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HL Canis Majoris in Preoutburst and SS Cygni -- The Interoutburst Disk Instability
Garnavich, P. M.; Kaitchuck, R. H.; Dinshaw, N. +2 more
SS Cygni and HL Canis Majoris were observed by IUE for three consecutive nights in November of 1992. During the first two nights, simultaneous photometric ground-based observations of SS Cyg were made at the Ball State University Observatory. Observations of SS Cyg and HL CMa were also obtained simultaneously with the 90-inch telescope at the Stew…
The Effect of Double Stars on the Guiding System of the Hubble Space Telescope
Hershey, John L.; Bely, Pierre Y.
The interferometric system used for guidance of HST is sensitive to close binaries. Before the launch of HST it was believed that up to 25% of all guide star pairs would lead to guidance failure due to duplicity. After more than 3 years of operation the actual failure rate ascribable to duplicity is estimated to be just below 1%. A computer simula…
Optical and Ultraviolet Spectroscopy of VW Hydri
Saygac, A. Talat
Spectra of the SU UMa type dwarf nova VW Hydri obtained in the visual (lambda-lambda 3400-7200A) and ultraviolet (lambda-lambda 1150-3200A) spectral regions are presented. During the quiescent phase, visual spectra of VW Hydri present strong double-peaked Balmer emission lines. In addition, He I lambda 5876, Fe II lambda-lambda 4233, 5196 He I lam…
The UV Polarization of X-Ray Binary Systems Observed with the Hubble Space Telescope
Wolinski, Karen
The High-Speed Photometer (HSP) was one of the four axial instruments on the Hubble Space Telescope (HST) from April, 1990 to December, 1993. We used this instrument to observe the X-ray binary systems HD 153919, Vela XR-1 and Cyg XR-1 both photometrically and polarimetrically in the UV. The photometric and polarimetric light curves of each target…
The Hot White Dwarf Companions of HR 1608, HR 8210, and HD 15638
Bergeron, P.; Simon, Theodore; Landsman, Wayne
We have obtained low-dispersion IUE spectra of the late-type stars HD 15638 (F3 V), HR 1608 (=63 Eri, K0 IV), and HR 8210 (A8m). Each of these stars had been detected as a strong EUV source with the Wide Field Camera (WFC) aboard the ROSAT satellite. The short-wavelength IUE spectrum of each star reveals the presence of a hot white dwarf companion…
The Boron Abundance of Procyon
Lambert, David L.; Edvardsson, Bengt; Lemke, Michael
The B I 2496.8 A resonance line and HST/GHRS echelle spectra are used with model atmospheres and synthetic spectra to derive the B abundance of the F dwarfs Procyon (alpha CMi), Theta UMa, and Iota Peg. The B abundance (log epsilon(B)~/=2.3) of Theta UMa and Iota Peg is similar to that derived by Boesgaard and Heacox from the B II resonance line i…
A General Bayesian Image Reconstruction Algorithm with Entropy Prior. Preliminary Application to HST Data
Nunez, Jorge; Llacer, Jorge
This paper describes a general Bayesian iterative algorithm with entropy prior for image reconstruction. It solves the cases of both pure Poisson data and Poisson data with Gaussian readout noise. The algorithm maintains positivity of the solution; it includes case-specific prior information (default map) and flatfield corrections; it removes back…
The Spectrum of the Planetary Nebula NGC 6567
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H.
Because of the similarity of its spectrum to that of NGC 6572 particularly in the UV we have made a detailed study of NGC 6567 using both the IUE for the UV region and the Hamilton Echelle at Lick Observatory for the optical region. Plasma diagnostics suggest an electron temperature of about 11,500K and an electron density near 9000 cm^-3. The che…
Periodic Low Amplitude Variations in the Brightness of Proxima Centauri
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +10 more
Using data acquired with Fine Guidance Sensor #3 on board the Hubble Space Telescope we find that the brightness of Proxima Centauri varies with an amplitude of 0.01 magnitude and a period P=41.6 +/- 0.6 days. We interpret this variation as rotational modulation of star spots or bright regions in the photosphere of Proxima Centauri. In a total of …
Imaging the Bipolar Nebula around HM Sagittae
Paresce, Francesco; Hack, Warren J.
Hubble Space Telescope Faint Object Camera UV images are presented for HM Sge showing a bipolar optical nebula similar to that in R Aquarii and RX Puppis. The nebula extends to a distance of 0.174" with a P.A. of 135 degrees inside a faint halo extending to a radius of 0.28". A kinematic distance to HM Sge based on positions of features in the neb…