help with asttimes

Francisco Valdes wrote on Dec 05, 2005

Hola Cristina,
The task you want is ASTHEDIT in the ASTUTIL package.  The command that I think works for your data is:

as> asthedit ngc7094-001B lst.dat
as> hselect ngc7094-001B lst yes
18:52:47.74

where

as> type lst.dat
lst = mst (@"date-obs", obsdb ("osn", "longitude"))

This takes your DATE-OBS, where the time is supposed to be UT, and the information from the observatory database and computes the LST and puts it in your header as keyword LST.  I assume your observatory database has OSN since it is in the file I have here.

Let me know if you have questions or if you think this is wrong.

Yours,
Frank Valdes

On Nov 30, 2005, at 5:03 AM, Cristina Rodríguez López wrote:

Dear sirs,

I would like to use the task asttimes to calculate the sidereal time of .fits files. I need it to be written to the headers as I need it afterwards to calculate the airmass with setarimass.

My file headers look like:

ngc7094-001B.fit[1024,1024][ushort]:
No bad pixels, min=0., max=0. (old)
Line storage mode, physdim [1024,1024], length of user area 1094 s.u.
Created Thu 19:27:59 13-Oct-2005, Last modified Thu 19:27:59 13-Oct-2005
Pixel file "ngc7094-001B.fit" [ok]
BSCALE  =   1.0000000000000000 /physical = BZERO + BSCALE*array_value
BZERO   =   32768.000000000000 /physical = BZERO + BSCALE*array_value
TELESCOP= 'Sierra Nevada Observatory 1.5m' /telescope used to acquire this
         image
INSTRUME= 'Roper   '                         /instrument or camera used
DATE-OBS= '2005-08-27T20:41:37' /YYYY-MM-DDThh:mm:ss observation start, UT
EXPTIME =   20.000000000000000 /Exposure time in seconds
EXPOSURE=   20.000000000000000 /Exposure time in seconds
SET-TEMP=  -110.00000000000000 /CCD temperature setpoint in C
CCD-TEMP=  -110.00000000000000 /CCD temperature at start of exposure in C
XPIXSZ  =   27.000000000000004 /Pixel Width in microns (after binning)
YPIXSZ  =   27.000000000000004 /Pixel Height in microns (after binning)
XBINNING=                    2 /Binning factor in width
YBINNING=                    2 /Binning factor in height
XORGSUBF=                    0 /Subframe X position in binned pixels
YORGSUBF=                    0 /Subframe Y position in binned pixels
FILTER  = 'B       ' /          Filter used when taking image
IMAGETYP= 'Light Frame' /       Type of image
OBJCTRA = '21 36 54' /          Nominal Right Ascension of center of image
OBJCTDEC= '+12 47 05' /         Nominal Declination of center of image
TRAKTIME=   1.0000000000000000 /Exposure time used for autoguiding
FOCALLEN=   12000.000000000000 /Focal length of telescope in mm
APTDIA  =   1500.0000000000000 /Aperture diameter of telescope in mm
APTAREA =   1608102.7883235784 /Aperture area of telescope in mm^2
SWCREATE= 'MaxIm DL Version 4.09' /Name of software that created the image
SBSTDVER= 'SBFITSEXT Version 1.0' /Version of SBFITSEXT standard in effect
SWOWNER = 'Ignacio de la Cueva' /Licensed owner of software

I know the task needs: observatory (which is already in the headers) and year, month, day which I can easily hedit for a group of images. I don't know how to hedit the local time of the observation, as is included in 'date-obs' in my headers, and also it is UT time, not local time. I have edited it for one of my images (there are thousands, so I can't do it one by one) just for trying, but it doesn' seeem to read the keywords from the header. And I would also need that the calculated siderial time is added afterwards to the header, that I don't know if it's possible.

If I edit all the parameters in asttimes, just for trying the calculations, are you sure that is it taking into account the 'daylight saving time'? When it displays the calculations at the end:

PACKAGE = astutil
   TASK = asttimes

(files  =                     ) List of files containing dates and times
(header =                  yes) Print header?
(observa=       )_.observatory) Observatory

(year   =                 2005) Year
(month  =                    8) Month
(day    =                   27) Day
(time   =      22.683333333333) Local zone time

(ut     =      21.683333333582) Universal time (output)
(epoch  =      2005.6547665222) Epoch (output)
(jd     =      2453610.4034722) Julian date (output)
(lmst   =        19.8723593445) Local mean siderial time (output)
(mode   =                   ql)

# ASTTIMES: Observatory parameters for Observatorio de Sierra Nevada
#       timezone = -1
#       longitude = 3:23:05
##YR MON   DAY          ZT         UT      EPOCH           JD       LMST
2005   8 27 SAT 22:41:00.0 21:41:00.0 2005.65477 2453610.4035 19:52:20.5

UT should be 20:41, while local time zone in summer time in Spain: 22:41

Thanks sincerely for your help,

Cristina Rodríguez.
PhD student at Instituto de Astrofísica de Andalucía (IAA)
Spain.

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pnord wrote on Dec 05, 2005

That will give Cristina an answer, but it will be wrong.
IRAF will fail to read the OBJCTRA and OBJCTDEC in that format.

OBJCTRA = '21 36 54' / Nominal Right Ascension of center of image
OBJCTDEC= '+12 47 05' / Nominal Declination of center of image

IRAF expects this:
OBJCTRA = '21:36 :54' / Nominal Right Ascension of center of image
OBJCTDEC= '+12:47:05' / Nominal Declination of center of image

And will interpret Cristina's file as this:
OBJCTRA = '21:00:00' / Nominal Right Ascension of center of image
OBJCTDEC= '+12:00:00' / Nominal Declination of center of image

It appears that both formats are being used by the community. How can we change IRAF to either:
A) Read both formats properly without user intervention.
B) Report an error when it cannot interpret the format correctly.

Thanks!
Paul

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Last post on Dec 05, 2005