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Ramping Up the Technosignature Search

In the ever growing realm of acronyms, you can’t do much better than COSMIC – the Commensal Open-Source Multimode Interferometer Cluster Search for Extraterrestrial Intelligence. This is a collaboration between the SETI Institute and the National Radio Astronomy Observatory (NRAO), which operates the Very Large Array in New Mexico. The news out of COSMIC could not be better for technosignature hunters: Fiber optic amplifiers and splitters are now installed at each of the 27 VLA antennas.

What that means is that COSMIC will have access to the complete datastream from the entire VLA, in effect an independent copy of everything the VLA observes. Now able to acquire VLA data, the researchers are proceeding with the development of high-performance Graphical Processing Unit (GPU) code for data analysis. Thus the search for signs of technology among the stars gains momentum at the VLA.

Image: SETI Institute post-doctoral researchers, Dr Savin Varghese and Dr Chenoa Tremblay, in front of one of the 25-meter diameter dishes that makes up the Very Large Array. Credit: SETI Institute.

Jack Hickish, digital instrumentation lead for COSMIC at the SETI Institute, takes note of the interplay between the technosignature search and ongoing work at the VLA:

“Having all the VLA digital signals available to the COSMIC system is a major milestone, involving close collaboration with the NRAO VLA engineering team to ensure that the addition of the COSMIC hardware doesn’t in any way adversely affect existing VLA infrastructure. It is fantastic to have overcome the challenges of prototyping, testing, procurement, and installation – all conducted during both a global pandemic and semiconductor shortage – and we are excited to be able to move on to the next task of processing the many Tb/s of data to which we now have access.”

Tapping the VLA for the technosignature search brings powerful tools to bear, considering that each of the installation’s 27 antennas is 25 meters in diameter, and that these movable dishes can be spread over fully 22 miles. The Y-shaped configuration is found some 50 miles west of Socorro, New Mexico in the area known as the Plains of San Agustin. By combining data from the antennas, scientists can create the resolution of an antenna 36 kilometers across, with the sensitivity of a dish 130 meters in diameter.

Each of the VLA antennas uses eight cryogenically cooled receivers, covering a continuous frequency range from 1 to 50 GHz, with some of the receivers able to operate below 1 GHz. This powerful instrumentation will be brought to bear, according to sources at COSMIC SETI, on 40 million star systems, making this the most comprehensive SETI observing program ever undertaken in the northern hemisphere. (Globally, Breakthrough Listen continues its well-funded SETI program, using the Green Bank Observatory in West Virginia and the Parkes Observatory in Australia).

Cherry Ng, a SETI Institute COSMIC project scientist, points to the range the project will cover:

“We will be able to monitor millions of stars with a sensitivity high enough to detect an Arecibo-like transmitter out to a distance of 25 parsecs (81 light-years), covering an observing frequency range from 230 MHz to 50 GHz, which includes many parts of the spectrum that have not yet been explored for ETI signals.”

The VLA is currently conducting the VLA Sky Survey, a new, wide-area centimeter wavelength survey that will cover the entire visible sky. The SETI work is scheduled to begin when the new system becomes fully operational in early 2023, working in parallel with the VLASS effort.


Comments on this entry are closed.

  • Michael Fidler April 6, 2022, 8:32

    What is interesting is how far is the nearest civilazation that is still useing radio waves to communicate at interstellar distances. Half way around the galaxy? The majority of advance civilazations will be way beyond this type of communications. That is what we need to be studying what could be within 40 lightyears from earth. The closer to earth the more likly they will be way beyond anything we understand…

    • ljk April 6, 2022, 16:04

      We should be careful about assuming what hypothetical ETI may or may not be using for interstellar communications. This assumes an alien species has evolved in a similar fashion to us both biologically and technologically, and we cannot make that assumption. This is why we need to keep searching with as many plausible methods as possible until we know who and what we are dealing with.

    • Gary Wilson April 6, 2022, 16:09

      Could you expand on this a little Michael? I don’t understand the relationship between distance from Earth and level of technology of a potential advanced alien species. Shouldn’t the distribution of such a species be random?

