Alternate Site Prediction

Suppose you want to provide prediction data from the perspective of a station other than the launch site? This may come in handy for folks who want to get a feel for the expected flight track as it relates to their fixed locations whether it be a home station or a Tracking and Recovery station that is essentially stationary in its position.

This only works with predictions. There is a window that shows real time data in the Alternate TRACKING screen.

First you must generate a standard prediction for the balloon flight from its launch site. Once that data is in memory ...

On the Main Screen click [Calculators/Alternate Site Prediction] the program will automatically calculate the prediction for your Alternate Site.

If you haven't yet set an Alternate Prediction Site, the program will lift the alternate TRACKING site used in the terminal area of the program as set on the Setup Screen and use that for the prediction. If there is no alternate tracking location available the program will wait for you to select one.

If you wish to use a different location or enter a new location, press the "Select or Add New Site" button at the top.  A small dialog box will pop open with all the sites related to your various launch locations and Alternate Tracking locations. Pick one of these or add a new site. Don't forget to Click Activate on that dialog box or the new site will not be used and a new prediction for that site will not be made. See the Setup Screen Page for more info on these dialog boxes.

The new site will replace the one shown at the top of the screen and the prediction relative to that location will be generated. Anytime you select a new Alternate Prediction Site location, the program will save that info to the INI file. From then on, that station will be the default location and this screen will open with the prediction made for that location.

Once the prediction for the alternate site has been run, this screen will appear.

The Site being used for the prediction is located in the center of the screen. The yellow dot indicates where, relative to that site the balloon first appears over the horizon. The yellow line is the ascent phase of the flight. The smaller pink dot is the burst point. The red line is the descent phase and the red dot is the point at which the payloads descend below the horizon.

The light blue dot can represent either the closest approach point (case above) or the point at which the balloon reaches maximum elevation relative to the site. You select which is represented by clicking one of those options at the bottom of the screen.

If you are close enough to "see" both liftoff and landing locations then the yellow and red dots will represent those points. But If you are distant from the flight, this track will shrink in length substantially as it only displays that part of the prediction that places the balloon above the local horizon for the prediction site.

The range from the prediction site at the center to each circle is shown on the plot. These figures will move around to avoid writing over the track line and so may appear in different quadrants. The cross hatch indicates North, South, East and West.

Below is a screen shot of the same flight but using Cheyenne, WY as the Alternate Prediction Site.

The length of the track is greatly reduced. The primary factor is scaling. In order for Cheyenne, WY to be in the center of the screen the distance to the screen edge is much greater thus shrinking down the track line's relative length. However, also note that the balloon doesn't ascend above Cheyenne's local horizon until it has attained an altitude of 35,095 feet and similarly, the balloon descends below the local horizon at 45,869 feet. So, what you are looking at is only the ascent and descent phases of the flight that are between these two altitudes. This contributes to a significant shortening of the track length. Note also that the smaller light blue dot representing the maximum elevation in this case is apparently missing. That is because the maximum elevation and burst were  coterminous. The pink burst dot has overwritten the light blue maximum elevation dot.

The Table Tab depicted below will still show the entire flight including those portions of the flight that occur below the alternate site's local horizon.

To go to the extreme, here's the same flight predicted for Wichita, KS.

In this example, the balloon is above the horizon at Wichita only during the final phases of the flight. The point is, at this great distance you don't see any track. Because of the size of the "dots", the track is obscured. All you see (if you look very closely) is the yellow dot of the rise, the pink dot of the burst, a tiny sliver of the blue dot showing closest approach and the halo of the red dot being overwritten by both the closest and burst points. This is a typical printout for very distant stations relative prediction reports.

There are two tabs on this screen. The default tab is "Plot". If you click "Table" you will see this representation of the prediction.

