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RadioT4Scanning

What the problem was

  • The problem was that scanning (2006) was not as regular as it was hoped to be:

Newer version as of revision 1.20.2.17 in cvs

horiozontal/vertrical alt-azimuthal and equatorial scanning algorithms in cvs as of 2008-06-20

  • stan ("vertical" scans) is now a wrapper for scan ("horizontal" scans) - no need to duplicate nearly identical code;
  • Both scan (horizontal) and stan (vertical) should give more or less straight/rectilinear scans in their coordinate systems for both zen-azimuth (poh) and equatorial (poe) coordinates;
  • However, the cost is that for equatorial scans there is a playoff between having straightness/rectilinearity and speed: decreasing SCAN_LINE_TOLERANCE_DEG in rt_main.h decreases pseudo-lissajousness for equatorial scans but slows down scanning speed;
    • possible TODO: if this parameter is seen as useful, probably it should be made into an optional telescope user parameter
  • scripts/scan.sh can be used for non-interactive testing to generate files such as the ones below.
  • possible TODO: In SetCoor, replace rST ("real Sidereal Time") with an estimate of the future sidereal time at which the telescope is expected to arrive at the coordinates which are being transformed between alt-azimuth ("Hor" or "H") and equatorial coordinates.
    • Complications: this would require SetCoor to do much more than just transform coordinates, it would require it to have some sort of model (e.g. linear) of the near future telescope motion, which depends not only on what sort of command is presently active, but also on the new "set" coordinates themselves. Would such an algorithm be worth the effort?

Figures below:
  • The two zen-azimuth scans at dec=85 deg use this cvs revision 1.20.2.17 of 2008-06-20 which deals with absolute azimuth or longitude offsets > 180 deg
  • The equatorial scans here are shown using the Lambert equal area projection - for this reason, scans starting at "equatorial offset" poe -1 -1 become successively narrower and more intestine-like as they near the celestial north pole, especially for the vertical scans.

scan times

  • AZ means an azimuth-zenith scan
  • EQ means an ra-dec scan
  • hor0 and hor1 mean the two scanning directions
  • decXX means declination XX degrees
  • cvs of 19 June 08 has #define SCAN_LINE_TOLERANCE_DEG 0.05

date.coordinatetype.hor/vert.declinationdeg full scan time in sidereal minutes
log.0806200103.AZ.hor0.dec20 23.9982
log.0806200103.AZ.hor0.dec30 24.0066
log.0806200103.AZ.hor0.dec40 24.0635
log.0806200103.AZ.hor0.dec50 24.1236
log.0806200103.AZ.hor0.dec60 24.1221
log.0806200103.AZ.hor0.dec70 24.1814
log.0806200103.AZ.hor0.dec80 24.3418
log.0806200103.AZ.hor0.dec85cvs080620 39.4008
log.0806200103.AZ.hor1.dec20 11.4861
log.0806200103.AZ.hor1.dec30 11.5785
log.0806200103.AZ.hor1.dec40 12.0603
log.0806200103.AZ.hor1.dec50 12.3407
log.0806200103.AZ.hor1.dec60 12.5156
log.0806200103.AZ.hor1.dec70 12.4701
log.0806200103.AZ.hor1.dec80 12.28
log.0806200103.AZ.hor1.dec85cvs080620 16.5324
log.0806200103.EQ.hor0.dec20 24.7422
log.0806200103.EQ.hor0.dec30 22.1508
log.0806200103.EQ.hor0.dec40 19.0002
log.0806200103.EQ.hor0.dec50 18.1453
log.0806200103.EQ.hor0.dec60 18.9601
log.0806200103.EQ.hor0.dec70 20.5995
log.0806200103.EQ.hor0.dec80 22.3769
log.0806200103.EQ.hor0.dec85 23.7562
log.0806200103.EQ.hor1.dec20 13.2268
log.0806200103.EQ.hor1.dec30 16.9989
log.0806200103.EQ.hor1.dec40 19.6668
log.0806200103.EQ.hor1.dec50 19.2686
log.0806200103.EQ.hor1.dec60 17.0493
log.0806200103.EQ.hor1.dec70 13.9249
log.0806200103.EQ.hor1.dec80 10.0885
log.0806200103.EQ.hor1.dec85 7.11091

scan plots

  • AZ means an azimuth-zenith scan - scales are to +- 1 degree
  • EQ means an ra-dec scan - dec is +- 1 degree; r.a. is to +- 1 "r.a. degree" by default, or in great circle degrees where the plot has this in the title

