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The Neptunian satellite system is unusual, comprising Triton, a large ($\sim2700$ km) moon on a close-in, circular, yet retrograde orbit, flanked by Nereid, the largest irregular satellite ($\sim$300 km) on a highly eccentric orbit. Capture…

We have measured the solar phase curves in B, V, and I for 18 Trans-Neptunian Objects, 7 Centaurs, and Nereid and determined the rotation curves for 10 of these targets. For each body, we have made ~100 observations uniformly spread over…

A trending astronomical phenomenon to study is the variation in brightness of asteroids, caused by its rotation on its own axis, non-spherical shapes, changes of albedo along its surface and its position relative to the sun. The latter…

We present the results of Sun-as-a-star observations by the NEID Solar Telescope at WIYN Observatory, spanning January 1, 2021 through June 30, 2024. We identify 117,060 observations which are unlikely to be significantly affected by…

Efforts with extreme-precision radial velocity (EPRV) instruments to detect small-amplitude planets are largely limited, on many timescales, by the effects of stellar variability and instrumental systematics. One avenue for investigating…

T Tauri stars are low-mass pre-main sequence stars that are intrinsically variable. Due to the intense magnetic fields they possess, they develop dark spots on their surface that, because of rotation, introduce a periodic variation of…

New observations are presented of four evolved objects that display long, multi-year variations in their light curves. These are interpreted as good evidence of their binary nature, with the modulation caused by the barycenter motion of the…

We present an analysis of J, H, and K time series photometry obtained with the southern 2MASS telescope over a 0.84 x 6 deg^2 region centered near the Orion Nebula Cluster. These data are used to establish the near-infrared variability…

As part of our continuing study of light variability in proto-planetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval…

The electromagnetic counterpart to the Galactic center supermassive black hole, Sgr A*, has been observed in the near-infrared for over 20 years and is known to be highly variable. We report new Keck Telescope observations showing that Sgr…

The Cepheid Period-Luminosity law is a key rung on the extragalactic distance ladder. However, numerous Cepheids are known to undergo period variations. Monitoring, refining, and understanding these period variations allows us to better…

An extensive photometric monitoring of KH 15D, an enigmatic variable in the young star cluster NGC 2264, has been conducted. Simultaneous and accurate near-infrared (JHKs-bands) photometry is presented between 2003 December and 2005 March…

We present results of high-cadence monitoring of the optical light curve of the nearby, Type Ia SN 2014J in M82 using the 2.3m Aristarchos telescope. $B$ and $V$-band photometry on days 15-18 after $t_{max}(B)$, obtained with a cadence of 2…

Transiently accreting neutron stars in quiescence (Lx<10^34 erg/s) have been observed to vary in intensity by factors of few, over timescales of days to years. If the quiescent luminosity is powered by a hot NS core, the core cooling…

In an effort to characterize variations on the time scale of hours and smaller during the high and low states of the novalike variable TT Ari, light curves taken over the course of more than 40 yr are analyzed. It is found that the well…

Meteor light curves are sometimes known to display flickering: rapid, quasi-periodic variations in brightness. This effect is generally attributed to the rotational modulation of the ablation rate, which is caused by the time-varying cross…

Photometry of the unique pre-main sequence binary system KH 15D is presented, spanning the years 2005-2010. This system has exhibited photometric variations and eclipses over the last 50 years caused by a precessing circumbinary disk.…

We have investigated the nature of the variability of CHS7797, an unusual periodic variable in the Orion Nebula Cluster. An extensive I-band photometric data set of CHS7797 was compiled between 2004-2010 using various telescopes. Further…

A review is presented of the past 165 years of observation of the 4-day Cepheid Polaris, including the exciting results of the last 50 years, an interval that has produced three orbital solutions for the spectroscopic binary subsystem,…

We present the light curve of an unusual variable object, DUO 2, detected during the search for microlensing events by the DUO project. The star remained stable for more than 150 days before it brightened by more than two magnitudes in 6…