Night Assistant FAQ.

Night assistant is a program that is designed to run on a laptop while you're observing with your telescope. It features:

• Based on a configuration file you can edit, display a list of objects that are currently in the sky as seen from your observatory based on the criteria you've specified either in the configuration file or interactively with the main screen.
• The object database currently contains almost 174,000 deep sky objects.
• You can create and display a finder chart for any of those objects.
• Findercharts are between 1 and 5 degrees square, and initially display stars down to 12mv. If the faint button is clicked, and you use the naData16.zip database, stars as faint as 16mv are displayed. See the screen shots below.
• Coordinates for all stars and deep sky objects are given with both J2000 and true of date (the current time) values.
• Both local and sidereal time are displayed, They are updated every second.
• A special chart for the North celestial pole can be created to assist in aligning an equatorial mount.
• If you're using an alt-az mounted telescope, a line showing the direction of the zenith is available to assist you in orienting the finder chart with the view in your eyepiece.
• Detailed information about any object or star on the chart is but a click away.
• You can record observations after you've made them with the program. If you're observing a variable star, comparison stars can be selected from the finder chart and their information included with the observation. Detailed information about the object (name, position, spectrum, etc.) is stored in each observation.
• Your initial object list can contain all objects in the current sky, or exclude those that are already in your database.
• The orientation of the finder chart can be instantly changed, to reflect the view from a refractor or catadioptric with a star diagonal to one seen with a Newtonian, to one seen with binoculars.
• Each finder chart has a circle around its center that gives the view of an eyepiece of your choice.
• There are 12.5 million entries in the deep sky object and brighter stars database. The faint star database has about 100 million entries.

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  Finder chart for the Praesepe cluster, M 44 in Cancer. Variable stars are red circles, Normal stars are filled in circles, with the color showing the star's temperature. Stars as faint at 12mv are shown. Red crosses denote NGC or IC objects. The column on the right shows the text of the clicked on object. The variable in the top right of the circular eyepiece field has been clicked.

  

  Here's the same chart, after the "Faint" button has been clicked, showing stars down to 16mv. No stars have been clicked.

  What does Night Assistant do?

  • Creates a list of double stars, variable stars, galaxies, clusters and nebulae based on your input criteria.
  • From this list, you can click on an object
  and make a finder chart for it, or enter a new observation.
  

  A list of objects in the sky.

  The program acts very much like the astronomer's night assistant at an observatory. Imagine you are the astronomer, getting ready for a night's work on say, double stars. You might have the following dialog with the night assistant:

  Astro: What doubles are in the sky right now?

  NA: Do you want all the doubles, or just those you've not measured yet?

  Astro: Let's have just the unmeasured ones.

  NA: OK. What else?

  Astro: Hmmm, the seeing's only fair tonight, so only show me ones farther apart than 2 arc seconds.

  NA: OK.

  Astro: But closer than 30 arc seconds. Those wide ones are pretty much CPMs.

  NA:Yep. The telescope is Alt-Az. Do you want a line that indicates the direction of the zenith?

  Astro: Absolutely!

  NA: Right.

  Astro: These charts are exact for the year 2000. Could you precess all the objects in them to today's date?

  NA: No problem.

  Astro: Remember to enter our latitude, longitude, and time.

  NA: I'm way ahead of you. You'll get local and sidereal time updates every second. You configured latitude and longitude when you set me up.

  Astro: Great!

  NA: (pauses) We've got about 1200 stars to look at.

  Astro: Whoops! Better limit it to primaries brighter than 8th magnitude... and secondaries brighter than 9th magnitude.

  NA:(another pause) OK. Now there are only 350 doubles to observe.

  Astro: It would be nice if we could predict the position angle and separation of these pairs, some of them haven't been observed in decades.

  NA: Well, we have that data for only around 770 of our binaries. The entire list is a bit over 117,000 entries long. If we have the data, though, the position angle and separation will be for today's date, as per the orbital elements given by the USNO's double star listing.

  Astro: Let's get started.

  

  Night Assistant's initial screen.

