A Summary of Don's Web Applications

By Don Carona
TAMU Dept of Physics and Astronomy
Physics Observatory Manager

Over the years, I've programmed more than 150 astronomy related desktop applications. A number of those applications were specific to observing programs. Everything from full observatory automation to complete data collection, reduction and analysis pipelines. The languages I've used include C, C++, Objective-C, Carbon, Swift, Java, Basic, Visual Basic, Pascal and a few others. Although today, I restrict all of my programming projects to Objective-C and Swift for Apple computers. I'm sure we could have a debate over which OS's or computers are the best. I'm always happy to discuss why I choose Apple computers, but the bottom line is that the computer you like is the right one for you.

I never really intended to program applications for the web, but when I started programming solely for the Macintosh, it was difficult for students to utilize some of the desktop applications that weren't written in Java. The web was the best alternative and since the code I write is native to Apple computers, I started employing Mac servers in order to leverage the code I had already written for the desktop applications. It's worked out quite well and I'm not restricted by security issues inherent in most of the scripted languages that can be used on the web.

The first web-based application I wrote was the Sunlit Earth, a very simple application that displays the sunlit region of the Earth in real-time along with the geographic sub-earth position of the Sun. It was originally programmed as a “dashboard widget” for Mac OS X. It was the top download from Apple for months and I received a number of requests to make it available in different formats. Today, special versions of it are served to airports and travel kiosks in several countries. Other versions are used by teachers when discussing the seasons and topographical demarcations. If you have a Mac and would like a copy of the original widget, let me know.

Today, there are more than 40 applications used by various groups residing on my servers with 19 of those applications accessible to everyone . . . including the code written to manage the weather station, which I don't discuss here. What follows is a brief summary of 18 public web applications you'll find on my servers. I also include a few secrets about a couple of these applications that I've never shared publicly.

I have only one request of users . . . please do not link to any generated image from a page using a timer. For instance, don't have a timer set on your personal web page to update the position of a satellite every second. It needlessly taxes the server several times per second times the number people that are accessing your page. However, you are more than welcome to statically link to any image or data generated by the server.

Note: The last word in each heading for each application is a web link to the app.

Apps —> WebCCD

The most popular app is Web CCD. This is used by astronomers everywhere. It provides a simple means of perfectly matching an imaging system to create detailed finder charts. Enter the appropriate information for your system and the equatorial coordinates for the object-of-interest. The image that is created is exactly what your imaging system should produce. I created this app in order to positively identify the field where a minor body should be located in order to verify that the telescope is pointed correctly. When chasing down faint targets that require a long exposure, it's good to know you're pointed in the right place before wasting the time.

Apps —> ART

The Astrometric Reduction Tool is a way to embed a high accuracy World Coordinate System (WCS) in the header of a FITS file that takes advantage of the Simple Imaging Polynomial (SIP), which accounts for image distortion. This is a public variant of one of the data pipelines controlled by the servers. All of the information about ART can be found on the ART page; so, I won't go into more detail here.

Apps —> Spectrum —> 1D Spectrum Plot

If your interest is in spectroscopy, I've written a couple of helpful applications to help identify element signatures and create plots from raw 1D spectra. A 1D spectrum is the result of the reduction process of a CCD image taken through a spectrograph. The reduced spectrum will be 1 pixel in height and the width, in pixels, of your detector. At the bottom of the page, you can download a couple of sample spectra taken from the Observatory using our SBIG DSS-7 spectrograph and use those to practice with the plotting app.

Apps —> Spectrum —> Element Spectrum

This application is an aid to identifying spectral features. The resulting spectrum for any element or combination thereof is based on the NIST measurements and weighted by energy level. Get familiar with the options by using Hydrogen and the “Create as Plot” button. You have up to 5 elements in a single plot. The “Relative Abundance” fields allow you to reduce the levels of particularly strong element signal so that other elements are more visible. For instance, if using both Hydrogen and Sodium, the Sodium signal will over-power the Hydrogen signal. Reducing the relative abundance of Sodium to ~20% will yield a much better result.

