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Changes between Version 4 and Version 5 of GPC_BrightStarAstrometry_Issue


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Timestamp:
Apr 1, 2011, 1:06:42 PM (15 years ago)
Author:
watersc1
Comment:

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  • GPC_BrightStarAstrometry_Issue

    v4 v5  
    1313== 2mass comparison ==
    1414
    15 The SMF files for two exposures from the galactic plane (o5407g0385o and o5407g0385o) were matched against the 2mass catalog, and the shifts between the GPC1 and 2mass positions analysed as a function of magnitude.  The following figures show dRA, dDEC, from the catalogs, along with these offsets transformed using the platescale and position angle into dx and dy coordinates.  The flip in direction between OTA34 and OTA42 is due to the different orientations of the detectors.  The x-axis in all figures shows the instrumental magnitude of the star.
     15The SMF files for two exposures from the galactic plane (o5377g0572o and o5407g0385o) and one from another dense star field taken more recently (o5636g0041o) were matched against the 2mass catalog, and the shifts between the GPC1 and 2mass positions analysed as a function of magnitude.  The following figures show dRA, dDEC, from the catalogs, along with these offsets transformed using the platescale and position angle into dx and dy coordinates.  The flip in direction between OTA34 and OTA42 is due to the different orientations of the detectors.  The x-axis in all figures shows the instrumental magnitude of the star.
    1616
    17 || || OTA34                             || OTA42 ||
    18 || dRA || [[Image(o5407g0385o.ota34.dR.png)]] || [[Image(o5407g0385o.ota42.dR.png)]] ||
    19 || dDEC|| [[Image(o5407g0385o.ota34.dD.png)]] || [[Image(o5407g0385o.ota42.dD.png)]] ||
    20 || dx || [[Image(o5407g0385o.ota34.dx.png)]] || [[Image(o5407g0385o.ota42.dx.png)]] ||
    21 || dy || [[Image(o5407g0385o.ota34.dy.png)]] || [[Image(o5407g0385o.ota42.dy.png)]] ||
     17|| || o5407g0385o/OTA34                       || o5407g0385o/OTA42                   || o5636g0041o/OTA34 ||               
     18|| dRA || [[Image(o5407g0385o.ota34.dR.png)]] || [[Image(o5407g0385o.ota42.dR.png)]] || [[Image(o5636g0041o.ota34.dR.png)]] ||
     19|| dDEC|| [[Image(o5407g0385o.ota34.dD.png)]] || [[Image(o5407g0385o.ota42.dD.png)]] || [[Image(o5636g0041o.ota34.dD.png)]] ||
     20|| dx || [[Image(o5407g0385o.ota34.dx.png)]]  || [[Image(o5407g0385o.ota42.dx.png)]] || [[Image(o5636g0041o.ota34.dx.png)]] ||
     21|| dy || [[Image(o5407g0385o.ota34.dy.png)]]  || [[Image(o5407g0385o.ota42.dy.png)]] || [[Image(o5636g0041o.ota34.dy.png)]] ||
    2222
    23 The lack of any trend in dy illustrates that this shift occurs along the rows of the detector. 
     23The lack of any trend in dy illustrates that this shift occurs along the rows of the detector.  This is further confirmed by the large rotation (pos_angle = 43.745338) for o5636g0041o which shows the trend in both RA and DEC, but after transformation, only in dx.
    2424
    2525A scan of all OTAs shows that this shift occurs only among 2-phase devices: