| extracting
a power spectrum |
|||
| input command/response | description of input command/response |
software response to input |
information
returned after execution of input command/response and before software response |
| Type powspec |
Opens the power spectrum routine |
Ser. 1 filename +options (or
@file of filenames +options) [ ] |
|
| filename.lc or @filename.txt |
if finding the power spectrum of
a single light curve if finding the power spectrum of a concatenated set of files; see below |
Name of the window file ('-' for default window). |
Displays information about the *.lc file, e.g., source name, coordinates, start/stop time, bin time, etc. |
| Type - |
Tells xselect what window file
you want to use. |
Newbin Time or negative rebinning [3.241] |
Displays Minimum Newbin Time(s); this should match time resolution Displays Default Newbin Time (which must be an integer multiple of the Minimum Newbin Time); Default Newbin Time chosen so that number of bins is close to an integer power of 2 (helpful for Fourier transform process) |
| 3.2410400 | A bin is an interval
of time over which the data is lumped together for analysis. Select the Minimum Newbin Time to match the time resolution ("timedel" in fits header for image) of the data. It is commonly used unless there are too few photons in this bin size. The Newbin Time entered MUST be an integral multiple of the Minimum Newbin Time.In general, enter the default value |
Number of Newbins/Interval [14433] | Confirms the Newbin Time entered. Displays number of Newbins covering the exposure time interval. |
| 14433 |
The prompt is asking
how many bins you want the complete data set broken into. Select Maximum Newbin No. in order to see the entire observation. In general, enter the default value |
Number of Intervals/Frame [1] | Confirms number of Newbins and Newbin TIme interval. |
| 1 |
A
frame is the
average of the
results of analysis of several intervals.
1 provides a sum of the data, whereas a number N averages N number of
files in the data set. Tells powspec that all data should be collected in one inteval of time |
Rebin results? |
Confirms that all data will be collected in 1 interval. |
| 0 |
Rebins
results into
different
time segments. Default is 0. (allows another opportunity for rebinning?) |
Name of output file? [powspec_objectname] |
|
| suggest
using obsid |
Saves power spectrum
results in an output .fps file which can then be manipulated
by the fdump routine. The default option saves the power spectrum with a filename identical to that used for the input file (either a .lc or a ) but ending with the .fps extension. |
Do you want to plot your results? [yes] | power spectrum file has .fps
extension |
| yes |
plots power spectrum |
Enter PGPLOT device [/xw] |
|
| /xw | Selects device used for drawing the graph on screen. Most commonly this is /xw or sometimes /xterm | Power Spectrum Ready! |
|
| Under the PLT> type hardcopy |
Saves the power spectrum file
and closes the window |
||
| Type exit |
Exits PLT> and returns to
either UNIX or xselect prompt |
||
| concatenating files for use in powspec Run lcurve on each data set separately to obtain a .flc file for each List all .flc files, one per line, in a text file, e.g., powcat.txt i.e., filename1.flc filename2,flc etc. Run the powspec routine, but respond when prompted for the filename with @powcat.txt when prompted for the number of intervals per frame: choose 1 if you want a concatenation of the data by adding (this is best) choose N (= number of files in the concatenated list) if you want to concatenate by averaging |