<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 98.1p1 release (March 2nd, 1998) originally by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>Preparing Data Frames</TITLE> <META NAME="description" CONTENT="Preparing Data Frames"> <META NAME="keywords" CONTENT="vol2"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <LINK REL="STYLESHEET" HREF="vol2.css"> <LINK REL="next" HREF="node69.html"> <LINK REL="previous" HREF="node67.html"> <LINK REL="up" HREF="node67.html"> <LINK REL="next" HREF="node69.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html2289" HREF="node69.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html2286" HREF="node67.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html2280" HREF="node67.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html2288" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html2290" HREF="node69.html">Setting the Low and</A> <B> Up:</B> <A NAME="tex2html2287" HREF="node67.html">Procedures to Follow</A> <B> Previous:</B> <A NAME="tex2html2281" HREF="node67.html">Procedures to Follow</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION00731000000000000000"> Preparing Data Frames</A> </H2> Data frames to be run with <TT>INVENTORY</TT> commands should be <I>clean</I>. It is desirable that they do not contain any dark spots situated close to objects. This could result in an unpredictable outcome! Bright spots are less dangerous. They are partly detected by the <TT>SEARCH/INV</TT> command, but the <TT>CLASSIFY/INV</TT> command usually classifies them as defects, unless they look like galaxies. Unwanted frame defects can be removed using the <TT>MODIFY/PIXEL</TT> command. Frames that have not been properly cleaned or even frames which have not been cleaned at all can also be used but the user should in this case check visually which objects may be affected by defects. Irregular or sloping background is not a problem. One has only to know if background variations are related to changes in sensitivity or are caused by some additive factor. Depending on what is the case, the keyword <TT>FIELDVAR</TT> should be set to 0 (sensitivity changes) or to 1 (additive factor - default). Unused parts of CCD-frames should be removed with the help of the <TT>EXTRACT/CCD</TT> command. There is a problem when valid data is on a circular image. In this case it is convenient to set the unused part of a frame to the value close to the average background value or to the value of low cut. This can be done with the help of a properly shaped mask. The same holds true for other cases of non-rectangular images. When more than one frame of the same field is analysed, it is convenient to align all frames to common physical coordinates. This can be done by using commands such as <TT>CENTER</TT>, <TT>ALIGN</TT>, or <TT>REBIN</TT>. <P> When a user plans to manually select the standard stars for point spread function determination, he should identify these stars by means of MIDAS command <TT>GET/CURSOR STARS/DES</TT> before using the <TT>ANALYSE/INV</TT> command. <P> <HR> <!--Navigation Panel--> <A NAME="tex2html2289" HREF="node69.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html2286" HREF="node67.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html2280" HREF="node67.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html2288" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html2290" HREF="node69.html">Setting the Low and</A> <B> Up:</B> <A NAME="tex2html2287" HREF="node67.html">Procedures to Follow</A> <B> Previous:</B> <A NAME="tex2html2281" HREF="node67.html">Procedures to Follow</A> <!--End of Navigation Panel--> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