The fields displayed above are:

  • Time (either in time of day or elapsed minutes, depending on the choice made on the setup screen).
  • Altitude
  • Bear = Bearing
  • Rng =  Range
  • Elev = Elevation
  • DPM = Degrees per minute
  • Crse = Balloon's current course
  • Speed = Balloon's current speed
  • Climb/Descent = the climb/descent rate in Feet per minute
  • Latitude
  • Longitude
  • Grid X coordinate
  • Grid Y coordinate

What is Degrees per Minute (DPM)? The program calculates the movement from one prediction record to the next and then generates a DPM. This was included to keep observers aware of the rate of "perceived" movement so they could maintain pointing angles on telescopes, antennas, whatever. When this figure starts to increase, a check of the changes in Bearing AND Elevation should be made to prepare for the direction of this apparent increased speed of movement.

Another thing to consider, if the balloon is flying close to the zenith of the Alternate Prediction site it will move through degrees of azimuth at a phenomenally fast rate as it crosses the zenith. This greatly inflates the degrees per minute. It is an accurate figure, but it is pretty meaningless. But it gets your attention and indicates the balloon will be flying close to directly overhead.

Pressing "Print to File" will generate this text file (for the Fowler, CO example above):

Balloon Track for Windows                                Version 1.9.0
__________________________________________________________________________
Alternate Site Prediction
Friday, December 17, 2004          eoss086      Profile_04_12_12_1500Z.dat
7:19:41 PM                        Fowler CO                   wbaltrak.ini
__________________________________________________________________________
Winds DataFile
-----------------------
Station: UNK
Date: 1500Z 12 12 2004
DataFile Status: Intact
Intact Records: 18
Corrupt Records: 0
Grid Placement Data
-----------------------
Reference Site: Hawley
Latitude: 37.9991� lat.
Longitude: -103.7204� long.
X_Offset: 45.00
Y_Offset: 50.00
Grid Origin
Latitude: 37.275� lat.
Longitude: -104.5474� long.
Alt Predict Site - Fowler CO
-----------------------
Location: 38.1335� lat.   -104.024� long.
Grid: X=-1.64 Y=71.17
Ascent Rate: 1100 feet per minute
Descent Rate: 910 feet per minute
Altitude: 5000 feet
Burst Data
-----------------------
Burst Point: 37.9468� lat.  -103.8157� long.
Grid: X=39.8 Y=46.4
Burst Time: 81.8 minutes
Burst Altitude: 95,000 feet
Burst Bearing: 40.3�
Burst Range: 17.5 Mi.
Predicted Landing Site
-----------------------
Landing Point: 37.7537� lat.  -103.3506� long.
Grid: X=65.3 Y=33.1
Altitude: 4900 feet
Flight Time: 124 Minutes
Bearing: 125.4� True
Range: 45.1 Mi.
Closest Approach to Site
------------------------
Flight Time: 16:37:09
Altitude: 45,869 feet
Elevation: 77�
Bearing: 193.3� True
Range: 1.8 Mi.
Maximum Elevation
------------------------
Flight Time: 16:37:09
Altitude: 45,869 feet
Elevation: 77�
Bearing: 193.3� True
Range: 1.8 Mi.
__________________________________________________________________________
Ascent/
Descent
Time         Alt  Bear  Rng    El  DPM  Cse  Spd   Rate     Lat      Long      GridX   GridY
--------------------------------------------------------------------------------------------
16:00:03    5,050  292   32  -0.2    0  112    0   1100   38.3057  -104.5777    -1.6    71.2
16:01:32    6,680  292   32   0.3    1  112    8   1100   38.3047  -104.5743    -1.5    71.1
