J/AJ/161/55 Observation of 31 G-stars at 1.5GHz with GBT (Margot+, 2021)
A search for technosignatures around 31 Sun-like stars with the Green Bank
Telescope at 1.15-1.73GHz.
Margot J.-L., Pinchuk P., Geil R., Alexander S., Arora S., Biswas S.,
Cebreros J., Desai S.P., Duclos B., Dunne R., Lin Fu K.K., Goel S.,
Gonzales J., Gonzalez A., Jain R., Lam A., Lewis B., Lewis R., Li G.,
MacDougall M., Makarem C., Manan I., Molina E., Nagib C., Neville K.,
O'Toole C., Rockwell V., Rokushima Y., Romanek G., Schmidgall C., Seth S.,
Shah R., Shimane Y., Singhal M., Tokadjian A., Villafana L., Wang Z., Yun
In, Zhu L., Lynch R.S.
<Astron. J., 161, 55 (2021)>
=2021AJ....161...55M 2021AJ....161...55M
ADC_Keywords: Stars, G-type; Milky Way; Radio sources; Exoplanets;
Spectral types; Parallaxes, trigonometric
Keywords: Search for extraterrestrial intelligence ; Technosignatures ;
Astrobiology ; Exoplanets ; Solar analogs ; Radio astronomy ;
Milky Way Galaxy
Abstract:
We conducted a search for technosignatures in 2018 and 2019 April with
the L-band receiver (1.15-1.73GHz) of the 100m diameter Green Bank
Telescope. These observations focused on regions surrounding 31
Sun-like stars near the plane of the Galaxy. We present the results of
our search for narrowband signals in this data set, as well as
improvements to our data processing pipeline. Specifically, we applied
an improved candidate signal detection procedure that relies on the
topographic prominence of the signal power, which nearly doubles the
signal detection count of some previously analyzed data sets. We also
improved the direction-of-origin filters that remove most radio
frequency interference (RFI) to ensure that they uniquely link signals
observed in separate scans. We performed a preliminary signal
injection and recovery analysis to test the performance of our
pipeline. We found that our pipeline recovers 93% of the injected
signals over the usable frequency range of the receiver and 98% if we
exclude regions with dense RFI. In this analysis, 99.73% of the
recovered signals were correctly classified as technosignature
candidates. Our improved data processing pipeline classified over
99.84% of the ∼26million signals detected in our data as RFI. Of the
remaining candidates, 4539 were detected outside of known RFI
frequency regions. The remaining candidates were visually inspected
and verified to be of anthropogenic nature. Our search compares
favorably to other recent searches in terms of end-to-end sensitivity,
frequency drift rate coverage, and signal detection count per unit
bandwidth per unit integration time.
Description:
We selected 31 Sun-like stars (spectral type G, luminosity class V)
with a median galactic latitude of 0.85°. We observed these stars
with the Green Bank Telescope (GBT) during two 2hr sessions separated
by approximately 1yr. During each observing session, we recorded both
linear polarizations of the L-band receiver with the GUPPI back end in
its baseband recording mode. The center frequency was set to 1.5GHz,
and we sampled 800MHz of bandwidth between 1.1 and 1.9GHz.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 31 *Target host stars listed in order of observation
table3.dat 67 20000 Properties of artificial signals used for the signal
injection and recovery analysis
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Note on table1.dat: Spectral types, galactic coordinates, and parallax
measurements were obtained from the SIMBAD database. Distances in
light years were calculated from the parallax measurements.
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See also:
B/simbad : Simbad objects catalogue (M.Wenger 2000)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJS/207/35 : Kepler pipeline signal-to-noise studies (Christiansen+,2013)
J/ApJ/767/94 : 1.1-1.9GHz SETI survey of KOIs. I. (Siemion+, 2013)
J/AJ/152/181 : SETI observations of exoplanets with the ATA (Harp+, 2016)
J/ApJ/869/66 : Search for extraterrestrial intelligence with ATA (Harp+, 2018)
J/MNRAS/498/5720 : Extended Breakthrough Listen sample (Wlodarczyk-Sroka+,2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Target name
17 A1 --- f_Name [a] Flag on Name (1)
19- 21 A3 --- SpT Spectral Type
23- 27 F5.1 deg GLON [185/217] Galactic longitude
29- 33 F5.2 deg GLAT [-2.1/3.13] Galactic latitude
35- 40 F6.4 mas plx [0.31/9.99]? Parallax
42- 47 F6.4 mas e_plx [0.02/0.1]? Error on plx
49- 53 I5 al Dist [327/10407]? Distance
55- 57 I3 al e_Dist [1/850]? Error on Dist
59- 72 F14.8 d MJD [58235.8/58600] Modified Julian Date of scan 1
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Note (1): Flag as follows:
a = The source paired with TYC 739-1210-1 was observed only once and
not analyzed.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Target name
17- 17 I1 --- Scan [1/2] Scan number
19- 36 F18.7 Hz Freq [1151579746/1729676870] Frequency of injection at the
start of the scan
38- 58 F21.18 Hz/s df/dt [-8.87/8.87] Injected frequency drift rate
60- 61 I2 --- SNR [10/20] Injected signal to noise
63- 63 A1 --- DET? Signal was recovered by the pipeline
65- 67 A3 --- DOO? Direction-of-origin filter made the correct
assignment, (Y)es, (N)o, or N/A.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 25-Mar-2021