      • Michael Fidler April 6, 2022, 20:47

        Yes, they are random and a radio civilazation could be right next to us, but here is the zinger almost all civilazation will be thousands to miillions of years ahead and the radio ETs will be very far apart or we would have picked them up by now. It’s like how many babies are around you and how many adults thru the day??? The radio era will be short lived till a much safer form will be used, maybe higher end X-rays, tight beam and reaches much further in space. Radio like a boom box or use a laser pen to hit the mark. There not talking to us because we are still the load crying baby civilazation… and their not our parents. ;-}

        • Michael Fidler April 7, 2022, 9:18

          We have had some 120 years of radio, do you really think in a thousand years we will still be useing radio to communicate? If you believe that’s fine, but if you think there are millions of ETs in our galaxy then all of them except maybe 2 or 3 are going to be much older then us. That is what I’m trying to explain, the nearest ETs are not going to be using microwaves to communicate over interstellar distances. If you think the galaxy is dead except for us, that’s fine…

          • Alex Tolley April 7, 2022, 19:43

            But don’t you believe ETI is already here, as UFOs? Wouldn’t simple hand signals, or flashlights be sufficient to communicate with them if they were interested? Since 75 years of post-WWII sightings have not indicated any desire of UFOnauts in communicating with us, perhaps they are not interested? [Just as we don’t use chemicals to communicate with ants, nor do we have instruments to “listen” to their chemical signals, and therefore ignore them – apart from using pesticides to kill them.]

            • Michael Fidler April 8, 2022, 2:20

              Since you brought it up read Paul R. Hill’s Unconventional Flying Objects. He was a well respected NASA scientist that radiation in the upper X-ray band was responsable for injuries associated with UFOs. Chapter 4 “How Hot IS UFO Radiation” gives an excellent explanation as to how X-rays can be the only form of radiation that can caused the observed effects.

              Since X-rays penetrate through plasmas that would make sense. X-ray lasers are now being built and will be used in space for interstellar transmission of data. It would be normal for any technical civilization to advance up into the X-ray/gamma ray as they become interplanetary and interstellar travelers. The only problem is, are they going to be sending out beacons in the X-ray band and if so how fast will these be? In 1/1000 you cold transmit a lot of data in the X-rays, so are we looking in that sort of time frame for ETs X-ray blast?

              Femtosecond-Attosecond-Zeptosecond X-ray Pulses.

              “As the driving laser wavelength (period) is increased, the electron’s wavefunction spreads transversely due to quantum diffusion, which rapidly reduces the single-atom HHG yield. 1 Bohr radius = 0.53 Å. Theoretically the high harmonic phase matching cut-off increases from the vacuum ultraviolet and extreme ultraviolet into the soft and hard X-ray regions of the electromagnetic spectrum. This global phase-matching picture has been validated experimentally using several laser wavelengths and nonlinear media demonstrating that bright, phase-matched HHG emission is possible over broad regions of the X-ray spectrum. Experimental phase-matched soft-X-ray supercontinua can support very short single attosecond pulses that are isolated automatically – as short as 2.5 attoseconds (1 attosecond is 1 billionth of a billionth of a second). This concept of coherent X-ray generation is predicted to scale even into the zeptosecond regime (1 zeptosecond is 1 trillionth of a billionth of a second).”


            • Michael Christopher Fidler April 12, 2022, 1:50

              For the same reason they have not landed on the white house lawn. Any advanced culture would have made contact with many other intelligent species and know what psychological shock it would cause if open contact was used.

    • Henry Cordova April 7, 2022, 0:13

      There are very good reasons why microwave radio frequencies are a good place for SETI-active civilizations to broadcast on, and SETI- passive civilizations to monitor. They have little to do with the technological capability of the civilization.

      The interstellar medium is extremely transparent to microwave radio emissions, there is little noise, or natural signals, there and the natural emission that is found there is limited to only a few extremely narrow frequency bands–all of significant astrophysical interest. Even a civilization that no longer communicates with radio is very likely to be monitoring this part of the radio spectrum because much valid radio astronomy can be done there.

      Those civilizations eager to advertise their presence are likely to broadcast at those frequencies, and those with no interest in SETI are still likely to be listening at those frequencies. If our hypothetical ET uses telepathy, tachyons, or Q-rays for routine communications, they might still employ microwave beacons because it makes sense to do so. A strong but modulated microwave emission at those frequencies would be instantly recognizable as one of artificial origin, even by a species with only modest radio expertise (like us). And it would be detectable at great distances.

