Sky Charts 

This panel allows you to change the appearance of the stars and nebulae.
The first section gives you the option of changing the colors of the stars and nebulae according to their B-V color index, the background color and the coordinate grids. 
Click on the corresponding element to change its color.
The section "Color" gives you the option to choose the appearance, in color, black and white, or in red. The selection "invisible" means that only the image with the labels but without the objects are displayed. If you want to switch to night vision you have to change the color of the window as well. You can do that by first running the file "schemesnuit.reg" and then choose "NuitRouge" as the appearance model of the display parameters.
The section "Galaxy Plot" lets you choose between a fill in or a border-line selection. Select "Solid" when you work on the screen or when printing to a color printer and select "Line" when you print to laser or impact printers. This selection is preferable also if you want to draw on a picture.
The last selection lets you adjust the size of the stars according to their magnitude. Use the buttons brightness +/- and contrast +/- to alter the absolute or relative size of the stars.

The choice "Individual Selection" means that only the selected objects will be given a permanent label until you remove them with the option "Clear Selection". 
In the case of stars it is possible to assign a label only to those objects that are at least a certain value brighter than the faintest star currently displayed on the chart.

This panel lets you choose the projection you want to be used when displaying a chart according to the selected field width. Not all the projections can be used in any case. I.e. the tangent projection has a great distortion for fields larger than 45° and diverge for 90°. The sinus projection overlaps at more than 90°.
The available projections are:

• ARC : Arc length. It is the default projection up to 180°. It corresponds to the projection of a Schmidt camera.
• TAN : Tangent. It corresponds to the projection of a picture obtained with a telescope or a photographic lens. 
• SIN : Sinus. Used to display images in radio-astronomy.
• CAR : Cartesian. The default projection between 180° and 360°. It is not of great interest apart from the fact that it can display very large fields of vision. 

The selected projection described up to here can be modified according to the header of the file in FITS format containing WCS when you load such an image.

This panel lets you select the image that will be displayed together with the chart. 

The image is loaded in a preview window. You can modify the display tresholds (min and max), the color palette (composite colors LUT and intensity tables ITT) and zoom a portion of the image.
It is also possible to display the image in its original dimension and then zoom it by using the + and - keys. 

In the case of FITS format files, which contain the coordinates RA, DE or GLAT, GLON (i.e. the images provided from DSS-ESO or IRAS) the program uses the coordinates and the projection from the header of the FITS format to automatically positioned to the current chart. Please notice that it is only possible to zoom a section of the image from the preview window and not on the main screen, otherwise the automatic positioning does not work.  In the case of other image formats it is necessary to place the image on the chart manually.  You can of course use the function "Online Resources "to download an image directly from the Internet. 

It is possible to derive the initial thresholds from the information contained in the file header, from the lowest and highest values or from the average plus one or two standard deviation values. 
If the image file contains more than one plane (NAXIS3 > 1) you can select between them with the option "Plane". 
In the case that the sequence of the pixels is not standard you can mirror the image with the option "Reverse Image". 
You may also apply a convolution filter to the image. Only pixels with a value bellow treshold are filtred.

The right mouse button on a file name displays the header of the file in the format FITS or PIC. 

In the case of bitmap formats its is possible to check the option "Bitmap Palette" from the selection box "Image Color". In this case all the other functions are disabled. Otherwise and if the image is a 24 bit format, the program generates a gray level from the average of all the RGB planes (plane=0) or each color independently (plane=1,2,3). In both cases the image can be modify as for the files in format FITS or PIC. 

You can save the current image in a file in BMP format and reuse it later with the same appearance. 

The following formats are supported: 
FITS    integer 8,16,32 bits, real 32,64 bits *.fit *.fts *.fits
PIC     (MIPS) integer 16 bits *.pic
Bitmap  8,24 bits *.bmp *.dib
JPEG    *.jpg *.jpeg (not progressive)
GIF     *.gif (not progressive)
TGA     *.tga
RLE     *.rle 
PCX     *.pcx

With the OK button you load the image into the current chart. 

