Observatory Marlin (Ben) Schuetz June 26, 2018

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1 August 7, 2018 Observations and other updates A new paper titled, "Recent Developments at the Boquete Optical SETI Observatory and Owl Observatory", was posted at: The paper summarizes the observatories' latest capabilities and the new work in progress. New Detector goes into service at the Boquete Optical SETI Observatory Marlin (Ben) Schuetz June 26, 2018 The Boquete Observatory has been dedicated to optical SETI for over 8 years. During that time several innovative detector systems have been developed. The latest version employs very high speed PECL chips and a digital discrimination method to detect peculiarities embedded in random stellar noise. It is believed to be the first such system to demonstrate over a wide range the relationship of multiple events occurring in extremely short intervals, i.e., 50 ns, in accordance with that predicted by Poisson statistics. The detector also has greater sensitivity for the sought after signals than any of its predecessors. The first attempt at this type of detector was done about two years ago using TTL integrated circuits. While the design was confirmed, the circuits were too slow to be useful on the telescope. Much faster emitter coupled logic (ECL) components were available, but this researcher had no experience using them and at that time was fearful that the available prototyping methods would not be adequate. Still, it was the only way forward and it was eventually decided to begin developing a background with such devices. The simplest approach was to use positive emitter coupled logic (PECL) integrated circuit chips and to develop a board employing an analog discriminator method. That detection method has been used here successfully for several years with TTL ICs. If that performed well, another board would be built using the more desirable digital discriminator technique.

2 After a somewhat difficult learning process, the first PECL board was completed and put into service on the telescope in the fall of 2017 where it has performed well. In early 2018 work began on the more difficult design having a digital discriminator. The fabrication was completed in April and it had been undergoing bench tests until completion yesterday. During testing, the results were both very good and for a time baffling. Out of a group of events that occur randomly over time, Poisson statistics predicts the number of events that occur within any subinterval of that time. For example, if there were 1000 random events in 1 second, how frequently would there be 2 events within 1/100th of a second. For the case of the optical SETI detector it is a bit more stringent, e.g., for set of 100,000 events in every second how frequently should two, three or four events occur within any 50 billionths of a second interval. Poisson statistics provides those answers and for the largest part the detector mirrors that very well. Now for the baffling, some might say humorous, part. The data on the bench using simulations of starlight followed Poisson's prediction nicely over the wide range of 10,000 counts per second to 1 million counts per second. Below 10,000 counts there are few "hits" of double, triple counts within the 50 nanosecond interval. But in that low range the data was somewhat divergent. Defensively I can say that with these very high speed devices and a fairly complicated circuit, the tests can be difficult and mistakes easily made. So, clearly there had to be some devious noise source in the circuit that was yet to be found. After another month and many, many hours of work, only a few minor discrepancies were found and corrected, but the noise persisted. The most recent data was nearly identical to that taken the month before. It was immutable. One might say that the design was robust, but I found no comfort there.

3 However, when at last I verbally conceded that the data was immutable (along with a few other expletives), the lights came on. Cosmic rays are ever present, have approximately the same rate as my persistent noise and it has been known for well over half a century that photomultipliers are sensitive to them. It will be difficult to nail this down precisely because cosmic rays interact with photomultipliers in complex ways, but for now, it is a good fit and responsible for the greatest share of the noise. Even more comfort can be found in the fact that the noise has no negative impact on the operation of the photometer - I was simply obsessed with the issue. Thus, the instrument was mounted on the telescope, ready to continue the search for our cosmic brethren and I can get back to obsessing about that. Ben April 7, 2018 Today marks a milestone for optical SETI detector development her in Panama. The newly designed and constructed PECL detector board has been successfully tested and put in operation on the telescope. This has the system performance we've been working toward for several years. It replaces a TTL based board that was commissioned only about 6 month ago. The new board has the following performance enhancements: no preamplifier stages are needed, 50% less noise, at least 10% greater sensitivity improved input pulse time resolution, after the 1 st discriminator all input pulses are dimensionally nearly equal, greater 2 nd discriminator signal to background margins, more effective coincident pulse detection. It is hard to put a number on the improvement in detection efficiency, but there are a few points of comparison that suggest it is significantly better than with previous circuitry. So as not to mislead, I have previously stated that the systems minimum detectable limit was about 60 photons per meter sq. That number may be only slightly improved with the new circuitry, but improvements in the ability to pull signals out of a noisy background and the improved margins of detection are clearly advantageous. There are yet more improvements coming in the month or so. With PECL, the speed is such that a digital discriminator is now possible. My previous attempt with such a discriminator, but using TTL circuitry, failed because of the lack of sufficient processing speed. The plan is to make the new discriminator a drop in article that can quickly be compared against the analog version. The design is complete and parts are on-hand. I just need a little time (and rest) to get it assembled and tested. After I get some telescope time with the new board, I'll write it up and publish it in the "Detectors" section of the website. Below are some o'scope traces and a photo of the new board. In the next few days I will report on the photometer's performance with stellar observations.

4 Figure 1 Figure 3 Figure 4 Figure 1 shows a single photoelectron pulse and its associated integration level that is stored for 50 ns. Similarly, in figures 2, 3, 4, 5 and 6 one can see the integration levels for multiple photoelectron pulses. The plateau in Figure 1 is the baseline below which there is only single pulse noise. At high pulse rates, there may be an extra noise pulse or two within the 50 ns integration time. Downstream, software disregards nearly all of these random events. Since these oscope pics were taken, additional plateau filtering has been installed that reduces the noise considerably.

5 Figure 5 Figure 6 PECL ckt board with analog discriminator February 12, 2018 For the third year, Bruce Howard, director of the Owl Observatory in Michigan, returned to Panama for a week of highly productive optical SETI brainstorming. We both came away with long lists of things to research, develop and implement. Included in these were:

6 revisiting an improved pmt cooling method toward improving the signal to background count at further elevated pmt voltages, Bruce will fabricate a new pmt cooling unit for test. Bruce will implement optional means for single pmt photometer operation at Owl. This includes adding movable optical stage and a new circuit board with the addition of a second discriminator and additional board outputs. Bruce to fabricate parts for Boquete to add a telescope "Home" position switch and precision apertures for the aperture plate to replace current crude components. Bruce to fabricate parts for Boquete to improve the declination drive performance. Installation will wait for the rainy season. Ben to move "Periodicity" software to adjacent computer for better load balance. Awaiting parts delivery. Other minor improvements to the software will also be made. Ben to create software for batch processing data files. Ben to improve the detector electronics front end with ecl devices for higher speed and to possibly eliminate the front end amplifier. Ben will implement temperature compensation as needed for test pulse detection such that 128 second period test pulses will be on continuously during observations as proof of detector performance at the lowest signal level. Completed and operational. We continue to work toward achieving synchronous data time stamping for our two observatories. Boquete has the most work to do in that regard. And many lesser items. During the week, Bruce and I spent many nighttime hours observing and taking note of ways to improve performance, credibility and to reduce the observers workload. It was an exceptionally good week. Ben January 23, 2018 An article written for METI publication. Optical SETI, after nearly 20 years, where are we and what's ahead? November 14, 2017 Marlin (Ben) Schuetz, Boquete, Panama Optical SETI Observatory

7 Ben Schuetz has been developing the Boquete Optical SETI Observatory since 2009 and has observed well over 4000 stars for signal indications. Bruce Howard, at Owl Observatory in Michigan has also been developing his system for many years. Bruce and Ben collaborate frequently to enhance their efforts. Nearly every paper on this subject begins with the history of optical SETI dating back to a 1961 paper in "Nature" magazine by Schwartz and Townes (1961) and followed by a litany of the work that has followed. For this article, we will forgo much of that, remarking only that relevant to today's activities and with the advent of very high energy pulsed lasers, the more serious optical SETI efforts were begun just before the turn of the century. Let me also state that the preponderance of historical references to optical SETI are with regard to the detection of pulsed signals. Continuous wave (cw) signal detection methods are altogether different and have been done primarily with data mining techniques, Reines and Marcey (2002, 2017) and others. CW laser signaling has the advantage of requiring far less laser energy than pulsed techniques, but there are significant offsetting disadvantages that suggest it may not be the best method of interstellar beaconing. Twenty years may seem like ample time to comprehensively observe a few hundred thousand nearby stars for indications of laser signals, but the reality is very different. With a few notable exceptions, most of the work proceeds something like this. A university decides to initiate an optical SETI program. Each program defines itself with a technical advantage such as improvements in sensitivity, optical band, signal to noise improvements, and so on. After funding is acquired, there would typically be a year or so of development. The university telescope may then be used for an observing program that includes perhaps one thousand to a few thousand stars and which results in several published scientific papers. That is as it should be and that work is highly prized. But, those efforts do not embody any really serious optical search for ETI. Also note that there have been only a few original papers and very little work has been reported in the last half dozen years. So, what have we learned and how do we proceed from here? The following is my assessment of the situation given the current technology. High energy lasers currently in use on earth are capable of being detected against stellar backgrounds with small telescopes many hundreds of light years distant. Thus it is proven that even emerging technological civilizations can have the ability to transmit interstellar beacons. Considering the transmission parameters, background interference and distances, the detection of interstellar pulsed laser signals has the advantage of relative simplicity; requiring only small telescopes, generally of 1 meter aperture and less. For ground based detection, the most advantageous optical band appears to be the visible to near infra-red region; bracketed by atmospheric transmission, system size and complexity. Note that as the wavelength is increased the transmission facility size and complexity increases and is bounded by some limit of manageability. Signal attenuation due to cosmic dust is not a factor for distances less than about 1000 ly, thus, for the distances we are mostly concerned with

8 (<500 ly, for small telescopes and the time element) the optical band from ~350 to ~950 nm has the fewest technical issues both for transmission and reception. The anticipated pulse length is from <1 nanosecond to as much as 100 nanoseconds. Longer pulse lengths have the capacity to include embedded data, but pulse length is limited by increased background noise. The anticipated pulse repetition rate is from one pulse per second to one pulse every few hundred seconds (possibly out to as much as 1 pulse in 1000 seconds). The limitations here are economic and technical. For transmission, one pulse per second represents a very large energy expenditure over time. Rapid pulses also greatly limit the number of stars that can be targeted by a single laser. At the other extreme, very long period pulses may, for a variety of reasons, escape detection. Long period pulses do, however, allow many stars to be targeted by a single transmitting facility. It seems most likely that the preferred pulse repetition rate will be in the range of 0.05 to Hz. Note that only few of the researchers have reported on the range of periodicities their systems were capable of detecting, however, stellar dwell times are good indicators of those capabilities, i.e., a stellar dwell time of less than 3 pulse periods is inadequate for a determination. Notably, the Harvard All Sky Survey (2006) was a groundbreaking effort wherein the survey contained large portions of the observable sky and continued for an extended period. However, because the telescope was fixed in right ascension the stellar dwell time was, at most, 60 seconds. Those three parameters, pulse length, pulse width and pulse periodicity, provide a nice little box for us to work within. As time passes we will surely find reasons and supporting technology to further expand the box or perhaps even define an altogether new box. But, for now, it seems clear that we need to design systems capable of detecting signals that, at the least, occur anywhere within the box. A fourth important parameter is system sensitivity. The Boquete and Owl Observatories systems have minimum detectable limits of about 60 and 140 photons per square meter respectively. These compare favorably with other survey systems. As an example, many of the past detection schemes only looked for coincident photon events occurring within 1 or a few nanoseconds, only at optical wavelengths and only with high repetition rates, e.g., 1 pulse every 20 seconds or so. That may be roughly represented by the left hand parameter box of Figure 1. Over time, that box was expanded (vertically) to include the near infra-red part of the spectrum as in the central boxes of Figure 1. The NIR work ( nm) was done with the NIROSETI program of 2016 and Lick Observatory's Nickel telescope (Maire & Wright, 2016). At the beginning of 2017, Bruce Howard (Owl Obs.) and I met again in Panama resulting in projects to greatly expand the parameter space. New photomultipliers were installed in the photometers that are sensitive over the optical band from 200 to 850 nm and have improved quantum efficiency. At Boquete, hardware improvements enabled a pulse width detection range increase of from 1 to 25 nanoseconds to a range of 1 to >50 nanoseconds. Custom

9 software also provides both observatories with a simple method for the detection of pulse periods greater than 250 seconds. Thus, on the right, we have a parameter box that is greatly expanded over all previous search methods. Niroseti (approximate) Optical Band Periodicity Pulse Width Prior to ~ Owl and Boquete Observatories present Figure 1. Of course, this demands that whenever the parameter box is expanded, all candidate stars must be revisited lest that one extraordinary star system we've been looking for may be missed. Thus, to avoid wasteful expenditures of time and resources, we need to make the box as large as possible and as soon as possible with fresh, innovative thinking. We also need to apply today's devices and software methods to best advantage. Having been retired for many years, to that end, I am way out of date. The message this researcher would like to emphasize is that while in recent years interest in optical SETI has seemingly waned, it was never given anything remotely approaching a chance for success. We can also easily see that funded institutional programs in their present form, while clearly necessary, are not the vehicle for sustained comprehensive optical SETI enterprise. This has been and is more than ever an excellent opportunity for innovative independent researchers and underutilized small observatories to make significant contributions. At the risk of losing the casual reader I have tried to pack a great deal into very few words. My apology if it has seemed too abrupt and without sufficient background information. For those who have found it of particular interest, this may be a useful starting point for further inquiry. Additional information about the Boquete and Owl observatories may be found at the websites: optical-seti.org and owlobservatory.com.

10 Above left : Owl Observatory 16" Cassegrain. Right: Boquete 20" Newtonian w/14" Cassegrain. Ben (left) and Bruce at Boquete Observatory

11 References Maire J., Wright, S.A, et al. 2016, "A near-infrared SETI experiment: commissioning, data analysis, and performance results", Proc. SPIE 9908, 2016 Raines, A.E. and Marcy. G.W. "Optical Search for Extraterrestrial Intelligence: A Spectroscopic Search for Laser Emission from Nearby Stars," PASP 114, , 2002 Schuetz, M.N., Vakoch, D.A., Shostak, S. & Richards, J., APJL 825, L5 Schwartz, R.M. & Townes, C.H. 1961, Nature, 190,205 Tellis, N.K. and Marcy, G.W. "A Search for laser Emission with Megawatt Thresholds from 5600 FGKM Stars," The Astronomical Journal, , 2017 December 28, 2017 Objects Observed section updated. December 18, 2017 The dry season has begun at last big sigh. One knows the first day (usually in early December) when high winds pick up out of the north. Since that day, the observatory has been in full swing. I am continuing to pursue all of the very bright nearby stars and mix in a few others as is convenient. The bright stars list is a short one and the stars currently available for scrutiny will be used up in a few days. Then, all of the other several thousand stars within 100 ly will come next. The new detector circuit board has exceeded expectations. As earlier mentioned I failed with the all digital detector design (TTL is just not fast enough) and I have no experience with ECL chips. So the new detector is a hybrid design that has at times made my head hurt, but which does everything I d hoped. The second discriminator threshold tracks the stellar magnitudes and maintains the highest sensitivity for group events. Coincident events are processed differently. When combined with the custom periodicity detection software, the system is very stable and a pleasure to use. Three files are generated and stored for each star: the raw hits data (with between 0.5 and 2 hits per second), the first culling file and a final culled file. All of the data points are time stamped to 1 millisecond (relative accuracy), and a few seconds of absolute accuracy. After the 20 minute stellar dwell time and the collection of 500 to 1000 data points, the software takes a few seconds to examine the data for periodicity. If anyone is interested, the data can be made available. I may even create a new section on the website and make it readily available. What do you think? Early next year, it is planned to add a bit of hardware such that all of the timing will have precision absolute accuracy. Yet another generation of the photometer circuit board is in the works. This board will be very similar to that now used, but will be developed targeting a slightly lower noise factor and little

12 higher speed. The current board is excellent, but I can t leave well enough alone. Given the hardware I can work with, the quest continues for improved sensitivity and reduced noise. The Objects Observed section has been updated to include recent observations. Ben November 20, 2017 October usually has the most rainy days and in that regard this year was not disappointing. We re now getting more clear nights and it is a pleasure to start the season with many new capabilities. All of the observatory systems are running well. The recent discoveries of many nearby exoplanets buoy the potential for SETI and my energy. For the next few weeks I ll be concentrating on our bright, nearby neighbors that have previously been ignored as they were too bright for the detector. Installation of the new aperture plate does a nice job of opening up these star systems to scrutiny. Here are the results of the photometer focusing tests with the improved analog presentation. Note that the horizontal unit is 500 ms/divn., in accordance with the stellar drift rate. The photometer position is indicated by the potentiometer voltage. Note that volts has been selected as the best focused position. The sloping peak top is either an artifact of the small positional change on the photomultiplier photocathode or possibly a slight offset in declination from the star s center. With clouds moving in, there was no time to sort this discrepancy out. The data is, however, sufficient to properly position the photometer volts volts volts

