@article{MTMT:31843869, title = {Towards the attitude determination of nano-satellites with thermal imaging sensors}, url = {https://m2.mtmt.hu/api/publication/31843869}, author = {Dálya, Gergely and Takátsy, János and Bozóki, Tamás and Kapás, Kornél and Mészáros, László and Pal, A.}, doi = {10.1117/12.2562114}, journal-iso = {PROCEEDINGS OF SPIE}, journal = {PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING}, volume = {11451}, unique-id = {31843869}, issn = {0277-786X}, year = {2020}, eissn = {1996-756X}, orcid-numbers = {Dálya, Gergely/0000-0003-3258-5763; Takátsy, János/0000-0002-2657-5094; Bozóki, Tamás/0000-0002-1672-1510} } @article{MTMT:30605429, title = {The Weakening Outburst of the Young Eruptive Star V582 Aur}, url = {https://m2.mtmt.hu/api/publication/30605429}, author = {Zsidi, Gabriella and Ábrahám, Péter and Acosta-Pulido, J. A. and Kóspál, Ágnes and Kun, Mária and Szabó, Zs. M. and Bódi, Attila and Cseh, Borbála and Segura, N. Castro and Hanyecz, O. and Ignácz, B. and Kalup, Csilla and Kriskovics, Levente and Mészáros, L. and Ordasi, A. and Pál, András and Sárneczky, Krisztián and Seli, B. and Sódor, Ádám and Szakáts, Róbert}, doi = {10.3847/1538-4357/ab05c9}, journal-iso = {ASTROPHYS J}, journal = {ASTROPHYSICAL JOURNAL}, volume = {873}, unique-id = {30605429}, issn = {1538-4357}, year = {2019}, eissn = {0004-637X}, orcid-numbers = {Bódi, Attila/0000-0002-8585-4544} } @article{MTMT:30307617, title = {"TNOs are Cool": A survey of the trans-Neptunian region. XIV. Size/albedo characterization of the Haumea family observed with Herschel and Spitzer}, url = {https://m2.mtmt.hu/api/publication/30307617}, author = {Vilenius, E. and Stansberry, J. and Müller, T. and Mueller, M. and Kiss, Csaba and Santos-Sanz, P. and Mommert, M. and Pál, András and Lellouch, E. and Ortiz, J. L. and Peixinho, N. and Thirouin, A. and Lykawka, P. S. and Horner, J. and Duffard, R. and Fornasier, S. and Delsanti, A.}, doi = {10.1051/0004-6361/201732564}, journal-iso = {ASTRON ASTROPHYS}, journal = {ASTRONOMY & ASTROPHYSICS}, publisher = {EDP Sciences S.A.}, volume = {618}, unique-id = {30307617}, issn = {0004-6361}, abstract = {Context. A group of trans-Neptunian objects (TNOs) are dynamically related to the dwarf planet 136108 Haumea. Ten of them show strong indications of water ice on their surfaces, are assumed to have resulted from a collision, and are accepted as the only known TNO collisional family. Nineteen other dynamically similar objects lack water ice absorptions and are hypothesized to be dynamical interlopers. Aims: We have made observations to determine sizes and geometric albedos of six of the accepted Haumea family members and one dynamical interloper. Ten other dynamical interlopers have been measured by previous works. We compare the individual and statistical properties of the family members and interlopers, examining the size and albedo distributions of both groups. We also examine implications for the total mass of the family and their ejection velocities. Methods: We use far-infrared space-based telescopes to observe the target TNOs near their thermal peak and combine these data with optical magnitudes to derive sizes and albedos using radiometric techniques. Using measured and inferred sizes together with ejection velocities, we determine the power-law slope of ejection velocity as a function of effective diameter. Results: The detected Haumea family members have a diversity of geometric albedos 0.3-0.8, which are higher than geometric albedos of dynamically similar objects without water ice. The median geometric albedo for accepted family members is pV = 0.48-0.18+0.28, compared to 0.08-0.05+0.07 for the dynamical interlopers. In the size range D = 175-300 km, the slope of the cumulative size distribution is q = 3.2-0.4+0.7 for accepted family members, steeper than the q = 2.0 ± 0.6 slope for the dynamical interlopers with D < 500 km. The total mass of Haumea's moons and family members is 2.4% of Haumea's mass. The ejection velocities required to emplace them on their current orbits show a dependence on diameter, with a power-law slope of 0.21-0.50. Herschel is an ESA space observatory with science instruments provided by a European-led Principal Investigator consortia and with important participation from NASA.