Polar Align Wizard

PEMPro uses the polar drift alignment method to help you achieve good polar alignment. This method, although very accurate, has a reputation of being difficult. PEMPro takes the tedium out of this method. Although you can use this wizard if you do not have a GOTO mount, if you have a GOTO mount PEMPro can make Polar Alignment less painful.

If you do not have a GOTO mount, click here for the procedure.


Polar Alignment Wizard Procedure - "Goto" mounts

Note: The procedure below sometimes indicates to point the telescope to the South. This applies only to users in the Northern Hemisphere. If you are in the Southern Hemisphere please substitute each occurrence of "South" with "North".

1. Select the Setup tab of the PEC page (the initial page displayed when PEMPro starts).

2. Setup Camera:

a) Select the camera control program you wish to use in the drop down list box to the right of the Connect Camera button.

b) It is best if you already have the camera control program active and the camera connected to it.

c) Focus the telescope on a star.

d) Make sure that the Min Star Brightness and Max Star Brightness are set to reasonable values (e.g., 1000/30000 for CCD, or 100/255 for Video). You can later tweak these settings as needed while the Wizard is measuring the Altitude or Azimuth alignment error.

e) Connect to the camera control program by pressing "Connect Camera". When connected the button will change to green and will say "Disconnect Camera".

3. Setup Telescope:

a) Select your telescope in the drop down list box to the right of the Connect Camera button. If this is a new telescope use the Mount Wizard in PEMPro's Wizards menu to define your mount/scope.

b) Connect to the telescope by pressing "Connect Scope ". When connected the button will change to green and will say "Disconnect Scope ".

4. Select the Polar Align Wizard tab and press Next to start the wizard:

 

5. Optionally check off the items in the Pre-Start checklist:

a) The telescope should be roughly aligned, although it can be off by roughly 10 degrees or more and this procedure should still work.

b) If possible level the tripod or pier as much as possible. Doing so will reduce the number of Altitude and Azimuth iterations to achieve best polar alignment.

c) Synch to a star. If you cannot find a known bright star position the scope near where you think the bright star should be and use PEMPro's Star Finder feature. It will perform a spiral search around your current location. Once you find the star in one of the frames, you can slew to it by double clicking that frame.

Note that if polar alignment is not accurate (as is probably the case) slews after synching will not be very accurate. However, the slews do not need to be accurate. PEMPro just needs to be able to position the scope to roughly to the correct part of the sky (e.g. South near 0 declination.) After accurate polar alignment is achieved you will want to synch again on a known star, and once again Star Finder might be able to help you find a bright star that is not in your field of view but nearby.

Click Next to go to the next page.

6. On the Site Information page enter your latitude, longitude, elevation, and approximate temperature. These values are used to later calculate refraction as well as local sidereal time and the scope's approximate altitude/azimuth.

Note that the longitude/latitude will effect the telescope position in the graph on the bottom of the page. The small red square is the location in the sky that the telescope is currently pointing.

After entering the above values you can click the Slew button to slew the scope to an ideal sky position. It is recommended that you you chose to move West of the meridian so that you do not have to deal with possible side effects of crossing the meridian (weight shifting in the scope/mount).

However, if the West is obscured you can choose to slew to the East. You may then want to increase the distance from the meridian. The scope tracks about one degree every 4 minutes so 5 degrees is usually more than enough to do the initial measurement and adjustments.

You should choose a declination as close as possiblle to 0 declination. The closer to 0 degrees that you can get the more accurate the next step will be able to determine camera angle and pixel scale.

Click Next to go to the next step.

7. The Camera Information page defines the pixel scale of the image and the camera angle. You can enter the values manually, import them from the Calibration Wizard, or use the Measure Now button.

It is highly recommended that you click Measure Now, which will take an exposure with tracking stopped.

CUSTOM Start/Stop Commands: Allows you to send low-level commands to the mount to start/stop tracking and to issue moves East, West, South, and North. You may want to try this option if you do not get star trails in the image when you do a Measure Now or if you get an ASCOM command error. To use this feature you will need to get the low-level protocol definitions for your mount. See this section for more details.

Re-center after Measure: When checked PEMPro will re-center the scope at the starting RA/Dec coordinates when you clicked the Measure Now button. You may want to uncheck this option if you have a Meade LX200 series scope and you get an occasional wild slews (caused by a bug in the Meade firmware).

After the exposure completes a new window will open with hopefully a number of star trails. Just click the star and end of one trail. Then close the window. If you cannot see a star trail you might want to click the Adjust Image button. This will bring up the Histogram stretch control, which will allow you to adjust the brightness/contrast of the image.