13 11.27 volts volts volts September 15, 2017 We ve had only a few clear nights for observations since the last report. However, I am happy to say that the aperture plate is working very well. It is now possible to observe stars to magnitude 2 (for a total range of 2 to 14.5). With this new capability, it is convenient to observe very bright stars on hazy nights when conditions aren t good enough for more general SETI searches. This along with the ability to detect extended periodicity makes the system quite powerful and a pleasure to use. An improvement for photometer focusing has also been installed. Instead of using the log amplifier signal, an integrated total count signal is used. The log amp had a very long settling time and did not adequately reflect reality. The new method reduces the settling time to about 50 milliseconds and will be far better. The new focusing data will be published in this section soon. (The older method s results may be found in the August 11, 2016 entry of this section.) I erred in saying that no more new projects would be tackled this dry season. An additional wind barrier is needed to permit operation during the windiest nights of the dry season. It s a difficult nut to crack and I m still noodling how to achieve to desired result without making an eyesore out of the building. Also, the photometer pcb has been modified so many times it is getting shopworn. Parts are on order to fabricate a new one. A few improvements in methods and hardware are planned. There is still plenty of time to get these items completed before the dry season. Meanwhile I take advantage of every break in the wx either for tests and calibration or for SETI searches. Note that the Objects Observed section has been updated and includes a new column for the latest parameter space expansion. Bruce Howard (Owl Optical SETI Observatory) is planning another trip to Boquete late this year or early next. It will be the third International Symposium on Optical SETI. If anyone else is interested, let me know and we ll see how that might work out. Bruce and I do a good

14 deal of productive brainstorming and Boquete is a particularly beautiful place to visit at that time of year. Ben August 11, 2017 I hate to admit defeat regarding the digital discriminator, but for a number of reasons it just didn t pan out. After reverting back to the analog discriminator, improvements were made using additional pulse conditioning and the pulse width sensitivity range was extended from 25 ns to 50 ns. After the circuit changes were completed, tests with the LED pulser confirmed good performance. The photometer was put back on the telescope and after a productive night of observations I am satisfied with the results. The modified circuit will be posted in the Detectors section in a few days. The good news is that all is ready for clear nights. A shortcoming of most, if not all, optical SETI systems has been that nearby, bright stars have been too bright to be observed without fitting masks on either the photometer or the telescope aperture. It s a shame too, because our near neighbors include some excellent candidate star systems. To correct the deficiency the photometer was outfitted with a motor driven disk having a variety of apertures. It is a project that has been on the wish list for a long, long time, but was always down on the priority list. The disk is driven with a stepper motor and controlled at the computer keyboard. The apertures will permit observation of stars up to about second magnitude. As experienced is gained, the aperture sizes will be changed to better suit the needs. One might argue that against such bright stellar backgrounds the laser energy requirements would be extreme. But, the particular stars of interest all fall within 100 light years. Thus, with precise targeting, a tightly confined laser beam could be detected. No additional major projects are anticipated before the next dry season. Ben July 14, 2017 Testing of the periodicity detection software has been completed out to periods of 200 seconds with good results. The timing for future stellar observations will be 20 minutes per star and allowing for at least 5 pulse detections having up to 200 second periods. That also allows for up to 2 to 3 missed pulses while still detecting periodicity (in which case, the observation can be repeated as necessary). As mentioned elsewhere, the greatly expanded parameter space (pulse width x pulse period x optical band) makes it necessary to reexamine all stellar systems. So, the list begins again. A new column has been added to the Objects Observed list that indicates progress in that regard. Tests continue on the digital discriminator. Progress has been slowed while waiting for IC chips to arrive; there is a 2 week ordering cycle. The 100 MHz clock tests indicated good performance, but other chips are needed to complete the system. The concept is simple, but not so simple to implement. More as this develops.

15 In anticipation of the dry seasons wind conditions, the overhead lift assembly, (right hand photo below), will be modified to provide a moveable western windbreak. The east side has had a moveable windbreak for the past year. Wind has always been the main obstacle against reliable nightly observations during the dry season. Much of this website is now out of date and needs significant rework. Over the next couple of months I ll try to sort this out. Ben June 17, 2017 Even though the weather has been poor, there has been a lot of activity during the past month. The new aluminum declination and RA drive sectors arrived and their installation took 3 full days. Thereafter, it took another 4 days to sort out some funny business and get the telescope targeting where it ought to be. Now, the telescope targeting is within 25 arc seconds with some hope of further improvement after careful documentation of the roller pressure versus the degree of error. Many, many thanks go to Bruce Howard for taking the time and effort to machine these sectors. They are beautiful and oh so effective. The next big effort was an attempt at a new method of cooling photomultipliers. The result to date is a 75% reduction in dark counts using just 3 watts of power to a Peltier cooler. (For the configuration, additional power had little effect.) I was disappointed that it did not reduce the dark count further, but there s more work to do and I ll report more on this as progress is made. Next, a crystal controlled clock was added to the pulser (LED test pulser) resulted in a very nice package with selectable pulse rates from 2 pulses per second down to 1 pulse every 512 seconds, in eleven steps. This was needed to complete the new periodicity detection software that has been developed during the past 2 months. The new software replaces the FFT software package that has been used here for the last 5 years. The change was necessary in order to have good detection sensitivity at very low laser pulse rates, i.e., <1 pulse per 100 seconds. The software/hardware combination result in detection accuracies of 1 millisecond and less. The LED Pulser section of this website will soon be updated with circuits and a full description of the setup.

