The peak-flux of GRB 221009A measured with GRBAlpha

The brightest gamma-ray burst ever observed, long-duration GRB 221009A, was detected by GRBAlpha nano-satellite without saturation. We present light curves of the prompt emission in 13 energy bands, from 80 keV to 950 keV, and perform a spectral analysis to calculate the peak flux and peak isotropic-equivalent luminosity. Since the satellite's attitude information is not available for the time of this GRB, more than 200 incident directions were probed in order to find the median luminosity and its systematic uncertainty. We found that the peak flux in the $80-800$ keV range (observer frame) was $F_{\rm{ph}}^{\rm{p}}=1300_{-200}^{+1200}$ ph cm$^{-2}$s$^{-1}$ or $F_{\rm{erg}}^{\rm{p}}=5.7_{-0.7}^{+3.7}\times10^{-4}$ erg cm$^{-2}$s$^{-1}$ and the fluence in the same energy range of the first GRB episode lasting 300 s, which was observable by GRBAlpha, was $S=2.2_{-0.3}^{+1.4}\times10^{-2}$ erg cm$^{-2}$ or $S^{\rm{bol}}=4.9_{-0.5}^{+0.8}\times10^{-2}$ erg cm$^{-2}$ for the extrapolated range of $0.9-8,690$ keV. We infer the isotropic-equivalent released energy of the first GRB episode to be $E_{\rm{iso}}^{\rm{bol}}=2.8_{-0.5}^{+0.8}\times10^{54}$ erg in the $1-10,000$ keV band (rest frame at $z=0.15$). The peak isotropic-equivalent luminosity in the $92-920$ keV range (rest frame) was $L_{\rm{iso}}^{\rm{p}}=3.7_{-0.5}^{+2.5}\times10^{52}$ erg s$^{-1}$ and the bolometric peak isotropic-equivalent luminosity was $L_{\rm{iso}}^{\rm{p,bol}}=8.4_{-1.5}^{+2.5}\times10^{52}$ erg s$^{-1}$ (4 s scale) in the $1-10,000$ keV range (rest frame). The peak emitted energy is $E_p^\ast=E_p(1+z)=1120\pm470$ keV. Our measurement of $L_{\rm{iso}}^{\rm{p,bol}}$ is consistent with the Yonetoku relation. It is possible that, due to the spectral evolution of this GRB and orientation of GRBAlpha at the peak time, the true values of peak flux, fluence, $L_{\rm{iso}}$, and $E_{\rm{iso}}$ are even higher. [abridged]Comment: 7 pages, 7 figures, 1 table, accepted for publication in Astronomy & Astrophysic

GRBAlpha: the smallest astrophysical space observatory -- Part 1: Detector design, system description and satellite operations

Aims. Since launched on 2021 March 22, the 1U-sized CubeSat GRBAlpha operates and collects scientific data on high-energy transients, making it the smallest astrophysical space observatory to date. GRBAlpha is an in-obit demonstration of a gamma-ray burst (GRB) detector concept suitably small to fit into a standard 1U volume. As it was demonstrated in a companion paper, GRBAlpha adds significant value to the scientific community with accurate characterization of bright GRBs, including the recent outstanding event of GRB 221009A. Methods. The GRB detector is a 75x75x5 mm CsI(Tl) scintillator wrapped in a reflective foil (ESR) read out by an array of SiPM detectors, multi-pixel photon counters by Hamamatsu, driven by two separate, redundant units. To further protect the scintillator block from sunlight and protect the SiPM detectors from particle radiation, we apply a multi-layer structure of Tedlar wrapping, anodized aluminium casing and a lead-alloy shielding on one edge of the assembly. The setup allows observations of gamma radiation within the energy range of 70-890 keV with an energy resolution of ~30%. Results. Here, we summarize the system design of the GRBAlpha mission, including the electronics and software components of the detector, some aspects of the platform as well as the current way of semi-autonomous operations. In addition, details are given about the raw data products and telemetry in order to encourage the community for expansion of the receiver network for our initiatives with GRBAlpha and related experiments.Comment: Accepted for publication in Astronomy & Astrophysics, 9 pages, 10 figure

Analysis of serum thyrotropin dynamics after TRH stimulation in normal children

In order to establish the quantitative parameters indicating serum thyrotropin dynamics after TRH stimulation, we measured the maximum incremants in TSH above the baseline level (max. ⊿TSH), the percentage ratio of the TSH level at 30 min to that at 15 min (R 30/15) and the percentage ratio of the TSH level at 120 min to that at 30 min (R 120/30) in 145 normal children. The geometric means (-2SD and+2SD) of max. ⊿TSH, R 30/15 and R 120/30 were 11.2% (3.9 to 32.5) uU/ml, 101.1% (75.9 to 134.7) and 38.9% (25.8 to 58.5), respectively. The values were compared with those of variables computed from the mathema- tical model of Okuno et al. (1977), i.e., C=(a/(β-α))•(Q(0)/V)(e(-αt)-e(-βt)＋Coe(-βt)where α=the rate constant for TSH release, β=the rate constant for TSH elimination, and Q(0)/V=the serum TSH releasing value per minute. Highly significant correlations were found between max. ⊿TSH and Q(0)/V (p<0.001), between R 30/15 and α (p<0.001) and between R 120/30 and β (p<0.001). The values of max. ⊿TSH also correlated well with the integrated secretion of TSH (p<0.001). These results suggest that our three parameters are more practical and useful indicators of serum TSH dynamics after TRH stimulation than the cumbersome mathematical model of Okuno et al. (1977), facilitating the detection of mild delayed TSH response

GRBAlpha: The smallest astrophysical space observatory

Aims. Since it launched on 22 March 2021, the 1U-sized CubeSat GRBAlpha operates and collects scientific data on high-energy transients, making it the smallest astrophysical space observatory to date. GRBAlpha is an in-orbit demonstration of a gamma-ray burst (GRB) detector concept suitably small to fit into a standard 1U volume. As was demonstrated in a companion paper, GRBAlpha adds significant value to the scientific community with accurate characterization of bright GRBs, including the recent outstanding event of GRB 221009A. Methods. The GRB detector is a 75 × 75 × 5 mm CsI(Tl) scintillator wrapped in a reflective foil (ESR) read out by an array of SiPM detectors, multi-pixel photon counters by Hamamatsu, driven by two separate redundant units. To further protect the scintillator block from sunlight and protect the SiPM detectors from particle radiation, we applied a multi-layer structure of Tedlar wrapping, anodized aluminium casing, and a lead-alloy shielding on one edge of the assembly. The setup allows observations of gamma radiation within the energy range of 70–890 keV with an energy resolution of ~30%. Results. Here, we summarize the system design of the GRBAlpha mission, including the electronics and software components of the detector, some aspects of the platform, and the current semi-autonomous operations. In addition, details are given about the raw data products and telemetry in order to encourage the community to expand the receiver network for our initiatives with GRBAlpha and related experiments

Photoproduction of Neutral Kaons on Liquid Deuterium Target(I. Nuclear Physics)

We have performed the experiment of K^0 photoproduction on the liquid deuterium target with Neutral Kaon Spectrometer (NKS) at LNS-Tohoku. The K^0s were measured via K^0_S→π^+π^- decay channel in the threshold region. The momentum spectra of K^0 photoproduction cross sections were derived and compared with the calculations using representative models