This site will provide support to GALEX guest investigator programs, FUV & NUV obtained simultaneously using dichroic beam splitter also acting as a field. NUV: Flux [erg sec-1 cm-2 Å-1] = x x CPS. To convert from GALEX counts per second (CPS) to magnitudes in the AB system (Oke ): FUV: mAB . GALEX uses microchannel plate detectors to obtain direct images in the near-UV (NUV) and far-UV (FUV) and a grism to disperse light for low resolution.
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A sample of the GR7 subdeliveries are:. Each orbit GALEX collects data during night segments eclipses of its orbits during visits to a single pre-programmed target. All are in normalized units with the exception of UIT.
Currently, intensity and count maps contain x pixels, each measuring 1. Relative and absolute astrometric correction of satellite motion is performed in short s time intervals using stars measured by the NUV detector.
Figure 3 above shows time-series telemetry plots for a set of observations described in Table 2. With the lifting of bright star limits, a variety of areas previously unexplored were targeted, including completion of the AIS survey within the plane of the Milky Way. For plans with sub-visit targets, a 20 second slew time is required to move between each leg of the observation.
Because GALEX records time-tagged photon positions with digitization that oversamples the instrumental Galed by a factor of 3—5the pipeline map accumulator can re-bin photon positions onto an idealized projection.
Only one optics wheel configuration is set once per visit. Lim [m AB ]. Various documentation, analysis tools, and new data products potentially including the photon list files are planned for and beyond, so continue to look for new data and analysis tools within MAST.
[astro-ph/] Panoramic GALEX FUV and NUV imaging of M31 and M33
For each sub-visit the spiral dither pattern is restarted. The dither spiral has the following angular rate profile:. Eclipses and are single pointing visits. These surveys are ga,ex concurrently. The grism and the imaging window positional tolerances are loose because they are dioptric components with only a low power.
Also, unlike the GR datasets, a unique identifer is assigned to each astronomical source. Click here for a tutorial.
Chapter 1 – Instrument Overview
GALEX performs its surveys with plans see Glossary for definitions of terms in bold that employ a simple operational scheme requiring only two observational modes and two instrument configurations. Processing of observations made subsequent to February 1. The final set of tiles, fjv with the remaining NUV camera and predominantly observed after February 1, comprise the GR7. From All Available Tiles. Facebook Twitter Follow Us.
GR6 Spectra are now available, click here to find out more. The dither spiral has the following angular rate profile: Background levels for non-DIS fields may be times higher, with a corresponding reduction in the exposure time to reach background limitation. During any visit or sub-visit observation the spacecraft attitude is controlled in a tight, spiraled dither.
Diamond symbols are spaced every seconds 1 revolution every two minutes. For faint UV observations, the combination of low background zero read noise and high red rejection that these detectors possess represents a favorable trade-off against the superior QE and field flatness of more conventional CCD detectors. A high-level description of data retrieval modes is provided on the Getting Started page.
Sky images are generated using a gnomonic projection onto the tangent plane. These two components are mounted on a rotating wheel that also provides an opaque position, and is the only moveable part of the telescope. All-sky survey sub-visit eclipses and show discrete jumps in count rate throughout.
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Individual photons incident at the cathode set off an isolated avalanche of current inside parallel micron diameter microchannel plate MCP pores as they accelerate through a few-keV field. The instrument integration, central processor, thermal control, test and project management were all provided by the Jet Propulsion Laboratory Pasadena, CA. GR6 Spectra are now available, click here to find out more Oct 07, Allowance has been made for a small wedge on this aspheric window to compensate for the coma it induces in the NUV convergent beam.
The layers of the anode form a pair of orthogonal delay lines. Because the satellite begins the eclipse inside the South Atlantic Anomaly the total exposure time is shorter than the maximum possible. The two instrument modes used for astronomical observations are imaging aka direct and grism. These included a number of redelivered GR6 data additional visits and associated coadds from onwardsalong with new tiles within GR7, which span approximately from Jan. It turns out that the resulting deviation is low, a primary advantage to switch between imagery and slitless spectroscopy.
With the final data release GR7the AIS coverage of the sky was greatly increased, in particular at lower Galactic latitudes, thanks to a lifting of this safeguard towards the end of the mission. This motion is used for all targeted observations. Area [deg 2 ].