16 The pulse detection software has also been completed with excellent results. Testing is underway to determine the limits of the overall detection system, but as a teaser, the detection of 1 pulse in 128 seconds has been reliably achieved with a 100 khz simulated stellar background. That s about one anomalous pulse in 13 million. There is a lot more testing to do to optimize performance and to determine the discriminator threshold set points needed for the range of stellar magnitudes out to a periodicity maximum of 1 pulse in 256 seconds. All detected pulses are time stamped to 1 millisecond relative (< 1 seconds absolute). In the next months, GPS timing will be added yielding 1 millisecond time stamp accuracy in absolute terms. The digital discriminator mentioned in the May 22 report was tested in a rudimentary form and found to be very promising. However, it was clear that a 100 MHz clock was necessary to achieve the best results. The clock module is on order. More on this later. Ben May 22, 2017 The new drive sectors are due here in the next few days. Every preparation has been made for their installation the work is expected to take a few days. Other new developments include a photometer upgrade design from using group pulse analog integration to a digital method. The solution, long thought to be too complicated, was simpler than thought possible; only requiring minor circuit changes and the addition of a few components. The components are on order and the modification/tests will be done as soon as possible. If successful, there will be an improvement in performance especially for the detection of long periodicity pulsed signals. Also, good advantage will be found with cooling the new photomultipliers to reduce the dark counts. Tests are underway using a simple method that won t require cooling blocks, heat sinks or circulated fluids. The needed components are also on order. More on this if/when it works out. Bruce, Doug Vakoch (METI) and I are working on a paper and are hopeful it will be published in the near future. Lastly, during this rainy season now in full swing, I hope to get up to speed on the VB.net programming language for the eventual upgrade of the observatory s custom software. The past few weeks have been busy and busier times are yet to come. Ben April 26, 2017 As had been hoped, newly developed hardware and software allow us to detect very low

17 periodicity without ambiguity (false positives) and without mechanical contrivances. The website sections regarding fast Fourier transform analysis will be replaced with details of the new methods. But, as a teaser, our region of detectable periodicity has expanded by a factor of ten - down to Hz. Factoring that in with the 2x improvement in optical bandwidth a few months back and this year s overall improvement is impressive. Also, and henceforth, each hit detection will be time stamped and recorded in files associated with the target star. Note: hit detections include the occasional random pulse; a consequence of Poisson statistics. There will be more on all of this later. Bruce is finishing up newly machined large driven aluminum sectors to replace the plywood sectors, (one visible in the photo below). An overhead x-y crane has been fabricated to enable their installation sometime in late May. The crane rides on the roof tracks which have been extended. The plywood sectors have worked well for years, but targeting and tracking will both be improved with the new precision sectors. When the installation is complete, I ll report on those improvements. Bruce is also busy with several other projects to further enhance the performance of his observatory. March 20, 2017 The Second International Symposium on Optical SETI at Boquete convened last week. In the spirit of the current crop of hyperbole, thousands were in attendance. Although the photo doesn t provide evidence of that, Bruce Howard (right) from the Owl Observatory and I may be seen in the photo below.

18 Bruce and I had a great week sorting out a host of issues and pursuing a new approach to signal discrimination. We also had several good observing sessions. In the coming months our thinking will be put to the test with new hardware and software. We have hopes of significantly increasing the performance of our systems and pushing the boundaries of detectors capabilities into untapped regions. March 8, 2017 Check out the newly added section New Paradigm. It s a great starting place for understanding why after 9 years I continue to be excited about optical SETI and the possibilities for success. Good weather last night. I m continuing to plow through the low hanging fruit of stars most often less than 100 light years away. When that has been completed, the stars targeted will shift outward; from 100 to 200 light years distant. Bruce Howard (Owl Observatory) will be visiting here all next week. We have many interesting things to do and discuss. The Objects Observed section is updated after each observing session. February 20, 2017 The weather has been much improved for the last few days and accompanied with good progress. The Objects Observed section is now up and accessible from the home page (bottom left). I will try to update the list weekly, as weather and observations permit. February 13, 2017 The last week has been very gusty-windy and has slowed the rate of stellar observations. Meanwhile, parts arrived that enabled the completion of the tape deck modifications. After a good bit of work, the tape speed feedback regulation holds to about +/-0.1% for both the high and low speeds. Erring on the side of dependability, the resultant ratio of tape speeds fell short of the original 10 to 1 goal at only 6 to 1. Early tests with the tape system have been good. The high speed tape playback versus the real time detection of 0.05 Hz pulsed signals shows a 10x improvement in the detection amplitude with roughly the same background level. It is expected that the detection range can now be extended to about 0.02 Hz. Additional tests are to be completed in the next week. With the greater pulse periodicity detection range, it is necessary to extend the stellar dwell time from 5 to 10 minutes per star. Clearly that will affect the stellar observation rate quite a bit, but as mentioned elsewhere, the sweet spot(s) may be at a lower pulse rate.

19 It also means an extra 30 minutes or so of time required for tape playback, but that can be done during daylight hours. A new list having all of the observed stars is mostly up to date. It lists stars observed multiple times, those using the R1548 pmt and those using the R3896 pmt. The home page will be modified to include a link to this pdf file in the next few days. December 25, 2016 Revised optical SETI strategy at the Boquete Observatory. Over the years my strategy for optical SETI searches has evolved considerably. In part this has been a result of our new understanding of the number of nearby habitable worlds. Other factors included observational limitations, laser transmission parameters and the loose guesses of the proportion of worlds with civilizations having communications capabilities. Early on it seemed reasonable to concentrate on the most promising nearby stars with hourlong and longer observations. In part that was due to the crude telescope targeting methods of the time. But about 5 years ago I considered it better to acquire the greatest number of stellar systems using observational dwell times that were a good compromise between detection criteria, workload and system capability. That included multiple observations of many of the star systems. Over that period of development there were many pressing technical issues and defining a preferred search strategy was of a lesser concern. Recently, however, there has been time to reconsider and improve the search strategy. The following remarks reflect another step in these thought processes. From an engineering point of view the design and implementation of a laser beacon system would go something like the following. Space based lasers would be preferred over a ground based systems. Systems in space have the advantage that stellar energy can be abundantly and efficiently collected, there is no atmospheric dispersion/loss of a laser beam and any planetary system can be accurately targeted over a long term, (i.e. multiple platforms orbiting the parent star such that transmissions would be independent of the home planets rotation/orbital position). One assumes that such systems would have the means to sequentially target thousands of stars with well considered repetition rates. A further assumption is that the aliens would have the technology to observe exoplanetary indicators of life (e.g., atmospheric spectral data) and, as S. Shostak suggests, know the planetary transiting schedules. They would also have the means of confining laser beams so as to achieve an easily detectable signal level at each of the targeted exoplanets. The aliens would also understand that: the project would be extremely long term and open-ended, signal detection at the targeted planet should be reliably repeatable,

