mentally different in the 2016B
OT. The 2016A OT handled nonsidereal targets using a mix of
data — Minor Planet Center and
Jet Propulsion Laboratory (JPL)
minor planet orbital elements, a
selectable list of the eight major
planets, and manually generated
ephemerides — which can be
confusing and cause errors when
preparing observations.
Figure 5.
Position Editor
showing the position
of Saturn’s moon
Titan (green line)
with the start of the
observation indicated
by the yellow circle.
2016B Observing Tool
The 2016B Gemini Observing Tool (OT) was
released on June 3, 2016. Installers for Mac,
Linux, and Windows may be downloaded
from the OT webpage. This version of the
OT has several significant improvements to
make preparing Gemini observations easier.
The first big change is the removal of the button to trigger the Automatic Guide Star (AGS)
search. Guide star queries are now performed
automatically in the background whenever
users create or modify observations. This new
feature works with all instruments and will
update the guide star whenever an observation, or observing conditions, is/are updated.
It will also automatically select the best guide
star when the nighttime observer updates
the time of non-sidereal or parallactic angle
observations. If you don’t like the automatically chosen guide star you may use the Catalog Query Tool (new in 2016A) to manually
select your preferred one. Manually selected
guide stars (and guide stars from previous
semesters) are displayed in a “Manual” target
group, and the auto-guide star system will
not modify them.
The second big change is an overhaul of
non-sidereal target support, which is funda-
14
GeminiFocus
The 2016B OT supports all non-sidereal targets using automatically generated and updated ephemerides from JPL HORIZONS.
When a user creates an observation the OT will download a low (~6-hour
sampling) resolution ephemeris covering
the entire semester for planning purposes.
For accurate visualization in the Position Editor and optimal guide star selection, this is
augmented by ~5-minute resolution data
for the scheduled night observation. The
Observing Database independently keeps
track of active non-sidereal observations
and downloads high (1-minute sampling)
resolution ephemerides the day before an
observation might be scheduled.
New plotting capabilities in the Position Editor accompany these infrastructure changes,
displaying the path of non-sidereal targets
throughout the semester. The red line in Figure 5 shows the orbit of Titan as seen from
Maunakea in March-April 2016. The yellow
circle in the center marks the start of an observation, and the green line segment shows
the position of Titan during the scheduled
observation.
There were many smaller improvements and
bug-fixes too numerous to mention. Please
see the OT Release Notes for more details,
and for more news on upcoming software
changes please follow the Gemini Science
Software Blog.
July 2016