ING logoING-GSS2-17: Operations manual for Guide Star Server II


Issue 0.2, 26 November 2007

Frank Gribbin, ING (fjg@ing.iac.es)

 

Introduction

      Guide Star Server II (GSS2) finds guide stars for WHT (and later INT cass). It runs under linux and
searches the HST Guide Star Catalog version 2.2. GSS2 is currently undergoing tests and is designed to
replace the VAX GSS.

Running GSS2

Log into whtgss linux PC  using ssh with userid gss and the usual password (same as for
VAX GSS, but use lowercase)
    ssh -X gss@whtgss  
    

   Type: 

   gss 

   The GSS2 - Simple Search screen will appear (see below)

Finding Guide Stars

     With the initial screen as seen below:  


 

 To find a guide star

(i)   Enter the coordinates (RA and Dec) in the Target box 
(ii)  Select the telescope/instrument in use under Configuration
(iii) Press Search button.  

 The screen enlarges to show the search results. Use the probe 
R and THETA or X and Y values with appropriate autoguider probe
command.  
    




   When finished with the guide star results, it's possible to 
hide the lower part of display with Hide button. 

   By default, rotator sky pa and aperture offsets are zero. Change 
these as necessary.

   Equinox may be specificied after RA & Dec, e.g. 
 
       12 13 14.5 45 46 47.8 J2007.5 

   If specified this is the value used for searching. If no value
is given, the default specified by Equinox box is used (may be 
B1950.0 or J2000.0).

Selecting a Rotator Angle   

   For ISIS it may be important to keep slit vertical. As an aid to selecting
appropriate angle, the StarALT button provides a graqph of the target's  
altitude annotated with parallactic angle.


Advanced configuration (finding more stars) 

   Press the Edit Configuration button to access further options. This will
display the following screen 


  Change the numeric values in above screen to vary maximum number of guide 
stars shown (up to possible 99), to vary magnitude range (allowing fainter 
stars will give more results) and change to minimum separation (guiding is
difficult with double stars). Press the OK button to apply the changes, 
which are shown on the Current Values display. To exit the display screen 
press Cancel (this cancels any changes not already applied). Default GSS2
values for the configuration can be restored by pressing Restore Defaults.
Changes to the values affect only this instrument configuration. They 
remain in effect only for this session. 

  By default GSS2 only displays stars found in the catalog. Checking box 
Show non-stars in list makes GSS2 show other objects from catalog (galaxy,
blend, non-star, unclassified, defect). 

  Checking Output Debug Messages causes more diagnostic information to be 
output and to be sent to the talker log/ syslog. This would be helpful in 
in case of problems with GSS2.

Additional Notes

1. GSS2 supports cut and paste of coordinates from TCS info display (string
   DEC is ignored).

Troubleshooting

1. GSS doesn't find guide stars

     General recovery

       a)  Try allowing fainter stars (or maybe brighter stars) 
       b)  Try a search for alternative coordinates/instrument configurations. 
       c)  Check that  web server is responding 
                 http://whtgss.ing.iac.es
           should show Fedora Core test page. If not, reboot whtgss (to 
           restart httpd).  
       d)  Try a query direct to web server 
              http://whtgss.ing.iac.es/cgi-bin/gsc22query.exe?ra=10:11:12.3&dec=01:02:03.4&r2=1
       e)  Select Output Debug Messages in the Search Defaults Screen. Try search again.
           Messages are sent to /var/log/talker/talker.debug   
 
     Specific error messages and recovery 

       i)  Error querying server: IOException: java.net.ConnectException: Connection refused
  
           Cause: web server (httpd daemon) down 
           Recovery: As per step c above.

       ii) Error querying server: MalformedURLException: java.net.MalformedURLException: unknown protocol: htp      
           Query was:htp://whtgss.ing.iac.es/cgi-bin/gsc22query.exe?ra=1:02:03.0&dec=+4:05:06.0&r2=11.427587980019723&m1=8.0&m2=16.0&n=1000

           Cause: invalid URL, in this case caused by (deliberate) programming error. Unlikely in practice.
           Try general recovery above and/or use backup system.        

2. Backup System 
      For now if the whtgss PC fails, use the VAX guide star server. 
   Once operational testing has finished, there will be an alternative machine
   (intgss) in the INT.