This is not a real observation. It's a generated .fil file that was created using fake tool from sigproc. It was created using the following command:
fake -period 714 -nbits 16 -nchans 16 -tobs 30 -fch1 463.1875 -foff 0.375 > fake.fil
Parameters mean period 714ms, samples are 16 bits, there are 16 channels, simulated observation was 30s, the first channel was 463.18175, each channel width is 0.375MHz. The parameters were chosen so to get something as close to 2021-10-24 observation as possible.
Inspecting the file:
$readfile fake.fil
Assuming the data is a SIGPROC filterbank file.
1: From the SIGPROC filterbank file 'fake.fil':
Telescope = Parkes
Source Name = P: 714.000000000000 ms, DM: 715.662
Backend = Unknown
Obs Date String = 1995-10-10T00:00:00
MJD start time = 50000.00000000000000
RA J2000 = 00:00:00.0000
RA J2000 (deg) = 0
Dec J2000 = 00:00:00.0000
Dec J2000 (deg) = 0
Tracking? = True
Azimuth (deg) = 1.976263e-323
Zenith Ang (deg) = 6.931535e-310
Number of polns = 2 (summed)
Sample time (us) = 80
Central freq (MHz) = 460.375
Low channel (MHz) = 457.5625
High channel (MHz) = 463.1875
Channel width (MHz) = 0.375
Number of channels = 16
Total Bandwidth (MHz) = 6
Beam = 1 of 1
Beam FWHM (deg) = 0.700
Spectra per subint = 2400
Spectra per file = 375296
Time per subint (sec) = 0.192
Time per file (sec) = 30.02368
bits per sample = 16
bytes per spectra = 32
samples per spectra = 16
bytes per subint = 76800
samples per subint = 38400
zero offset = 0
Invert the band? = False
bytes in file header = 245
After some experiments (-time 10, -time 1, -time 3, -time 10 -noclip) I found that -time 3 works best.
Bad attempt:
$ rfifind -time 10 -o fake10 fake.fil
Pulsar Data RFI Finder
by Scott M. Ransom
Assuming the data are SIGPROC filterbank format...
Reading SIGPROC filterbank data from 1 file:
'fake.fil'
Number of files = 1
Num of polns = 2 (summed)
Center freq (MHz) = 460.375
Num of channels = 16
Sample time (s) = 8e-05
Spectra/subint = 2400
Total points (N) = 375296
Total time (s) = 30.02368
Clipping sigma = 6.000
Invert the band? = False
Byteswap? = False
Remove zeroDM? = False
File Start Spec Samples Padding Start MJD
---- ---------- ---------- ---------- --------------------
1 0 375296 0 50000.00000000000000
Analyzing data sections of length 124800 points (9.984 sec).
Prime factors are: 2 2 2 2 2 2 2 3 5 5 13
Writing mask data to 'fake10_rfifind.mask'.
Writing RFI data to 'fake10_rfifind.rfi'.
Writing statistics to 'fake10_rfifind.stats'.
Massaging the data ...
Amount Complete = 100%
There are 99 RFI instances.
Total number of intervals in the data: 64
Number of padded intervals: 16 (25.000%)
Number of good intervals: 0 ( 0.000%)
Number of bad intervals: 48 (75.000%)
Ten most significant birdies:
# Sigma Period(ms) Freq(Hz) Number
----------------------------------------------------
1 9.87 118.857 8.41346 248
2 9.82 119.569 8.36338 238
3 8.78 178.286 5.60897 233
4 8.41 179.892 5.55889 201
5 8.05 356.571 2.80449 242
6 7.50 59.606 16.7768 114
7 7.48 89.5426 11.1679 155
8 7.41 47.8849 20.8834 3
9 7.40 363.055 2.75441 203
10 7.38 59.4286 16.8269 117
Ten most numerous birdies:
# Number Period(ms) Freq(Hz) Sigma
----------------------------------------------------
1 248 118.857 8.41346 9.87
2 242 356.571 2.80449 8.05
3 238 119.569 8.36338 9.82
4 233 178.286 5.60897 8.78
5 203 363.055 2.75441 7.40
6 201 179.892 5.55889 8.41
7 200 237.714 4.20673 6.90
8 179 89.1429 11.2179 7.11
9 160 118.154 8.46354 7.19
10 155 89.5426 11.1679 7.48
Done.
Good attempt:
$ rfifind -time 3 -o rfifind_time3 fake.fil
Pulsar Data RFI Finder
by Scott M. Ransom
Assuming the data are SIGPROC filterbank format...