Apps —> Horizon

Horizon plots the sky using a stereographic projection similar to typical desktop planetarium programs. It has several options for displaying features. If you change the date/time parameters manually, you’ll also need to select the “Rebuild Chart” button to update the plot. Selecting the “Now” button will update the date/time to current and rebuild the chart. Other options add or remove from the chart, but do not update the date/time. When using this or any of my applications that allow you to change the city, state and country, you must tab off of the fields in order for the page to pick up on your changes.

I wrote Horizon for two reasons:

It's a way for observational students to check the atlas chart skills they learn in the class.
Horizon is the base code that will be used to control the domed telescopes and cameras from anywhere in the world without the need for the user to install additional software on their computer. This has been successfully tested but is not yet in production. In the end, Horizon is just a nice way to see what's above the horizon from any location.

Apps —> Minor Body

For those interested in minor body hunting or follow-up, everything you need to be successful can be found on the minor body page. There's actually a lot here to discuss and will probably be best to leave the whole concept of minor body hunting to a separate article. In summary, you can get current ephemeris for any known minor body; create an observing report; predict the position of a potential discovery; and verify known objects within a field to flag potential discoveries.

Apps —> Minor Body —>Ephemeris

This is the ephemeris generated that I programmed with subtle position differences from the Minor Planet Center's (MPC) ephemeris service, which is linked from the page. If you need the coordinates for an object with a near-earth approach, you should use the ephemeris from the MPC since their orbital information for the target will update faster than my service.

Apps —> Minor Body —> Reporting

The reporting tool is used to generate a report of observations for submission to the MPC. Read the “Usage Information” linked at the top of the page for instructions. If you do not have an observatory code, you must read the MPC's “Guide to Minor Body Astrometry.”

Apps —> Minor Body —> Vaisala

Vaisala is a method of orbit determination when all you have are a couple of observations preferably spaced a day or two apart. Position Predict is my algorithm for determining the position of a minor body when the observations are spaced apart by hours or days. More information about usage can be found on the page.

Apps —> Solar System —> Earth —> Earthquakes

This is a quick reference to identify the earthquakes registered to the USGS during the given day (UTC). Clicking on the “Place” will link to the specific information about the quake from the USGS. Keep an eye on the area around and north of Dallas, TX. It has become very active over the last few years that could lead to a massive earthquake in the future.

Apps —> Solar System —> Earth —> Sunlit Earth

A simple equirectangular projection plotting the sunlit region of the Earth with the position of the Sun marked by an icon. The shadowed region includes the current lights-at-night data. As the mouse pointer moves across the image, the geographic position is also displayed.

Apps —> Solar System —> Earth —> Satellites

This application is based very loosely on my complete software package for tracking any artificial object in orbit. By default, the current position of the ISS and its ground-tracks are displayed on a Miller Cylindrical projection. Current ephemeris appears below the image. A few buttons are located at the top of the page to display various satellites and constellations. Here's a secret . . . if you know the NORAD ID for a given satellite, a plot can be created using the link:

http://doncarona.tamu.edu/cgi-bin/trakker?norad=# where '#' would be the official NORAD designator i.e.(HST=20580).

It should be noted that this application will undergo a significant upgrade in the future to handle several upgrades. It does not update automatically nor should you link to an image from a web page with a timer.

Apps —> Solar System —> Earth —> ADS-B Station

The Observatory is an ADS-B flight tracking station out to 200 NM. This page will display current flights that are ADS-B equipped. The deadline for aircraft to be upgraded with ADS-B equipment is January, 2020. The web page is a modification of a standardized page used by makers of ADS-B equipment, which gets its data from my backing application. The small antenna mounted outside on the north end of the classroom building is the ADS-B signal antenna.

Apps —> Solar System —> Moon

There are several Moon and Sun related products on this page. Each product has a brief description next to its button; so, I won't go into detail here. All of the products are created using my MEphem code, which is a high-accuracy lunar and planetary ephemeris generator that resides on its own server. It may very well become self-aware someday; so, I keep a close eye on it. All of the lunar renders are derived directly from data gathered by the Lunar Reconnaissance Orbiter (LRO). The “Current Moon”, “Phase Calendar” and “Moon Atlas” are all renders created on-the-fly from the LRO data. At the top of the page is where you'll enter the start time and output parameters for the ephemeris products.