}, keywords = {infrared: planetary systems; techniques: photometric; methods: observational; Kuiper belt: general}, year = {2018}, eissn = {1432-0746} } @article{MTMT:30307591, title = {TESS in the Solar System}, url = {https://m2.mtmt.hu/api/publication/30307591}, author = {Pál, András and Molnár, László and Kiss, Csaba}, doi = {10.1088/1538-3873/aae2aa}, journal-iso = {PUBL ASTRON SOC PAC}, journal = {PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC}, publisher = {IOP Publishing Ltd}, volume = {130}, unique-id = {30307591}, issn = {0004-6280}, abstract = {The Transiting Exoplanet Survey Satellite (TESS), launched successfully on 2018 April 18 will observe nearly the full sky, and will provide timeseries imaging data in ∼27-day-long campaigns. TESS is equipped with four cameras, each of which has a field of view of 24 × 24°. During the first two years of the primary mission, one of these cameras, Camera #1, is going to observe fields centered at an ecliptic latitude of 18°. While the ecliptic plane itself is not covered during the primary mission, the characteristic scale height of the main asteroid belt and Kuiper Belt implies that a significant amount of small solar system bodies will cross this camera’s field of view. Based on the comparison of the expected amount of information of TESS and Kepler/K2, we can compute the cumulative étendues of the two optical setups. This comparison results in roughly comparable optical étendues however, the net étendue is significantly larger in the case of TESS because all of the imaging data provided by the 30-minute cadence frames are downlinked rather than the pre-selected stamps of Kepler/K2. In addition, many principles of the data acquisition and optical setup are clearly different, including the level of confusing background sources; full- frame integration and cadence; the field-of-view centroid with respect to the apparent position of the Sun; as well as the differences in the duration of the campaigns. As one would expect, TESS will yield timeseries photometry, and hence rotational properties for only brighter objects, but in terms of spatial and phase space coverage, this sample will be more homogeneous and more complete. Here, we review the main analogs and differences between the Kepler/K2 mission and the TESS mission, focusing on scientific implications and possible yields related to our solar system.}, keywords = {Astrophysics - Instrumentation and Methods for Astrophysics; Astrophysics - Earth and Planetary Astrophysics}, year = {2018}, eissn = {1538-3873} } @article{MTMT:3420166, title = {Finding flares in Kepler data using machine-learning tools}, url = {https://m2.mtmt.hu/api/publication/3420166}, author = {Vida, Krisztián and Roettenbacher, Rachael M.}, doi = {10.1051/0004-6361/201833194}, journal-iso = {ASTRON ASTROPHYS}, journal = {ASTRONOMY & ASTROPHYSICS}, publisher = {EDP Sciences S.A.}, volume = {616}, unique-id = {3420166}, issn = {0004-6361}, abstract = {Context. Archives of long photometric surveys, such as the Kepler database, are a great basis for studying flares. However, identifying the flares is a complex task; it is easily done in the case of single-target observations by visual inspection, but is nearly impossible for several year-long time series for several thousand targets. Although automated methods for this task exist, several problems are difficult (or impossible) to overcome with traditional fitting and analysis approaches.
Aims: We introduce a code for identifying and analyzing flares based on machine-learning methods, which are intrinsically adept at handling such data sets.
Methods: We used the RANSAC (RANdom SAmple Consensus) algorithm to model light curves, as it yields robust fits even in the case of several outliers, such as flares. The light curves were divided into search windows, approximately on the order of the stellar rotation period. This search window was shifted over the data set, and a voting system was used to keep false positives to a minimum: only those flare candidate points were kept that were identified as a flare in several windows.
