ObsReduce 1.3

(C) 2003-2005 by Ted Molczan. All Rights Reserved.

2005 August 17

 

ObsReduce is an MS Windows program that reduces observations of satellites relative to the background stars into their precise coordinates. Observers identify their reference stars in a simulated binocular or telescope field of view, select them using the mouse, enter the observed geometric and positional data, and the program automatically produces a formatted observation report.

ObsReduce supports all three reporting formats in common use: IOD, UK and RDE (Russell Eberst's abbreviated form of the UK format.) All R.A. and Dec formats and epochs are supported, as are visual magnitude and optical period reporting.

ObsReduce supports three traditional observational geometries: satellite in-line with reference stars, satellite forming right-angled triangle with reference stars, and appulses (satellite passing near a single star).

Observations in the form of images recorded by cameras may be reduced using two geometries: satellite located to the right or left of a pair of stars, or any configuration of a satellite and three stars. The user enters the pixel coordinates of the satellite and reference stars, or the measured lengths between them, obtained independent of ObsReduce.

Several star databases, derived from the Tycho 2 catalogue, are available for ObsReduce. The magnitude 8.5 database includes nearly 72,000 stars. The magnitude 10.5 database includes more than 540,000 stars. The magnitude 12.0 database includes more than 2 million stars. The complete set of Tycho 2 stars is also available, consisting of more than 2.5 million stars to about magnitude 13. The latter two databases are available only to positional observers who share their observations, and who have a demonstrated need. The star data bases range in size from 1.0 MB to 30 MB. ObsReduce enables the addition of stars missing from the database, as well as coordinates of planets and asteroids.

The star databases store Epoch 2000.0 coordinates, proper motion and visual magnitude. About 4 percent of the stars in Tycho 2 do not have proper motion data, and though they are Equinox 2000.0, their epoch is c.1991. I hope to eventually provide data from alternative sources for many of those stars. Where available, ObsReduce makes use of proper motion in the reduction of observations, though it rarely materially affects accuracy.

To aid in finding and confirming reference stars used in observations, ObsReduce has the ability to display predicted satellite tracks computed using the SGP4 and SDP4 orbital models. It also displays the difference between the satellite's predicted and observed time and track, and can compensate for Earth's rotation in the interim, to produce accurate plots of satellite tracks.

ObsReduce can be configured to simultaneously write its results to as many as four text files. One file logs only the IOD, UK or RDE formatted observations. Another logs the underlying details of each observation: the position and magnitude of reference stars, the observational geometry, and the orbital elements used to locate the reference stars. The remaining two files are single session versions of these file types.

ObsReduce provides numerous configuration options. For example, default values for site code, time uncertainty, position uncertainty, and the number of significant decimal points to be reported, can all be set via an easily editable initialization file. Many of the default settings may be readily changed on a per observation basis at run time.

The manual and a screenshot are available here:

Manual

Screenshot

New/Improved Features in ObsReduce 1.3

Added Support for Cameras

Observations in the form of images recorded by cameras may be reduced using two geometries: satellite located to the right or left of a pair of stars, or any configuration of a satellite and three stars. The user enters the pixel coordinates of the satellite and reference stars, or the measured lengths between them, obtained independent of ObsReduce.

Bug Fixed

Version 1.3 corrects an error in versions 1.1 and 1.2 that caused incorrect rounding of the arc min or arc sec components of RA and Dec, when rolling over from 59 to zero. For example, in DDMMm format, values between 34:59.1 and 34:59.5 would be reported correctly as 34591 to 34595, but those between 34:59.6 and 34:59.9 would all be reported as 35000.

Version History

Learn about new/improved features in previous updates.

Download Version 1.3 Patch

To upgrade ObsReduce from any earlier version to 1.3 download the patch file, ObsReduce130exe.zip, and extract its contents into the folder (directory) where the earlier version is installed. First time users must download and install the full package.

Download Version 1.3 Full Installation

Disclaimer: You install and use ObsReduce at your own risk. Ted Molczan accepts no responsibility for any adverse consequences arising from installing and using ObsReduce.

1. Download ObsReduce.zip, which contains all except ObsReduce's star files.

2. Download one of the following sets of star files:

Tycho85.zip (71,704 stars, 1.0 MB)

Tycho105.zip (540,312 stars, 6.6 MB)

Two additional Tycho star files exist; one contains stars to mag 12; the other contains all Tyhco stars. They are available only to positional observers who share their observations, and who have a demonstrated need. For further information, please contact webmaster@satobs.org.

For a given limiting-magnitude setting, regardless of the database size, there is no perceptible difference in the speed with which ObsReduce finds the stars to be displayed; therefore, the decision as to which set of star files to download should be based upon need, available disk space, and the speed and reliability of your Internet connection.

3. You may install ObsReduce in the same folder as a previous version, but before doing so, it is strongly recommended that you first make a copy of the old ObsReduce.ini file, then delete the old version of ObsReduce, using Windows' Add/Remove programs. ObsReduce.ini has changed from the beta version, but has many of the same entries, so you may wish to refer to it to help customize the new one. Eventually, I hope to eliminate ObsReduce.ini in favour of using Windows' Registry.

4. Copy ObsReduce.ZIP to a temporary directory, unzip the file, run Setup.exe, and respond to the prompts. You may receive an erroneous warning that you have insufficient disk space, which may be safely ignored. Some beta testers commented that Setup tended to issue overly conservative warnings, which they found best to ignore. You should respond according to your experience and confidence using Windows.

Unless you specify otherwise when prompted, ObsReduce will be installed at C:\Program Files\Obsreduce. You should make note of the installed directory, so that you may edit the initialization file located there, ObsReduce.ini.

5. To complete the installation, unzip the contents of the star files into the directory of your choice. As downloaded, ObsReduce expects to find the star files in the same directory in which it has been installed. If you choose to install them in a different directory, you must tell ObsReduce the path by editing line 34 of ObsReduce.ini.

6. ObsReduce comes with a sample orbital elements file, which may be outdated by the time you install it, so it is recommended to obtain a replacement containing the most recent available elements. Sources of orbital elements are listed here. To find your elements file, ObsReduce follows the path and name entered at line 33 of the ObsReduce.ini file.