... The exact directions of the offsets are parallel to the rows and columns of the CCD on which the aperture is specified. ... It is often useful to explicitly specify the desired rotation of the WFPC2 field-of-view on the sky. ... Figure 7.8 shows the CCD orientation and aperture locations relative to the U3 axis. ... Obtain the Position Angle (PA) of the source axis on the sky, measured in the standard way, North through East. ... desired source angle in field-of-view measured CW from +U3 axis) . ...

Next: Catalog Construction Up: Observations and Analysis Previous: Source Detections . ... It was assumed that the highest signal gives the most likely position of the source. ... Comparing the summed map with the maps from the individual energy ranges, the one which produced the smallest error box was chosen to represent the source position, as long as was greater than 4, a level chosen to reflect a reasonable degree of confidence in the detection. ...

... GCN 8471 | ... TITLE: GCN CIRCULAR NUMBER: 8516 SUBJECT: GRB 081102: MASTER refind and final results DATE: 08/11/11 15:50:10 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina, D.Kuvshinov, P.Balanutsa Sternberg Astronomical Institute, Moscow State University A. Tlatov, A.Parkhomenko Kislovodsk Solar Station of the Pulkovo Observatory V.Krushinski, I.Zalognikh Ural State GCN Circ 8470, Lipunov et al., ...

Since the 1980s VLBI observations at two frequencies, 8.4 (X-band) and 2.3 GHz (S-band) have been used to locate the positions of compact radio sources with unprecedented accuracy. ... Observations of selected strong compact extragalactic radio sources, using this now mature technique, have been used to define and maintain a radio reference frame with sub-milli-arcsecond (mas) precision. ... Additionally, it will provide more reference sources for phase referencing VLBI observations. ... References . ...

The offsets (in focal plane and sky) are shown for various configurations (.ps) ( .pdf ): . Each plot shows the location of the 19 dipoles in various positions. ... On 29jun10 i switched to use the measured center locations on the sky.. but: . ... Page 1,2 have the dipoles as they are mounted on the positioner with no rotation. ... Page 3: Dipoles at center (focal plane) . ... Page 5: Dipoles at center and positions A1-A6 (focal plane) . Page 6: Dipoles at center and positions A1-A6 (on sky) . ...

... The ODFs are generated with scisim-2.1. 1.1 scisimsimple This test ODF contains one X-ray source (1 keV, broadened with a 20 eV Gaussian), and several optical sources. The ODF was generated u