gstar

The gstar script can be used to predict guide star positions. 


% gstar --help 


% gstar 06:15:20.46 +39:51:50.6 304.0 gc2 

Usage: gstar 06:15:20.46 +39:51:50.6 304.0 gc1
arg1 - RA  (sexigecimal)
arg2 - DEC (sexigecimal)
arg3 - Azimuth of HET structure (degrees)
arg4 - probe name
NOTE: There are various local files that you can build for gstar that will alter performance (Angle.Offset, IHMP.Position, Default.greyscale, etc.). You can read about those aby CLICKING HERE.

  1. Results from gstar.
  2. Early working notes.
  3. Improving gstar.


Results from gstar.

The gstar code has undergone many updates, but the basic approach has been the same. The user specifies a position on the sky for where the IHMP center is located. The HET structure azimuth and the probe we are concerned with are also specified. A picture of the field is diplayed in a ds9 window. The user must mark an intended guide star with a green circle. A lot of text comes to the screen, but in the end three importsnt things will happen: 

 

1) You see: 
   For gc2 star, use x_ang,y_ang = -0.136 -0.073
2) You will have a nice finder chart
3) You will have local:   acam_dss.fits
The TO can use acam_dss.fits to easily setup on field using the ACAM. In early Feb2016 the output of gstar was modified slightly to list some information that the RAs were finding useful to record: 
 

For gc1 star, use x_ang,y_ang = 0.15343 0.05217
 
Ra,Dec,Az(IHMP):
 06:15:20.46 +39:51:50.6 304.0 
Telecen_X, Telecen_Y, (Ra,Dec)_probe, Probe_name: 
 0.15343 0.05217 06:15:05.251 +40:01:31.31 gc1 
syscmd -T -v 'Guider1_set_position( x_ang=0.15343, y_ang=0.05217) '
syscmd -T -v 'pfip_move_probes()'



Early working notes.

You can read about some of the computing steps used in gstar in my Jan2016 review of how to label probe names. This doc was a big effort to summarize my virus tools, and it consists largely of links to scocode documents.

I had a lot of notes on routines I developed to overplot VIRUS and HET features on DSS (and other ) images. These notes, and support run scripts are all in: 

 Test_Data_for_Codes/T_runs/Image_Render/ex0_n3379/S
Because I always seem to loose these things (I spent an hour one night trying to remember how to plot guide probe annuli, and then I found notes about the routine het_gp_pickle.sh) I have now assembled all of these notes into a single big file of notes about image rendering routines using (mostly) ds9+xpa.



Improving gstar.

A number of things were initially hard-coded into gstar. Things like where we assigned the X,Y position of the IHMP on the ACAM, or what plate scale was used were fixed early on. In hindsight, these should have been free parameters, and an efoort was made in late Jan2016 to make nearly every important parameter alterable. In the course of these upgrades, I began to make a systematic study of how changing these parameters can improve the performance of gstar.



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