

                            ASTROMETRICA SHAREWARE
                           


 This  is  a  shareware-version  of  "Astrometrica",  with  roughly the same
 functions  as  the  first  few  test-versions  of  "Astrometrica":  It  can
 calculate ephemeris,  display star charts  based on the "Hubble Space Tele-
 scope Guide Star Catalog"  and measure astrometric positions  from ST-4 and
 ST-6 CCD-images.  Later improvements  of these functions,  like the ability
 of loading compressed ST-6 files, have been taken over.

 The  full  version  of   "Astrometrica"  offers  the  following  additional
 functions:

 * Simultane  display of a  CCD-image  and  the corresponding  star chart in
   order to simplify  the selection of reference star.  Position and size of
   the starchart  will be calculated automatically  according to the  image-
   data and the orbital elements.

 * Determination of the brightness of the object of interest.

 * Tools for scaling and filtering CCD-images.

 * Comparison of two CCD-images by electronically blinking them.

 * Calculation of ephemeris for the end of evening twilight or the beginning
   of morning twilight.

 As usual,  you may use this shareware  two weeks  for free.  After you have
 tested this software,  you either delete all copies,  or  register yourself
 as licensed user. To do this, send US$ 25.- to the author of "Astrometrica"
 and you will get a licensed copy of the program.

 As a shareware author,  you may use  the program  for free,  but you should
 contact the author of  "Astrometrica", too:  After sending a description of
 your  shareware-programs  to the address  given  below,  you will receive a
 licensed copy of "Astrometrica".

 The address of the author,  from where you can also order  full versions of
 "Astrometrica", is:

                             Herbert Raab
                            Schrammlstr. 8
                             A-4050 Traun
                               Austria


 The following documentation  refers to the full version of  "Astrometrica".
 Some of the functions are therefore  not  available for users of the share-
 ware-version.




                               ASTROMETRICA 1.2
                              


  ABOUT ASTROMETRICA
  

  "Astrometrica"  1.0  was  implemented  between  February and June 1993  in
  order to check the possibility  of using  CCD-cameras for astrometric work
  on minor planets and comets.

  During the developement of "Astrometrica",  in the months mentioned above,
  about  150  CCD-images of comets were measured successfully.  Thus, it was
  possible to adapt the program to the needs of practical working amateurs.

  Version 1.1 was created in September 1993.  It allowed  loading compressed
  ST-6 files and writes,  besides the conventional REPORT file, a file named
  CREPORT,  which is compatible to the standard format given on M.P.C. 18847
  to 18849 (October 1991).  This file  may be used  for sending  astrometric
  observations via computer networks or on diskette.

  Version 1.2,  which was released in October 1993,  supports the comparison
  of two  ST-6  CCD-images  by electronically blinking them. The method used
  for displaying ST-6 images was improved,  and takes now only about  40% of
  the time when  compared to older versions.  The access  to GSC regions has
  been sped up, too.


  WHAT YOU NEED
  

  * PC-compatible computer with 80286 (or later) CPU,  standard VGA graphics
    card, Microsoft-compatible mouse, and 512kB free memory.

  * MS-DOS 3.3 (or later version).

  * The  "Hubble Space Telescope  Guide Star Catalog"  (GSC)  on  CD-ROM  or
    copied onto the computer's hard disk,  with the same directory structure
    as on the CD-ROM.
    The two GSC CD-ROM's are available from the following adress:

                    Astronomical Society of the Pacific
                    HST Orders Dept.
                    390 Ashton Ave.
                    San Francisco, CA 94112


  * SBIG's ST-6 CCD camera and the ST6OPS software.

  * A telescope having a focal length between about 1000mm and 3000mm.
    While the field of view  may be too small to find enough reference stars
    when using longer focal lengths, the image scale may be to low to derive
    accurate positions when using shorter focal lengths.



  WHAT'S ON THE DISK
  

  The diskette holds the following files:

  * ASTROMET.EXE: The executeable "Astrometrica"-program.

  * REGIONS.DAT: A file which holds information  on the location of the GSC-
    regions.

  * ST4TO6.EXE: A tool to convert ST-4 images into ST-6 file format.

  * README.BAT und README.TXT: The text you are reading  and a batch-file to
    display it.

  * LIESMICH.BAT und LIESMICH.TXT: The german version of this text and a the
    batch-file to display it.



