Chandra X-Ray Observatory (CXC)

PRoVis Reference Manual

TABLE OF CONTENTS

1.0 OVERVIEW
2.0 ACTIONS BUTTONS
2.1 RESOLVE NAME
2.2 CLEAR TARGET
2.3 RESET DATES
2.4 RESET OPTIONS
2.5 GENERATE PLOT
2.6 GET POSTSCRIPT
2.7 CANCEL
2.8 HELP
3.0 TARGET PARAMETERS INPUT FRAME
3.1 START AND END DATE
3.2 TARGET COORDINATES
4.0 PLOT OPTIONS INPUT FRAME
4.1 VIEW PITCH ANGLE
4.2 VIEW PITCH CURSOR
4.3 VIEW ROLL ANGLE
4.4 VIEW ROLL CURSOR
4.5 VIEW AVERAGE VISIBILITY
4.6 VIEW VISIBILITY CURSOR
4.7 VIEW PITCH ANGLE RESTRICTIONS
4.8 SHOW CROSSHAIR
4.9 VIEW PLOT DATA
4.10 AUTOFIT PLOT IN FRAME
4.11 AXIS ZOOM FACTOR
4.12 AXIS MOVE FACTOR
4.13 POSTSCRIPT SIZE
4.14 FONT TYPE AND SIZE
4.15 AXIS LINE WIDTH
5.0 PLOT FRAME
5.1 MOUSE POINTER POSITION
5.2 AXIS BUTTONS
5.2.1 MOVE LIMITS UP
5.2.2 MOVE LIMITS DOWN
5.2.3 ZOOM IN
5.2.4 ZOOM OUT
5.2.5 RESET LIMITS
6.0 GENERATING PLOTS
6.1 NAME RESOLUTION
7.0 MANIPULATING PLOTS
8.0 MAXIMUM EXPOSURE TIMES
9.0 CAVEATS




1.0 OVERVIEW   TOP
PRoVis is a web based application that allows viewing and interactive manipulation of Roll, Pitch and Visibility Plots. There are a number of options that users can modify to customize the resulting plots. Postscript version of plots can also be generated. PRoVis uses a recent projected Chandra spacecraft ephemeris to generate plots. Since Chandra's orbit does not change much from year-to-year, plots are also closely applicable for any mission year. The plots are generated directly into the browser, unless postscript is requested, for which the browser needs to have an external viewer configured to retrieve and view postscript. The PRoVis GUI consists of 4 elements: buttons frame, target parameters frame, plot options frame and actual plot frame. To use: enter the J2000 sky coordinates of the source of interest in the boxes on the left in the target parameters frame and press enter or click on 'Generate Plot' button in the buttons frame. A number of different formats for RA and Dec coordinates of the target are accepted (see Target Coordinates). Alternatively, type in a target name in the 'Target Name' input box in the target frame and either press return which will resolve the name to sky coordinates or click on "Generate Plot' which will resolve the name to coordinates and generate plot in one step. See Plot Frame for info on plot layout.

2.0 ACTION BUTTONS    TOP
Action buttons allow the user to perform the following tasks:

The buttons are enabled/disabled based on the current state of PRoVis. Initially only the help button is enabled. Target coordinates or target name must first be entered to enable other buttons. Some of the buttons are enabled if target input or plot options have changed. The cancel button is enabled whenever there is a pending request in progress.

2.1 RESOLVE NAME    TOP
PRoVis accepts target name in the target frame. If the 'enter' key is pressed or 'Resolve Name' button is clicked in the buttons frame after typing in a target name, PRoVis will attempt to resolve this target name into sky coordinates using the SIMBAD server. Users can click on Cancel if SIMBAD is busy and the request is taking too long. If there are too many hits that match the target name, a 'Multiple results' message is displayed in target coordinates input box. If no target was found, a 'No results found' message is displayed.

2.2 CLEAR TARGET     TOP
Clears the information in Target Coordinates and Target Name input boxes in Target Frame

2.3 RESET DATES    TOP
Resets Start and End Dates in target frame. The dates are reset to the default values for observation cycle.

2.4 RESET OPTIONS   TOP
Resets values of options in the plot options frame to defaults.

2.5 GENERATE PLOT    TOP
Generates new plot or regenerates the existing one if a plot is already displayed. Values from target frame and plot options frame are used to set attributes of the new plot. If a target name is present and target coordinates box is empty in target frame, then this target name is resolved first and then a plot is generated.