If the trails are too long or too short, you can adjust the time that tracking is stopped in the Measure (secs) field. If you do that just press Measure Now again.

Here is an example of a trail before being marked:

And again, after each end of the trail is clicked:

To proceed close the form and click Next to go to the next step unless you want to adjust the advanced settings. When closing the form the scope will slew back to its starting RA/Dec if you have the option to do so checked.

Advanced Camera Settings:

Exposure (secs): This field shows if Fixed Exposure Duration is checked (recommended). It is the exposure duration of images taken. A good starting value is 1 second.

Max Exposure (secs): This field shows if Fixed Exposure Duration is unchecked. It is the maximum exposure that the star searching mechanism will attempt. A good starting value is 5 seconds.

Inter-Exposure Delay (secs): The amount of time in seconds between exposures. If the delay is less then the exposure duration plus overhead processing then the next exposure starts immediately. The default value is 1 second but it is recommended to set this value at least 1 second greater than the exposure duration.

Min Star Brightness: PEMPro will adjust the exposure time to be in the range of this value and Max Star Brightness.

Max Star Brightness: PEMPro will adjust the exposure time to be in the range of this value and Min Star Brightness.

Note: Two separate sets of Min/Max star brightness are stored for your convenience. One set is for a CCD camera and another set for when the Video Interface is selected on the PEC/Setup page. When the Video Interface is selected the range is initially set to 100-255. When Maxim/AstroArt/CCDSoft is selected the range is 1000-30000.

Binning when finding star: To reduce download times, PEMPro can bin full-frame images. You should only select a binning value that will work with your camera. If you select an invalid value then the star finding mechanism will stop with an error.

Tracking Rect (pixels): This setting determines the size of the tracking rectangle when using a CCD. If the drift is high you can increase the size of the tracking rectangle to make sure PEMPro does not lose tracking.

Dark Subtract Images: If checked PEMPro will dark subtract images in the Determine North, South, East, and West step.

Fixed Exposure Duration: If Checked PEMPro will use Max Exposure for all exposures. If not checked PEMPro will adjust exposure to make sure the tracking star is in the range of Min/Max star brightness.  NOTE: it is HIGHLY recommended that you check this option! This will allow the wizard to find a star faster.

Color to Mono (MaximDL 4.58+ Only): Use this feature to setup the color conversion for your one-shot color camera. If enabled then all images in the Polar Alignment wizard will be internally converted by MaximDL from raw data to color and then ultimately to monochrome. The converted monochrome image will allow PEMPro to more accurately calculate a star's center. When you check this option another group box with additional controls becomes visible.

NOTE: Do NOT select this option is you have a monochrome camera.

Camera Type:

LISAA - Apogee one-shot color cameras, the Starlight Xpress SXV-H9, and other cameras using the SONY ICX285AQ, ICX084AK, and similar sensors

MX5C - Starlight XPress MX5C

MX7C Fast - Starlight XPress MX7C operated in fast mode

MX7C Interlaced - Starlight XPress MX7C operated in interlace" mode

Meade DSI - Meade Deep Sky Imager

RGGB High Quality - Same as LISAA, but uses a high-quality algorithm

Orion StarShoot Deep Space Imager 1

Orion StarShoot Deep Space imager 2

Red, Green, and Blue: Scale factors (in percent) to apply to each color in the debayer process. Leave at the defaults (100/100/100) if you are not sure to what you should set these values.

X Offset: X-axis offset flag (may be required by some cameras).

Y Offset: Y-axis offset flag (may be required by some cameras).

Select File: Click this button to select a raw single frame image to test the settings.

Test: When clicked two images will be created in MaximDL to test the selected settings. One image will be the converted color image from the settings above and the second is the monochrome version of that image.

PEMPro does not create color images in the polar alignment wizard but it does use the color settings to internally convert a raw image to an accurate monochrome image. The purpose of the color image that displays after clicking the test button is for you to make sure that the color translation settings are correct.  So, carefully check that the colors in the color image look correct. If they do not then adjust the above settings and click Test again until they do.

Once you are satisfied with the accuracy of the color you can proceed to the next step.

8. In this step the compass directions are determined. PEMPro starts off by taking a snapshot image at the current position. Then it moves the scope North and takes another image. Lastly, PEMPro moves the scope East and takes one final image.

Once done the first of the three images is displayed. Locate a notable star and click it. The next image of the three will display automatically. Click the same star in that image. That will cause the last image to display. Click the same star there. PEMPro will then show the compass directions directly on the window.

