Guiding Simulator

Welcome to the Guiding Simulator. This tool will help you learn how to manually guide your astrophotos and practice the drift method of polar alignment. The simulator is a FLASH application, so you will need to have Flash installed in your system. This simulator is part of the Classic Astrophotography tutorial. You may wish to visit this site to learn other techniques of classic astrophotography techniques using conventional film, inexpensive cameras and commercial telescopes.

Click the TITLE SCREEN to begin the Simulator.

The Guiding Simulator contains four objects.


Hand Controller
The Hand Controller allows you slew the scope in RA and DEC, make guiding corrections, set the slew speeds, and turn the Periodic Error Correction (PEC) on and off. The display tells you what speed the slew buttons at set at.
Illuminated Reticle
The Illuminated Reticle Eyepiece has dual crosshairs in red light so you can see them against the black backdrop of space
Power Box
The Power Box turns on power to your mount and hand controller. There is a small RESET button here to reset the simulator in case you get all messed up. The tiny gear in the corner lets you know the RA tracking system is working.

Telescope box
The Telescope Box has a Polar Viewer in the polar axis so you can see the Celestial Pole if wanted (cheat!). It also has buttons to rotate the eyepiece, select a refractor or Newtonian telescope, adjust the mount in azimuth and altitude, and slew the scope to the Celestial / Meridian intersection or the Eastern Horizon.


CHOOSE A LESSON
MANUAL DRIFT METHOD
For highly accurate polar alignment.
MANUAL GUIDING TECHNIQUES
For long exposure astrophotography


MANUAL DRIFT METHOD

This tutorial assumes you have read the DRIFT ALIGNING tutorial first.
If you have not done so, please go back to the tutorial and read the lesson first.

Once the simulator loads, click on the startup screen to begin. Immediately you may see stars moving across the eyepiece field of view. Do not worry, they will loop around so you can track one when you are ready.

The first thing you need to do is turn the POWER on. Click on the button in the lower LEFT corner labeled "Power". This will start the mount tracking in Right Ascension (RA).

This simulated equatorial mount has a random polar alignment - The mount's polar axis is pointing towards the celestial pole but is not very accurate. You will get a lot of declination drift, enough to ruin most astro photos. This is what you will now correct!

Periodic Error Correction (PEC) is NOT turned on so you may see some small RA drift. If your own equipment does not have PEC, you should leave the PEC off on this simulator too. To rturn on PEC, click the tiny word "PEC" on the hand controller.

This simulator starts off with the telescope ointing at the intersection of the Celestial equator and Meridian, which is the best place to start the drift alignment procedure. Later you will be able to swing the scope over to the Eastern sky to correct for Altitude misalignment.

Press the #5 or #6 button on the hand controller to switch the slew speed to a fairly fast speed. You can play with the hand controller's arrows to get a feel for how the scope responds when slewing up/down and left/right.

Using the LEFT, RIGHT, UP and DOWN slew buttons move the scope to locate a suitable guide star. You need to quickly line up the illuminated guiding reticle lines with the EAST/WEST axis of your scope. To rotate the eyepiece correctly, use the LEFT or RIGHT arrows on the telescope control box. Quickly move the star to the left and right using the left and right slew buttons and then ROTATE the eyepiece until guiderstar moves along one of the lines of the eyepiece. The star may be drifting up or down (north/south) but this can be ignored for now.

Using a slower SLEW speed, place the guidestar along one of the reticle lines in the center box. If you select slew speed 1, this is called GUIDE SPEED and it simply doubles the normal RA tracking rate when you want to move forward, and simply STOPS it for reverse. I suggest you use a fster speed to get close to center, then switch to a slower speed when ready to begin making corrections.

- You will notice that the guidestar is probably moving off your chosen line. Any back and forth movement along the RA loine is due to periodic error of your RA drive. This will show up as movement in the East or West (Right Ascension-RA) direction only. You may also note a lot of drift in the North or South (Declination-DEC) due to polar misalignment.