20 the system may/should not require a means for detection beyond the capability of newly emerging civilizations, Therefore, it seems reasonable to expect that when we observe a star system, the signal will either be there or not. That assumes, of course, we are using the proper detection scheme. There is concern that a signal from a particular planetary system might be found next year, but not this year. However, the probability for success would be significantly diminished by frequently revisiting stars. So, I have recently chosen not to re-observe stellar systems unless there are good reasons to do so. That comes with the exception that the new photomultiplier extends the spectral range and promising stellar systems will be rechecked once. The observation logs have been altered to account for this strategic change. Thus, to achieve the biggest bang for the buck, the goal here in Boquete is to observe as many star systems within 300 light years (some F, and most K, G and M types) as possible. Stars between 300 and 400 light years will be targeted when convenient and when there is little impact on normal observation progress. Ben December 14, 2016 The Hamamatsu R3896 photomultiplier, purchased on the used market, was installed and the system has been recalibrated. I am pleased to report that the overall system sensitivity was seen to be increased by a factor of 2. However, it should not be interpreted that the system sensitivity has improved from ~50 photons/m 2 to half that as there was only a small improvement in quantum efficiency in the region from 300 to 500 nm. The reason the sensitivity is seen to be increased by 2x is that photons are now detected over a broader spectral range. This greater bandwidth opens up new territory to be explored. A graph of the 20 inch Newtonian system s response over the range of visual magnitudes may be seen below. For the near term, the added sensitivity limits this range to magnitude 6 stars. An iris assembly will soon be added at the entrance of the photometer to enable the observation of all bright stars.

21 November 27, 2016 Because of the high cost of the latest high performance Hamamatsu photomultiplier (R12896), I ve been vacillating about when to spring for it. A second option was to locate an R3896 photomultiplier on the used market and take a chance with it. The R3896 doesn t have quite the performance of the R12896 pmt, but it is reasonably close. After a short search a used tube was found at a cost of about 10 cents on the dollar with respect to the R It has been ordered and should be here within a couple weeks. The installation will be straightforward requiring only a couple of days. Characterization of the photometer will consume a lot more time, but won t hold up nightly observations. Below is a graph showing comparison of the quantum efficiency of the currently installed R1548 pmt versus the newly ordered tube. As may be seen there will be a very large improvement in spectral wavelength range and overall sensitivity.

22 November 22, 2016 IOP Publishing has generously allowed me to reprint the full text of the paper OPTICAL SETI OBSERVATIONS OF THE ANOMALOUS STAR KIC The article was published July 1, 2016 in the The Astrophysical Journal Letters 825:L5. The full text of this article may be found at the end of this section. November 14, 2016 Since the last report we ve had about 10 nights with good observing weather resulting in an average of 25 stars visited each night. On one night, just having shifted to a new star, an excellent signal showed up on the autocorrelator of the spectrum analyzer. I nearly jumped out of my skin. Shortly, however, it was discovered that the Fkey that initializes test pulses was accidently tapped. It was exciting while it lasted. From now through much of May the weather will be more cooperative. Otherwise everything is working nicely. The tape recorder scheme has been successfully tested, but needs a minor low speed adjustment before routing use. At the very low rate, there is an off-speed trip that drops out irregularly after about 20 minutes of operation. Otherwise, the method of detecting very low repetition rate pulses works well. I ll sort out the problem in a few days. Over time I find errors and additions to the Star List. The list has been updated.

23 September 28, 2016 The Sidereal Technologies servo system is now fully operational and was a major step toward increasing the number of stars that can be targeted in an evening. The conversion from RA/Dec stepper motors with my own driver software to DC servos, the SiTech servo amplifiers and their advanced software was a major effort. I m sure it has been mentioned elsewhere, but Bruce Howard provided first class upgrades to the drive hardware also. Anyway, after months of work the telescope targeting accuracy is now about as good as any friction drive system can be. Slewing over large angular distances now results in only 1 to 2 arc-minutes of error. Better yet, when the targeted angular distance is only a few degrees, the error is much less than an arc-minute and very often it is exactly on target. Thus, the time to acquire each new star has been reduced to only a few seconds. With good weather perhaps as many as 50 stars can be observed in a single evening. Thus far and because we re still in the rainy season, the nightly observations have been limited to just 2 or 3 hours, but 30 stars have been observed in a single session. The work toward detecting laser pulsed signals with very low repetition rates, i.e., down to Hz will soon be complete. Toward that end, a tape deck recorder was purchased and modifications are nearly complete to allow recording at very low tape speeds, but with a 10x playback speed. Completion is awaiting a new capstan motor that was ordered from a Russian source. The motor has a generator output for speed regulation. A servo amplifier has been installed to drive the new motor. Additional circuitry was also added to the photometer to provide output signals with longer pulse widths such that when played back at high speeds, the audio signals will be well below the 20 khz upper limit. The operations will go something like this: One audio channel will record the photometer output pulses and the second audio channel will be used for annotation of stellar designations and other remarks. Recordings will be continuous throughout each observing session to be played back later at high speed into the fft analyzer for the detection of periodic signals. It s primitive, but the total materials cost was less than $100. I should report that the piggybacked telescope arrangement has worked very well. Clearly, it is important to maintain the center of the field of view for both the 14 and 20 telescopes in very close alignment. Considering there are lots of things that can move, albeit only a tiny amount, it was reasonable to expect that there might have been difficulties with long and/or short term variations. The good news is that only minor offsets occur over time and these don t often require correction. The piggybacked 14 Cassegrain is, however, mounted to the 20 Newt using die springs and adjustments can be made quickly and easily as necessary. On the horizon is an upgrade to a new, high performance photomultiplier. The pmt has improved quantum efficiency (up to 30%) and a broad spectral range (out to NIR). It is a costly item and will have to wait for my pocketbook to heal, but the improvements will be equivalent to having a larger, much more costly telescope. Ben

