[Home]
[Links]
[Images]
[Download]
[Equipment]
[Impressum/Contact]
[This site online]
[Deutsch]
Errors in positions in RA and DEC probable caused by atmospheric fluctuations
Some preliminary results.
From: Christoph Flohr
Some details on the drift-scan image:
(The telescope drive was shut off)
The seeing was bad, so results form other sides should
be better.
DEC, centre of the image 11.9588023 deg
(same declination as alpha Leo)
RA, centre of the image 162.9756104 deg
Alt: 45.87, Az: 147.93
RA, start of the image 155.91 deg
RA, end of the image 170.04 deg
DATE-OBS= '2002-03-10' / UT date of integration
TIME-OBS= '21:02:20.01' / UT time
(The time the integration was started )
( End of the exposure was: 21:58:42.30
Width of the image in pixels: 765
Height of the image in pixels: 20135
INSTRUME= 'SBIG ST-7' / Camera Type
TELESCOP= '6 inch reflector 751 mm focal length'
Software: 'WinScan2.02'
Effective Exposure time: 85.67 sec
(SHIFTIME * CCDHEIGH, time to shift all lines from the CCD )
PIXWIDTH= 0.00900 / in mm
PIXHEIGH= 0.00900 / in mm
FOCALLEN= 29.567000 / in inch
APERTURE= 28.27000 /in square_inch
FILTER = 'None' / filter used
SHIFTIME= 0.1679806808510600 / interval to read out one line
CCDHEIGH= 510 / number of lines on the CCD
Astrometry by ViewScan:
Reference stars (1542, form mag 9 - mag 16) were added form the GSC- ACT
Positions and residuals were calculated (linear fit)
The errors in RA and DEC in
relation to the positions in RA are shown in the following diagrams (XY) :
As you can see, the errors in RA and DEC are changing with the
position in RA (and so also with the midexposure time) .
Between the positions in DEC and errors in RA or DEC I found no relations.
To get the exact position of an object, it may be a good idea to
slice the image in smaller parts.
see also:
SDSS Astrometry
and:
Carlsberg Meridian Catalogue 12
especially:
documentation for CMC12 (4.86 MB)
[Home]
[Links]
[Images]
[Download]
[Equipment]
[Impressum/Contact]
[This site online]
[Deutsch]