  INSTALLING ASTROMETRICA
  

  Installing  "Astrometrica"  on  your  computer's  hard disk drive  is very
  simple.  Using  the  MS-DOS  command  MD  (for  Make Directory),  create a
  driectory to operate from and then copy the files from your "Astrometrica"
  floppy disk onto your hard disk.

  When you start  "Astrometrica"  for the first time,  a message will appear
  telling  you  that the  file for  initializing  the  software could not be
  found.  You should go  trough the 'Options'-menue  now  and  configure the
  sofware, as described later.


  COMMANDS
  

  ͻ
   Menue    Command           Description                               
  ͹
   File     Load Image        Load an uncompressed  ST-6 image from the 
                              disk into the main memory.                
           Ķ
            View Text-File    Load an display a text-file.              
           Ķ
            Change Dir        Change the default directory.             
           Ķ
            DOS Shell         Temporarily exit to DOS.                  
           Ķ
            Exit              Exit "Astrometrica".                      
  Ķ
   Display  Chart             Display a chart of a part of the sky.     
           Ķ
            Image             Display the current image.                
           Ķ
            Parameters        Display information on the current image. 
           Ķ
            Load User         Load and set a color table.               
            Color Table                                                 
           Ķ
            Set Standard      Set the standard color table.             
            Color Table       (Gray-scale)                              
  Ķ
   Measure  Select Reference  Display a  chart of that  part of the sky 
            Stars             seen on the CCD-image  in order to select 
                              the  reference stars,  which will be used 
                              to calculate the  position and/or bright- 
                              ness of the object in question.           
           Ķ
            Measure Position  Display  the current  image  in  order to 
                              measure  the  position of  the  reference 
                              stars and the object in question.         
           Ķ
            Measure           Display  the current  image  in  order to 
            Position & Mag    measure the position  and  brightness  of 
                              the  reference  stars  and  the object in 
                              question.                                 
  Ķ
   Utility  Scale             Scale  the  image  so  that  a  specified 
                              percentage  of pixels appears  black (Low 
                              Limit) and white (High Limit).            
           Ķ
            Smooth            Apply a mean value filter to the image.   
           Ķ
            Median Filter     Apply a median filter to the image.  This 
                              removes  speckles and  noise  just as the 
                              mean  value  filter  does,   but  without 
                              sacrificing image sharpness.              
           Ķ
            Blink Images      Compares two images by blinking.          
           Ķ
            Edit Parameters   Edit  informationn on the  image which is 
                              important  for  astrometric  work.   This 
                              function  will  also  be called  after an 
                              image has been loaded from the disk.      
  Ķ
   Ephem    Load Elements     Load orbital elements  from the disk into 
                              the main memory.                          
           Ķ
            Save Elements     Save the current set of  orbital elements 
                              to disk.                                  
           Ķ
            Discard Elements  Remove the  current orbital elements from 
                              the main memory.                          
           Ķ
            Calculate         Calculate an  ephemeris from the  current 
                              set of orbital elements for a given time, 
                              at  the  end of  evening  twilight or the 
                              beginning of morning twilight.            
           Ķ
            Display Elements  Displays the current set of elements.     
           Ķ
            Edit Elements     Edit orbital elements.                    
  Ķ
   Options  Directories       Set paths  for the  CCD-images,  GSC-data 
                              and ephemeris-files.                      
           Ķ
            Observatory       Set default  information on the  location 
                              and equipment of the observatory.         
           Ķ
            Delta T           Set the default value for  T = TDT - UT, 
                              used while calculating an ephemeris.      
           Ķ
            User              Set default information on the user.      
  Ķ
   Windows  Resize/Move       Change the size or position of the active 
                              window.                                   
           Ķ
            Zoom              Enlarge or restore the size of the active 
                              window.                                   
           Ķ
            Next              Make the next window active.              
           Ķ
            Close             Close the active window.                  
           Ķ
            Tile              Arrange windows by tiling.                
           Ķ
            Cascade           Arrange windows by cascading.             
  Ķ
   About    About             Display information about "Astrometrica". 
            Astrometrica                                                
           Ķ
            License Info      Display license information.              
  ͼ



  USING "ASTROMETRICA"
  

  Setup
  

  When you use  "Astrometrica"  for the first time, you should go trough the
  'Options'-menue at first. The 'Directory'-subcommand allows yo to  specify
  the path where the CCD-images are stored, the CD-ROM-drive where to search
  for the GSC-data  (or a  subdirectory on a  hard disk,  with the same tree
  of subdirectories as on the CD-ROM)  and the path where the files  holding
  the orbital elements are to be found.

  The 'Observatory'-subcommand is used to set the default information on the
  location  and  equipment  of your  observatory,  which is used  during the
  calculation of an ephemeris and the preparation of the REPORT-file.

  The 'Delta T'-subcommand allows you  to set  the value for  T = TDT - UT,
  which is used while  calculating an ephemeris to convert universal time to
  dynamical time and vice versa.

  The 'User'-Subcommand asks you  for your name and your adress,  which will
  appear in the REPORT-file.


  The Status Window
  

  The status  window  appears  on the  bottom of the  desktop when you start
  "Astrometrica". Like other windows, it can be moved around,  but you can't
  close it. It shows the filename  of the image loaded,  the filename of the
  color table loaded, the filters applied to the current image, the filename
  of the  current  orbital  elements,  and the  number of selected reference
  stars held in the  computers  main memory.  In some cases,  short messages
  appear within the status window.


  Loading Images
  

  Using the 'Load Image'-command from the File-menue,  you can load the CCD-
  images you want to measure. The 1.2 version of  "Astrometrica"  reads ST-6
  images of file version 2 or 3 and data version 1. After the image has been
  loaded from disk,  the most important  parameters  are diplayed and may be
  changed, if necessary. "Astrometrica"  calculates the time of mid-exposure
  by adding half the  exposure time used to the  time  when the exposure was
  started. As these times are taken from the header of  the image file, they
  depend on the  internal clock  of the computer  that was used while taking
  the images.

  CAUTION:  When loading an image taken with the ST6 'Track and Accumulate'-
  mode, the time of mid-exposure can  NOT BE CALCULATED CORRECTLY!  You have
  to calculate the time of  mide-exposure manually by averaging the times of
  mid-exposure of the individual images.

  ALWAYS check the date and universal time of mid-exposure carefully!


  Filtering Images
  

  The  'Smooth'  function  and the  'Median Ffilter'  can be used to  remove
  specks  in the image or reduce  the effects of noise.  The smooth function
  applies  a mean value filter  to the image,  which sets the  gray value of
  each  pixel  to the  mean  value of the  pixel  itself  and  its  adjected
  neighbours, which blurs the image a bit.

  The median filter removes specks and noise without sacrifying sharpness by
  setting  the  gray value  of  each  pixel to the  median of itself and its
  adjected  neighbours.   However,  it  takes  about  three times  longer to
  process the image this way as with the smooth function.

  Be  careful  when measuring images processed by filters other than the two
  mentioned above!  Some filters  (such as the high pass filter  used by the
  'Sharpen' function of the  ST6OPS software) may modify  the image in a way
  that  the  calculation  of the  centeroid  of an image  is influenced.  In
  general, try using unfiltered and unscaled images for astrometric work.

  The scaling function of  "Astrometrica",  by the way,  does not change the
  values of the  pixels in the image,  and therefor may be used  safely.  It
  just sets the display parameters (background and range)  so that the image
  may be viewed at optimum contrast.


  Compare Images
  

  By using the 'Blink Images' command from the 'Utility' menu, two ST-6 CCD-
  images can be compared,  in order  to detect  moving  or variable objects.
  First,  the file  holding the comparison image must be selected.  Then you
  have to mark a reference point (a bright star, for example) on both images
  by clicking on it, so the images can be aligned.

  For comparison,  the images  will be displayed alternately.  The time each
  image will be displayed  can be controlled  by the keys '0' to '9',  where
  pressing the key '1'  means that each image  will be displayed  for  50ms,
  while it will be displayed  for 450ms  when you press '9'.  After pressing
  '0', each image  will be  displayed  until  the user  allows  switching by
  pressing a key.

  Pressing the Escape-key exits the blinking procedure.


  Selecting Reference Stars
  

  By issuing the 'Measure - Select Reference Stars' Command,  you can select
  the reference stars,  whose data from the  GSC are later used to calculate
  the position and brightness of the object in question.

  From the data stored with the  ST-6 image and  from orbital elements,  the
  computer is able to select the region of the sky so that the chart and the
  CCD-image can be displayed at the same scale. If there are no orbital ele-
  ments loaded, the user has to enter the position of the object at the time
  the image was taken.

  If you have rotated the camera  so that north is not up in the image,  you
  can compensate this field Rotation,  so the cahrt and the CCD-image may be
  displayed with the same orientation.

