In rotation (successive) sampling, it is common practice to use the information collected on a previous occasion to improve the precision of the estimates at current occasion. The previous information may be in the form of an auxiliary character, the character under study itself, or both. In the present work, information on an auxiliary character, which is readily available on all the occasions, has been used along with the information on study character from the previous and current occasion. Consequently, chain type difference and regression estimators have been proposed for estimating the population mean at second (current) occasion in the two occasions rotation (successive) sampling. The proposed estimators have been compared with sample mean estimator when there is no matching and the optimum estimator, which is the combination of the means of the matched and unmatched portions of the sample at the second occasion. Optimum replacement policy is also discussed. Theoretical results have been justified through empirical interpretation.

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We present a study of far-UV (FUV) bright horizontal branch (HB) stars to understand the peculiarities seen in the HB sequence of the globular cluster NGC 1851, using ground- and space-based multiwavelength data. Optical and UV color–magnitude diagrams are used to classify HB stars and their membership from Hubble Space Telescope and Gaia DR2 data. The spectral energy distributions (SEDs) of the hot HB stars located from the core to tidal radii are constructed. The SEDs reveal that the HB stars near the “Grundahl jump” show a decrease in the FUV flux when atmospheric models of cluster metallicity are used for fitting, but a better fit is found with higher-metallicity models, as expected due to atmospheric diffusion. We report on four particularly interesting extreme HB (EHB) stars, two each in the inner and outer regions. We detect a subluminous EHB and “blue-hook” candidates with temperatures T eff  ∼  25,000 K and 31,000 K, respectively. We found an EHB star (T eff  ∼  17,000 K) with a radius that lies between the BHB and normal EHB stars. The most peculiar of our EHB stars (T eff  ∼  28,000 K) is found to be a photometric binary to a blue straggler star (BSS; T eff  ∼  7000 K), which is an important target for spectroscopic study. This discovery of the candidate EHB+BSS binary system could help to explain the mass loss in the red giant branch phase, leading to the formation of EHB stars.

A field experiment was carried out with 109 diverse indigenous genotypes of bread wheat along with four checks in Augmented Block Design for study of character association and path coefficient, divided in to 7 blocks of equal size. Each block had 15 plots of test entries along with 4 checks (viz.

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A variety of practical problems can be addressed in the framework of rotation (successive) sampling. The present work presents a sample rotation pattern where sampling units are drawn on two successive occasions. The problem of estimation of population variance on current (second) occasion in two -occasion successive (rotation) sampling has been considered. A class of estimators has been proposed for population variance that includes many estimators as a particular case. Asymptotic properties of the proposed class of estimators are discussed. The proposed class of estimators is compared with the sample variance estimator when there is no matching from the previous occasion. Optimum replacement policy is discussed. Results are supported with the empirical means of comparison.

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We present dynamical status of the Galactic globular cluster NGC 6656 using spatial distribution of Blue Straggler Stars (BSSs). A combination of multi-wavelength highresolution space and ground-based data are used to cover a large cluster region. We determine the centre of gravity (C grav ) and construct the projected density profile of the cluster using the probable cluster members selected from HST and Gaia DR2 proper motion data sets. The projected density profile in the investigated region is nicely reproduced by a single mass King model, with core (r c ) and tidal (r t ) radius as 75 ′′ .2 ± 3 ′′ .1 and 35 ′ .6 ± 1 ′ .1 respectively. In total, 90 BSSs are identified on the basis of proper motion data in the region of radius 625 ′′ . An average mass of the BSSs is determined as 1.06 ± 0.09 M ⊙ and with an age range of 0.5 to 7 Gyrs. The BSS radial distribution shows a bimodal trend, with a peak in the centre, a minimum at r ∼ r c and a rising tendency in the outer region. The BSS radial distribution shows a flat behaviour in the outermost region of the cluster. We also estimate A + rh parameter as an alternative indicator of the dynamical status of the cluster and is found to be 0.038 ± 0.016. Based on the radial distribution and A + rh parameter, we conclude that NGC 6656 is an intermediate dynamical age cluster.