24 August 11, 2016 Where to start? OK, we spent many, many hours quantifying the minimum detectable limit of the system. We can define system to include the photometer and downstream fft analysis. Why did it take so long? The criterion for this measurement revolves around the detectors hit rate. The hit rate may be varied by adjusting the 2 nd discriminator threshold voltage and is typically in the range of ~0.1 to 10 counts per second. Then, using the LED pulser/background test unit, for each LED pulsed repetition rate, the background LED is adjusted stepwise over the range of 0 to 1 Mcps. Threshold voltage data was taken for each setting over the range. When measuring such low hit rates, they must be averaged over several minutes for accuracy. That was done automatically. But it still required someone to sit there hour after hour collecting the data and to make adjustments; eventually covering the whole matrix. That was tiring just writing about it. Anyway, a small part of the data seemed strange and it took a while to understand that it was all OK. From there it was possible to determine compromise threshold settings that covered the detectable range and which could be automatically set dependent upon stellar magnitude. The final result was that the system sensitivity was somewhat better than previously determined using a less rigorous test procedure. I put out a wanted add for an audio tape deck recorder. Good grief! What s wrong with digital recorders? Well for a starter, I needed something that could record the photometer output at a normal rate and play it back at 10x speed. The current crop of digital stuff (that I searched) wouldn t do the job. Anyway, I was able to get a recorder and it is now in the process of being modified with a PWM type servo amplifier to run the capstan drive motor. Recording will stop/start with the autoguider. What s the 10x speed needed for? Well, to be able to detect signals at the Hz rate, I ll record the photometer output pulses at normal speed and then play the entirety of a nights observing session through the spectrum analyzer looking for signals at a minimum of 0.01 Hz. This will take a little fiddling, but I m hopeful it will be successful. The input pulse will need to be modified such that when played back at 10x it will remain in the audible range. Alternatively, I could change the fft parameters to include Hz, but that would create problems for observing the higher repetition rates. We re only getting spotty nights with a starry sky. So, testing of the new telescope targeting servo system has been very limited. It looks pretty good though. Here s something kind of fun and interesting. The photometer does not currently have a flip mirror or other means of checking position/focus. But, I have found a neat way to do focusing. The photometer total count pulsed output branches to a log amp that outputs an analog signal proportional (but logarithmic) to the input count rate. Looking at this signal with a scope set on 0.5 seconds/horiz divn (0.5 RA sec./divn), I centered on a star, then moved the telescope slightly to the west and turned off the tracking. The star then drifted across the 0.01 aperture plate and the scope traced out a representation of the stellar signal with time. Below are several o scope plots that show the progression toward a good focus. Another bit of data that can be pulled from these images is the stellar image size i.e., the width of the up or down slope.

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27 There will be more stuff to report on soon. Ben July 28, 2016 Although we re in the rainy season the last few months have been very fruitful. Julia Sullivan from the U.K. has been here working as a summer intern and providing a lot of help in circuit board fabrication and has put in many hours of data collection toward better system performance and a better understanding of the details. In the next week or so, I ll detail all of the new work we ve done. For now, suffice it to say that the system detectable limits have been proven over a broader range of pulse repetition rates and that work leads the way toward being able to detect laser pulses having repetition rates as low as Hz out of stellar background rates as high a 1 megahertz. Detection of such a low pulse rate was once thought to be possible only with coordinated observations from two or more observatories. I m very excited about this since it opens up a more probably regime of pulsed beacon signals. It is interesting to note that although the photometer circuit is quite simple there are many complexities involved in optimizing the performance and the deeper I dig, the better it gets. The new circuit board and other improvements have extended the photometers dynamic range. We can now look for laser pulses from stars having magnitudes 5 to 14+. New RA/Dec mechanical and electronic drives have been installed and are now in the process of being calibrated. The new system will reduce the old targeting time of 1 to 3 minutes down to a few seconds. Thus, it will be possible to observe many more stars per unit of time while also easing the observer s work load. Bruce Howard (Owl Observatory) deserves big kudos for his efforts in designing and machining the excellent new mechanical drives. He also gave good advice regarding the change to the Sidereal Technologies servo system. So you see, there are many things to report on with pictures, diagrams and data. I ll get to it as soon as I can. Ben May 14, 2016 We ve been fortunate to have clear skies for the last ~10 days and the star count continues to grow. My observation techniques are improving and I m learning more about the subtleties of recent photometer modifications.

