Why meridian flip

On most systems you can image several mins past the meridian. Before an automatic flip and reacquiring of guide stars takes place. Your session will then continue.

You will see a message like this in the Status Window:. Moon Alt: 7. Since the mount was still east at this point, the label reflects that. You will also notice that in your image names, you will see the following change as well:.

If it is more that minutes increase the Flip Moment. Meridian flip is also possible when your mount doesn't need guiding. Make sure that you are using dark frames in PHD2 to avoid selection of hot pixels during guiding star auto-selection. It is advisable to confirm the limits of your setup. Once the scope is aligned move it to position East from celestial meridian near Zenith via the handset, control panel of your driver or Gear Tab.

Start making fine movements towards meridian and keep an eye on Meridian Flip Clock. See if the default limit of 5 minutes before meridian passing is safe for your kit. If not increase Flip Moment to a value that fits better. Meridian Flip Clock will show values close to minutes this is the time of next meridian passing - the lowest object position. If the position that shows is not safe see the value that fits better and subtract it from , set the result as Delay Flip Move. The points 1 and 2 have to be checked on every session.

The other point are needed in the first time or after scope change. You can skip point 7 only if you are trying the default settings and you are keeping an eye on the process!!!

If the execution of this command fails enable the option Flip via GoTo. This area show the Session Craft status. During the flip process it shows the current step or the remaining time of pause defined by Delay Flip Move. When Session Craft is in "Monitoring" status you can use the Flip button to start the process manually.

If automatic meridian flip is in progress this button becomes Stop that will immediately stop all movements, tracking, guiding, solving and imaging. If the last automatic meridian flip process failed or Stop button is clicked this button becomes Reset that can clear all errors and flip process can be restarted.

Note that you will have to start the scope tracking manually by Tracking in Gear Tab. Make Automatic Flip. On enabling SessionCraft will check the settings and will give an error message in case of problem. Once you enable this option APT will check all the required parameters for unsupported combinations. To change the settings below, you must uncheck this option.

When AMF is enabled a small blinking indicator will be displayed in the upper left corner of the Status panel to show that SessionCraft is monitoring when flip has to be made. Flip Moment.

Defines how many minutes before the celestial meridian passing to start the preparations for flipping the mount. On process start it will determine the current position via taking a short image and plate solving it in PointCraft. It will stop the tracking and guiding once the position is determined. If an imaging plan is in progress and there is no time to take the next exposure before the flip moment occurring, the imaging will be paused earlier and the additional time will not be counted as delay - it is an extra pause to prevent collisions.

See the notes. If this value is negative this means that process will start after meridian passing. We suggest to investigate very carefully the behavior of your mount before using negative values! As the left-pointing yellow arrow near the red camera at the bottom of the photo indicates, if the telescope were pointing higher in the sky and continued tracking westward, the camera equipment hanging off the rear might collide with the concrete pier.

To avoid this, the mount must perform a "meridian flip" to swap the position of the telescope and the counterweight so the telescope can continue to track westward without hitting anything. You or automation software must initiate this explicitly; the mount does not "know" when to flip.

Here the scope has rotated through north, and continues rotating and "falling backward" on the east side of the mount as the counterweight moves upward on the west side yellow arrows. The software that initiated the meridian flip commands the mount to point at the same target which crossed the meridian while the mount was performing the flip , so at the end of the flip, the telescope again will be at declination 0, and tracking westward.

After the meridian flip, the telescope is pointing due south at the same target, but the telescope and counterweight have swapped positions, with the telescope on the east side of the mount and the counterweight on the west side. The arrows in this photo show how the mount continues to track westward RA axis rotating clockwise, curved red arrow , with the telescope in no danger of hitting anything beneath the mount.