      The SETI pioneers of the 1960s arrived at this conclusion because it made perfectly good sense. It still does. My own best guess is that the best place to listen would be at some harmonic of the 21 cm neutral hydrogen line. That is the frequency that is useful for mapping the spiral structure of the Milky Way, any civilization with an interest in astronomy and microwave technology capability would be familiar with it. I would choose a harmonic in order to avoid the natural background hum at 21 cm.

      And from a purely practical and Terran-Centric point of view, doing SETI with radio telescopes makes perfect sense because we’ve already deployed this equipment and know how to use it for all sorts of other applications. And even if we never pick up a signal, our investment in radio telescopes will still deliver useful scientific results.

      We don’t need to wait until we’ve mastered telepathy, tachyons or Q-rays.

      • Michael Fidler April 7, 2022, 8:52

        There is a very good reason X-rays for interstellar communications;



        X-rays might be a better way to communicate in space.


        Interstellar communication. VI. Searching X-ray spectra for narrowband communication.

        We have previously argued that targeted interstellar communication has a physical optimum at narrowband X-ray wavelengths λ≈1nm, limited by the surface roughness of focusing devices at the atomic level (arXiv:1711.05761). We search 24,247 archival X-ray spectra (of 6,454 unique objects) for such features and present 19 sources with monochromatic signals. Close examination reveals that these are most likely of natural origin. The ratio of artificial to natural sources must be <0.01%. This first limit can be improved in future X-ray surveys.


        My father was trained in microwave radar during WWII when it was as secret as the atomic bomb and I sat in front of a radar scope at the age of four so do not tell me abour how great microwaves are.

        You are still living in the 1950s and need to realize tha that higher the frequency the tighter the beam and a much higher data rate, X-rays are it…

      • Alex Tolley April 7, 2022, 9:30

        I Agree. Mammals and birds don’t have radio technology, so we use sound to listen for them when they are hidden in a forest, or communicating between themselves.

        If technological intelligence and civilization are rare in the galaxy, then it makes sense to try to detect new civilizations using the most likely, easy technology they (we) have, so radio is the probable method.

        Beyond this, we just get into speculations about motives, and the anthropocentric biases we have.

  • Alex Tolley April 6, 2022, 9:04

    No sign of Jodie Foster… ;)

    I take it the glass of water analogy is getting more like an aquarium in volume, or a beaker, or just a larger glass?

    I wish there was more comparative data, for example, how does the VLA datastream compare with the ATA in terms of coverage and range?

  • Simon April 6, 2022, 11:01

    Very interesting that this new SETI array is located near Socorro, NM as that was the location of one of the most famous “Close Encounters of the 3rd Kind” ever…

    • ljk April 6, 2022, 15:59

      Um, no…


      Quoting from the above link:

      Apart from the ‘strip’ itself, the landing site is real and has since become a major tourist attraction. The striking sawn-off peak of Devil’s Tower National Monument can be found in the northeast corner of Wyoming in the Black Hills National Forest.

      According to native legend, the strange formation was made by giant bears clawing at a mountain to reach a princess on the summit. More prosaically, according to science, it’s an ‘igneous intrusion’ – solidified magma which had welled up inside (since eroded) sedimentary rock.

      Devil’s Tower was designated the US’ first national monument, in 1906. It’s open all year round, and there’s a visitor centre open from April to October, about three miles from the entrance. It’s 33 miles northeast of Moorcroft, I-90.

      More on Devil’s Tower National Monument from the U.S. National Park Service:


      And a nice video on the filming locations:


      • randomengineer April 7, 2022, 13:20

        I took it he was referring to Roswell.

    • orion e April 10, 2022, 1:55

      The VLA is not new;
      it went online in the late 70s.

  • ljk April 6, 2022, 11:13


    [Submitted on 26 Oct 2021]

    Evolutionary and Observational Consequences of Dyson Sphere Feedback

    Macy J. Huston, Jason T. Wright

    The search for signs of extraterrestrial technology, or technosignatures, includes the search for objects which collect starlight for some technological use, such as those composing a Dyson sphere. These searches typically account for a star’s light and some blackbody temperature for the surrounding structure. However, such a structure inevitably returns some light back to the surface of its star, either from direct reflection or thermal re-emission.

    In this work, we explore how this feedback may affect the structure and evolution of stars, and when such feedback may affect observations. We find that in general this returned light can cause stars to expand and cool.

    Our MESA models show that this energy is only transported toward a star’s core effectively by convection, so low mass stars are strongly affected, while higher mass stars with radiative exteriors are not.

    Ultimately, the effect only has significant observational consequences for spheres with very high temperatures (much higher than the often assumed ~300 K) and/or high specular reflectivity. Lastly, we produce color-magnitude diagrams of combined star-Dyson sphere systems for a wide array of possible configurations.

    Comments: 21 pages, 12 figures, accepted to ApJ

    Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

    Cite as: arXiv:2110.13887 [astro-ph.SR]
    (or arXiv:2110.13887v1 [astro-ph.SR] for this version)


    Focus to learn more

    Related DOI:

    Submission history

    From: Macy Huston [view email]
    [v1] Tue, 26 Oct 2021 17:43:27 UTC (12,368 KB)


  • ljk April 6, 2022, 11:37

    COSMIC: All Antennas at the Very Large Array Ready to Stream Data for Technosignature Research

    Source: SETI Institute

    Posted April 4, 2022 11:24 PM


    To quote:

    There are several advantages to conducting SETI research with the VLA:

    The size of the VLA: Each of the VLA’s 27 antennas is 25 meters in diameter, spread over 22 miles

    The VLA has a combined collecting area equivalent to a single-dish antenna of 130 meters across

    Each VLA antenna has 8 cryogenically cooled receivers covering the radio spectrum continuously from 1 to 50 GHz

    Some receivers can operate below 1 GHz down to 54 MHz, a band used on Earth for television broadcasting

    Once up and running, it is estimated that COSMIC SETI will observe about 40 million galactic star systems in two years. It will be the most comprehensive SETI observing program undertaken in the Northern Hemisphere, with high sensitivity and a huge target list.

    “I am excited by the ability of COSMIC to conduct the most comprehensive technosignature search ever in the Northern Hemisphere,” said Cherry Ng, SETI Institute COSMIC Project Scientist.

    “We will be able to monitor millions of stars with a sensitivity high enough to detect an Arecibo-like transmitter out to a distance of 25 parsecs (81 light-years), covering an observing frequency range from 230 MHz to 50 GHz, which includes many parts of the spectrum that have not yet been explored for ETI signals.”

    The system should be fully operational by early 2023 and will conduct its first major observational campaign in parallel with the ongoing VLA Sky Survey (VLASS).

    “We look forward to partnering with the SETI Institute on this exciting initiative and are pleased to see this important milestone in the technical work that will make this new science possible,” said NRAO Director Tony Beasley.

    Only 25 years after they were doing SETI work in Contact…




    Arecibo might have been bigger and better than the VLA at conducting SETI, but guess what? It’s the only game in our part of the town now. Yes there is FAST in China, but with the current state of things we in the West may not have access to it if the geopolitical situation deteriorates.

    That we are in this situation shows how far science needs to go to enlighten and uplift humanity. I am not saying it is science’s fault, only that the PR isn’t quite reaching the people it needs to in order to keep our civilized society from collapsing. This should also be a lesson to those who would ideally like to keep science and politics separate. Maybe you can on a personal level, but not a global one, and especially not if you want to do real science.

  • Steve Muise April 6, 2022, 21:04

    “We will be able to monitor millions of stars with a sensitivity high enough to detect an Arecibo-like transmitter out to a distance of 25 parsecs (81 light-years)”

    This would require a technical civilization that’s also currently broadcasting to be within 100 ly of us AND to exist concurrently with our own.

    While this isn’t impossible it does appear unlikely. I have a sneaking suspicion that technological civilizations are separated as much by time as they are by distance.

    It’s worth the effort to search, but a null result may not mean much.

  • Jeff Wright April 8, 2022, 4:26

    Meteor Crater could be a great dish.