28 In mid-june, a summer intern will arrive from the UK and take up a series of projects that hold promise for future optical SETI improvements. She will also be participating in the Blue Marble Young Scientist Program. More on this later. Be sure and check out the revised section, Is Amateur OS Viable? A lot of new stuff has been added and there is greater clarity in the answer. Last November, METI coordinated efforts of SETI Institute s Allen Telescope Array and the Boquete OS Observatory for the observations of a peculiar Kepler star. The observations resulted in a paper titled Optical SETI Observations of the Anomalous Star KIC The paper has recently been accepted for publication in The Astrophysical Journal Letters. Ben April 20, 2016 With clear skies and only little wind during March and the first half of April, the weather has been excellent for SETI searches. The 2.5 to 3 hour observing sessions logged an average of 20 stars a night. Added to that, the instruments all performed well and the recent photometer improvements have exceeded expectations. My month s successes were even topped off with fixing a nagging problem with the car. What s not to like? The latest ideas for improving photometer performance were long in coming, yet simple to implement. Evaluation of the changes involved many hours of data collection and evaluation, but they paid off with a greater useful range of visual magnitudes and improved sensitivity to pulsed signals. Just a few weeks ago I was thinking that this photometer had about reached its performance limit and it was time to start working on a new design. Now it is clear that there are yet more things that can be done before having to build a new box. Also noteworthy has been the improvement in signal detectability using the spectrum analyzer s (Spectrum Labs) autocorrelation feature. According to Wikipedia (and cut down a bit), autocorrelation is the cross-correlation of a signal with itself at different points in time. Informally, it is the similarity between observations as a function of the time lag between them. It is a mathematical tool for finding repeating patterns, such as the presence of a periodic signal obscured by noise. I started using it about a month ago and found that it could prominently display signals that were otherwise only marginally observable. Bruce Howard (Owl Observatory) has finished the machined parts for upgrading the telescope mechanical drives. They will be here in about a month. Installing those parts and associated electronics will be big job for the upcoming rainy season. The upgrades will improve the telescope s targeting speed and accuracy and reduce the observer s workload. METI International has been assisting with efforts to find a summer intern to help with the various projects. Candidate selection will be made soon after the application closing date of May 1. Joan and I are looking forward to hosting the intern and confident that those months will be mutually interesting and productive.

29 Clouds have been gathering recently and today we had the first rain in about two months. The beginning of the wet season isn t expected for another month or so, but today was a reminder that the good nights for observing are slipping away. I hope to do a little better job arranging my daytime activities for more evening hours at the observatory. That s a really brief description of the considerable happenings of the last 6 weeks. I m eager to see how the next month plays out. March 18, 2016 Things are looking up around here. A couple of weeks ago I found a bug in the targeting software and after fixing that, targeting was improved. It s still not up to the needs, but much more useable. The full fix will have to wait until the new drive parts are installed along with the Sidereal Tech. servo drivers. But, the software fix, and new targeting strategy (described in the Feb. 23 discussion below), are making it possible to target up to 10 stars per hour and accumulate pretty nice nightly totals. The weather has also been perfect for searches. In addition to the upcoming drive hardware fixes, I m planning to make changes to the photometer detection circuit. The modifications should allow for a greater range of stellar brightness and improve the general sensitivity to laser signals. When it has proven out, I ll publish the circuit changes and details. A long awaited universal counter will soon be here. It will help in making the new circuit changes and improve the photometer calibration accuracy. Errata: In the Sweetspot Section a typo was discovered in the Poisson equation and fixed. Ben

30 February 23, 2016 One big recent change is the association with METI International (formerly SETI International). Their website at is now accessible to everyone. I am excited at the prospects of greater activity in optical SETI and having a center for the advancement, coordination and dissemination of information regarding search activities. In addition to optical SETI, the organization has other interesting priorities. Through METI International, and during the month of November, this observatory participated in coordinated observations of KIC with SETI Institute s Allen Telescope Array. KIC is a visual magnitude 11.7 star that was identified by the Kepler telescope as having peculiar characteristics, (these were widely reported by the press). Observations were complicated by several factors: the star was edging close to the western limits of observation, it was the tail end of the rainy season and a on some occasions a full moon made a large contribution to the background counts. Even with these difficulties, the new telescope and photometer performed well. I am looking forward to future collaborative activities. The dry season is finally here. The star list (out to 100 ly) will continue to be used for the primary target stars, but during each stellar observation and using Stellarium, the immediate neighborhood will be scrutinized for other targets within ~300 ly. Given advanced targeting and beam confinement, laser transmissions from the proximity of these stars may well have sufficient intensity for detection. Since stars very close to the primary target stars can be quickly acquired, the number of possible stellar observations in an evening can be increased. This game is all about numbers. If one makes assumptions about the proportion of planets with ETI, it inevitably comes down to the number of observations needed before a real hit occurs. Even with the most optimistic assumptions, the required number of stellar observations is daunting; even more so when timing/pointing synchronicity is taken into account. Admittedly, the targeting strategy is flawed in many ways, but it is a necessary compromise given the available (me) resource. As was mentioned, the rainy season limited nighttime observatory activities. On clear nights, when the telescope was not being used for the Kepler star experiment, there was much to do to finish the new installation s hardware/software details. However, there have been some opportunities for regular SETI searches. With the new telescope it had been planned to observe 20 to 30 stars for each 3 to 4 hour observing session. Sadly, the telescope targeting accuracy has fallen short of expectations mainly because of a recently discovered polar axis misalignment. Attempts at making the corrections in software were not satisfactory. Thus, targeting has taken more time than expected. The long term solution seemed to require a complete disassembly to relocate the axial alignment. But, in early February, Bruce Howard (Owl SETI Observatory) came to Boquete for a 1 week visit. We discussed the various workarounds and with his valued input I decided to change the drives and drivers to those provided by Sidereal Technologies. Those modifications are currently underway, but won't be finished for another month or so. Sidereal Technologies firmware has provisions for correcting axial misalignments, thus a complete disassembly may not be needed after all.

31 Shortly after Bruce returned home to Pennsylvania, I fell ill to some kind of nasty virus that for the past two weeks has sapped my energy. This too is passing and I am eager to get back out to the observatory. Note also that some additions have been made to the "SweetSpot" section to further clarify transmitting telescope and laser energy requirements. Ben Article reprint begins on next page

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