Common Classes
AzCam's common classes are often combined with the classes which define tools to provide common functionality cross multiple tools. For example, the controller, instrument, and telescope tools may all use the header class to define header information.
The common classes used thorughout azcam is listed here.
Tool Class
AzCam's tools are used to define and control a system.
The base Tools class described below is inherited by all other tools.
Documentation for the Tool class
Image Class
The Image Class defines Azcam's image object. Within azcam it is also used to define
the exposure.image object which receives image data from a camera controller. It is imported automatically into the azcam namespace from the azcam.image module.
Usage Example:
im1 = azcam.Image('test.fits')
Documentation for the Image class
Database Class
This class defines the azcam.db object.
Documentation for the Database
Header Class
Azcam uses object-specific keyword indexed dictionaries to maintain textual informational about some tools. These are typically called headers as they are used to provide information in image headers. The keywords and their corresponding values, data type, and comment field are stored in each of the controller, instrument, and telescope header dictionary. These dictionaries are manipulated by commands both from clients and internally in azcam. Most of the values are written to the image file header (such as a FITS header) when an exposure begins.
The header information is accessed through methods such as
controller.header.get_keywords() to get a list of all keywords and
instrument.get_keyword('FILTER1') to get the currentvalue for the keyword.
The read_header() method of each tools will actively read hardware to obtain
information (such as controller.read_header() or instrument.read_header()).
In general there is a method of the same name in both the header class and the actual tool's class, such as controller.header.get_keyword() and controller.get_keyword(). The .header version reads the current data as stored in the header dictionary while the tool's version usually reads actual hardware values and then stores that data in the header dictionary.
The telescope and instrument dictionaries are considered temporary and re-read every time an exposure starts. This is so that rapidly changing data values do not become stale. Most dictionary information is written to the image file header if the selected image format supports headers. When an object such as an instrument or telescope is disabled, the corresponding object database information is deleted and no longer updated.
Documentation for the Header class
Image Related Classes
An azcam image is described by the Image, Focalplane, and WCS classes. The Focalplane class defines all aspects of the focal plane and sensor configuration used to create an image. The WCS class defines the World Coorindate System paramaters for the image.