The Telescope tab allows you to monitor and control all aspects of the telescope, including manual slews, auto-center, and parking.
The status field at top shows the current telescope status, including connected and tracking states, RA and Dec in both JNow and J2000 epochs, the altitude and azimuth, and the status of any current telescope operation. Note that altitude and azimuth can only be displayed if the geographical position has been entered; click the Site button to enter this information (see File menu Settings, Site and Optics tab for more information).
Basic Telescope Control
To enter a specific position on the sky, enter the Right Ascension (RA) and Declination (Dec). These should be entered as hours/degrees, minutes, seconds. You can skip the seconds field, or skip both the seconds and minutes fields. The last number entered can be entered with a decimal point; for example, 12.8417 is the same as 12 50.5 or 12 50 30. The spin controls (up/down buttons) can also be used to dial in the position. The cursor position determines whether the spin affects the hours/degrees, minutes, or seconds. The coordinates can be entered either in JNow or J2000 coordinates.
You can click Image Center from PinPoint to load the Target Coordinates with the plate solution for the currently selected image, provided it has been solved. This is useful when you wish to take more images with the same framing as one previously acquired.
Once you have entered a position, you can click Go To to slew the telescope. If you need to stop the slew, click the Abort button.
To synchronize the telescope position, click the Sync button. You will be given the option of either synchronizing to the entered RA/Dec or the PinPoint solved location of the currently-selected image.
You can nudge the telescope in eight cardinal directions using the appropriate Nudge buttons. The distance moved is determined by the settings below the buttons. This is handy for centering objects; however, the auto-center function is much quicker.
Auto-Center
Auto-center is an extremely quick and easy way to center and compose your pictures. It allows you to click on a spot in your image, and have it automatically centered precisely with a small movement of the telescope. This completely eliminates the protracted sequence of nudges that is usually required.
The auto-center function must be calibrated before it can be used; calibration is described in the subsequent paragraphs.
To center an object, you first take an image of it. Next, click the Select New Center Point button, and then click on the part of the image that you want to center. The telescope will automatically slew the distance required to center the object. That's all you need to do! If the Observatory Control window is not open, you can conveniently access this function by pointing the cursor at the spot you wish to center, then right-click and select Point telescope here from the context menu.
As stated above, before you can use auto-center you must first calibrate it. Calibration is quick and easy, although there are several ways to do it so some explanation will be required. Once the calibration has been done, you do not need to repeat it unless you change camera or telescope, or you rotate the camera on the telescope.
There are three ways to calibrate; the simplest and most accurate is to use PinPoint Astrometry. First take an image with the camera, and then run a PinPoint solve on it. Then, in the Center on Image section, click Calibrate.
Make sure Type is set to Auto, then click the Use PinPoint button. The scale and rotation angle information from the image will be entered automatically.
The second method is to use the Go To capability of the mount. This method requires an isolated bright star. First make sure the telescope is properly synchronized. Next, take an image of a bright star. Set up the Auto Exposure settings (see below) to get a reasonably good image of the star; it is best if the image is clear but not saturated. Next click the Calibrate button and, enter a Slew Distance corresponding to approximately 1/4 of the size of the CCD array (this is not critical, but the star should move a fair distance but not leave the sensor)). Then click the Calibrate button. The camera will take one image, the telescope will move Slew Distance to the west, then a second image will be taken before returning the telescope to its original location. The movement of the star will be used to determine the centering calibration.
The third method is to set Type to Manual and enter Image Scale and Orientation manually. This would be useful if you have previously recorded this information.
Once the auto-center calibration has been set, it will be remembered indefinitely. You may need to recalibrate if you change the camera or telescope, or rotate the camera on the telescope.
Please note that if your camera produces reversed images, either due to an odd number of mirrors in the optical system or the use of a secondary readout amplifier, you need to turn on the Mirror check box. If this is not the case, turn off this setting.