- You may correct any RA movement (Left/Right) to keep the star centered, but do NOT correct any Declination drift. You must however NOTE which way any DEC drift is.. either Up or Down.

AZIMUTH IS MAD!

Now it's time to CORRECT any Polar misalignment in AZIMUTH (East/West). This is because your MOUNT's POLAR AXIS may be pointing too far EAST or too far WEST of the true celestial pole. On your own mount you must know how to adjust the Azimuth of your mount, and on most mounts it's a large screw that slowly rotates the mount to the East or West. On the SIMULATOR, you simply press the EAST or WEST buttons on the TELESCOPE control box next to the label AZIMUTH. These move the mount in small amounts to the East or West - when looking north. That is, the north end of the scope will move slightly to the left or right, with WEST being to the LEFT and EAST being to the right. This may look backwards in your eyepiece, since the scope is pointing South.

While watching declination (DEC) drift only, if the guidestar moves UP, rotate the mount's AZIMUTH so that the guidestar moves to the RIGHT in your eyepiece. If the guidestar moves DOWN, rotate the azimuth so that the star moves LEFT. The reason you make these moves is described in the TUTORIAL. DO NOT use the slew buttons on the hand controller to do this. Use the AZIMUTH buttons on the telescope control box. On your own mount, you must physically rotate the mount as described above.

- The faster the guidestar drifts up or down, the more azimuth corrections you must make. If the guidestar drifts quickly, your mount is much further away from the celestial pole, and will need to be moved a lot further.. so far in fact that the guidestar will move right out of the field of view! No worry.. you can always grab another star to finish the alignment process.

- After you make the mount correction, quickly re-center the guidestar with the HAND SLEW CONTROLS. Again, you can use any star in the area if you can not find your original guidestar.

- Repeat these steps by watching the guidestar's movement in DEC and adjusting the mount in AZIMUTH until you no longer see any drift for several minutes. For very long astrophotography, you should not see any drift for 5 minutes. Once the DEC drift has stopped, you can go on to the next section to correc the Altitude.

ALTITUDE IS EASY!

Now it's time to correct any North or South) misalignment. This is ALTITUDE misalignment. Your mount may be too far ABOVE or BELOW the celestial pole, too far North or too far South.

On your own scope you must now rotate the mount's RA axis and move to the EASTERN or WESTERN horizon. DO NOT move the mount azimuth or altitude position... just the scope in RA. On the SIMULATOR, press the EASTERN HORIZON button and press "YES" to slew to the correct position.

Again, be sure the eyepiece is correctly oriented so that any East or West movement in RA will cause a star to move along the reticle lines. When done, choose a bright guidestar and center it again just as you did before.

Watch for any DEC drift again. Remember, you can adjust the scope in RA (East or West) but do not adjust for any declination drift.. just simply watch for it.

If the guidestar drifts UP, adjust the mount's altitude to LOWER the star. If the guidestar drifts DOWN, adjust the mount to RAISE the guidestar. You are just reversing the direction the guidestar is moving. To RAISE or LOWER the simulator's mount, press the North or South buttons on the Telescope control box (not the hand controller). The North button will RAISE the mount. The South button will LOWER it.

- Keep raising or lowering the mount until you no longer see any DECLINATION drift. Recenter the guidestar after each movement just like before.

Repeat the whole process by going back to the celestial equator and meridian and checking the AZIMUTH again. This method will allow you to get VERY HIGH precision in Polar Alignment with your mount, suitable for very long astrophotography exposures. If you have to make a large change in Azimuth, go back and re-check the Altitude again too.

After you feel you have achieved accurate polar alignment, press the small round button in the UPPER LEFT corner of the RIGHT SIDE control box. This will turn on the POLAR VIEW and show you the location of the Celestial Pole as a blue circle and cross-hair. If you have done your job well.. the pole will be centered in the red cross hairs of the mount's Polar Axis.

So, in review:

To correct AZIMUTH.. watch a star near the celestial equator and meridian. If it moves UP, rotate the MOUNT so the star moves to the RIGHT in the eyepiece. If the star drifts DOWN, rotate the MOUNT so the star moves to the LEFT.