  That's pretty much what the program does, but it's only the first part. Once you've made your list, it makes a finder chart of the object if you want, showing stars down to 12th magnitude. The charts can be between 1 and 5 degrees on a side, and are oriented with north at the top of the chart. The charts can be reversed (for viewing through a star diagonal) or inverted (for straight through viewing) with a click of a mouse. Clicking the "Faint" button, if you've used the naData16.zip database, will show stars as faint as 16mv.

  Once you've made the observation, the program allows you to type in an observation, on a form tailored to variable stars, doubles, NGC, and solar system objects. It uses the list of observed objects you've made to filter them out of an observing list if you want, or mark them as "seen".

  Could you be a bit more specific about the objects it can list?

  The double stars are taken from the Washington Double Star Catalog.

  The variable stars are taken from Moscow's Sternburg General Catalog of Variable stars.

  The galaxies, clusters and nebulae are taken from the Revised NGC and IC.

  Overall, there are upwards of 174000 objects to choose from.

  How about planets, asteroids, comets and other denizens of the solar system?

  Not yet. Your author is a confirmed stellar astronomer. As will be pointed out in these notes in numerous places, the source code is included, and you are welcomed, nay encouraged, to rectify this shortcoming.

  

  Finder chart for M 31, the great galaxy in Andromeda. The galaxy has been clicked, and two faint stars within 5 pixels of it are also listed in the column to the right.

  Tell me more about the finder charts.

  To really understand these, you'll have to download, install, and run the program. That said, I'll try give a short introduction. When you click on an object and then hit the "Create Finder Chart" button, the program goes off and works for a few seconds (A modern machine will be faster) and soon up pops the chart. It is a square of sky 3x3 degrees in size (the default) and it contains all of the objects in the above mentioned databases that are in that field. That's the least of it. It also contains all of the AC_2000, Tycho, SAO, UCAC4 stars brighter than 13mv, and Bright star stars that are in the field as well. After you click "Faint", stars from the UCAC4 catalog as faint as 16mv are shown if you used the naData16.zip database.

  The narrow rectangle to the right of the chart lists the information from all of these databases on all objects within around 4 pixels of any object in the chart you click on. The chart can further reverse (actually it's the default) and invert, so if you use a Newtonian, the chart can be set up to look like an eyepiece view. If you're a refractor or SCT user, the chart is already set up for your eyepiece view. The eyepiece field itself is set to appear as a one degree field inscribed on the chart (Again, this is a default, you can change it). Clicking the "Faint" button brings up a pop up window asking how faint you want to go. You can choose to go as faint as 16mv, 15mv is the default.

  The program "pickles" (to use Python's delightful terminology) an object's chart once it's made it, so if you want to look at it again, the chart comes up much faster.

  There are around one hundred million stars in the UCAC4 database (to 16mv), and over 6.7 million stars in AC_2000 and Tycho (both to 12mv). The SAO, at 1/4 million stars, and Bright Star, at 7000 or so stars hardly make a dent.)

  Defaults are easily changed by using a text editor, like Vim or Note pad to edit the "defaultParameters" file in the "doc" directory (folder).

  How do I download the program?

  The space needed for the program is tiny compared to the databases. You can choose between two databases, naData12.zip (0.84Gb) or naData16.zip (6.5Gb). NaData12.zip has all stars down to 12mv, and naData16 to 16mv. Both databases have all of the deep sky objects in them

  Java needs to be installed on your system. This is not pre-installed with Windows OR Linux. If you haven't done so already, install it! Go here to do so.

  Go to Night Assistant's sourceforge page (below). Click on "View all files" and choose the latest zip version if you're using Windows or the .tgz version for Linux and Mac.

  Be sure to download the data, naData12.zip or naData16, as well. Night assistant won't work without it!

  If you're trying to save disk space, and don't need stars fainter than 12mv, naData12.zip is what you want. NaData16.zip is 6.5Gb, but contains all stars 16mv or brighter.

  Night assistant on Sourceforge

  Instructions for a Linux/Unix/OS10 system.