There are two hidden treasures unknown to the world until now that you might enjoy. The lunar phase calendar can be presented as a strip chart for a single month or for an entire year.

The base URL to access the lunar phase calendar is: http://doncarona.tamu.edu/cgi-bin/lunarcal
If you add the “strip” parameter with the value “0” i.e.( http://doncarona.tamu.edu/cgi-bin/lunarcal?strip=0), you get the current month.
Change the strip value to “1” and you get the whole year.
http://doncarona.tamu.edu/cgi-bin/lunarcal?strip=1
If you want a different month and/or year, add the “month” and “year” parameters set to whatever you want. You must add both month and year even if you just want the year. These two parameters are taken as a single value in the code.

Apps —> Solar System —> Jupiter

This is where you'll find tools for all things Jupiter. At the top of the page is where you'll enter the date of interest. The applications are only concerned with the Julian Date (JD). If you have the JD just enter it in the 'Julian Date' text field and select the button for the product. If you don't know the JD, enter the appropriate information in the Universal Time section.

Apps —> Solar System —> Saturn

Tools for all things Saturn. Everything here is the same as the Jupiter application noted above.

Apps —> Solar System —> PDS Viewers

This application offers quick access to the “NASA Planetary Data System: Ring-Moon Systems Node” Planet Viewers. It prevents the need to enter a lot of information into their forms when all you might want to know are the positions of the moon around a given planet. There are a number of excellent tools on their web site, which is linked by button from the page.

Apps —> Charting

The charting application produces an orthographic projection of the celestial sphere for a given field size. The web page offers a simple means of plotting the current positions of the planets with basic ephemeris and event times. Also, on the page is the ability to plot any object given its ID with three available search options depending on the object of interest. For instance, entering “C/2018 V1” for the object ID and selecting the “Comet” button will produce the equatorial coordinates for a bright, recently discovered comet. Choosing the “Chart” button will plot the position of the object on a basic chart with current event times for the Central Time Zone (America/Chicago). Choosing the “Aladin” button will plot its position against the DSS2 color plates using the Aladin Lite Sky Atlas.

Parameters for Typical Observer

I programmed the charting application initially for duplicating the atlas charts from the Peterson Field Guide: Stars & Planets. Students can make a printed copy for annotating and writing notes as part of their observing log. It's actually become a rather powerful application used by dozens of college and university programs. Here's a few parameters that might benefit the typical observer.

If you're not interested in showing the grid, grid labels or constellation lines, set their respective colors equal to the background color for the chart. Below are some examples using the above parameters.

Stars only centered on M42.
Peterson Chart #42 using "obsv" preset.
Expanded Peterson Chart #42 with white stars on black background.

Event Plot - Observing Planner

This plots altitude versus time versus airmass of an object. It also includes the altitude versus time for the Moon on the plot, which is colored in gray. In other words, it plots the full path of an object instead of just rise, transit and set. This way, you can compare the object's path against the Moon's path to know whether or not it's worth the observation time. The plot has a color key for airmass in order to determine (at a glance) the best time of airmass for observing.

The date calculation can be set to use either UTC or a specific time zone (location). The default is our Central Time Zone (America'Chicago/, but can be changed in the “Location Parameters” by entering a city, state and country. If the selected country is any other than the U.S., the state field is unused. Click on the “Set Location” button to lookup and set the location and time zone information, which will be displayed as an alert if it’s in the database.

The object's ID can be looked up in the next section based on the type of object. I’ve included buttons for each of the planets for easy access to their coordinates. The coordinates for the selected planet do not update automatically (yet) when you change the date. You'll have to select the planet's button again if the date is adjusted to reflect the proper coordinates.

Once the date and coordinates for the object have been entered, click on the “Create Plot” button. This project will take a long time to complete, but this first step is a big part of any observing plan . . . especially, if imaging is involved.

I think that should cover things for now. There are some areas that could use a separate article for discussion such as weather station data, spectroscopy and minor body hunting. Until then keep checking the apps page for new or updated versions.