Recent ultrahigh-energy gamma-ray observations by the High Altitude Water Cherenkov Observatory up to 100 TeV and LHAASO observatories up to 1.4 PeV energies from the direction of Fermi Large Area Telescope 4FGL source 4FGL J2028.6 + 4110e (Cygnus Cocoon) are indicative of a hadronic origin over a leptonic process for their creation. The IceCube Neutrino Observatory has reported IceCube-201120A, a neutrino event coming from the same direction, suggesting that the Cygnus Cocoon may correspond to one of the most plausible sources of high-energy cosmic rays. The apparent relationship of the neutrino event with the observed ultrahigh-energy gamma rays from the Cygnus Cocoon is investigated in this work to study if it can be explained consistently in hadronic interactions of accelerated cosmic rays with ambient matter. Our findings reveal that leptonic mechanisms, together with pure hadronic mechanisms, make a considerable contribution to the understanding of the total electromagnetic spectrum as well as the observed neutrino event. The estimate of expected muon neutrino events from the Cygnus Cocoon agrees with the one muon neutrino event detected so far in IceCube multiyear observations. Thus, our results are indicative of the potential of the Cygnus Cocoon to be a Galactic cosmic-ray source capable of accelerating at least up to PeV energies.

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Aerosol optical characteristics AOD and Ångström exponent is often used to asses environmental aerosol loading. AOD or Aerosol Optical Depth is an indirect measure of atmospheric aerosol loading by means of total extinction of incoming solar radiation due to scattering and absorption whereas Ångström exponent(α) is used to get qualitative understanding of aerosol particle size. Analysis of long term time series AOD data reveals how AOD vis-à-vis aerosol on a particular place changes over time. Similar study with Ångström exponent(α) gives an idea how particle size distribution is changing over some area. Such studies cannot be conducted by data measured by ground based stations alone because they are inadequate in numbers on earth moreover such data for considerably long period are not available for most places. To overcome this, radiance data sensed by MODIS instruments on board Aqua and Terra satellite have been used by many authors. In this study 13 years of MODIS level 2 data by Terra have been analyzed for four Indian mega-cities namely Delhi, Mumbai, Kolkata and Chennai using well known Mann-Kendall statistics and Sen's non-parametric estimation of slopes.

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