Small Telescopes Research Articles

Multi-aperture seeing profiler with multiple guide stars

The daytime atmospheric turbulence profile is crucial for the design of both optical systems and the control algorithm of a solar Multi-Conjugate Adaptive Optics (MCAO) system. The Multi-Aperture Seeing Profiler (MASP) is a portable instrument which can measure the daytime turbulence profile up to ∼ 30 km. It consists of two portable small telescopes that can deliver performance similar to a Solar-Differential Image Motion Monitor + (S-DIMM+) on a 1.0 m solar telescope. In the original design of MASP, only two guide stars are used to retrieve the turbulence profile. In this paper, we studied the usage of multiple guide stars in MASP using numerical simulation, and found that there are three main advantages. Firstly, the precision of the turbulence profile can be increased, especially at a height of about 15 km, which is important for characterizing turbulence at the tropopause. Secondly, the equivalent diameter of MASP can be increased up to 30%, which will reduce the cost and weight of the instruments. Thirdly, the vertical resolution of the turbulence profile near the ground increases with the help of multiple guide stars.

Emotional evaluation for pictures displayed with small FOV telescope environment in virtual reality headset

We carried out an experiment to examine emotional effect associated with images displayed in small field of view (FOV) telescope like virtual screen environment with VR-HMDs. We manipulate FOV of a virtual camera in VR to change the view of contents. Decreasing FOV makes view of angle narrow, and therefore, the view in VR looks like telescope, in which environment the view greatly moves with even small HMD movement. With smaller value of FOV, the view in VR is more sensitive to HMD movement and requires subjects to keep concentrating not to move their heads to watch target contents properly. Stronger emotional responses were observed with smaller value of FOV in the experiment. The result indicates the possibility of controlling effectiveness of the same contents with the same VR-HMD. This result is expected to improve a wide range of medical usage of VR contents.

Constraints on Lorentz invariance and CPT violation using optical photometry and polarimetry of active galaxies BL Lacertae and S5 B0716+714

Various quantum gravity approaches that extend beyond the standard model predict Lorentz Invariance and Charge-Parity-Time Violation at energies approaching the Planck scale. These models frequently predict a wavelength dependent speed of light, which would result in time delays between promptly emitted photons at different energies, as well as a wavelength-dependent rotation of the plane of linear polarization for photons resulting from vacuum birefringence. Here, we describe a pilot program with an automated system of small telescopes that can simultaneously conduct high cadence optical photometry and polarimetry of Active Galactic Nuclei (AGN) in multiple passbands. We use these observations as a proof-of-principle to demonstrate how such data can be used to test various Lorentz Violation models, including special cases of the Standard Model Extension (SME). In our initial campaign with this system, the Array Photo Polarimeter, we observed two AGN sources, including BL Lacertae at redshift z = 0.069, and S5 B0716+714 at z = 0.31. We demonstrate that optical polarimetry with a broadband Luminance filter combined with simultaneous $I_c$-band observations yields SME parameter constraints that are up to ~10 and ~30 times more sensitive than with a standard $I_c$-band filter, for SME models with mass dimension d = 5 and d = 6, respectively. Using only a small system of telescopes with an effective 0.45-m aperture, we further demonstrate d = 5 constraints for individual lines of sight that are within a factor of ~1-10 in sensitivity to comparable constraints from optical polarimetry with a 3.6-m telescope. Such an approach could significantly improve existing SME constraints via a polarimetric all-sky survey of AGN with multiple 1-meter class telescopes.

Multistar turbulence monitor: a new technique to measure optical turbulence profiles

The strength and vertical distribution of atmospheric turbulence is a key factor determining the performance of optical and infrared telescopes, with and without adaptive optics. Yet, this remains challenging to measure. We describe a new technique using a sequence of short-exposure images of a star field, obtained with a small telescope. Differential motion between all pairs of star images is used to compute the structure functions of longitudinal and transverse wavefront tilt for a range of angular separations. These are compared with theoretical predictions of simple turbulence models by means of a Markov-Chain Monte-Carlo optimization. The method is able to estimate the turbulence profile in the lower atmosphere, the total and free-atmosphere seeing, and the outer scale. We present results of Monte-Carlo simulations used to verify the technique, and show some examples using data from the second AST3 telescope at Dome A in Antarctica.

The Simons Observatory: science goals and forecasts

The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scientific goals of the experiment, motivate the design, and forecast its performance. SO will measure the temperature and polarization anisotropy of the cosmic microwave background in six frequency bands centered at: 27, 39, 93, 145, 225 and 280 GHz. The initial configuration of SO will have three small-aperture 0.5-m telescopes and one large-aperture 6-m telescope, with a total of 60,000 cryogenic bolometers. Our key science goals are to characterize the primordial perturbations, measure the number of relativistic species and the mass of neutrinos, test for deviations from a cosmological constant, improve our understanding of galaxy evolution, and constrain the duration of reionization. The small aperture telescopes will target the largest angular scales observable from Chile, mapping ≈ 10% of the sky to a white noise level of 2 μK-arcmin in combined 93 and 145 GHz bands, to measure the primordial tensor-to-scalar ratio, r, at a target level of σ(r)=0.003. The large aperture telescope will map ≈ 40% of the sky at arcminute angular resolution to an expected white noise level of 6 μK-arcmin in combined 93 and 145 GHz bands, overlapping with the majority of the Large Synoptic Survey Telescope sky region and partially with the Dark Energy Spectroscopic Instrument. With up to an order of magnitude lower polarization noise than maps from the Planck satellite, the high-resolution sky maps will constrain cosmological parameters derived from the damping tail, gravitational lensing of the microwave background, the primordial bispectrum, and the thermal and kinematic Sunyaev-Zel'dovich effects, and will aid in delensing the large-angle polarization signal to measure the tensor-to-scalar ratio. The survey will also provide a legacy catalog of 16,000 galaxy clusters and more than 20,000 extragalactic sources.

A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes

Kuiper belt objects (KBOs) are thought to be the remnant of the early solar system, and their size distribution provides an opportunity to explore the formation and evolution of the outer solar system. In particular, the size distribution of kilometre-sized (radius = 1-10 km) KBO represents a signature of initial planetesimal sizes when planets form. These kilometre-sized KBOs are extremely faint, and it is impossible to detect them directly. Instead, monitoring of stellar occultation events is one possible way to discover these small KBOs. Hitherto, however, there has been no observational evidence for the occultation events by KBOs with radii of 1-10 km. Here we report the first detection of a single occultation event candidate by a KBO with a radius of $\sim$1.3 km, which is simultaneously provided by two low-cost small telescopes coupled with commercial CMOS cameras. From this detection, we conclude that a surface number density of KBOs with radii exceeding $\sim 1.2$ km is $\sim 6 \times 10^5 \ {\rm deg^{-2}}$. This surface number density favours a theoretical size distribution model with an excess signature at a radius of 1-2 km. If this is a true detection, this implies that planetesimals before their runaway growth phase grow into kilometre-sized objects in the primordial outer solar system and remain as a major population of the present-day Kuiper belt.

Extreme background-rejection techniques for the ELROI optical satellite license plate.

The extremely low-resource optical identifier (ELROI) is a concept for an autonomous, low-power optical "license plate" that can be attached to anything that goes into space. ELROI uses short, omnidirectional flashes of laser light to encode a unique ID number that can be read by a small ground telescope using a photon-counting sensor and innovative extreme background-rejection techniques. ELROI is smaller and lighter than a typical radio beacon, low-power enough to run on its own small solar cell, and can safely operate for the entire orbital lifetime of a satellite or debris object. The concept has been validated in ground tests, and orbital prototypes are scheduled for launch in 2018 and beyond. In this paper, we focus on the details of the encoding scheme and data analysis that allow a milliwatt optical signal to be read from orbit. We describe the techniques of extreme background-rejection needed to achieve this, including spectral filtering and temporal filtering using a period- and phase-recovery algorithm, and discuss the requirements for an error-correcting code to encode the ID number. Worked examples with both simulated and experimental (long-range ground test) data illustrate the methods used. We present these techniques to describe a new optical communication concept, and to encourage others to consider observing and analyzing our upcoming test flights.

Demonstrating the Principles of Aperture Synthesis with Table- Top Laboratory Exercises

Many undergraduate radio astronomy courses are unable to give a detailed treatment of aperture synthesis due to time constraints and limited math backgrounds of students. We have taken a laboratory-based approach to teaching radio interferometry using a set of college-level, table-top exercises. These are performed with the Very Small Radio Telescope (VSRT), an interferometer developed at the Haystack Observatory using satellite TV electronics as detectors and compact fluorescent light bulbs as microwave signal sources. The hands-on experience provided by the VSRT in these labs allows students to gain a conceptual understanding of radio interferometry and aperture synthesis without the rigorous mathematical background traditionally required. The data are quickly and easily processed using a user-friendly data analysis Java package, VSRTI_Plotter.jar. This software can also be used in the absence of the equipment as an interactive computer activity to demonstrate an interferometer’s responses to assorted surface brightness distributions. The students also gain some familiarity with Fourier transforms and an appreciation for the Fourier relations in interferometry using another Java package, the Tool for Interactive Fourier Transforms (TIFT). We have successfully used these tools in multiple offerings of our radio astronomy course at Union College

Development of Teaching Materials for Teachers about Small Astronomical Telescopes

Textbooks used in elementary and junior high schools must be written based on the Courses of Study in Japan. Science textbooks show observation of the moon and the sun using a small astronomical telescope. However, most in-service teachers have never used an astronomical telescope. Teachers have to use it safely to secure the safety of pupils, students, and teachers. I examined wrong and unsafe acts while in-service teachers and students assembled astronomical telescopes. Then I developed digital teaching materials for teachers including risks caused by wrong acts.

The First Solar Seeing Profile Measurement with Two Apertures and Multiple Guide Regions

Ground-based observations suffer from atmospheric turbulence perturbations, which seriously degrade the image quality. The seeing profile associated with the turbulence is critical to characterize an astronomical site. The optimal design and performance estimation of future solar ground-layer adaptive optics (GLAO) and multi-conjugate adaptive optics (MCAO) heavily rely on our knowledge of the seeing profile at a specific site. Many current optical seeing profile measurement techniques require one to use a large solar telescope for that purpose. The development of a portable instrument to measure and characterize the seeing profile is thus highly needed, in particular for testing potential new sites or for the regularly monitoring of the seeing condition at existing sites. Recently, we proposed the Advanced Multiple Aperture Seeing Profiler (A-MASP), which uses multiple small telescopes and multiple regions of interest (ROIs) on the solar surface to measure the seeing profile up to an altitude of 30 km. Here, we report our recent proof-of-concept observation run of the A-MASP technique with the Dunn Solar Telescope (DST) of the National Solar Observatory (NSO). We found that the Fried parameter, $r_{0}$ , was about 12 cm at the observed wavelength of 630 nm in the early morning and that there were three main turbulence layers. The strongest one was the mix layer near the ground. We observed the evolution of the top of the mix layer and found that it can rise to about 1.5 km in about 18 min, which is consistent with the theory of daytime boundary layer evolution. Another turbulence layer was observed from 8 to 15 km, which is at the top of the convective layer. Comparing an instrument with two sub-apertures with a real A-MASP instrument, we found that they should lead to similar results except for the altitude $h = 0$ .

CCD observation of daylight crescent moon at Bosscha observatory

Bosscha Observatory, Institut Teknologi Bandung, has been experimenting to observe crescent moon using small telescope equipped with digital cameras since 2007. The initial motivation was to provide evidence, i.e. digital image, of the first crescent moon visible after new moon (hilal) for moslem community in determining the first day of Ramadan and Shawwal. Initially, observation was done after sunset, following common believe that crescent moon can be detected only after glare from the Sun disappear. In early 2000’s it was shown that crescent moon can be detected using CCD camera before sunset (in daylight) with special setup. We catched up the idea in 2013. In this paper we summarize what we have learned so far. Now, detection of crescent moon with elongation e > 4° is not a problem. Detailed report will be written somewhere else.