  • scan.0806200103.AZ.hor0.dec20.png:
    scan.0806200103.AZ.hor0.dec20.png
  • scan.0806200103.AZ.hor0.dec30.png:
    scan.0806200103.AZ.hor0.dec30.png
  • scan.0806200103.AZ.hor0.dec40.png:
    scan.0806200103.AZ.hor0.dec40.png
  • scan.0806200103.AZ.hor0.dec50.png:
    scan.0806200103.AZ.hor0.dec50.png
  • scan.0806200103.AZ.hor0.dec60.png:
    scan.0806200103.AZ.hor0.dec60.png
  • scan.0806200103.AZ.hor0.dec70.png:
    scan.0806200103.AZ.hor0.dec70.png
  • scan.0806200103.AZ.hor0.dec80.png:
    scan.0806200103.AZ.hor0.dec80.png
  • scan.08062015xx.AZ.hor0.dec85.png:
    scan.08062015xx.AZ.hor0.dec85.png
  • scan.0806200103.AZ.hor1.dec20.png:
    scan.0806200103.AZ.hor1.dec20.png
  • scan.0806200103.AZ.hor1.dec30.png:
    scan.0806200103.AZ.hor1.dec30.png
  • scan.0806200103.AZ.hor1.dec40.png:
    scan.0806200103.AZ.hor1.dec40.png
  • scan.0806200103.AZ.hor1.dec50.png:
    scan.0806200103.AZ.hor1.dec50.png
  • scan.0806200103.AZ.hor1.dec60.png:
    scan.0806200103.AZ.hor1.dec60.png
  • scan.0806200103.AZ.hor1.dec70.png:
    scan.0806200103.AZ.hor1.dec70.png
  • scan.0806200103.AZ.hor1.dec80.png:
    scan.0806200103.AZ.hor1.dec80.png
  • scan.08062015xx.AZ.hor1.dec85.png:
    scan.08062015xx.AZ.hor1.dec85.png
  • scan.0806200103.EQ.hor0.dec20.L.png:
    scan.0806200103.EQ.hor0.dec20.L.png
  • scan.0806200103.EQ.hor0.dec30.L.png:
    scan.0806200103.EQ.hor0.dec30.L.png
  • scan.0806200103.EQ.hor0.dec40.L.png:
    scan.0806200103.EQ.hor0.dec40.L.png
  • scan.0806200103.EQ.hor0.dec50.L.png:
    scan.0806200103.EQ.hor0.dec50.L.png
  • scan.0806200103.EQ.hor0.dec60.L.png:
    scan.0806200103.EQ.hor0.dec60.L.png
  • scan.0806200103.EQ.hor0.dec70.L.png:
    scan.0806200103.EQ.hor0.dec70.L.png
  • scan.0806200103.EQ.hor0.dec80.L.png:
    scan.0806200103.EQ.hor0.dec80.L.png
  • scan.0806200103.EQ.hor0.dec85.L.png:
    scan.0806200103.EQ.hor0.dec85.L.png
  • scan.0806200103.EQ.hor1.dec20.L.png:
    scan.0806200103.EQ.hor1.dec20.L.png
  • scan.0806200103.EQ.hor1.dec30.L.png:
    scan.0806200103.EQ.hor1.dec30.L.png
  • scan.0806200103.EQ.hor1.dec40.L.png:
    scan.0806200103.EQ.hor1.dec40.L.png
  • scan.0806200103.EQ.hor1.dec50.L.png:
    scan.0806200103.EQ.hor1.dec50.L.png
  • scan.0806200103.EQ.hor1.dec60.L.png:
    scan.0806200103.EQ.hor1.dec60.L.png
  • scan.0806200103.EQ.hor1.dec70.L.png:
    scan.0806200103.EQ.hor1.dec70.L.png
  • scan.0806200103.EQ.hor1.dec80.L.png:
    scan.0806200103.EQ.hor1.dec80.L.png
  • scan.0806200103.EQ.hor1.dec85.L.png:
    scan.0806200103.EQ.hor1.dec85.L.png