If you are having trouble finding the stars you can expand PEMPro full screen to get a better look. If you still cannot find any stars then reposition the scope manually or use PEMPro's Star Finder feature.

If the stars move too far or not enough try adjusting Dec Move Distance (arc min).

CUSTOM Move Commands: Allows you to send low-level commands to issue moves East, West, South, and North. You may want to try this option if you do not recognize the star pattern in all the three images produced in this step or if you get an ASCOM command error. To use this feature you will need to get the low-level protocol definitions for your mount. See this section for more details.

Re-center after Measure: When checked PEMPro will re-center the scope at the starting RA/Dec coordinates when you clicked the Measure Now button. You may want to uncheck this option if you have a Meade LX200 series scope and you get an occasional wild slews (caused by a bug in the Meade firmware).

After the exposure completes a new window will open with hopefully a number of star trails. Just click the star and end of one trail. Then close the window. If you cannot see a star trail you might want to click the Adjust Image button. This will bring up the Histogram stretch control, which will allow you to adjust the brightness/contrast of the image.

Also, this step does not require much precision. There are no precise calculations made from the clicks you make. The only intent to roughly determine compass directions.

NOTE: You can click the FULL SCREEN View button and the images will display on the entire screen.

You can click the Adjust Image button to bring up the Histogram Stretch Tool.

After determining compass directions:

Click Next to continue.

9. Click the Slew button to slew the scope to near the Meridian. Click Next to continue.

10. In this step PEMPro will Measure Azimuth Error.

a) Click Start Measuring and wait for a couple minutes for the trend line to stabilize. If PEMPro is having trouble locking onto the star move the scope to a new field of view using the buttons in the Slew Scope field at the bottom left of PEMPro. You do not need to stop measuring while the repositioning the scope. PEMPro will automatically try to re-acquire a star.

b) Once the trend is established you can manually adjust the mount based on PEMPro's on the azimuth alignment error that displays at the bottom of the graph (see example picture below).

Note: If after making the recommended adjustment the drift increases you should adjust the mount the opposite of what the direction says.

c) Once you make an adjustment go back to step 10a above. Continue making adjustments until the measured drift is less than about 5 arc-minutes.

When the drift value is less than 5 arc-minutes over at least the whole 5-minute period, you can then proceed to the next step which will allow you to make a precise final adjustment to the Azimuth axis. Proceed to that step by clicking Next.

 

11. Click Next to reach Step 6 - see picture below. Unless you had difficulty getting less than 5 Arc-mins error in the last step this step can be skipped.

Click Reference Image to take a snapshot of the current position in the sky.

NOTE: Clicking the Overlay Color button brings up a dialog that allows you to configure the color and transparency of the text, arrows and circle used at times in this step.

 

After the reference image comes up click on one of the bright stars, PEMPro will mark the direction with an arrow how far you will need to move the star to polar align the mount's azimuth axis. If the arrow goes off the screen you should adjust the star in the direction of the line and backup to the previous step to do another measurement.

Next, click Take Image. If Continuous is checked PEMPro will continuously take images. Adjust the mount's Azimuth carefully until you have the star centered in the circle as well as possible. You can compare the current image to the reference image by clicking Reference Image. Make sure to click Current Image to go back to viewing the current position of the scope.

If you need a larger view, you can click Full Screen, which will use all of the screen except for the Windows Task Bar.

 

12. Click Next again - see picture below.

Press Slew to move the scope to the East or West about 30-60 degrees from the meridian. The more away from the meridian the better but because of refraction try not to have the scope point below 20 degrees from the horizon.

Click Next.

13. Measure Altitude Error.

a) Click Start Measuring and wait for a couple minutes for the trend line to stabilize. If PEMPro is having trouble locking onto the star move the scope to a new field of view using the buttons in the Slew Scope field at the bottom left of PEMPro. You do not need to stop measuring while the repositioning the scope. PEMPro will automatically try to re-acquire a star.

b) Once the trend is established you can manually adjust the mount's altitude alignment based on the value displayed at the bottom of the graph (see example picture below).

Note: If after making the recommended adjustment the drift increases you should adjust the mount the opposite of what the direction says. If this happens please report this to the PEMPro Beta forum stating your equipment (Telescope, camera, and camera control program), whether you are in the Northern or Southern hemisphere, and which side of the meridian the scope was pointing.

c) Once you make an adjustment go back to step 13a above. Continue making adjustments until the measured drift is minimal.

