Search Publications
Modeling Visual Photometry I: Preliminary Determination of Visual Bandpass
Collins, Peter L.
This paper addresses the issue of spectral sensitivity as part of the overall visual model. A mathematical theory and observational method are presented for the determination of color coefficient with error term for an individual observer.
AAVSO Photoelectric Photometry and Hipparcos Photometry of the Pulsating Red Giant AG Cet
Percy, John R.; Marinova, Margarita
The pulsating red giant AG Ceti was observed by the observers in the AAVSO photoelectric photometry program, and by the Hipparcos satellite. The data have been analyzed using light curves, autocorrelation diagrams, Fourier transforms, and phase diagrams. The AAVSO data show seasonal gaps, and Hipparcos data are also distributed non-uniformly in ti…
HR 211 From Maple Observatory and Hipparcos
Thompson, Raymond R.
Starting in October 1993, HR 211 was observed photoelectrically in V on 76 nights over 5 years. The complete light curve and the power spectrum reveal a period close to a month with a possible long-term variability present. This is compares with the Hipparcos wide-band photometry, which runs from December, 1989, to February, 1993, and consists of …
The Onset of Pulsation in Red Giants
Percy, John R.; Guler, Metin
The Hippercos astrometric and photometric database has many applications for undergraduate research projects. As one example, we have investigated the onset of variability in red giants by noting the excess scatter (above and beyond the instrumental scatter) in the Hipparcos photometric measurements of 7600 giants with +1.35 < (V-I) < +1.70.…
IUE Observations of the Pulsation of RY SGR
Holm, Albert V.
The correlation of the onsets of RY Sgr's deep minima with pulsational phase suggests that the formation of dust is somehow driven by the pulsation. Observations were obtained using the International Ultraviolet Explorer (IUE) to investigate whether every pulsation cycle is accompanied by the condensation of small amounts of dust. During the 46-da…
Hipparcos Versus GCVS Amplitudes of Non-Mira M-Type Giants
Hoffleit, Dorrit
A recent paper by Dumm and Schild deals with the determination of radii and masses for Hipparcos stars with non-Mira giant M-type spectra. Their list contains 350 stars, of which 205 are either verified or suspected variables, including 53 SR (semiregular) and 51 Lb (irregular) variables. The authors determined that the masses and radii of the non…
Photometry of Hipparcos Variable Stars
Stencel, Robert E.; Ostrowski, Therese A.
Among the discoveries reported by the Hipparcos team was the detection of short-term photometric fluctuations in several long period, or Mira, variables (de Laverny et al. 1998). Nearly 15 percent of the 250 Miras surveyed in the broadband 380 to 800 nm filter showed variation of 0.2 to 1.1 magnitudes on timescales of 2 to 100 hours, preferentiall…