Results: The code was tested on short-cadence K2 observations of TRAPPIST-1 and on long-cadence Kepler data of KIC 1722506. The detected flare events and flare energies are consistent with earlier results from manual inspections.}, keywords = {methods: data analysis; techniques: photometric; Stars: late-type; Stars: activity; stars: low-mass; stars: flare}, year = {2018}, eissn = {1432-0746} } @inproceedings{MTMT:3408120, title = {CAMELOT: Design and performance verification of the detector concept and localization capability}, url = {https://m2.mtmt.hu/api/publication/3408120}, author = {Ohno, Masanori and Werner, Norbert and Pál, András and Ripa, Jakub and Galgóczi, Gábor and Tarcai, N and Várhegyi, Z and Fukazawa, Y and Mizuno, T and Takahashi, H and Tanaka, K and Uchida, N and Torigoe, K and Nakazawa, K and Enoto, T and Odaka, H and Ichinohe, Y and Frei, Zsolt and Kiss, L. László}, booktitle = {Space Telescopes and Instrumentation 2018}, doi = {10.1117/12.2313228}, volume = {10699}, unique-id = {3408120}, abstract = {A fleet of nanosatellites using precise timing synchronization provided by the Global Positioning System is a new concept for monitoring the gamma-ray sky that can achieve both all-sky coverage and good localization accuracy. We are proposing this new concept for the mission CubeSats Applied for MEasuring and LOcalising Transients (CAMELOT). The differences in photon arrival times at each satellite are to be used for source localization. Detectors with good photon statistics and the development of a localization algorithm capable of handling a large number of satellites are both essential for this mission. Large, thin CsI scintillator plates are the current candidates for the detectors because of their high light yields. It is challenging to maximize the light-collection efficiency and to understand the position dependence of such thin plates. We have found a multi-channel readout that uses the coincidence technique to be very effective in increasing the light output while keeping a similar noise level to that of a single channel readout. Based on such a detector design, we have developed a localization algorithm for this mission and have found that we can achieve a localization accuracy better than 20 arc minutes and a rate of about 10 short gamma-ray bursts per year.}, year = {2018}, orcid-numbers = {Ripa, Jakub/0000-0003-3994-7528; Frei, Zsolt/0000-0002-0181-8491; Kiss, L. László/0000-0002-3234-1374} } @article{MTMT:3408116, title = {CAMELOT: Cubesats Applied for MEasuring and LOcalising Transients mission overview}, url = {https://m2.mtmt.hu/api/publication/3408116}, isbn = {9781510619517}, author = {Werner, Norbert and Ripa, Jakub and Pál, András and Ohno, Masanori and Tarcai, N and Torigoe, K and Tanaka, K and Uchida, N and Galgóczi, Gábor and Fukazawa, Y and Mizuno, T and Takahashi, H and Nakazawa, K and Várhegyi, Z and Enoto, T and Odaka, H and Ichinohe, Y and Frei, Zsolt and Mészáros, László and Kiss, L. László}, doi = {10.1117/12.2313764}, journal-iso = {PROCEEDINGS OF SPIE}, journal = {PROCEEDINGS OF SPIE - THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING}, volume = {10699}, unique-id = {3408116}, issn = {0277-786X}, abstract = {We propose a fleet of nanosatellites to perform an all-sky monitoring and timing based localisation of gamma-ray transients. The fleet of at least nine 3U cubesats shall be equipped with large and thin CsI(Tl) scintillator based soft gamma-ray detectors read out by multi-pixel photon counters. For bright short gamma-ray bursts (GRBs), by cross-correlating their light curves, the fleet shall be able to determine the time difference of the arriving GRB signal between the satellites and thus determine the source position with an accuracy of similar to 10'. This requirement demands precise time synchronization and accurate time stamping of the detected gamma-ray photons, which will be achieved by using on-board GPS receivers. Rapid follow up observations at other wavelengths require the capability for fast, nearly simultaneous downlink of data using a global inter-satellite communication network. In terms of all-sky coverage, the proposed fleet will outperform all GRB monitoring missions.