Reading SIGPROC filterbank data from 1 file:
'fake.fil'
Number of files = 1
Num of polns = 2 (summed)
Center freq (MHz) = 460.375
Num of channels = 16
Sample time (s) = 8e-05
Spectra/subint = 2400
Total points (N) = 375296
Total time (s) = 30.02368
Clipping sigma = 6.000
Invert the band? = False
Byteswap? = False
Remove zeroDM? = False
File Start Spec Samples Padding Start MJD
---- ---------- ---------- ---------- --------------------
1 0 375296 0 50000.00000000000000
Analyzing data sections of length 38400 points (3.072 sec).
Prime factors are: 2 2 2 2 2 2 2 2 2 3 5 5
Writing mask data to 'rfifind_time3_rfifind.mask'.
Writing RFI data to 'rfifind_time3_rfifind.rfi'.
Writing statistics to 'rfifind_time3_rfifind.stats'.
Massaging the data ...
Amount Complete = 100%
There are 27 RFI instances.
Total number of intervals in the data: 160
Number of padded intervals: 16 (10.000%)
Number of good intervals: 143 (89.375%)
Number of bad intervals: 1 ( 0.625%)
Ten most significant birdies:
# Sigma Period(ms) Freq(Hz) Number
----------------------------------------------------
1 5.95 61.44 16.276 1
2 5.84 60.8317 16.4388 2
3 5.70 62.0606 16.1133 1
4 5.65 186.182 5.37109 1
5 5.47 62.6939 15.9505 1
6 5.21 87.7714 11.3932 1
7 4.94 90.3529 11.0677 7
8 4.69 59.6505 16.7643 18
9 4.69 175.543 5.69661 1
10 4.65 118.154 8.46354 20
Ten most numerous birdies:
# Number Period(ms) Freq(Hz) Sigma
----------------------------------------------------
1 20 118.154 8.46354 4.65
2 18 59.6505 16.7643 4.69
3 8 180.706 5.53385 4.57
4 8 120.471 8.30078 4.35
5 7 90.3529 11.0677 4.94
6 6 60.2353 16.6016 4.45
7 6 59.0769 16.9271 4.41
8 5 91.7015 10.9049 4.52
9 4 236.308 4.23177 4.59
10 3 102.4 9.76562 4.37
Done.
I'm particularly pleased with the good intervals being 89%. This is what the rfifind generated in the .ps file. .ps files can be viewed with gv tool.
prepdata -nobary -o rfifind_time3_rfifind_zerodm -dm 0.0 -mask rfifind_time3_rfifind.mask fake.fil
This step generated rfifind_time3_rfifind_zerodm.dat file. It can be explored using exploredat rfifind_time3_rfifind_zerodm.dat.
realfft rfifind_time3_rfifind_zerodm.dat then processed the data through another FFT. The resulting file (rfifind_time3_rfifind_zerodm.fft) can be viewed with explorefft. To view anything useful, I had to change the Y scale a bit (hit + couple times).
$ accelsearch -numharm 4 -zmax 0 rfifind_time3_rfifind_zerodm.dat
Fourier-Domain Acceleration and Jerk Search Routine
by Scott M. Ransom
Analyzing P: 714.000000000000 ms, DM: 715.662 data from 'rfifind_time3_rfifind_zerodm.dat'.
Reading and FFTing the time series...done.
Removing red-noise...done.
Normalizing powers using median-blocks (default).
Full f-fdot plane would need 0.00 GB: using in-memory accelsearch.
Searching with up to 4 harmonics summed:
f = 1.0 to 6250.0 Hz
r = 30.0 to 191999.0 Fourier bins
z = 0.0 to 0.0 Fourier bins drifted
Generating correlation kernels:
Harm 1/1 : 1 kernels, 0 < z < 0 (2048 pt FFTs)
Total RAM used by correlation kernels: 0.000 GB
Done generating kernels.
Starting the search.
Amount of search complete = 100%
Done searching. Now optimizing each candidate.
Removed 9 likely harmonically related candidates.
Amount of optimization complete = 100%
width < len (14) in center_string(outstring, ' 0.3(2.2)x10^1', width=12)
Searched the following approx numbers of independent points:
1 harmonic: 191969
2 harmonics: 95984
4 harmonics: 47992
Timing summary:
CPU time: 0.040 sec (User: 0.040 sec, System: 0.000 sec)
Total time: 0.050 sec
Final candidates in binary format are in 'rfifind_time3_rfifind_zerodm_ACCEL_0.cand'.
Final Candidates in a text format are in 'rfifind_time3_rfifind_zerodm_ACCEL_0'.
Those two files (rfifind_time3_rfifind_zerodm_ACCEL_0 and rfifind_time3_rfifind_zerodm_ACCEL_0.cand) are super useful.
Here's content of the rfifind_time3_rfifind_zerodm_ACCEL_0 file:
Summed Coherent Num Period Frequency FFT 'r' Freq Deriv FFT 'z' Accel...........................
