the case when a completely new pointing model is created, it may take several iterations until the star field is identified. If after 99 iterations the star field has not been found, the iteration is aborted and //ModelCreator// moves on to the next pointing without any changes.+//PlateSolve// identifies the stars in the respective star field and compares their position with star catalogs. Starting from the coordinates provided by the telescope, a spiral outward search is performed. In the example above (the screenshot in the middle), the first step of the iteration was already successful and the star field was successfully identified. If the pointing model is not yet as good as in this example, which is usually the case when a completely new pointing model is created, it may take several iterations until the star field is identified. If after 99 iterations the star field has not been found, the iteration is aborted and //ModelCreator// moves on to the next pointing.
  
 </WRAP> </WRAP>
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 The Periodic Error Correction (PEC) can help to improve the tracking accuracy of the mounting by accounting for periodic errors of the worm gear. This error usually has a period of approx. 3 min 20 sec (3.3 minutes), while the PEC can correct for shorter periods, too. The error of the worm gear is usually irrelevant as long as the observations are only carried out with an eyepiece -- in case longer observations are taken with CCDs, the corrections of this error are getting important. The Periodic Error Correction (PEC) can help to improve the tracking accuracy of the mounting by accounting for periodic errors of the worm gear. This error usually has a period of approx. 3 min 20 sec (3.3 minutes), while the PEC can correct for shorter periods, too. The error of the worm gear is usually irrelevant as long as the observations are only carried out with an eyepiece -- in case longer observations are taken with CCDs, the corrections of this error are getting important.
  
-The PEC has to be calibrated before it can operate properly. For this purpose, the mount needs detailed information on the deviations from the ideal tracking behavior. One possibility to achieve this is by centering a bright star in an eyepiece and following its motions with the hand terminal (the N - S - E - W buttons) for a while. A more sophisticated option is based on the [[en:ost:ccds:ccdops#Guiding|autoguide functionality]] of our CCD cameras, as the precision is higher this way. Start the PEC calibration on the hand terminal with:+The PEC has to be calibrated before it can operate properly. For this purpose, the mount needs detailed information on the deviations from the ideal tracking behavior. One possibility to achieve this is by centering a bright star in an eyepiece and following its motions with the hand terminal (the N - S - E - W buttons) for a while. A more sophisticated option is based on the [[en:ost:ccds:ccdops#Guiding|autoguide functionality]] of our CCD cameras, as the precision is higher this way. It is recommended to train the PEC directly via the handheld terminal. The training algorithm of the PEC is started by means of:
  
 <code>Drive -> A-PEC control -> A-PEC Training</code> <code>Drive -> A-PEC control -> A-PEC Training</code>
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   * Will follow soon ...    * Will follow soon ... 
  
-==== Reinigung der Spiegel ====+==== Cleaning the mirror ====
  
-Für die Reinigung des Spiegels müssen im Prinzip die gleichen Schritte durchgeführt werden wie für die Reinigung der Schmidtplatten bei den Schmidt-Cassegrain-Teleskopen mit folgenden Ausnahmen:+To clean the mirror, basically the same steps must be followed as for cleaning the Schmidt plates on Schmidt-Cassegrain telescopes with the following exceptions:
  
-**Zusätzlich benötigte Materialien:** +**Additional materials needed:** 
-  * Papierhandtücher+  * Paper towels
  
-**Änderungen bei der Vorgehensweise:** +**Changes in procedure:** 
-  * Bei Reinigung des Hauptspiegels: +  * When cleaning the primary mirror: 
-    - Zusätzlich sollte man einige Papierhandtücher in die Kohlefaserhülle um den Spiegel legen, sodass überflüssige Reinigungsflüssigkeit von diesen aufgenommen wird und nicht hinter den Spielgel läuft und dort z.B. in Kontakt mit der dort verbauten Elektronik kommt. Die Papierhandtücher dürfen nicht in Kontakt mit dem Spiegel kommen.  +    - In addition, some paper towels should be placed in the carbon fiber sleeve around the mirror so that excess cleaning fluid is absorbed by them and does not run behind the mirror and come in contact with the electronics installed there. The paper towels must not come into contact with the mirror.  
-  * Bei Reinigung des Sekundärspiegels: +  * When cleaning the secondary mirror: 
-    - Das Teleskop sollte in diesem Fall ein paar Grad über den Horizont schauen.+    - The telescope should look a few degrees above the horizon in this case.
  
 ===== Problems and their solution ===== ===== Problems and their solution =====
  • en/ost/telescope/setup.1622305740.txt.gz
  • Last modified: 2021/05/29 16:29
  • by rhainich