Long-Term Optical and Spectral Variability of FSRQ 3C454.3

3C454.3 is a widely studied and monitored flat spectrum radio quasar. We use the observations from the Small and Moderate Aperture Research Telescope System (SMARTS) to analyze the long-term optical and spectral variabilities of 3C454.3 at B, V, R, J, and K (BVRJK) bands. Based on the relation: Fν∝ν-α, we calculate the multiband spectral indices (α) and analyze the relations between α and Fν, where Fν is the flux density at ν band (ν=B, V, R, J, K). Main results are as follows. (1) The largest variations at BVRJK bands are ΔB = 3.37±0.08 mag, with the timescale ΔTB≈ 1015 days, at B band; ΔV = 3.31±0.07 mag, with the timescale ΔTV≈ 1014 days, at V band; ΔR = 3.62±0.12 mag, with the timescale ΔTR≈ 679 days, at R band; ΔJ = 4.08±0.01 mag, with the timescale ΔTJ≈ 763 days, at J band; and ΔK = 5.03±0.03 mag, with the timescale ΔTK≈ 2715 days, at K band. (2) We analyze the long-term BVRJK lightcurves and obtain the quasiperiodicities: P1=86.92±2.21 days, P2=204±8.1 days, and P3=1.24±0.19 years. (3) Multiband lightcurves show time delays: τVB = 0.15±0.12 days, τRB = 0.37±0.28 days, τJB = 0.58±0.40 days, and τKB = 1.02±0.47 days. (4) The relations between α and Fν show strong correlations, which are typical RWB behaviors; when the source turns to be brighter, the spectral indices turn to be redder.

Mirach’s Goblin: Discovery of a dwarf spheroidal galaxy behind the Andromeda galaxy

Context. It is of broad interest for galaxy formation theory to carry out a full inventory of the numbers and properties of dwarf galaxies, both satellite and isolated, in the Local Volume. Aims. Ultra-deep imaging in wide areas of the sky with small amateur telescopes can help to complete the census of these hitherto unknown low-surface-brightness galaxies, which cannot be detected by the current resolved stellar population and HI surveys. We report the discovery of Donatiello I, a dwarf spheroidal galaxy located one degree from the star Mirach (β And) in a deep image taken with an amateur telescope. Methods. The color-magnitude diagram (CMD) obtained from follow-up observations obtained with the Gran Telescopio Canarias (La Palma, Spain) reveals that this system is beyond the local group and is mainly composed of old stars. The absence of young stars and HI emission in the ALFALFA survey is typical of quenched dwarf galaxies. Our photometry suggests a distance modulus for this galaxy of (m − M) = 27.6 ± 0.2 (3.3 Mpc), although this distance cannot yet be established securely owing to the crowding effects in our CMD. At this distance, the absolute magnitude (MV = −8.3), surface brightness (μV = 26.5 mag arcsec−2), and stellar content of Donatiello I are similar to the “classical” Milky Way companions Draco or Ursa Minor. Results. The projected position and distance of Donatiello I are consistent with this object being a dwarf satellite of the closest S0-type galaxy NGC 404 (“Mirach’s Ghost”). Alternatively, it could be one of the most isolated quenched dwarf galaxies reported so far behind the Andromeda galaxy.

