... WFPC2 ISR 95-03 . ... Data . ... WFPC2 Home . ... Figure 5 shows that in most cases where two subexposures have been taken, performing the standard cosmic ray removal procedures removes the majority of the tails. ... Cases where real objects cross the bad column, such as the object just above 2-637 in Figure 5, . ... The same region as shown in Figure 1, but after cosmic ray removal. ... c1h (data quality) image which is included on the data tape, and the STSDAS task wfixup or the IRAF task fixpix ....

... If two or more spectra have been taken under the same conditions, a very efficient way of removing particle hits from the raw data is to replace pixel values with large deviations from other observations with a local estimator, as done in the command COMBINE/LONG . If multiple images are not available, cosmic ray hits have to be filtered out by a different method. ... where subframe defines the region to filter. ... This step is done twice to remove the hits on the sky on each side of the object. ...

... Above are two images of the microwave sky, north and south of our galaxy's equator, based on data from NASA's COsmic Background Explorer (COBE) satellite. ... The Sun orbits the center of the Milky Way Galaxy. ... Comet Hale-Bopp Enters the Evening Sky . ... Both writer/editors of APOD are impressed by how bright Comet Hale-Bopp has become, and how easily visible it is. ... In the Center of NGC 604 . ... The Milky Way, like NGC 891 pictured above, has the width of a typical spiral galaxy. ...

... It is notoriously difficult to identify weak cosmic ray events in long exposure observations. ... The method is to compare the probability distribution function (PDF) of cosmic ray events between an observation and a dark frame matched in exposure time. We illustrate the basic idea using dark exposures from a Tek 1024 1024 CCD with varying exposure lengths and read-out times. ... Figure: Histogram of cosmic ray events in a two hour dark frame. ... Original PostScript figure (78 kB) . ...

... Sources found in the local detection step (task eboxdetect ) at significance levels (column SIGMA of eboxdetect source list) exceeding a user-specifiable threshold (input parameter mlmin ) in the respective energy band are removed from the image using a suitable PSF and source brightness dependent cut-out radius (determined to be the radius at which each source contributes more than a user-specifiable number of counts/arcsec to the background; parameter scut ; default value: 0.01). ...

The CHIANTI database consists of 4 primary ASCII files for each ion in the database. contains the energy levels in cm^(-1) It includes both experimental data and theoretical values of the levels energies. ... Wavelengths are based on experimental level energies where available; wavelengths calculated from theoretical energies are less accurate and are given as negative values. References: %observed energy levels: Kelly, R.L., 1987, J.Phys.Chem.Ref.Data 16, Suppl. ...

Previous section: CCD image processing . ... Figure 6: A small region from a CCD image showing various bad columns. Some pixels are damaged: they cannot transfer the electrons when the image is read out. ... Most telescopes have a 4-legged spider, which produces the typical cross-shaped diffraction pattern visible around the brightest stars. 1-legged spider produces a bar through the star, and some telescopes (like the Keck) have 6-legged spider, so the star images exhibit a 6-legged pattern. ...

The revision of the MASS/DIMM star catalogue N. Shatsky, V. Kornilov March 16, 2008 Abstract The compilation of the (updated) version of the MASS (MASS/DIMM) device target catalogue is described. ... Then the list was cleaned according to following criteria: I. Remove stars too faint for a MASS device. ... Here the color equation of the Sternb erg device was taken: M AS S mag = V mag + 0.45 (B - V ); stars with M AS S mag > 3.2 were removed. ... This was made based on the GCVS4.2 catalogue data. ...

The Doppler shift is the effect of sound increasing or decreasing in pitch as an object moves towards or away from you. ... Light works the same way, except light is shifted to redder colours when an object is moving away, and to blue colours when an object is travelling towards us. ... Almost every object he observed had its light stretched to redder colours, indicating essentially everything in the Universe was moving away from us. ... So the Hubble constant tells us how old the Universe is. ...

. Please standby and you will be automatically connected to the new location of the unframed Supernova page. Or, click on the link above. If you have questions or problems, please email me at David Bishop dbishop@vhdl.org . Last modified: Mon Aug 27 12:40:15 EDT 2001

... Positive Start of the data set. fragments present at the centre of the region and negative ones scattered around. Two major negative fragments locate at both east and west sides of the positive ones. At the west, positive fragments touch the negative ones. ... 01:45 The BP becomes A few negative fragments emerge near the stronger and positive ones at the east and move toward bigger. them. At the west, positive fragments keep moving toward the negative ones and cancellation continues. ...

. Remove a file that has hard links to it the same way as you would remove any other file: rm filename(s) . Any files that were created by making hard links to the filename will continue to exist in their own right. Removing a file to which symbolic links have been made has a different effect. Although the linkname remains, the actual file that this name points to does not. Trying to use a command on the linkname will give you the message: command : filename : No such file or directory .