Night Assistant User's Manual

Night Assistant Program Manual.

Table of Contents

Configuring Night Assistant

Using the list of observable objects

Using the Finder Charts

Adding observations

A chart of the North Celestial Pole

Observing notes


Download and Install Night Assistant


In your internet browser, go to:

Download the most recent version of Night Assistant.

You'll also need the database, or, if you want stars as faint as 16mv, the database.

As Linux, Mac, and Windows system can all decompress .zip files, these databases are in zip format only.



You must have Java's JRE installed on your system. If you don't know if you have it, just click here

You can get oracle's latest version by clicking here.

You'll need 10GB (that's giga bytes, 10^10 bytes) of free disk space for Night Assistant, as it contains the entire UCAC4 astrometric star catalog.

After you're got java installed and working, we can install Night Assistant.

Set up a directory or folder for Night assistant

The name of the folder is unimportant. It's "nightAssistant" on many machines, and that what we'll call it in this manual.

Windows installation

Copy to the nightAssistant folder you just made.

Unzip and using WinZip or any file decompression program on your machine that can deal with zip files.

X here just means the number of the most recent Night Assistant program and database number you downloaded.

Using your "My Computer", "windows explorer", or commmand line window, go to the nightAssistant folder and have a look at it. You should have the following folders:

To run the program, go to the doc folder and execute the "runNightAssistant.bat" file. Night Assistant's configuration screen should come up.

The configuration screen will have most of it's information wrong for your observatory, telescope, location, and preferences. You'll want to edit the defaultParameters file so it reflects your setup. The instructions to do this are here.

Note: The defaultParameters file is a simple TEXT file, not a .doc or .rfc file. You must save it as such when using word, wordPad, or other Microsoft editors.


To unpack the program,

Make a directory for it

Unpack the program and dataset.

Configuring Night Assistant.

This form sets up the basic parameters for all of the objects and finder charts you'll create during this instance of the run.

Main page image not found

Note: With the exception of Western and Eastern Hours, and the buttons which make a list, all of these fields above can be given new defaults by editing the defaultParameters file. You can also overwrite the values given in any field.


Positions in the sky are given in the celestial coordinates system of right ascension and declination.

You begin by specifying the boundaries of the sky you'd like to observe for this run. Right ascension defaults to the sky that is 4 hours west and 5 hours east of your current sidereal time, based on what your computer's clock. This is what you get when you click "Make the list based on the current time", and at startup. You can edit the eastern and western hour to suit your current needs by replacing the current right ascensions with the desired right ascensions and clicking "Make the list".

Click here to learn about sidereal time.

Min and Max Dec :

Are the declination limits of the list's boundaries. These are read from your defaultParameters file. You can change them as you change the Western and Eastern hour fields above, or by editing defaultParameters.

Min Magnitude:

These fields give the faintest members of the given class of object. Bright Stars are just that, as are NGC/IC objects. Variables are stars from the GCVS and Espin red star catalog, and the Dbl Primary and Secondary limit the binary stars from the WDSC catalog.

BrightStars: Stars from the Bright star catalog must be brighter than this to be listed.

NGC/IC: Objects from these catalogs must be brighter than this to be listed.

Variables: Only variables that get brighter than this will be listed.

Dbl Primary: Only doubles with the primary component brighter than this will be listed.

Dbl Secondary: Only doubles with the secondary component brighter than this will be listed.

Other Parameters

Binary Delta mv: The maximum difference in brightness between a primary and secondary component in double star.

Show only Previously Viewed Objects: List only those object not seen before (as determined by your observations). The default is "Don't Show".

Min and Max double star separation: Only doubles within these limits will be listed. Units are arc seconds.

Show Direction of Zenith: This is most useful with an alt-azmuith mounted telescope. The field orientation of the finder charts always has north or south being at the top of the chart (depending on the invert flag's setting). If this box is set, a yellow line from the center of the finder chart towards the zenith will be shown. This greatly simplifies orienting the chart for use with the telescope.

Use this preformatted list.

Night Assistant ships with a preformatted list of the Messier objects. They are in the /doc directory. To use it enter "messier" in the text box and click "Show the list".

You can assemble other lists from the star and observingList files in the data directory. Copy desired object from these files into your new list with a text editor, being sure that you include the entire line with each object. Name the file and give it a ".na" suffix, and copy it into the doc directory. You can then invoke if as you would any other list.

Make a finder chart of this object:

Makes a finder chart of the named object. A good way, for example, to go directly to any object in the observing list. Note: The object's name must be correctly spelled!

Note: NGC objects can designated as N XXXX where XXXX is the NGC number. IC objects can also be abbreivated as IC XXXX where XXXX is the IC number.

Finder chart for coordinates:

This will make a finder chart centered on the coordinates you've entered into the two fields for right ascension and declinations. For example if you had a planet at 17h 13m 17s, -21° 11' 21", you'd enter 17 14 17 in the left field and -21 11 21 in the right hand one and click "Make the Chart" to the right of that. The coordinate location is shown as a red cross in the center of the field.


Simply click on the desired planet, and then "Make Planet's chart".

For Finder Charts:

Chart size: This is the linear chart size, in degrees. The default value of 3, for instance, will create charts that are 3x3 degrees in size. Currently, the program allows values between 1 and 5 degrees.