The Data Processor system of EUSO-SPB1

In this paper we present the Data Processor (DP) and the flight software of the EUSO-SPB1 mission. The EUSO-SPB1 experiment is a pathfinder mission of the EUSO program whose main objective is to detect Ultra-High Energy Cosmic Rays (UHECR) by measuring, for the first time from space, the fluorescence and the Cerenkov Ultra-Violet light produced by Extensive Air Shower. The instrument is a small telescope mounted on an unpressurized gondola of a super pressure balloon. Since a super pressure balloon could remain airborne up to 100 days, the requirements on the electronics and data handling are quite severe. The DP is the component of the electronics system performing the data handling, the monitoring, and the control of the instrument from ground through the interface with the telemetry system. EUSO-SPB1 was launched from Wanaka Airport (New Zealand) on the 24th of April 2017, at 22:51 UTC and the flight lasted for 12 days.

GRB 171205A/SN 2017iuk: A local low-luminosity gamma-ray burst

Context. Gamma-ray bursts (GRBs) occurring in the local Universe constitute an interesting sub-class of the GRB family, since their luminosity is on average lower than that of their cosmological analogs. Attempts to understand in a global way this peculiar behaviour is still not possible, since the sample of low redshift GRBs is small, and the properties of individual objects are too different from each other. In addition, their closeness (and consequently high fluxes) make these sources ideal targets for extensive follow-up even with small telescopes, considering also that these GRBs are conclusively associated with supernova (SN) explosions. Aims. We aim to contribute to the study of local bursts by reporting the case of GRB 171205A. This source was discovered by Swift Burst Alert Telescope (BAT) on 2017, December 5 and soon associated with a low redshift host galaxy (z = 0.037), and an emerging SN (SN 2017iuk). Methods. We analyzed the full Swift dataset, comprising the UV-Optical Telescope (UVOT), X-ray Telescope (XRT) and BAT data. In addition, we employed the Konus-Wind high energy data as a valuable extension at γ-ray energies. Results. The photometric SN signature is clearly visible in the UVOT u, b and ν filters. The maximum emission is reached at ∼13 (rest frame) days, and the whole bump resembles that of SN 2006aj, but lower in magnitude and with a shift in time of +2 d. A prebump in the ν-band is also clearly visible, and this is the first time that such a feature is not observed achromatically in GRB–SNe. Its physical origin cannot be easily explained. The X-ray spectrum shows an intrinsic Hydrogen column density NH,int = 7.4+4.1−3.6 × 1020 cm−2, which is at the low end of the N H, int, even considering just low redshift GRBs. The spectrum also features a thermal component, which is quite common in GRBs associated with SNe, but whose origin is still a matter of debate. Finally, the isotropic energy in the γ-ray band, Eiso = 2.18+0.63−5.0 × 1049 erg, is lower than those of cosmological GRBs. Combining this value with the peak energy in the same band, Ep = 125+141−37 keV, implies that GRB 171205A is an outlier of the Amati relation, as are some other low redshift GRBs, and its emission mechanism should be different from that of canonical, farther away GRBs.

The extraordinary composition of the blue comet C/2016 R2 (PanSTARRS)

We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23 and 24 January 2018 with the IRAM 30 m telescope, and in January to March 2018 with the Nançay radio telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH3OH, H2CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8 AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N2 ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.

Monitoring of the activity and composition of comets 41P/Tuttle–Giacobini–Kresak and 45P/Honda–Mrkos–Pajdusakova

We report on photometry and imaging of the Jupiter family comets 41P/Tuttle–Giacobini–Kresak and 45P/Honda–Mrkos–Pajdusakova with the TRAPPIST-North (TRAnsiting Planets and PlanetesImals Small Telescope) telescope. We observed 41P on 34 nights from February 16 to July 27, 2017, pre- and post-perihelion (rh= 1.04 au), and collected data for comet 45P after perihelion (rh= 0.53 au) from February 10 to March 30, 2017. We computed the production rates of the daughter species OH, NH, CN, C3and C2and we measured the dust proxy, Afρ, for both comets. The peak of water-production rate of 41P was (3.46 ± 0.20) × 1027molecules s−1on April 3, 2017, when the comet was at 1.05 au from the Sun. We have shown that the activity of 41P is decreasing by about 30–40% from one apparition to the next. We measured a mean water-production rate for 45P of (1.43 ± 0.62) × 1027molecules s−1during a month after perihelion. Our results show that these Jupiter family comets had low gas and dust activity and no outburst was detected. Relative abundances, expressed as ratios of production rates and the Afρparameter with respect to OH and to CN, were compared to those measured in other comets. We found that 41P and 45P have a typical composition in terms of carbon-bearing species. The study of coma features exhibited by the CN gas species allowed the measurement of the rotation period of 41P, showing a surprisingly large increase of the rotation period from (30 ± 5) h at the end of March to (50 ± 10) h at the end of April, 2017, in agreement with recent observations by other teams.