  • ljk April 8, 2022, 13:18

    If Aliens Were Sending us Signals, This is What They Might Look Like

    APRIL 7, 2022


    For over sixty years, scientists have been searching the cosmos for possible signs of radio transmission that would indicate the existence of extraterrestrial intelligence (ETI). In that time, the technology and methods have matured considerably, but the greatest challenges remain. In addition to having never detected a radio signal of extraterrestrial origin, there is a wide range of possible forms that such a broadcast could take.

    In short, SETI researchers must assume what a signal would look like, but without the benefit of any known examples. Recently, an international team led by the University of California Berkeley and the SETI Institute developed a new machine learning tool that simulates what a message from extraterrestrial intelligence (ETI) might look like. It’s known as Setigen, an open-source library that could be a game-changer for future SETI research!

    Full article here:


    To quote:

    The primary search algorithm used by SETI researchers is known as the “incoherent tree deDoppler” algorithm, which shifts the spectrum of radio waves to correct for frequency drift and maximizes the signal-to-noise ratio of a signal. The most comprehensive SETI search program ever mounted, Breakthrough Listen, uses an open-source version of this algorithm known as TurboSETI, which has served as the backbone of many “technosignatures” searches (aka. signs of technological activity). As Brzycki explained, this method has some drawbacks:

    “The algorithm makes the assumption that a potential SETI signal is continuous with a high duty-cycle (meaning that it’s almost always ‘on’). Looking for a continuous sine-wave signal is a good first step since it’s relatively easy and inexpensive in power for humans to produce and transmit such signals.

    “Since TurboSETI is targeted for straight-line signals that are always ‘on’, it can struggle to pick up alternate morphologies, like broadband and pulsed signals. Additional algorithms are being developed to try to detect these other kinds of signals, but as always, our algorithms are only as effective as the assumptions we make of the signals they are targeted for.”

    For SETI researchers, machine learning is a way of identifying transmissions in raw radio frequency data and classifying multiple types of signals. The main issue, says Brzycki, is that the astronomical community doesn’t have a dataset of ET signals, which makes supervised training difficult in the traditional sense. To this end, Brzycki and his colleagues developed a Python-based open-source library called Setigen that facilitates the production of synthetic radio observations.

    “What Setigen does is facilitate the production of synthetic SETI signals, which can be used in entirely synthetic data, or added on top of real observational data to provide a more realistic noise and RFI background,” said Brzycki. “This way, we can produce large datasets of synthetic signals to analyze the sensitivity of existing algorithms or to serve as a basis for machine learning training!”

    • Alex Tolley April 8, 2022, 18:11

      And if ETI doesn’t use radio…?

      • ljk April 11, 2022, 9:56

        If I were in charge of such projects there would be searches on multiple wavelengths. So until that day arrives I guess we just better hope there are some old school aliens about.

  • Mike Serfas April 10, 2022, 23:39

    I’m curious if the “quantum hair” of black holes implies the possibility of gravity-based signals other than the classical gravitational waves of general relativity. (See https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.128.111301 ) If anyone who figures out radio will figure out a dust-penetrating communications method in a couple of centuries, I can imagine aliens might not bother with it.

    • Ron S. April 11, 2022, 8:36

      Why do you think a new approach to information loss in black holes has anything to do with gravitational wave radiation?

  • ljk April 11, 2022, 11:57

    If we ever want to advance beyond being a one-planet tribal species barely keeping our civilization together, then yes…


  • ljk April 14, 2022, 11:22


    [Submitted on 12 Apr 2022]

    Is there a background population of high-albedo objects in geosynchronous orbits around Earth?

    Beatriz Villarroel, Enrique Solano, Hichem Guergouri, Alina Streblyanska, Lars Mattsson, Rudolf E. Bär, Jamal Mimouni, Stefan Geier, Alok C. Gupta, Vanessa Okororie, Khaoula Laggoune, Matthew E. Shultz, Robert A. Freitas Jr., Martin J. Ward

    Old, digitized astronomical images taken before the human spacefaring age offer a unique view of the sky devoid of known artificial satellites.

    In this paper, we have carried out the first optical searches ever for non-terrestrial artifacts near the Earth following the method proposed in Villarroel et al. (2022).

    We use images contained in the First Palomar Sky Survey to search for simultaneous (during a plate exposure time) transients that in addition to being point-like, are aligned.