Important: German Equatorial mounts have the potential to upset the calibration when flipping over the pier. MaxIm DL can compensate for this automatically. First make sure the mount type is identified as German Equatorial on the Status Tab. If not, switch to the Setup Tab, disconnect the telescope, and using the Options menu for the telescope manually set the mount type to German Equatorial.
Now turn on Use Scope Pier Flip, and perform the calibration. The mount will now move in the correct direction on both sides of the pier. You can also manually control the pier flip state, using the Pier Flip check box, which is enabled if you turn off Use Scope Pier Flip. In most cases it is recommended to use the automatic mode.
Important: The side of pier indication normally comes directly from the ASCOM telescope driver. Please note that some ASCOM drivers do not report the SideOfPier correctly. You can alter or override the SideOfPier reporting using the Setup tab Telescope Options menu. If necessary you can invert the ASCOM status, or override it with a calculated SideOfPier based on telescope azimuth. Please refer to the Setup tab documentation for more information.
Do not set Use Scope Pier Flip or Pier Flip is you are not using a German Equatorial mount.
Auto Exposure
You can set MaxIm DL to automatically take an exposure after each slew. This is useful when operating auto-center. Typically you will use a binned exposure for sensitivity and speed; in most cases deep-space objects can be detected in 5-10 seconds in a binned exposure.
Delay after Move (s) can be set to delay the exposure slightly after the slew completes. Some telescopes will report that they have completed slewing before they are 100% stabilized, especially if there is some backlash in the RA drive gears. A small extra delay can prevent you from seeing trailed stars.
Exposure Time (s) is the duration of the exposure you wish to use. Changing this value does not affect any of the Presets in Camera Control Window.
Binning combines multiple pixels in the camera to make larger, "super-pixels" that are more sensitive. This is handy for quickly locating objects. The range of valid settings depends on the camera in use. Often binning will be set to 2 or 3. For one-shot color imagers, it is strongly recommended to set the Binning to 2, as this will remove the color matrix from the image.
Apply Auto-dark calibration will cause the camera to take a dark frame if required. The dark frames are automatically stored in the Camera Control Window, so they will not have to be taken more than once a session unless you change the sensor temperature or exposure settings. Note that if the camera has no shutter, you will be prompted to manually cover the telescope. If your camera has no shutter but is adequately sensitive, it may be simpler to turn this option off.
Use Fast Download if available will select an alternate fast readout mode for the camera, if one is available. This depends on the particular camera you are using. Fast readout is typically noisier and may have more limited dynamic range or compression artifacts, but in some cases it is significantly faster than normal exposures. Also on DSLR cameras this will remove Bayer matrix artifacts (if you are not already binning).
Mount
Park will allow you to park the telescope. In most cases this moves the telescope to a "safe" position and turns off tracking. The exact behavior depends on the telescope mount and the ASCOM driver that is operating it. Please note that in some cases, MaxIm DL may become unresponsive during the park operation. This is a limitation of the ASCOM driver and is normal.
Unpark will resume normal mount operation.
You can also turn off Sidereal Tracking. This is equivalent to Park except the telescope is not stowed in a "safe" position.
Some mounts/drivers may not support Park or Sidereal Tracking.
Configuration
The Site button brings up the File menu Settings, Site and Optics tab. You can enter the geographical location of the telescope, which together with the time is used to calculate altitude and azimuth, as well as the position of the sky.
The Slew Limits button displays a dialog to define various regions into which MaxIm DL will not move the telescope. Minimum Altitude allows you to keep the telescope at least the specified angular distance above the horizon, which may be especially useful if there are mechanical obstructions or mount hard limits below a certain altitude. Maximum Altitude prevents access to the zenith, and is used to avoid an accidental collision on alt-azimuth fork mounts with insufficient clearance for the camera to pass through the fork. With some German Equatorial mounts the camera can strike a tripod leg when pointed near the zenith. Maximum Declination prevents access to the pole, and is appropriate for a fork mount on a wedge. In all cases, if you attempt to slew through an enabled limit, an error message is displayed and the telescope will not move.