2.6 GET POSTSCRIPT    TOP
Values from target frame and plot options frame are used to generate postscript version of a plot. Your browser must be configured to correctly handle application/postscript mime type.

2.7 CANCEL    TOP
Cancels any pending requests.

2.8 HELP     TOP
Displays this reference manual in the plot frame. The 'Generate Plot' button will return you to the plot, as long as a Target Name or Coordinates have been entered.

3.0 TARGET PARAMETERS INPUT FRAME     TOP
Target parameters input frame allows the user to specify start and end dates, target coordinates and/or target name for a desired observation.

3.1 START AND END DATES   TOP
Current ephemeris data covers Sep 30 2010 to Dec 31 2012.

For start and end dates, default values change with every observation cycle. Users may enter dates within the ephemeris provided to either zoom in or out.

If the dates entered are not within the ephemeris dates for the current cycle, the date will be displayed in yellow.

3.2 TARGET COORDINATES   TOP
Target coordinates should be specified as right ascension and declination in succession. Both RA and Dec can be specified in sexagesimal format (hours/minutes/seconds for RA, degrees/arcminutes/arcseconds for Dec) using either spaces or colons (:) as separators, or in decimal degrees. In addition, RA can be specified in decimal hours by appending either "H" or "h" (do not type the double quotes) to the decimal value. If the RA is specified in sexagesimal format then the Dec value must be separated from the RA value by a comma or a plus or minus sign, or the degree (or decimal degree) part of the Dec must have a "D" or "d" appended to it, or all three hours/minutes/seconds values must be included. In all other cases, trailing zero values for minutes/seconds (RA) or arcminutes/ arcseconds (Dec) may be dropped. Extra whitespace is always ignored.

Examples:
String entered Translation
-------------- -----------
23 59 59.9999 -89 59 59.999 23 59 59.9999 -89 59 59.999
23:59:59.9999 -89:59:59.999 23 59 59.9999 -89 59 59.999
23.7654, +0.6857 01 35 03.6960 +00 41 08.520
09h 16m 54.28s 32d 15' 6.1" 09 16 54.2800 +32 15 06.100
10.9876h, +14 10 59 15.3600 +14 00 00.000
0, 0 00 00 00.0000 +00 00 00.000
14 12, 16 10 14 12 00.0000 +16 10 00.000
14 12 +16 10 14 12 00.0000 +16 10 00.000
14 12 16d 10 14 12 00.0000 +16 10 00.000

4.0 PLOT OPTIONS INPUT FRAME   TOP
Plot options are used to set some of the attributes of the generated plots:

4.1 VIEW PITCH ANGLE   TOP
Selecting pitch angle will include the pitch angle vs. date curve in the generated plot and plot data display. The following attributes for the curve can be modified:

'Generate Plot' button must be clicked to update the plot with new attributes.

4.2 VIEW PITCH CURSOR   TOP
Selecting this option will display a marker projecting the cursor position onto pitch curve.

4.3 VIEW ROLL ANGLE   TOP
Selecting roll angle will include roll angle curve in generated plot and plot data display. The following attributes for the curve can be modified:

The 'Generate Plot' button must be clicked to update the plot with new attributes.

4.4 VIEW ROLL CURSOR   TOP
Selecting this option will display a marker projecting the cursor position onto roll curve.

4.5 VIEW AVERAGE VISIBILITY   TOP
Selecting average visibility will include average visibility curve in generated plot and plot data display. The following attributes for the curve can be modified:

The 'Generate Plot' button must be clicked to update the plot with new attributes.

4.6 VIEW VISIBILITY CURSOR   TOP
If selected, a marker will be displayed on the visibility curve at the date selected by the cursor location.

4.7 VIEW PITCH ANGLE RESTRICTIONS   TOP
Selecting this option will include bad pitch restriction regions in generated plot and plot data display. The following attributes for the curve can be modified:

The 'Generate Plot' button must be clicked to update the plot with new attributes.

Plot regions are labeled as Forbidden to indicate pitch angle constraints imposed by satellite thermal and safety considerations,as detailed in the Pitch Angle Constraints in the Proposers' Observatory Guide .

4.8 SHOW CROSSHAIR   TOP
If selected, crosshair will be displayed in the plot whenever mouse pointer hovers over it.

4.9 VIEW PLOT DATA   TOP
If selected, plot data will be displayed in tabulated format in a lower frame on the same webpage. It will be refreshed each time the date limits change. Selecting this option will automatically open another frame, while deselecting will close that frame. If autofit is selected, the plot will be regenerated to fit new frame size. Rolling mouse pointer over rows in the table will display (if selected) the cursor, crosshair and curve values in the plot for the corresponding date in the table. Clicking on a row in the table will select a row and generate shaded area on the plot corresponding to data in this row. Clicking on selected row will deselect it and corresponding shaded region in the plot will be removed.