Исследование солнечной активности радиотелескопами Службы Солнца KRIM

Radio astronomy diagnostic complex based on the RT-22 radio telescope and three small radio telescopes combined into the KRIM Sun Service is located at 330 59 '30'' E longitude and 440 23 '52'' N latitude. The KRIM Sun Service conducts observations of the Sun in monitoring mode and alerts. The complex is integrated into the World Service for Solar Activity Research, and the daily data is stored in real time in digital form and posted on the sites of the World Sun Service, which includes 14 ground stations in cooperation with orbital observatories. During the minimum period of the 11-year solar activity cycle from September 6 to 10, 2017, KRIM Sun Service radio telescopes recorded a number of strong solar radio bursts in the active region NOAA 12673. The information obtained correlates well with data from other ground-based and satellite observatories, such as RSTN (Network Solar Radio Telescopes) and GOES (Geostationary Operational Satellite for Surrounding Space). This confirms the high quality and accuracy of the KRIM Solar Service radio telescopes.

Do Status-Legitimizing Beliefs Moderate Effects of Racial Progress on Perceptions of Anti-White Bias? A Replication of Wilkins and Kaiser (2014)

In three studies, Wilkins and Kaiser found that both chronic and experimental salience of racial progress in the United States increased the perceptions of anti-White bias only among people high in status-legitimizing beliefs (SLBs). We conducted four preregistered high-powered replications of this research. Studies 1, 2, and 3a were close replications of studies 1–3, respectively. Study 3b was a close replication that included an additional experimental condition. Contrary to the original findings, none of the four expected interaction effects tested were statistically significant in the predicted direction, and only one of the four survived a “small telescopes” analysis. We provide additional tests addressing whether changing social contexts explain our failures to replicate, with mixed conclusions. Whereas it is possible that changing social contexts may have eliminated a once true effect, it is also possible that the original results were false positives.

Night Vision for Small Telescopes

We explore the feasibility of using current generation, off-the-shelf, indium gallium arsenide (InGaAs) near-infrared (NIR) detectors for astronomical observations. Light-weight InGaAs cameras, developed for the night vision industry and operated at or near room temperature, enable cost-effective new paths for observing the NIR sky, particularly when paired with small telescopes. We have tested an InGaAs camera in the laboratory and on the sky using 12 and 18 inch telescopes. The camera is a small-format, 320 × 240 pixels of 40 μm pitch, shortwave infrared (SWIR) device from Sensors Unlimited. Although the device exhibits a room-temperature dark current of 5.7 × 104 per pixel, we find observations of bright sources and low-positional-resolution observations of faint sources remain feasible. We can record unsaturated images of bright (J = 3.9) sources due to the large pixel well-depth and resulting high dynamic range. When mounted on an 18 inch telescope, the sensor is capable of achieving milli-magnitude precision for sources brighter than J = 8. Faint sources can be sky-background-limited with modest thermoelectric cooling. We can detect faint sources (J = 16.4 at 10σ) in a one-minute exposure when mounted to an 18 inch telescope. From laboratory testing, we characterize the noise properties, sensitivity, and stability of the camera in a variety of different operational modes and at different operating temperatures. Through sky testing, we show that the (unfiltered) camera can enable precise and accurate photometry, operating like a filtered J-band detector, with small color corrections. In the course of our sky testing, we successfully measured sub-percent flux variations in an exoplanet transit. We have demonstrated an ability to detect transient sources in dense fields using image subtraction of existing reference catalogs.