Now you can plot views of our galaxy on your SMP6 maps. This is possible due to SkyMap´s capabilities of getting data from external files (SDC files, or SkyMap Data Catalogue files). The MWSMP6.ZIP contains the source data files necessary to create the SDC´s. These files are, basicaly, of two kinds:

- SDD (SkyMap Data Definition): files containing the necessary format information to create SDC´s: (data file path, coordinate fields, symbols, colors, etc).

- DAT files: the data files themselves. Files containing RA/Dec coordinates and other information used by SkyMap when plotting objects

The ZIP file contains 10 SDD´s and 10 DAT´s, besides documentation files. Once compiled an included into the SkyMap´s catalogs reference, they will allow you to plot the Milky Way in up to five brightness levels. It will be possible to plot these levels as ‘outlines’ or ‘shades’. You can also use both outlines and shades at the same time, or any combination of them.

In order to create the SDC´s, you´ll have to compile the SDD´s and DAT´s using the Data Catalog Preparation Tool (DataPrep, which you get as part of SMP6, full or demo).

References:

-Printed manual: 'Using External Data Catalogs', page 265

-SkyMap Pro Help Topics: 'Using External Data Catalogs', on Help Contents

Simply create a directory for the DAT´s and SDD´s (for example C:\Program Files\SkyMap Pro\External\Catalogs\MilkyWay) and unzip all the contents of MWSMP6.ZIP into it.

-Open the DataPrep.

-Go to File - Open, select the directory to where you have just unzipped the MWSMP6 files and open one of the SDD's.

-Go to Tools - Compile. After a while, you will be prompted to save the SDC. Click on OK. You´re done, for this one.

-Repeat the process for the remaining SDD´s.

-Open SkyMap.

-Go to File - Preferences - External Data Calatogs.

-In the External Data Catalogs window, click on ‘Add...’.

-In the Add New Catalog window, click on ‘...’ and select one of the just created SDC´s. Click on ‘OK’

-Define the activation levels for the catalog.

-Repeat the process for the remaining files (a suggestion: using ‘copy’ and ‘paste’ for the SDC file pathname will make things easier).

Note: the ‘mw_sh*.sdc’ files must be included in order (that is., from ‘mw_sh1’ to ‘mw_sh5’). This is necessary because these files 'overlap’ when plotted on the maps, and the lower levels have to be plotted ‘behind’ the higher ones. The order is not important for the ‘mw_ol*.sdc’ files.

-Create a new map, using the following:

RA: 17h00’00’’

Dec: 30°S

Field of view: 60°

You will see the central galactic region, the best place for tests. If you don’t see anything, make sure that ‘Display Deep Sky Objects’ is selected on the Deep Sky Objects configuration window. Also, verify that the catalogs are active for the current view level. Try turning them on and off, to make sure that they are working fine. If you´ve done everything as described above, you shouldn’t find any problem.

-You can use SkyMap view levels to define which catalogs will be plotted according to the field of view. The shades are better viewed using 60° to 30°. For wide angle views, the dots are plotted too close together and you realize that SkyMap puts them in front of the stars. In this cases, a suggestion is using only outlines. These catalogs were not created to be used in high magnification views. The limit depends on each one´s opinion. Mine is 20°.

-One of the fields defined in the DAT files is a magnitude field. This was defined as ‘0’ for all the points. This way, the decision of showing or not a catalog is made just by activating it or not. Of course, if you put a negative magnitude in the filter (something that we normally wouldn´t use for deep sky objects), you won’t see anything of these catalogs on your maps

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The following behavior has been observed: beginning, for instance, with shades 4 and 5 activated, if you centre the map in a new location and activate shades 1, 2 and 3, they get plotted in front of 4 and 5, regardless the order you have added them to SkyMap´s references. To fix it, just centre the map again.

The outline 1 and shade 1 are based on the book ‘Uranografia, Descrição do Céu’, by R.R. de Freitas Mourão, a Brazilian astronomer. The equatorial coordinates were manually taken from his maps. Then, they were converted to galactic coordinates using Microsoft Excel and manually inserted onto a bitmap as black pixels over a white background. The bitmap dimensions were 450 by 3600 pixels, making each pixel correspond to 0.1 degree. The pixels were manually connected (and their connections smoothed) using Adobe Photoshop 3.0. That created the base for outline 1. Finally, the space between the two curves defining outline 1 was filled with black pixels, creating the base for shade 1.

The outlines and shades 2 to 5 are based on a photomosaic of the Milky Way created by the German astrophotographer Axel Mellinger. The original picture, dowloaded from his website (http://canopus.physik.uni-potsdam.de/~axm/astrophot.html), was 300 by 2400 pixels in size. It was expanded to 450 by 3600, using Adobe Photoshop. Still in Adobe Photoshop, an 1 pixel ‘minimum’ filter was applied to eliminate individual star images. After some adjustmests in brightness and contrast and conversion to a grayscale bitmap, a 2 pixels ‘gaussian blur’ filter was used to create a ‘cloudy’ aspect. Then, a ‘trace contour’ filter was applied in four brightness levels, creating the bases for outlines 2 to 5. These were filled with black pixels, creating the bases for shades 2 to 5.

Once the base bitmap files had been created, an application written in Microsoft Visual Basic 6.0 was used to scan the images, find black pixels, get their coordinates in pixels, convert them to galactic coordinates and then to equatorial coordinates which were sent to text files. These are the DAT files included in MWSMP6.ZIP.

The average distance between each point in the outlines is 0.1° or 6’. For the shades, it is 0.4º or 24’.