Citation: Mars previewer II - (c) 1997-1999 Leandro Rios


Introduction
Mars Previewer II

Introduction

Mars Previewer II is a handy tool for the amateur Mars observer. It was born as a observational aid for my own Mars observations. As it was growing, I realized it was really useful for me, and decided to post it in the Internet. It was on the 1997 opposition.

It's a program which given the date, time and timezone of the observer will calculate Mars Physical Ephemeris and draw an image of the globe. This image can be saved or printed. You can also hover over the planet's image with the mouse and MP II  will show Latitude, Longitude and the name of the albedo feature under the pointer.

You'll find it useful for planning an observation in advance, or to locate features in drawings or images taken beforehand.

The cost? Nothing, it's freeware. All I ask from you is just an email to keep record of how many people use this program. I hope you'll find Mars Previewer II useful for your observations. I do!


Quick Start
Mars Previewer II

Quick Start

To get started, just do the following:

1- 	Input the date of observation in the field "Date"

2 - 	Input the time of observation in the field "Time"

3- 	Verify the TimeZone field. It is positive for locations west of Greenwich

4- 	Pick your choice of orientation and circles.

5- 	Click button Go and you're done.


Fields
Mars Previewer II

Fields reference

Date

Enter the date of observation in this field. It must be entered using the Windows standard date format, dd/mm/yyyy, mm/dd/yyyy, mm/dd/yy or whatever you defined the Date Format in the Windows International settings.

Time

Enter the local time of observation in hh:mm format.Mars Previewer does not connsider Daylight Savings Time, so add or substract an hour as needed.

Timezone

Enter here your Time Zone, in hours west of Greenwich. if your location is east of Greenwich your time zone will be negative. Some examples are:

Argentina: 3

EST: 5

CST: 6

MST: 7

PST: 8

France: -1

Greece: -2

Spain: -1

By letting TimeZone to 0, you can enter universal time and date.


Check Boxes
Mars Previewer II

Check Boxes reference

South at Top

Checking this option will match the Celestial South with the top border of the image window.

Celestial east at left

This option will cause the celestial east (following) to be oriented towards the left border of the image window. If position angle of axis is zero, it coincides with Mars morning side.

Circles

With this option checked Mars Previewer will allow for the representation of equator, terminator, rotation axis and dark limb. Be warned, this option slows down the drawing routine a little.

B/W

This option is intended for easier comparison with B/W CCD images or sketches. It will force the drawing to Black and White.


Configuration
Mars Previewer II

Configuration Menu Command

This menu option displays the configuration window. Here you'll find three fields:

Default Timezone

It is the Time Zone to which the Timezone field is set when the "Default TZ" button is clicked.It is expressed in hours west of Greenwich. If your location is east of greenwich, enter as a negative value.

Delta T

This is the value for Delta T (in seconds) for the considered year of observation. Change it if you want to calculate far in the past or the future. If you left it unmodified, the error accumulated in CM will be about one degree every 100 years.

Auto Interval

This is the interval (in minutes) between two redrawings of the image window in Auto mode.


Button Commands
Mars Previewer II

Button Commands

Main Buttons

Go

Clicking on this button will open the image window using the values (Date, time, timezone) previously entered.

Show Circles

This command will show main circles (equator, terminator, dark limb and rotation axis) if the box "circles" was checked before clicking the Go button.

Save as File

Same as "Save Image" Menu Command (see File Menu Command )

Print

Same as "Print" Menu Command (see File Menu Command)

Secondary Buttons

Now

This button loads the system date and time in the corresponding fields.

Auto

Clicking on this one will start auto mode: The planet image will be redrawn every the lapse defined in the configuration window (see Configuration Menu Command). When clicked, it will toggle to "Normal"; clicking again will end auto mode.

Default TZ

This will force the TimeZone field to the value entered in the configuration window (see Configuration Menu Command)


File
Mars Previewer II

File Menu Command

Save Image

Saves the current image of Mars as a Windows .BMP file.

Print

Prints a report including the image of Mars and the physical ephemeris.

Exit

Guess what?


Acnowledgements
Mars Previewer II

Acknowledgements

I would like to thank people who directly or indirectly supported the developement of MP:

Dan Troiani from ALPO Mars Section, who allowed me to use its wonderful mars map .

ALPO Mars Section, on whose observations, drawings and CCD images the map is based.

Mike Mc Clure, from ALPO Computing Section, for beta testing MP2 and hosting MP on ALPOCS newsletter (The Digital Lens) server.

Rick Fienberg, from Sky & Telescope Magazine, for hosting MP on S&T's site from the beggining.

Roger W. Sinnott, from Sky & Telescope Magazine, for the freeware routine for Physical Ephemeris of Mars.

And all of you who sent email reporting errors, asking for improvements or just saying thanks.


Disclaimer
Mars Previewer II

Disclaimer

Use this program is entirely at your own risk. It is provided "as is" and there are no warranties of  any kind, either express or implied.


Database format
Mars Previewer II

Database Format

The albedo feature database is now text based and is contained in a file called albedo.txt. It is fully editable, what means you can add as many features as you want.

Open albedo.txt with notepad or any ascii text editor, and take a look at the format. You'll find a first line which reads:

NOMBRE,LAS,LAI,LOS,LOI

This is a header and must be present. Then you'll find a series of similar lines, ie:

Tempe,56.00000,43.00000,73.00000,59.00000

This line determines a rectangular  area, delimited at the north by LAS, at the south by LAI, at the west by LOS and at the east by LOI. NOMBRE, as you imagine, is the name of the albedo feature.

The available range for LAS and LAI is 80 to -80 degrees. Over 80 degrees it is considered as North polar cap and below -80  South Polar Cap.

The range of LOS and LOI is 0 to 360 degrees. It must be noticed that if a feature spans from, in example,  350 deg to 10 deg, it must be splitted in two areas covering from 350 to 360 and 0 to 10 degrees.

It can exist several areas with the same name and different areas covered. This allows to cover an area which doesn't fit in a rectangle by dividing it in a number of smaller rectangles.Two different areas can overlap, but MP will show the name of the area listed first.

If you decide to modify albedo.txt with many more features, please send me a copy of the file so I can include it in the distribution of MP.