  To unpack the program, from a command line terminal:

  Make a directory for it

  mkdir whateverSuperDirectoriesYouWant/nightAssistant

  Move the program to the new directory

  mv nightAssistant.tgz whateverSuperDirectoriesYouWant/nightAssistant

  Unpack the program and dataset.

  cd whateverSuperDirectoriesYouWant/nightAssistant
  
  gzip -d nightAssistant.tgz
  
  tar -xf nightAssisant.tar

  Unpack the data

  mv /Your/DownloadDirectory/naData12.zip .
  
  gunzip naData12.zip

  OR

  mv /Your/DownloadDirectory/naData16.zip .
  
  gunzip naData16.zip

  Bring up Night Assistant:

  cd whateverSuperDirectoriesYouWant/nightAssistant/classes
  
  java GetParams

  Night assistant's configuration screen should come up.

  Optional:

         If this is done, you won't have to run Night Assistant from its classes directory.
  • Add the class environment to your CLASSPATH variable (Unix, but windows is similar in their system properties tool)
           This is done in your .cshrc or .bashrc:
    • CLASSPATH="$CLASSPATH:whateverSuperDirectoriesYouWant/nightAssistant/classes"
    • export CLASSPATH;

  Create a shell script file in /usr/local/bin to run Night Assistant. In your favorite text editor, enter this code, altered for your java and Night Assistant directories:

  #! /bin/sh
  
  /Path/To/Your/Java/bin/directory/java -Xmx512m GetParams

  This program should run Night Assistant from a command line terminal. On my observing laptop, Night Assistant is run as part of the .bashrc startup file.

  Note: This program only runs from a GUI. For most of you, that is not a problem, but if you still use Linux's virtual terminals, it won't run from one of these.

  It *should* come up.

  Documentation written in HTML is in whateverSuperDirectoriesYouWant/nightAssistant/doc

  Instruction for a Windows system.

  Note: You need to have the Java JRE installed in the computer and in your path for this to work. Go here to install Java

  Go to https://sourceforge.net/projects/observethestars/ and download the latest version of Night Assistant.

  Note: You need to click the "Browse all Files" button so you can download not only the latest version of Night Assistant, but the data as well. You can download naData12.zip (stars brighter than 13mv, 0.84Gb) or naData16.zip (stars brighter than 16mv), 6.5Gb.

  Create a new folder for the program. Copy the Night Assistant program and the database to the new folder.

  Unzip the program and the data using your Windows Unzip or PK_Unzip program.

  From a command line terminal or Windows explorer, go to the folder you just created and then to the classes folder just underneath it. Execute the runNightAssistant.bat program. Night assistant will start. Later, you can set up a shortcut to start it from your desktop.

  Why are there such wide variations in star brightnesses between the various catalogs?

  The bandpass (range of colors) used to determine stellar magnitude varies widely between the various catalogs. There is no "right" way to do this, it's a matter of definition.

  Sometimes a variable star's red circle is shown centered on a star, sometimes not. Why?

  This is a difference of opinion between the GCVS and other catalogs. If you need a definitive answer, have a look a the WikiSky chart of the star. here

  Why Java?

  I'd like to say that after a careful consideration of all of the programming languages out there, it was the best.
  It's not.
  It's what I have to use at work, and it works pretty well, and your humble author is familiar with it. FORTRAN also works pretty well, for that matter, or <gasp> COBOL! However, Java is quite sesquipedalian and has so many disparate library features as to be almost as bad as the language it was designed to replace, C++. However! Had he written this in Forth or Lisp, very few of us (Including your aforementioned humble author) would have understood it. It also does a fairy good job of being cross platform compatible.

  Why not just run it from a jar file? It would be so much simpler.

  It's pretty much impossible to write to a jar file, and one of the features of this program is it's ability to save your observations. This means it needs to write to something.

  

  Night Assistant's observing form for an NGC object.

  For more information

  Read the user's manual.

  Emailing the author: send your rant (compliment? :-)) to rkk_529 at sign Hotmail.com and there's a slight chance he'll respond. He's worth what you're paying him, 'ya know.

  Actually, he loves feedback, and, delicate ego aside, tends to take user comments very seriously.