16:03:05    8,399  291   32   0.9    1  146   14   1100   38.3003  -104.5705    -1.3    70.8
16:04:45   10,230  291   31   1.6    1  153   21   1100   38.2928  -104.5657    -1.0    70.3
16:06:32   12,188  290   31   2.3    1  149   27   1100   38.2828  -104.5580    -0.6    69.6
16:08:26   14,285  289   30   3.2    1  136   32   1100   38.2722  -104.5450     0.1    68.9
16:10:29   16,532  288   29   4.1    1  127   36   1100   38.2615  -104.5270     1.1    68.1
16:12:41   18,947  287   27   5.3    1  121   39   1100   38.2509  -104.5044     2.3    67.4
16:15:04   21,565  287   26   6.8    1  119   46   1100   38.2381  -104.4750     3.9    66.5
16:17:39   24,416  285   23   8.8    1  118   54   1100   38.2222  -104.4371     6.0    65.4
16:20:31   27,562  285   20  11.7    2  111   61   1100   38.2070  -104.3871     8.7    64.4
16:23:42   31,079  284   17  16.3    3  105   68   1100   38.1933  -104.3226    12.2    63.4
16:27:22   35,095  286   12  25.2    6  101   77   1100   38.1801  -104.2379    16.8    62.5
16:31:42   39,872  287    6  46.8   16  104   81   1100   38.1592  -104.1332    22.5    61.1
16:37:09   45,869  193    2  77.1   22  122   72   1100   38.1086  -104.0314    28.0    57.6
16:44:28   53,911  125    7  52.3    1  110   55   1100   38.0748  -103.9158    34.3    55.2
16:56:52   67,559  118   13  41.7    0  110   30   1100   38.0434  -103.8089    40.2    53.1
17:13:42   86,079  121   15  45.4    3  140    7   1100   38.0215  -103.7859    41.4    51.5
17:21:49   95,000  139   17  44.6    4  197   40   1100   37.9468  -103.8157    39.8    46.4
17:23:14   86,079  141   18  40.8    2  197   40   6304   37.9338  -103.8209    39.6    45.5
17:27:46   67,559  141   18  32.9    3  140    7   4080   37.9279  -103.8148    39.9    45.1
17:32:24   53,911  138   20  24.4    3  110   30   2945   37.9161  -103.7749    42.1    44.3
17:35:43   45,869  134   23  18.5    3  110   55   2429   37.9007  -103.7227    44.9    43.2
17:38:34   39,872  133   26  13.9    2  122   72   2105   37.8741  -103.6698    47.8    41.4
17:41:07   35,095  130   29  10.8    1  104   81   1877   37.8616  -103.6088    51.2    40.5
17:43:28   31,079  127   32   8.5    1  101   77   1710   37.8528  -103.5547    54.1    39.9
17:45:41   27,562  125   34   6.8    1  105   68   1579   37.8429  -103.5101    56.6    39.2
17:47:49   24,416  125   37   5.5    1  111   61   1474   37.8313  -103.4731    58.6    38.4
17:49:53   21,565  124   38   4.4    1  118   54   1387   37.8184  -103.4434    60.2    37.5
17:51:52   18,947  124   40   3.5    1  119   46   1313   37.8075  -103.4190    61.6    36.8
17:53:48   16,532  124   41   2.7    1  121   39   1249   37.7979  -103.3994    62.6    36.1
17:55:41   14,285  124   42   2.1    1  127   36   1194   37.7879  -103.3831    63.5    35.4
17:57:31   12,188  124   43   1.5    1  136   32   1145   37.7776  -103.3708    64.2    34.7
17:59:18   10,230  125   44   1.0    1  149   27   1102   37.7676  -103.3634    64.6    34.0
18:01:01    8,399  125   44   0.5    0  153   21   1064   37.7598  -103.3585    64.9    33.5
18:02:41    6,680  125   45   0.1    0  146   14   1030   37.7550  -103.3546    65.1    33.1
18:04:28    4,900  125   45  -0.3    0  112    8    996   37.7537  -103.3506    65.3    33.1

All data in the header above is relative to the Alternate Prediction Site (Fowler, CO in this case)

This module was written to assist our telescopic observing team. However, others may find it of use too.