4.10 AUTOFIT PLOT IN FRAME   TOP
If selected, autofit causes PRoVis to regenerate the plot each time the frame size changes to fill the plot framesize considering min and max allowable dimensions for the plot image.

4.11 AXIS ZOOM FACTOR   TOP
A float value which is used when zooming in and out plot limits using mouse pointer. It determines what the new limits will be in relation to the current ones whenever zooming in/out takes place. Zoom factor of 2, when zooming in will decrease interval between lower and higher limit by factor of 2, when zooming out will increase this interval by factor of 2.

4.12 AXIS MOVE FACTOR   TOP
A float value which is used when moving limits using mouse pointer. It determines what the new limits will be in relation to the current ones whenever limits are moved up or down using mouse pointer. This factor specifies by how much limits are moved in relation to the current interval between low and high limits.

4.13 POSTSCRIPT SIZE   TOP
Specifies the width and height in inches of desired postscript version of plot. If left blank, the size will be matched to the actual screen size of plot image.

4.14 FONT TYPE AND SIZE   TOP
Size and type of font to be used in text in plots.

4.15 AXIS LINE WIDTH   TOP
Width of axis line.

5.0 PLOT FRAME   TOP
Plot frame contains image of a plot, buttons to manipulate the limits of x axis and fields to display position of mouse pointer in axis units.

5.1 MOUSE POINTER POSITION   TOP
The y-axis values for the target/spacecraft at the appropriate x-axis value (date) are automatically displayed when the mouse hovers over the plot image. In addition PRoVis displays calendar date as well.

5.2 AXIS BUTTONS   TOP
The bottom side of plot contains a set of buttons that allow

5.2.1 MOVE LIMITS UP   TOP
Button right arrow moves limits up by specified fraction (taken from 'Axis Move Factor' in Plot Options frame) of current limits interval for selected axis. Axis can be reset to old values using resetbutton.

5.2.2 MOVE LIMITS DOWN   TOP
Button right arrow moves limits down by specified fraction (taken from 'Axis Move Factor' in Plot Options frame) of current limits interval for selected axis. Axis can be reset to old values using reset button.

5.2.3 ZOOM IN   TOP
Button zoom zooms in limits by specified fraction (taken from 'Axis Zoom Factor' in Plot Options frame) of current limits interval for selected axis. Axis can be reset to old values using reset button.

5.2.4 ZOOM OUT   TOP
Button zoom zooms in limits by specified fraction (taken from 'Axis Zoom Factor' in Plot Options frame) of current limits interval for selected axis. Axis can be reset to old values using resetbutton.

5.2.5 RESET LIMITS   TOP
Button reset resets the values of selected axis limits to original values set when the last 'Generate Plot' was performed.

6.0 GENERATING PLOTS   TOP
Plots can be generated in 3 ways:

PRoVis disables 'Generate Plot' button if there is an error in the target parameters (dates or coordinates) or if the existing plot matches the parameter values entered. Date problems are highlighted in appropriate field.

6.1 TARGET NAME RESOLUTION   TOP
PRoVis uses the SIMBAD catalog (located at http://simbad.harvard.edu/) to resolve the target name to celestial coordinates. To use it, type in the name of target to be resolved in 'Target Name' entry box in the target frame and press enter or click on the "Generate Plot" button (make sure though the Target Coordinates box is empty). PRoVis will only display resolved coordinates if a single result is found. If multiple matches are found, PRoVis will display a "Multiple results" message in the Target Coordinates field. If no matches are found it displays "No results found" message.

7.0 MANIPULATING PLOTS   TOP
Plots can be manipulated using buttons at the bottom of the plot image. In addition, the mouse pointer and mouse buttons can be used to various degrees depending on your browser. For all browsers:

In Mozilla Firefox, SeaMonkey, Netscape and Internet Explorer the following additional functionality is supported:

8.0 MAXIMUM EXPOSURE TIMES   TOP
For proposers whose observations require constraints for scientific reasons, once the pitch angle for a given target is known, e.g., using PRoVis, you may need to examine detailed projected estimates of usable orbit intervals (and their unusable complement during the radiation zone) at the Orbits page.

9.0 CAVEATS   TOP

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10.6.1 Thursday, November 30, 2017
The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: cxcweb@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2017. All rights reserved.