Standard Mode

THE STANDARD ACQUISITION MODE

The PISCO interface has several Tabs. The first one, called Standard, makes available to the user the most traditional commands to perform astronomic exposures: acquisition of a single image or a series of images.

However, before using PISCO for the first time, you must configure a few parameters. For this purpose, use the Tab Settings then click the button Advanced Settings.

Indicate first, from the Printer Port section, at which port the Audine camera is connected to. Usually, the Audine camera is connected to the port LPT1.

The second parameter to be defined is the file type used to save your images. You must select the type you want to use in the Image File Type section. You can choose either the proprietary format PIC or the standard format FITS. If you decide to use the FITS format, you have the choice to use an extension .FIT or .FTS for your files (PIC image extension is always .PIC).

Finally, you must define the directory that will be used by default to save your images on disk. Go back in the Tab Settings by clicking the OK button. Then click on the button that has 3 dots in the section Save Directory. In the dialog box, select the directory you want to use. In the example below, this is the directory night2 on the C disk that has been chosen.

The other parameters in the Settings Tab are not critical and you can ignore them for the first images you are going to make with PISCO. Note that the parameter values are saved when you exit PISCO and that you get the same values at the next working session.

Go back now to the Standard Tab.

You must first indicate the exposure time (in seconds) along with the binning factor. For instance, if you want to set a 5 seconds exposure time and a 2x2 binning, here is what you will have to do:

You can define exposure times that have decimals, for instance 0.3 or 12.34 seconds. An exposure time of 0 is valid and it represents the minimum exposure time. This value is typically used to expose the offset images.

The binning factor corresponds to an aggregation of pixels within the CCD chip. The larger the binning factor, the most the pixels are grouped together and the smaller the image is. The CCD sensitivity increases while resolution decreases. The table below provides the image size according to the binning factor used:

**Image Size**
Binning Factor	Horizontal	Vertical
1X1	768	512
2X2	384	256
3X3	256	170
4X4	192	128

You must now provide PISCO with the name of the file that will contain the image to be exposed. An index number can be specified. In such a case, the index number will be appended at the end of the image file name. In the example below, the image will be saved as m42-1. On the disk, the file has of course and extension .PIC, .FIT or .FTS according to the choice made in the Settings Tab.

You can now run an exposure simply by clicking the button GO. PISCO displays all the operations that are performed, for instance the CCD cleaning before the exposure or the number of seconds spent since the beginning of the exposure.

It is possible to stop the exposure at any time just by clicking the Stop button. This action immediatly cancels the exposure and launch the image digitization.

During exposure time, you are free to display other images, perform some image processing actions, open other applications, ... However, while reading the CCD, the computer is totally dedicated to the data transfer. This is a very critical phase that can last from a few seconds to 15 seconds according to the binning factor that has been selected.

Just after the digitization phase (on 15 bits with the Audine camera), the image is displayed on the screen. To save the image to disk, you must click the Save button. If an index has been specified, it is automatically incremented each time an image is saved to disk. This is a good way to ensure that you will not overwrite a previous image when saving the current image.

Below the display window, you have access to two scroll bars that allow you to adjust the display thresholds. The image intensity histogram is displayed in red below the thresholds scroll bars (more exactly, the is the intensity logarithm). If you click the Auto button, PISCO computes its own display thresholds for an optimal display in the case of a deep sky image (assuming that you have correctly configured the parameters from the Display Thresholds section in the Settings Tab). Note that it is possible to reverse the high and low thresholds so that you get a negative image.

The 4 buttons on the right allow you to select the display palette.

By moving the mouse cursor over the image, you get at all time the position and the intensity of the pixel at the mouse cursor position. Note that the cursor can be moved using the keyboard direction keys (for a faster move, press the Ctrl key at the same time).

A set of buttons allows you to load an image and display it, to save the result of an image processing (note that this command pops up a dialog box), to display a tool box to control a telescope and to exit the program.

Except for the settings or to center an object, it is quite usual in astronomy that one wants more than just one image of an object. Therefore, the Standard Tab provides a specific mode to perform the acquisition of several images in an automatic manner. This frees you from tedious operations. Using this mode is very simple. All what you have to do is to check the box Series then to specify how many images you want in the series. In the example below, we are going to get 5 images of the M42 nebulae, the first one having the index 1. The images saved on disk will therefore be: m42-1, m42-2, m42-3, m42-4 and m42-5.

It is of course possible to start the indexing at a value different from 1. A value for Number equal to 0 is the same as not checking the Series box. For any value greater than 0, PISCO automatically saves images on the disk just after the digitization process. You do not have to press the Save button after each exposure. The small button labeled "1" allows you to quickly set the current index value to 1.

If you select the option Series and enter a negative number of images (-1 for instance), the acquisition process is performed indefinitely without saving the images. This can be useful for centering an object for example.

Clicking the mouse right button popups the following menu:

The functions PSF and Statistics apply to the image currently in memory (an image in memory is required to have these commands active). The PSF command allows you to figure out what is the spreading of a stellar image along with the exact position of this star (at a fraction of pixel). It also provides you with the intensity and the local sky background level. Before applying the PSF function, you must isolate the star by surrounding it with a selection rectangle (drag around the star with the mouse left button pressed).

Then activate the contextual menu by clicking the mouse right button and selecting the PSF command:

In the same manner, the command Statistics provides some statistical information about the area inside the selection rectangle.

The commands Zoom+ and Zoom- from the contextual menu allows you to enlarge or shrink the displayed image.

The command Monitor continuously displays on the screen a small window where is indicated the half-height width of the object below the mouse cursor according two directions (FWHM X and FWHM Y), the object intensity and the sky background level. This function is useful to control the telescope focusing since a focus defect spreads the stellar images.

The commands Console and Hand Controller are described further.

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