    We provide a shortlist of the most promising candidates of aligned transients, that must be examined with the help of a microscope to separate celestial sources from plate defects with coincidentally star-like brightness profiles.

    We further explore one possible, but not unique, interpretation in terms of fast reflections off high-albedo objects in geosynchronous orbits around Earth.

    If a future study rules out each multiple transient candidate, the estimated surface density becomes an upper limit of <10−9 objects km−2 non-terrestrial artifacts in geosynchronous orbits around Earth.

    Finally, we conclude that observations and analysis of multiple, simultaneously appearing and vanishing light sources on the sky merit serious further attention, regardless of their origin.

    Comments: Submitted to Astronomical Journal

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

    Cite as: arXiv:2204.06091 [astro-ph.EP]
    (or arXiv:2204.06091v1 [astro-ph.EP] for this version)


    Submission history

    From: Beatriz Villarroel [view email]
    [v1] Tue, 12 Apr 2022 21:51:54 UTC (23,322 KB)


  • ljk April 14, 2022, 11:30


    [Submitted on 21 Jun 2021]

    Exploring nine simultaneously occurring transients on April 12th 1950

    Beatriz Villarroel, Geoffrey W. Marcy, Stefan Geier, Alina Streblyanska, Enrique Solano Marquez, Vitaly N. Andruk, Matthew E. Shultz, Alok C. Gupta, Lars Mattsson

    Nine point sources appeared within half an hour on a region within ∼ 10 arcmin of a red-sensitive photographic plate taken in April 1950 as part of the historic Palomar Sky Survey. All nine sources are absent on both previous and later photographic images, and absent in modern surveys with CCD detectors which go several magnitudes deeper.

    We present deep CCD images with the 10.4-meter Gran Telescopio Canarias (GTC), reaching brightness r∼26 mag, that reveal possible optical counterparts, although these counterparts could equally well be just chance projections.

    The incidence of transients in the investigated photographic plate is far higher than expected from known detection rates of optical counterparts to e.g.\ flaring dwarf stars, Fast Radio Bursts (FRBs), Gamma Ray Bursts (GRBs) or microlensing events.

    One possible explanation is that the plates have been subjected to an unknown type of contamination producing mainly point sources with of varying intensities along with some mechanism of concentration within a radius of ∼ 10 arcmin on the plate.

    If contamination as an explanation can be fully excluded, another possibility is fast (t <0.5 s) solar reflections from objects near geosynchronous orbits.

    An alternative route to confirm the latter scenario is by looking for images from the First Palomar Sky Survey where multiple transients follow a line.

    Comments: 21 pages, 3 figures, 1 table. Published in Scientific Reports. Supplementary information can be found on the publishers webpage (open access)

    Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE); Space Physics (physics.space-ph)

    Report number: NORDITA 2021-059

    Cite as: arXiv:2106.11780 [astro-ph.IM]
    (or arXiv:2106.11780v1 [astro-ph.IM] for this version)


    Journal reference: Scientific Reports volume 11, Article number: 12794 (2021)

    Related DOI:

    Submission history

    From: Lars Mattsson [view email]
    [v1] Mon, 21 Jun 2021 13:49:34 UTC (2,422 KB)


  • ljk May 2, 2022, 17:02
  • stephen May 10, 2022, 22:34

    I was wondering…EM radiation of 1 meter wavelength is a billion times longer than gamma radiation, and the two are extremely different. So EM radiation of a billion meters wavelength might be extremely different from radio waves…? It would be weak and hard to detect, and maybe that’s why ETI might be using it…?

  • ljk May 12, 2022, 14:58

    An approximation to determine the source of the WOW! Signal

    Published online by Cambridge University Press: 06 May 2022



    In this paper it is analysed which of the thousands of stars in the WOW! Signal region could have the highest chance of being the real source of the signal, providing that it came from a star system similar to ours. A total of 66 G and K-type stars are sampled, but only one of them is identified as a potential Sun-like star considering the available information in the Gaia Archive. This candidate source, which is named 2MASS 19281982-2640123, therefore becomes an ideal target to conduct observations in the search for techno-signatures. Another two candidate stars have a luminosity error interval that includes the luminosity of the Sun, and 14 candidates more are also identified as potential Sun-like stars, but the estimations on their luminosity were unknown.