}, year = {2018}, eissn = {1996-756X}, orcid-numbers = {Ripa, Jakub/0000-0003-3994-7528; Frei, Zsolt/0000-0002-0181-8491; Kiss, L. László/0000-0002-3234-1374} } @inproceedings{MTMT:3405096, title = {Modular electronics design for small-size telescope and dome control}, url = {https://m2.mtmt.hu/api/publication/3405096}, author = {Mészáros, László and Pál, András}, booktitle = {GROUND-BASED AND AIRBORNE TELESCOPES VII}, doi = {10.1117/12.2314193}, unique-id = {3405096}, keywords = {Instrumentation: miscellaneous}, year = {2018} } @article{MTMT:3401139, title = {Spots, Flares, Accretion, and Obscuration in the Pre-main-sequence Binary DQ Tau}, url = {https://m2.mtmt.hu/api/publication/3401139}, author = {Kóspál, Ágnes and Ábrahám, Péter and Zsidi, Gabriella and Vida, Krisztián and Szabó, Róbert and Moór, Attila and Pál, András}, doi = {10.3847/1538-4357/aacafa}, journal-iso = {ASTROPHYS J}, journal = {ASTROPHYSICAL JOURNAL}, volume = {862}, unique-id = {3401139}, issn = {1538-4357}, abstract = {DQ Tau is a young low-mass spectroscopic binary, consisting of two almost equal-mass stars on a 15.8 day period surrounded by a circumbinary disk. Here, we analyze DQ Tau’s light curves obtained by Kepler K2, the Spitzer Space Telescope, and ground-based facilities. We observed variability phenomena, including rotational modulation by stellar spots, brief brightening events due to stellar flares, long brightening events around periastron due to increased accretion, and short dips due to brief circumstellar obscuration. The rotational modulation appears as a sinusoidal variation with a period of 3.017 days. In our model, this is caused by extended stellar spots 400 K colder than the stellar effective temperature. During our 80 day long monitoring, we detected 40 stellar flares with energies up to 1.2 × 1035 erg and duration of a few hours. The flare profiles closely resemble those in older late-type stars, and their occurrence does not correlate with either the rotational or the orbital period. We observe elevated accretion rates of up to 5 × 10‑8 M ⊙ yr‑1 around each periastron. Our Spitzer data suggest that the increased accretion luminosity temporarily heats up the inner part of the circumbinary disk by about 100 K. We found an inner disk radius of 0.13 au, significantly smaller than expected from dynamical modeling of circumbinary disks. Interestingly, the inner edge of the disk corotates with the binary’s orbit. DQ Tau also shows short dips of <0.1 mag in its light curve, reminiscent of the well-known “dipper phenomenon” observed in many low-mass young stars.}, keywords = {circumstellar matter; stars: pre-main sequence; stars: individual: DQ Tau}, year = {2018}, eissn = {0004-637X}, orcid-numbers = {Szabó, Róbert/0000-0002-3258-1909} } @misc{MTMT:3399607, title = {CAMELOT - Concept study and early results for onboard data processing and GPS-based timestamping}, url = {https://m2.mtmt.hu/api/publication/3399607}, author = {Pál, András and Mészáros, László and Tarcai, Norbert and Werner, Norbert and Ripa, Jakub and Ohno, Masanori and Torigoe, Kento and Tanaka, Koji and Uchida, Nagomi and Galgóczi, Gábor and Fukazawa, Yasushi and Mizuno, Tsunefumi and Takahashi, Hiromitsu and Nakazawa, Kazuhiro and Várhegyi, Zsolt and Enoto, Teruaki and Odaka, Hirokazu and Ichinohe, Yuto and Frei, Zsolt and Kiss, L. László}, unique-id = {3399607}, abstract = {Due to recent advances in nanosatellite technology, it is now feasible to integrate scintillators with an effective area of hundreds of square-centimeters on a single three-unit cubesat. We present the early test results for the digital payload electronics developed for the proposed CAMELOT (Cubesats Applied for MEasuring and LOcalising Transients) mission. CAMELOT is a fleet of nanosatellites intended to do full-sky monitoring and perform accurate timing-based localization of gamma-ray transients. Here we present the early results on the GPS timestamping capabilities of the CAMELOT payload electronics, concluding that the investigated setup is capable to timestamp the received gamma-ray photons with an accuracy and precision better than 0.02 millisecond, which corresponds to a timing based localization accuracy of $\sim 3.5^{\prime}$. Further refinements will likely allow us to improve the timing accuracy down to the sub-microsecond level.}, keywords = {Astrophysics - Instrumentation and Methods for Astrophysics; Astrophysics - High Energy Astrophysical Phenomena}, year = {2018}, orcid-numbers = {Ripa, Jakub/0000-0003-3994-7528; Kiss, L. László/0000-0002-3234-1374} }