Welcome to iraf.net Wednesday, April 24 2024 @ 01:51 PM GMT
Buglog #216
- Thursday, May 27 1993 @ 09:01 PM GMT
- Contributed by: admin
- Views: 988
MODULE: noao.astutil.asttimes
SYSTEM: V2.9
SYSTEM: V2.9
NUMBER: 216 MODULE: noao.astutil.asttimes SYSTEM: V2.9 DATE: Thu May 27 15:01:18 MST 1993 FROM: valdes BUG: The epoch printed is not clearly defined and the siderial time is incorrect by a few seconds. There is also a gross error at the new year for observatories with a negative time zone. The epoch used is the day of the year, including the fraction of the day, divided by a Julian year of 365.25 days. However the siderial time calculation assumes a J2000 Julian epoch which is not the same as the previous definition. The previous epoch definition is also no smoothly continuous at the new year since some years have 366 days and other 365 and no years have 365.25 days. Other tasks in the ASTUTIL package also use the astronomical time routines but it appears that generally the error cancels out (because the date->epoch->julian date transformations use the same epoch definition) or is insignificant (such as in precession or air mass calculations). STATUS: For V2.10.3 the routines have been modified to consistently use J2000 epochs. ASTTIMES will print these epochs and the sideral times will not have the errors of a few seconds.
The following comments are owned by whomever posted them. This site is not responsible for what they say.