I Attachment Action Size Date Who Comment
scan.0806200103.AZ.hor0.dec20.pngpng scan.0806200103.AZ.hor0.dec20.png manage 1 K 20 Jun 2008 - 12:13 BoudRoukema  
scan.0806200103.AZ.hor0.dec30.pngpng scan.0806200103.AZ.hor0.dec30.png manage 1 K 20 Jun 2008 - 12:13 BoudRoukema  
scan.0806200103.AZ.hor0.dec40.pngpng scan.0806200103.AZ.hor0.dec40.png manage 1 K 20 Jun 2008 - 12:14 BoudRoukema  
scan.0806200103.AZ.hor0.dec50.pngpng scan.0806200103.AZ.hor0.dec50.png manage 1 K 20 Jun 2008 - 12:14 BoudRoukema  
scan.0806200103.AZ.hor0.dec60.pngpng scan.0806200103.AZ.hor0.dec60.png manage 1 K 20 Jun 2008 - 12:14 BoudRoukema  
scan.0806200103.AZ.hor0.dec70.pngpng scan.0806200103.AZ.hor0.dec70.png manage 1 K 20 Jun 2008 - 12:14 BoudRoukema  
scan.0806200103.AZ.hor0.dec80.pngpng scan.0806200103.AZ.hor0.dec80.png manage 1 K 20 Jun 2008 - 12:15 BoudRoukema  
scan.0806200103.AZ.hor1.dec20.pngpng scan.0806200103.AZ.hor1.dec20.png manage 1 K 20 Jun 2008 - 12:15 BoudRoukema  
scan.0806200103.AZ.hor1.dec30.pngpng scan.0806200103.AZ.hor1.dec30.png manage 1 K 20 Jun 2008 - 12:15 BoudRoukema  
scan.0806200103.AZ.hor1.dec40.pngpng scan.0806200103.AZ.hor1.dec40.png manage 1 K 20 Jun 2008 - 12:15 BoudRoukema  
scan.0806200103.AZ.hor1.dec50.pngpng scan.0806200103.AZ.hor1.dec50.png manage 1 K 20 Jun 2008 - 12:16 BoudRoukema  
scan.0806200103.AZ.hor1.dec60.pngpng scan.0806200103.AZ.hor1.dec60.png manage 1 K 20 Jun 2008 - 12:16 BoudRoukema  
scan.0806200103.AZ.hor1.dec70.pngpng scan.0806200103.AZ.hor1.dec70.png manage 1 K 20 Jun 2008 - 12:16 BoudRoukema  
scan.0806200103.AZ.hor1.dec80.pngpng scan.0806200103.AZ.hor1.dec80.png manage 1 K 20 Jun 2008 - 12:16 BoudRoukema  
scan.0806200103.EQ.hor0.dec20.L.pngpng scan.0806200103.EQ.hor0.dec20.L.png manage 2 K 20 Jun 2008 - 12:17 BoudRoukema  
scan.0806200103.EQ.hor0.dec30.L.pngpng scan.0806200103.EQ.hor0.dec30.L.png manage 3 K 20 Jun 2008 - 12:40 BoudRoukema  
scan.0806200103.EQ.hor0.dec40.L.pngpng scan.0806200103.EQ.hor0.dec40.L.png manage 3 K 20 Jun 2008 - 12:41 BoudRoukema  
scan.0806200103.EQ.hor0.dec50.L.pngpng scan.0806200103.EQ.hor0.dec50.L.png manage 3 K 20 Jun 2008 - 12:42 BoudRoukema  
scan.0806200103.EQ.hor0.dec60.L.pngpng scan.0806200103.EQ.hor0.dec60.L.png manage 3 K 20 Jun 2008 - 12:42 BoudRoukema  
scan.0806200103.EQ.hor0.dec70.L.pngpng scan.0806200103.EQ.hor0.dec70.L.png manage 3 K 20 Jun 2008 - 12:42 BoudRoukema  
scan.0806200103.EQ.hor0.dec80.L.pngpng scan.0806200103.EQ.hor0.dec80.L.png manage 3 K 20 Jun 2008 - 12:42 BoudRoukema  
scan.0806200103.EQ.hor0.dec85.L.pngpng scan.0806200103.EQ.hor0.dec85.L.png manage 2 K 20 Jun 2008 - 12:42 BoudRoukema  
scan.0806200103.EQ.hor1.dec20.L.pngpng scan.0806200103.EQ.hor1.dec20.L.png manage 2 K 20 Jun 2008 - 12:43 BoudRoukema  
scan.0806200103.EQ.hor1.dec30.L.pngpng scan.0806200103.EQ.hor1.dec30.L.png manage 3 K 20 Jun 2008 - 12:43 BoudRoukema  
scan.0806200103.EQ.hor1.dec40.L.pngpng scan.0806200103.EQ.hor1.dec40.L.png manage 3 K 20 Jun 2008 - 12:43 BoudRoukema  
scan.0806200103.EQ.hor1.dec50.L.pngpng scan.0806200103.EQ.hor1.dec50.L.png manage 2 K 20 Jun 2008 - 12:44 BoudRoukema  
scan.0806200103.EQ.hor1.dec60.L.pngpng scan.0806200103.EQ.hor1.dec60.L.png manage 2 K 20 Jun 2008 - 12:44 BoudRoukema  
scan.0806200103.EQ.hor1.dec70.L.pngpng scan.0806200103.EQ.hor1.dec70.L.png manage 2 K 20 Jun 2008 - 12:44 BoudRoukema  
scan.0806200103.EQ.hor1.dec80.L.pngpng scan.0806200103.EQ.hor1.dec80.L.png manage 2 K 20 Jun 2008 - 12:44 BoudRoukema  
scan.0806200103.EQ.hor1.dec85.L.pngpng scan.0806200103.EQ.hor1.dec85.L.png manage 2 K 20 Jun 2008 - 12:45 BoudRoukema  
scan.08062015xx.AZ.hor0.dec85.pngpng scan.08062015xx.AZ.hor0.dec85.png manage 1 K 20 Jun 2008 - 14:49 BoudRoukema  
scan.08062015xx.AZ.hor1.dec85.pngpng scan.08062015xx.AZ.hor1.dec85.png manage 1 K 20 Jun 2008 - 14:11 BoudRoukema  
Topic revision: r3 - 06 Feb 2009, BoudRoukema
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