Cand Sigma Power Power Harm (ms) (Hz) (bin) (Hz/s) (bins) (m/s^2) Notes........
------------------------------------------------------------------------------------------------------------------------------------------------------------
1 20.77 245.12 93.63 4 714(2) 1.400(4) 43.00(13) 0.0000(5) 0.00(50) 0.0(1.1)x10^5.........................
2 4.23 23.53 18.53 1 23.028(9) 43.42(2) 1334.00(50) 0.000(2) 0.0(2.0) 0.0(1.5)x10^4 H 30 of Cand 1
3 2.73 17.93 10.85 1 0.1691378(5) 5912.34(2) 181627.00(50) 0.000(2) 0.0(2.0) 0.0(1.1)x10^2.........................
4 2.29 23.03 5.70 4 1.126647(5) 887.590(4) 27266.75(13) 0.0000(5) 0.00(50) 0.0(1.8)x10^2.........................
Power / Raw FFT 'r' Pred 'r' FFT 'z' Pred 'z' Phase Centroid Purity........................
Cand Harm Sigma Loc Pow Power (bin) (bin) (bins) (bins) (rad) (0-1) <p> = 1 Notes........
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1 1 21.83 242(22) 202 43.010(25) 43.00 0.09(20) 0.00 1.727(45) 0.487(13) 0.982(21)........................
2 0.00 0.27(73) 0.343 86.02(36) 86.00 0.2(1.3) 0.00 0.2(1.4) 0.12(39) 2.09(29).........................
3 8.14 36.2(8.5) 45.9 129.029(63) 129.00 0.28(48) 0.00 2.13(12) 0.421(34) 1.026(51)........................
4 0.63 1.3(1.6) 1.66 172.04(33) 172.00 0.4(2.5) 0.00 5.77(61) 0.39(18) 1.03(27).........................
2 1 5.63 18.5(6.1) 27.2 1333.790(90) 1334.00 -0.53(70) 0.00 0.42(16) 0.480(47) 1.002(73)........................
3 1 4.11 10.9(4.7) 19.3 181627.13(13) 181627.00 -1.7(1.2) 0.00 1.16(21) 0.506(62) 0.89(11).........................
4 1 1.63 3.0(2.4) 2.52 27265.75(80) 27266.75 0.3(2.2)x10 0.00 3.90(41) 0.69(12) 0.28(64).........................
2 3.28 7.6(3.9) 6.57 54531.50(13) 54533.50 6.75(91) 0.00 5.37(26) 0.544(74) 1.10(10).........................
3 1.11 2.0(2.0) 2.8 81797.26(26) 81800.25 10.1(1.9) 0.00 1.80(50) 0.60(14) 1.06(21).........................
4 1.76 3.2(2.5) 2.72 109063.01(30) 109067.00 13.5(3.2) 0.00 5.01(39) 0.47(11) 0.73(24).........................
Data file name without suffix = rfifind_time3_rfifind_zerodm
Telescope used = Parkes
Instrument used = Unknown
Object being observed = P: 714.000000000000 ms, DM: 715.662
J2000 Right Ascension (hh:mm:ss.ssss) = 00:00:00.0000
J2000 Declination (dd:mm:ss.ssss) = 00:00:00.0000
Data observed by = unset
Epoch of observation (MJD) = 50000.000000000000000
Barycentered? (1 yes, 0 no) = 0
Number of bins in the time series = 384000.....
Width of each time series bin (sec) = 8e-05
Any breaks in the data? (1 yes, 0 no) = 1
On/Off bin pair # 1 = 0 , 374399.....
On/Off bin pair # 2 = 383999 , 383999.....
Type of observation (EM band) = Radio
Beam diameter (arcsec) = 2518
Dispersion measure (cm-3 pc) = 0
Central freq of low channel (MHz) = 457.5625
Total bandwidth (MHz) = 6
Number of channels = 16
Channel bandwidth (MHz) = 0.375
Data analyzed by = thomson
Any additional notes:
Project ID unset, Date: 1995-10-10T00:00:00.
2 polns were summed. Samples have 16 bits.
The most important lines are 1 and 2:
Summed Coherent Num Period Frequency FFT 'r' Freq Deriv FFT 'z' Accel...........................
Cand Sigma Power Power Harm (ms) (Hz) (bin) (Hz/s) (bins) (m/s^2) Notes........
------------------------------------------------------------------------------------------------------------------------------------------------------------
1 20.77 245.12 93.63 4 714(2) 1.400(4) 43.00(13) 0.0000(5) 0.00(50) 0.0(1.1)x10^5.........................
The prepdata found out that there is a signal with 714ms, which is exactly what was using during generation of this fake.fil