Eyepiece: This draws the field of view of an eyepiece around the center of the chart. The default is 60 minutes, or one degree.

Checkbox Dark BG: If checked (this is the default), this will draw colored stars on a dark blue background. If not, black stars on a white background.

Checkbox Reverse: If checked (this is the default), this will reverse the chart, with east on the right side and west on the left.

Checkbox Invert: If not checked (this is the default), north is at the top of the chart.


Observatory: Name of the location from where the observation was made.

Telescope: The telescope used for the observation.


The latitude and longitude of your observatory.

Local / Sidereal:

Both local and sidereal time are shown. They update once per second.

Show AltAz

If this is checked, the finder chart will show the altitude and azmuith of the object, updated every two seconds.

Calibrate on Polaris and Polaris Az

This is used for telescopes with Alt Az setting circles. Enter the observed Azimuth of Polaris in the "Polaris Az" window, and then click the "Calibrate on Polaris" button. This will adjust the actual azimuth of the object to your telescope's azimuth.

Make the list using the current time

This makes a list of objects using all of your parameters except Western and Eastern hour. It sets the western hour to 4 hours behind the current sidereal time, and eastern to 5 hours ahead of that time.

Make the list

This makes a list of objects using all of your parameters including Western and Eastern hour.

Using the list of observable objects

All the objects that passed the filters in the first form are displayed in the list that comes up after you click on the "Make the list" button in the previous form.

The first field is the right ascension, in hours and minutes. This is the format used by Burnham in his celebrated Celestial Handbook, and is easiest to use with analog setting circles.

The second field is the declination, in degrees.

Both right ascension and declination are precessed to "True of Date", that is, for today's date.

The coordinates are followed by the object's name, and if it's a star, its spectral type, if known. NGC/IC objects are followed by Dreyer's short, cryptic, description.

At the bottom of the list is an item, "Add Solar System Object", with no coordinates. You can't make a finder chart of this, but you can use it to add an observation of a planet, asteroid, comet, ufo (Just kidding), etc.

The "Make Finder Chart" button makes a finder chart for the object, using the parameters you entered into the first form.

The "Add Observation" button adds a new observation for this object.

Below is a screen shot of a typical observing list. It shows objects that are in the observations database, they are marked as "seen"

Observing list Image not found

Using the Finder Charts.


Faint allows all stars between 12th and up to 16th magnitude to appear on the chart.

Invert toggles the North - South orientation of the field. If it's grayed out, the field is Not inverted and north is at the top.

Reverse toggles the East - West orientation of the field. If it's grayed out, the field is Not reversed and East is at the left.

Exit erases the chart.

Add Obs allows you to add an observation about the object.

More: If it appears in bold type, there are more catalog entries than appear in the current list. Repeated clicking of this button will show all of the catalog entries. Once all have been shown, the series repeats. If more is greyed out, only the current list shown contains the available catalog entries for this object.

Showing stars fainter than 12mv:

Click the "Faint" button. A small window will pop up, asking you to confirm or change the faintest star you want to have shown. Change it if you want, and then click "OK". Night Assistant queries its UCAC4 database and pull up all stars on your finder chart fainter than 12mv to the limit you set (the faintest star you can request is 16mv).

Note: Due to a bug in Java, after you've clicked on faint and the fainter stars have appeared on the chart, click either the invert or reverse button to properly redraw the finder chart!

Below is a screen shot of the finder chart for NGC 4565. NGC 4565 as been clicked

NGC 4565 Image not found

Reading Finder Charts:

Clicking on a star brings up its text data in the right hand column

A chart of the North Celestial Pole

If you enter "ncp" into the "Make a finder chart of this object" field, a finder chart of the north celestial pole will pop up, rotated to the current sidereal time. The chart acts like any other finder chart. It is useful for aligning your equatorial mount.

Below is a screen shot of the NCP chart:

NCP Image not found

Adding observations.

When adding an observation, a form comes up that is keyed to the type of object you've observed.

Observing notes.

Most laptops are egregiously bright when at the telescope, even in an urban environment. Under truly dark skies, they function as small street lights. I've managed to tame mine by taping sheets of clear red plastic over the screen.

A dim, red light that attaches to your hat is invaluable for lighting the keyboard. I've noticed, however that my touch typing skills have greatly improved when using Night Assistant without any light at all.

Changing the default program settings.

All of the defaults below are set by the defaultParameters file in the doc directory (folder). You can change any of them by editing the file with a text editor. If you use Word, and don't save it as a text only document, Night Assistant won't be able to read it.

Before you edit the file, make a backup copy of it, just in case.

You can change anything to the right of a colon.
DO NOT change anything to the left of a colon.
DO NOT delete or add any lines.

Items that are numbers, like chart size and minimum magnitudes need to be numbers. No letters! Letters will confuse Night Assistant.

Once you've saved the new version, run Night Assistant to check that all of the parameters in the startup screen are OK.

There are four parmeters that are not configurable in the main screen:

They can only be configured here. They are

These last two are useful if your display has labels that are too small, or are truncated by their text boxes. You'll have to experiment to see what values of these parameters work best for your computer.

Again, only change the text to the right of the colon in any line.