When you are satisfied with the drift proceed by clicking Next.

14. Click Next - to reach Step 9. Unless you had difficulty getting less than 5 Arc-mins error in the last step this step can be skipped.

Click Reference Image to take a snapshot of the current position in the sky.

NOTE: Clicking the Overlay Color button brings up a dialog that allows you to configure the color and transparency of the text, arrows and circle used at times in this step.

 

 

 

15. Click Next one more time to reach the Finished page. Here you can exit or choose to redo the Azimuth or Altitude measurements.


 

Polar Alignment Wizard Procedure - Non "Goto" mounts

Note: The procedure below sometimes indicates to point the telescope to the South. This applies only to users in the Northern Hemisphere. If you are in the Southern Hemisphere please substitute each occurrence of "South" with "North".

1. Select the Setup tab of the PEC page (the initial page displayed when PEMPro starts).

2) Do the following:

a) Select the camera control program you wish to use in the drop down list box to the right of the Connect Camera button.

b) It is best if you already have the camera control program active and the camera connected to it.

c) Focus the telescope on a star.

d) Make sure that the Min Star Brightness and Max Star Brightness are set to reasonable values (e.g., 1000/30000 for CCD, or 100/255 for Video).

3. In PEMPro connect to the camera control program by pressing "Connect Camera". When connected the button will change to green and will say "Disconnect Camera":

4. Select the Polar Align Wizard tab and press Next to start the wizard:

5. Optionally check off the items in the Pre-Start checklist:

a) The telescope should be roughly aligned, although it can be off by roughly 10 degrees or more and this procedure should still work.

b) If possible level the tripod or pier as much as possible. Doing so will reduce the number of Altitude and Azimuth iterations to achieve best polar alignment.

c) Point the scope to South approximately at the celestial equator.

6. Click Next to get to the Site Information page. You can skip this page. Click Next again to go to the Camera Information page.

a) Enter the Pixel Scale of the camera (arc-seconds/pixel).

b) Enter the Camera Angle of the RA axis with respect to the horizontal axis of the camera. You can easily figure this out by stopping the tracking on the scope and taking a 5 second exposure. If the star trails are horizontal, enter 0 in the Camera Angle field. If the trails are vertical, enter 90 in the Camera Angle field.

If the stars track on a diagonal rotate the camera until the stars track roughly horizontally or vertically and enter the respective angle.

7. Click Next several times until you reach step 5, Measure Azimuth Error. Make sure your telescope is still pointing near the South. Reposition it if necessary.

a) Click Start Measuring and wait for a couple minutes for the trend line to stabilize. If PEMPro is having trouble locking onto the star move the scope to a new field of view manually. You do not need to stop measuring while you move the mount.

b) Once the trend is established you can manually adjust the mount based on PEMPro's on the azimuth alignment error that displays at the bottom of the graph (see example picture below). Note that since the mount is not a GOTO, the test to determine North and South could not be done so the direction of the adjustment is not known. So, initially assume the direction (i.e., "clockwise" or "counter-clockwise") is correct and make that adjustment to the mount. If after making this adjustment the drift increases you will have to adjust the mount the opposite of what the direction says.

c) Once you make an adjustment go back to step 7a above. Continue making adjustments until the measured drift is minimal.

8. Click Next until you reach step 7 - see picture below.

a) Point the scope to the East or West about 30-60 degrees from the meridian. The more away from the meridian the better but because of refraction try not to point below 20 degrees from the horizon.

b) If you chose to point the scope to the West, make sure Measure West of Meridian is checked, otherwise select Measure East of Meridian.

c) Guess the number of degrees from the meridian. It doesn't have to be precise.

d) Click Next.

9. Measure Altitude Error.

a) Click Start Measuring and wait for a couple minutes for the trend line to stabilize. If PEMPro is having trouble locking onto the star move the scope to a new field of view manually. You do not need to stop measuring while you move the mount.

b) Once the trend is established you can manually adjust the mount's altitude alignment based on the value displayed at the bottom of the graph (see example picture below). Note that since the mount is not a GOTO, the test to determine North and South could not be done so the direction of the altitude adjustment is not known. So, initially assume the direction (i.e., "raise" or "lower") is correct and make that adjustment to the mount. If after making this adjustment the drift increases you will have to adjust the mount the opposite of what the direction says.

c) Once you make an adjustment go back to step 9a above. Continue making adjustments until the measured drift is minimal.

d) Click Next to continue.

10. Click Next one more time to reach the Finished page. Here you can exit or choose to redo the Azimuth or Altitude measurements.