Optical pulsar in the Large Magellanic Cloud remnant 0540-69. 3

We have detected pulsed optical emission from the Large Magellanic Cloud (LMC) X-ray pulsar PSR 0540-693 (Seward et al. 1984). The pulsed emission has a time averaged magnitude of approximately 22.7. The X-ray pulsar was discovered in the LMC remnant, 0540-69.3 as a pulse repetition period of approx. 50 milliseconds (ms) in Einstein Obsrvatory data (Seward et al. 1984). Earlier, Clark et al. (1982) had noted that this remnant resembles the Crab Nebula because of the X-ray power law spectrum, and suggested that the nebular emission was synchrotron radiation powered by a central pulsar. After the announcement of X-ray pulsed emission, Chanan et al. (1984) measured the broad optical band properties of the nebula and found evidence for synchrotron emission. They reported that the 4.5 arc second continuum emission remnant has only a tenth the luminosity of the Crab Nebula. We have recorded broad-band optical time-series data at 1 ms intervals with the 4-m and 1.5-m Cerro Tololo telescopes and have found strong pulsations, employing the usual Fourier transform methods. A summary of the observations, including magnitudes, barycentric frequencies and times of arrival is given

Optimal image subtraction method: summary derivations, applications, and publicly shared application using IDL

To detect objects that vary in brightness or spatial coordinates over time, C. Alard and R. H. Lupton in 1998 proposed an “optimal image subtraction” (OIS) method that constructs a convolution kernel from a set of matching stars distributed across the two images to be subtracted. Using multivariable least squares, the kernel is derived and can be designed to vary by pixel coordinates across the convolved image. Local effects in the optics, including aberrations or other spatially sensitive perturbations to a perfect image, can be mitigated. This paper presents the specific systems of equations that originate from the OIS method. Also included is a complete description of the Gaussian components basis vectors used by Alard & Lupton to construct the convolution kernel. An alternative set of basis vectors, called the delta function basis, is also described. Important issues are addressed, including the selection of the matching stars, differential background correction, constant photometric flux, contaminated pixel masking, and alignment at the subpixel level. Computer algorithms for the OIS method were developed, written using the Interactive Data Language (IDL), and applications demonstrating these algorithms are presented

A 200 × 200 CCD Image Sensor Fabricated On High-Resistivity Silicon

A charge coupled device (CCD) image sensor fabricated on high-resistivity silicon is described. The resistivity, about 10,000 \Omega\Gamma000 allows for operation of the CCD with the entire 300 ¯m substrate depleted. This results in better red to near infrared response when compared to conventional and thinned CCDs. In addition the CCD has good blue response when back illuminated. Since the substrate is fully depleted, thinning, with its inherent difficulties, is not necessary in order to enhance blue response. 1. Introduction Scientific imaging applications using charge-coupled devices often require photon detection with good quantum efficiency over a broad spectral range. CCDs that are illuminated at the front side of the device have poor quantum efficiency in the blue region of the visible light spectrum due to the strong absorption of short wavelength photons in the polycrystalline silicon gates. The blue response can be improved significantly by thinning the CCD substrate to a t..

Stellar variability from Dome A, Antarctica

The Antarctic plateau is one of the best observing sites on the surface of the Earth thanks to its extremely cold, dry, stable and transparent atmosphere conditions. Various astronomical activities are underway there and the Chinese Center for Antarctic Astronomy (CCAA) is dedicated to developing Antarctic astronomy at the highest point, Dome A or the Chinese Kunlun station. So far a large number of images have been collected from a 14.5-cm quad-telescope called the Chinese Small Telescope ARray (CSTAR) and the first two of a trio of 50-cm Antarctic Survey Telescopes (AST3-1 and AST3-2)

Stellar variability from Dome A, Antarctica

The Antarctic plateau is one of the best observing sites on the surface of the Earth thanks to its extremely cold, dry, stable and transparent atmosphere conditions. Various astronomical activities are underway there and the Chinese Center for Antarctic Astronomy (CCAA) is dedicated to developing Antarctic astronomy at the highest point, Dome A or the Chinese Kunlun station. So far a large number of images have been collected from a 14.5-cm quad-telescope called the Chinese Small Telescope ARray (CSTAR) and the first two of a trio of 50-cm Antarctic Survey Telescopes (AST3-1 and AST3-2)

An integral field spectrograph for SNAP supernova studies

A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by determining explosion parameters. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have very high efficiency and low spectral resolution (R {approx} 100), constant through the wavelength range (0.35-1.7{micro}m), adapted to the scientific goals of the mission