Note regarding the coordinates of the FITS files: 
There unfortunately is not a unique and standardized way of describing the WCS in a FITS file. This program support the three most common methods : CROTA2, CDi_j, PCiiijjj. 
It has been tested with many files obtained from different sources. It is however impossible to guarantee that a particular file has not implemented a variation of this format. In this case an error would certainly arise. If you are not certain of the format of an image please consult the comments in the header of the file.

This function computes the position of all asteroids for a given date. 
Please enter the complete path to the file "astorb.dat" and of the resulting file, the date and time of the observation and if the position has to consider the topocentric parallax.
It is advisable to keep the original values for the names of the files. 
The update of astorb.dat is available using the "Online Resources" option.
To display the position of the asteroids on the chart you have to use the option "External Catalogues", either according to the magnitude or to the size of a symbol. These definitions are available in "default.opt".
On a Pentium 166 it takes 40 seconds to calculate the position of 40,000 asteroids. 
Warning ! 
The original astorb.dat file is in UNIX format (end-of-line = LF). You must convert it to the DOS format (end-of-line = CR+LF) before you can use it with "Sky Charts". This done automaticaly if you use the "Online Resources" option to load the file.

This menu gets you directly to the Internet resources. 
You have to be connected to the Internet before you can use this function. 
If you want more information on the home pages themselves, just click on the information URL.

The following resources are available: 

Images corresponding to displayed chart: 

- SkyView  : Images in all wave lengths 

- ESO Skycat Digitized Sky Survey : Palomar atlas for the whole sky. The image dimension is limited to 1600 square minutes. The size of the corresponding file is 2.5 KB multiplied by the square size in minutes. 

- ESO Skycat Digitized Sky Survey 2 : The same survey but with a 15 micron scan ratter than 25 micron. The pixel resolution is 1 arcsec instead of 1.7 arcsec. The files are three time bigger.

Extraction of large star catalogs:

The data requested from these catalogs corresponding to the current chart is stored in a temporary file and automatically defined as catalog according to the magnitude, the disabling is done in this panel. 

HST Guide Star Catalog (20,000,000 stars)

- CDS VizieR : Stars up to the magnitude 15. The field is limited to 5 degrees or 5000 stars. 

- ESO Skycat : Stars up to magnitude 15. The field is limited to 2 degrees or 1000 stars. 
 

USNO-A (526,000,000 stars)

- CDS Vizier : USNO-A2.0 Stars up to magnitude 20. The field is limited to 2 degrees or 5000 stars. 

- ESO Skycat : USNO-A1.0 Stars up to magnitude 20. The field is limited to 2 degrees or 5000 stars.

Comets and asteroids
Data from CBAT/MPC :

• Update of the currently visible comets. If a file CAT\PLANET\COMETES.OLD exists, then this file is appended to the transferred file. This feature lets you keep old elements originating from previous observations.
• Update of the bright asteroid list at opposition during the current year. 

• Update the asteroid list from ASTORB data base to file CAT\PLANET\ASTORB.DAT. This list contain recent elements for more than 50'000 asteroids.

You can carefully modify some default options in the file EXTRES.INI. 

This panel gives you the possibility to directly obtain a sky image corresponding to the current chart. 
You have to be connected to the Internet before you can use this function. 

If you need more information on SkyView or if you which to obtain the description of all available catalogs as well as the dimension limits, please consult http://skyview.gsfc.nasa.gov

Do not modify the default value of "Coord" and "Field" if you want an image for the current chart.
Otherwise you can give an object name in the field "Coord", which will be resolved by SIMBAD.
The size of certain catalogs is limited (i.e. 4° in the case of the DSS).

Pixel X et Pixel Y represent the number of pixel of the image. If these two fields are empty, then the resolution of the catalog will be used. 
Warning: keep an eye on the size of the file you are going to transfer! 

If you plan to keep the file for later utilization, give a name to it in the corresponding field but do not modify the extension ".fit". 

Estimation of the file size: 
The data has a depth of 32 bit and the header is negligible. 
The size in bytes is: : pixelx * pixely * 4 giving 360 KB for an image of 300x300.