  The field of view given should not be changed,  if the focal length of the
  telescope is set correctly by the 'ST6OPS'-Software,  because the computer
  positions the box, which is used to measure an image, according to the po-
  sitions of the selected stars on the chart.

  You can also select reference stars from a chart  drwan after you selected
  the  'Display - Chart'  command.  However,  you have to care  for the  co-
  ordinates and the size of the field then.


  Measuring an image
  

  Before you use  CCD images  for  astrometric purposes,  substract the dark
  frame  and  apply  the  flat field correction  to the image.  It should be
  possible display the image in a way that the stars and the object you want
  to measure  appear  on a uniform,  dark  background.  Otherwise,  a longer
  integration time  may  be  necessary.  On  the  other  hand,  neither  the
  reference stars  nor the object  you want to measure should be overexposed
  (e.g. with a pixel-value of 65535).

  After  selecting  the   'Measure Position'-  or  'Measure Position & Mag'-
  command, the current CCD image will be displayed and a box,  which is used
  to measure the  position  and  magnitude  of the stars on the image,  will
  appear.  The size of this box may be changed using the keys  F1 to F4,  so
  it will fit the images of the objects to be measured: Using the  F1 and F2
  keys, the x-size of the box can be decreased and increased,  respectively,
  while the  F3 and F4  keys can be used to decrease and increase the y-size
  of the box.

  Before the object of interest and the refernce stars can be measured,  the
  brightness  of  the  backgound-sky  has to be  determined.  In order to to
  this,  move the box to a region  free of nebulae and stars,  and press the
  Enter key. If the background does not appear uniformly bright, measure the
  brightness of the background near the object of interest.

  If you have selected the 'Measure Position & Mag'-command,  the brightness
  of the  object of interest  will be measured next.  Locate the box so that
  the object lies completely within this box  -  including the faint,  outer
  coma in case of comets - and press the Enter key again.

  Then, the position of the object of interest will be measured.  Locate the
  box so that the  centeroid of light  lies near  the middle of the box.  In
  case of comets,  you  may  "cut off"  the coma  and  take into account the
  nucleus of the object only.

  Now, the reference stars will be measured. Locate the box so that the com-
  plete image  of each star  lies within  the box.  If you have selected the
  'Measure Position & Mag'-command,  the position and brightness will be me-
  asured simultaneously.

  After  the  measurement  has  been  cempleted, the results of the data re-
  duction  will be  displayed.  For  each reference star  and  the object of
  interest,  the measured  position  and  magnitude  will be shown. For  the
  reference stars,  the O-C (observed-calculated) residuals for position and
  magnitude will appear, too.  If you have selected the  'Measure Position'-
  command,  no magnitudes will be given.  The measured  pixel coordinates of
  each object will be displayed instead.

  If there are orbital elements loaded,  the O-C residual of the object will
  be shown as compared to the ephemeris.  In contrast to the residuals given
  for  the reference stars,  this value is not the  "true" residual,  as you
  usually measure the position of the object to refine it's orbit,  and thus
  the position of the object can not be calculated precisely.  However,  you
  can compare the value given with that for other images of the same object,
  taken during the same observing session.  This allows you  to make a guess
  of the quality of the measurements from the variation of the residuals.

  The results of the measurements will be summarized in the file REPORT.TXT.


  Editing orbital Elements
  

  After selecting 'Ephem - Edit Elements'from the Menue,  you have to decide
  weather  you want  to edit  the  orbital  elements  of a comet  or a minor
  planet.  If there is  already  a set of orbital elements loaded,  only the
  selection which does not conflict with these elements is possible.  Before
  you  load,  or key in,  any elements,  or  after  selecting  the  'Discard
  Elements' command, both selections are possible.

  The field  asking for the name  of the object  is split in two parts.  The
  firts part may be used to enter a name or number for the object, while the
  second part  may be used  to enter  a short name  (see informations on the
  file 'CREPORT.TXT'). In case you don't need the CREPORT-file, which uses a
  standard format for reporting astrometric observations,  this field may be
  left blank.

  The orbital elements  you key in now  may be given for any aequinox:  They
  will be converted to the standard epoch J2000.0 by the program.


  Calculatin an ephemeris
  

  "Astrometrica"  can calculate  a detailed ephemeris  from orbital elements
  keyed  in  by  the  user  or  read from  the  disk.  The ephemeris  may be
  calculated for  a given instance of time,  for the end of the astronomical
  evening twilight or the beginning of the astronomical morning twilight.

  The following information is given:

  Date, U.T. .... Date  and  universal Time for which the following data are
                  valid.

  R.A., Decl. ... Aequatorial coordinates of the object (J2000.0).

  Alt, Az ....... Horizontal coordiantes of the object.

  El ............ Elongation of the object from the Sun.

  Moon .......... Angular distance of the object from the Moon.  An asterisk
                  is printed  if the moon is above the horizon  at the given
                  instant.

  k ............. Illuminated fraction of the moon's disk in percent.

  mag ........... Predicted magnitude of the object.

  Ph ............ Phase angle of the object. (For minor planets only.)

  Tail .......... Predicted  position angle  of  the  ion-tail.  (For comets
                  only.)

  r, d .......... Distance of the object  to Sun  and Earth  in Astronomical
                  Units.

  , P.A. ....... Appearent motion  of the object:  Angular speed in arcsec.
                  per minute, position angle of the direction of motion.

  t ............. Period for the motor  which is used  to compensate for the
                  motion of the object. (The period at 1"/min may be entered
                  using the 'Options/Observatory' command.)


  Using ST-4 Images
  

  Because  of  the small size,  SBIG's  ST-4 CCD-camera  is hardly  used for
  astrometric work. However, if you would like to measure the position of an
  object on an ST-4 image,  you may convert the  ST-4 image to the ST-6 file
  format by using the ST4TO6 program supplied with "Astrometrica".

  Just start the ST4TO6 program from the  DOS command line with the filename
  of the image you want to convert as the  only parameter.  The program will
  convert the image to  ST-6  file format and  save the image using the same
  name, but with "ST6" as extension. For example, if you want to convert the
  image named  "COMET.CCD" to the ST-6 file format,  type "ST4TO6 COMET.CCD"
  at the DOS promp  and press  the Enter key.  The result  of the conversion
  will be saved as "COMET.ST6".

  It should be noted that the header of  ST-4  images does  not hold as many
  information as the header of ST-6 files. The ST4TO6 converter fills in the
  fields where possible.  Date and Time,  however,  are set  to the  default
  value of Jan. 1, 1980, 00:00:00.


  The file 'CREPORT.TXT'
  

  This file  holds the data  from the astrometric observations  according to
  the standard format given on M.P.C. 18847 to 18849 (October 1991)  and may
  be used  for sending astrometric observations  via computer networks or on
  diskette.

  To hold this format strictly, keep this in mind: The three-digit observer-
  code must be entered right-bound in the corresponding field of the dialog-
  window  'Options - Observatory'.  Also,  the short name  of a minor planet
  must be entered right-bound,  while that of an comet must be entered left-
  bound,  according to the examples  given below,  when entering the orbital
  elements of the object using the dialog window 'Ephem - Edit Elements'.

  Name:   [Ceres     ] [     00001]  --  Minor Planet (1) "Ceres"
  Name:   [1993HR4   ] [   J93H04R]  --  Minor Planet 1993 HR4
  Name:   [P/Halley  ] [J8603J820i]  --  Comet 1986II = 1982i "P/Halley"
  Name:   [1993e     ] [J930e     ]  --  Comet 1993e "P/Shoemaker-Levy 9"
  Name:   [P/Encke   ] [J9021    `]  --  Comet 1990XXI "P/Encke"

  Take care to enter the short name correctly!
  CREPORT, by the way, stands for Computerized REPORT.


  COPYRIGHT
  

  The copyright and all other rights are owned by the author:

  Herbert Raab
  Schrammlstr. 8
  A-4050 Traun
  Austria

  "Astrometrica" was implemented using Borland Pascal 7.0 (c).
  The user interface is based on Borland's Turbo Vision 2.0 (c).

  Brand and product names  mentioned  in the text are  usually trademarks or
  registered trademarks of their respective holders.



  DISCLAIMER
  

  "Astrometrica"  is  supplied as is.  The author  disclaims all warranties,
  expressed or implied, including, without limitation,  the warranty of fit-
  ness for any purpose. The author assumes no liability for damages,  direct
  or consequential, which may result from the use of "Astrometrica".

  However,  I tried hard to write  a program which is  easy to use  and does
  what you want it to do. Months of using it have shown that "Astrometrica",
  in  combination  with  SBIG's ST-6,  is a powerful instrument  which gives
  amateur astronomers the possibility to do scientific work on minor planets
  and comets.

  If you have discovered a bug or have any ideas for future releases of this
  software, please let me know!


                                           Have fun with "Astrometrica" !

                                                    Herbert Raab
