When the menu is displayed on the Grinnell TV monitor, move the cursor to the function required and press the ENTER button on the joystick controller to process the selection; nota bene: the TRACK switch, No. 3 in the bottom row, should always be up, i.e. ON). When the function selected requires further positional information, up to 4 cursors can be enabled on the screen depending on the function. When they appear they may well be overlaid and so only appear as one. On the joystick controller the cursor switches determine which cursor(s) the joystick will control at any one time (for these switches, UP is equivalent to ON). Once the cursors have been positioned as desired, ensure that at least switch 1 is on, and then press ENTER again to initiate the processing. A quick guide to the menu is given in the following sections. Grinnell Menu Functions: Page 1
Requires TWO cursors to be positioned in either the X or Y plane and draws the profile of the data contained in displayed image between the two cursor points on Overlay Plane 2. At the start the cursors are overlaid. This function is used for seeing estimates as it gives the FWHM of a star image in arcsecs. The PROFILE is automatically erased when DIRECT is pressed.
Define centre of Cassegrain or Prime field as viewed on the finder TV.
Plots on the Grinnell view of the finder field the `catchment area' for possible guide stars at Cass in the form of a circle which represents the autoguider probe range and an enclosed square in which the probe can vignette the field. The area between the two thus represents the available area in which guide stars may be acquired. The slit is also marked. At Prime the catchment area is a rectangle which will rotate with the rotation of the prime focus assembly. Gives a cursor for guide star selection.
Requires two cursors, one to select the star and one to place on the slit or desired new position.
Calculates the distance (x and y and total) in arcsecs between two cursor positions, on Overlay Plane 2.
Initialises the TV system. No cursors. Like pressing the RESET button, it resets display parameters.
Clears the areas of the overlay planes used for displaying information (i.e. the MENU)
Erases overlay plane number 2.
Erases the image plane.
Erases Overlay Plane 2 used to display profiles.
Displays the second page of the menu.
Displays the Grinnell test pattern.
Erases a test pattern.
Displays the current integration parameters on Overlay Plane 2 (i.e. the current status of the rotary switches).
Requires all four cursors to be positioned independently and then joins them up on Overlay Plane 1. Intended to be used for marking slits, but can be used to draw any quadrilateral.
Requires two cursors to be positioned to define the diameter of a circle which is then drawn on Overlay Plane 1. Useful for defining the position of photometer apertures.
Two cursors are enabled which are used to define the sides of a rhombus on Overlay Plane 1. The line joining the two points must have a positive gradient in the X-Y plane of the screen. If the two cursors have the same Y position, they will define the top side of a square. If they have the same X position, they define the left hand side of a square.
Zoom factors are determined by the state of the function switches FUN A and FUN B on the cursor controller. Setting one or both of these switches followed by ENTER causes a new zoom factor to become operational. The factors are: A for a factor 4, B for a factor 2, and A+B for a zoom factor 8. The zoomed image can be panned via the joystick. To exit from ZOOM, turn both function switches off (down) and press ENTER. The facility requires the TRACK switch to be up (ON).
Creates a `.BDF' file of the currently displayed Grinnell image on the EGLE disk.
Gives two cursors to select rotator orientation. Use ENTER to select and exit.