To correct for ALTITUDE, watch a about 15 to 20 degrees above the Eastern Horizon. If it drifts UP, move the mount so the star goes DOWN. If the star drifts DOWN, move it up!


MANUAL GUIDING

This tutorial assumes you have read the MANUAL GUIDING tutorial first.
If you have not done so, please go back to the tutorial and read the lesson first.

Once the simulator loads, click on the startup screen to begin. Immediately you may see stars moving across the eyepiece field of view. Do not worry, they will loop around so you can track one when you are ready.

The first thing you need to do is turn the POWER on. Click on the button in the lower LEFT corner labeled "Power". This will start the mount tracking in Right Ascension (RA).

This simulated mount has a random polar alignment - The scope is pointing towards the celestial pole but is not very accurate. You will get a lot of declination drift, enough to ruin most astro photos.

You have two options. You can MANUALLY DRIFT ALIGN the mount by following the instructions above (recommended), or you can quickly gain polar alignment by following these quick steps.

1. Press the tiny round button in the upper left corner of the Telescope Pointing Box. This will show you the location of the celestial pole (round blue cross-hairs) in relation to the mount's polar axis (red crosshairs). Ignore the Illuminated reticle eyepiece for now.

2. Using the N, S, E, W buttons on this box, move the mount so that the crosshair is lined up with the celestial pole. Now you have accurate polar alignment.

Periodic Error Correction (PEC) is NOT turned on so you may see some small RA drift. This will give you some practice guiding. If you reset the simulator, it will generate a new random alignment and you may find the drift different. For practice guiding I recommend you leave the PEC off, to allow enough RA tracking error to give you some guiding practice.

Four buttons will move the telescope in both right ascension and declination (DEC). The keypad has 4 arrows or diamond keys just above the number pad. The left and right arrow keys move the scope in Right Ascension (RA) east and west. The up and down arrows move the scope in Declination (DEC) north and south.

The speed that the telescopes slews in these four directions can range from 1 to 9. 1 is the slowest, and is called the GUIDING SPEED. This is the speed you will use when you are ready to begin guiding. The other numbers from 2 to 9 change the slew speed in increasing amounts. Speed five or six will be good for quickly moving the mount to make adjustments.

The Illuminated Eyepiece orientation is probably not aligned with the East/West RA axis, but you can fix that by adjusting the rotation of the eyepiece with the LEFT and RIGHT arrow keys located in the middle of the Telescope Pointing Box. Move the guidestar from the far left side to the far right side and make sure it follows a reticle line. Rotate the eyepiece as necessary until it follows a line on the reticle.

Once you have your reticle oriented to East/West, move the guidestar to the center. The most accurate way to monitor drift while guiding is the place the guidestar along the intersection of two lines, instead of in the center of the guiding box. This will give you a much higher accuracy while guiding.

You will probably start to see some periodic error as the guidestar moves to the left or right. This is what you have to correct to prevent a blurred image in your astro photos.

You should now press #1 to set the slew speed to the GUIDING setting. This will make the RIGHT arrow move the mount at double the normal RA speed while the LEFT arrow will simply STOP the RA motor to allow the Earth's natural rotation to move the star backwards in your eyepiece.

This is the point where you start your exposure. You should first record the frame number, date, time and seeing conditions . Double check that the camera is secure, centered on your target, focused and then re-center the guidestar and begin the exposure by pressing and locking the cable release. Now you must immediately start watching your guidestar and making corrections.

As you notice the guidestar moving out of your chosen starting position, you will use the arrows to keep the star centered on your original starting location. This is GUIDING! If you note any DEC (up/down) movement, you should correct it.. but understand that these tiny amounts of field ROTATION may show up on your final photograph. If you see a lot of this North or South movement, consider stopping the exposure and re-aligning your Polar axis.

The better your polar alignment is and the better trained your PEC, the less time will be spent continuously observing your guidestar. Also, the shorter your focal length, the less accurate you need to be. To determine just how accurate you must guide, go to the tutorial and read the section on Guiding Tolerances in the Guiding section.