Finder chart for the Prasepe 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. A 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.
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: Still too many. How about only the Struve list?
NA: OK, Let's see... STF... All right, it's down to 125.
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 115,000 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.
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".
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 166,000 objects to choose from.
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 87. The star just above the galaxy has been clicked, and we see its data in the column to the right.
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, and Bright star stars that are in the field as well. After you click "Faint", stars from the UCAC3 catalog as faint as 16mv are shown.
The narrow rectangle to the right of the chart lists the information from all of these databases on all objects within 5 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 UCAC3 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).
Go to Night Assistant's sourceforge page (below). Click on "View all files" and choose the zip version if you're using Windows or the .tgz version for Linux and Mac.
Be sure to download the data, naData.zip, as well. Night assistant won't work without it!
Night assistant on SourceforgeTo unpack the program,
Make a directory for it
Unpack the programo and dataset.
Optional:
If this is done, you won't have to run Night Assistant from its classes directory.Run the program:
java GetParams
It *should* come up.
Documentation written in HTML is in whateverSuperDirectoriesYouWant/nightAssistant0X_X/docNote: 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.
Create a new folder for the program. Copy the file you just downloaded, nightAssistant0X_X.zip (your version number will be the latest stable version) to the new folder.
Unzip the program using your Windows Unzip or PK_Unzip program.
From a command line terminal or Windows explorer, go to the directory you just created and then to the classses folder just underneath it. Execute the runNightAssistnant.bat program. Night assistant will start. Later, you can set up a shortcut to start it from your desktop.
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.
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
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 sesquipedelean (overly wordy)
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.
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.
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.