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Semester 2015B Instrument Availability and Target Accessibility

This page provides best estimates, at the time of the Call for Proposals, of instrument availability and target (RA, dec) restrictions for 2015B.

 

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Instrument and Instrument Configuration Restrictions

At each Gemini telescope, instruments are mounted at the Cassegrain focus on the instrument support structure (ISS). A science fold mirror mounted inside the ISS can be rotated to send the light from the telescope to any of four side-looking ports, or can be retracted so that the light goes to the up-looking port. At each site, the calibration unit and the Adaptive Optics system use two of the side ports, leaving two side-looking and one uplooking port for other instrumentation. As more than three instruments are offered each semester, instrument swaps will be required and not all instruments will be available for the entire semester. Instrument swaps will be driven by demand and scheduled to minimize impact on the queue. Certain targets or entire programs may not be feasible once the final schedule is determined, at ITAC or thereafter. If an instrument is requested for less than 6% of the Bands 1+2 time, the Observatory reserves the right to limit the RA range available to programs, or to not schedule the instrument. Changes to the instrument mounting are not permitted during classical runs.


 


 

 

Non-Sidereal Targets

Non-sidereal targets can have a broader range in RA than indicated in the Tables below due to, for example, the need to observe comets relatively close to the Sun. The ephemeris for any submitted target however must include a position that is accessible between evening and morning twilight at some point in the semester. For rapidly moving targets PIs should specify in the proposal when the target is accessible, and the coordinates of the target at that time, so that the observation can be checked for feasibility.


 


 

 

Time-Critical Observations

Gemini Observatory attempts to schedule all time-critical observations whenever possible within the constraints imposed by instrument availability, instrument configuration, weather, and science ranking band. Additional, nights not scheduled for multi-instrument queue including classical and other observing modes, fast-turnaround blocks, shutdowns, commissioning, etc., impose additional constraints on time-critical programs. Short observations (~1 hour) can often be accommodated during fast-turnaround and priority observing periods. Programs with time-critical observations are encouraged to include detailed scheduling constraints with their proposal, such that they can be considered along with other constraints when developing the telescope schedule each semester.


 


 

 

Gemini North Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

  • DSSI Speckle Camera will be available for up to 100 hours, subject to demand, in December; targets are therefore limited to RA 23h to 13h.
  • The Laser Guide Star (LGS) system must be used at or above 40 degrees elevation. How this translates into RA and dec restrictions is indicated in the Table.
  • A engineering shutdown is scheduled for 12 nights in late September, reducing the availability of observing time available in the RAs 19h to 5h by ~10%.
  • NIRI is likely to be unavailable in Semester 2016A and should not be requested by Large and Long Programs.
  • If new GMOS-N CCDs are ready for commissioning in Semester 2015B, GMOS-N will be unavailable for ~2 months. All PIs proposing to use GMOS-N should indicated available flexibility in target selections.

 

 


Accessible Restricted** Inaccessible
Declination,
non-LGS
-30° to +73° -37° to -30°,
+73° to +90°
< -37°
Declination,
LGS
-22° to +65° -27° to -22°,
+65° to +68°
< -27° and > +68°
Right Ascension,
non-LGS
19h to 11h 17h to 19h,
11h to 13.5h
13.5h to 17h
Right Ascension,
LGS
20h to 10h 18h to 20h,
10h to 12.5h
12.5h to 18h
Right Ascension,
DSSI
0h to 12h 23h to 0h,
12h to 13h
14h to 23h

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs with targets in this region should not require a large amount of time, or have strict timing or observing constraints.


 


 

 

Gemini South Instrument Availability and Target Accessibility

All instruments are restricted for sky visibility as described in the Table and Figure below. In addition:

  • Observations using GeMS are restricted to greater than 45 degrees elevation. How this translates into RA and dec restrictions is indicated in the Table.
  • As in Semester 2015A, GSAOI observations will likely be limited to two scheduled blocks. The scheduling of these blocks will be informed by demand.
  • A engineering shutdown is scheduled for 18 nights in late September, reducing the availability of observing time available in the RAs 19h to 5h by ~15%.

 

 


Accessible Restricted** Inaccessible
Declination -87° to +22° -90° to -87°,
+22° to +28°
> +28°
Declination,
GSAOI + GeMS
-70° to +10° -75° to -70°,
+10° to +15°
< -75° and > +15°
Declination,
GPI
-75° to +15° -80° to --75°,
+15° to +20°
< -80° and > +20°
Right Ascension 19h to 9h 16h to 19h,
9h to 12h
12h to 16h
Right Ascension,
GSAOI + GeMS
20h to 8h 19h to 20h,
8h to 11h
11h to 19h

**Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs with targets in this region should not require a large amount of time, or have strict timing or observing constraints.


 


 

 

Graphical Illustration

 

GN Target Accessibility

Figure 1: Schematic representation of target accessibility at Gemini North during semester 2015B. Green regions offer unrestricted access, red regions are inaccessible. Hatched areas indicate the more restricted LGS regions. The yellow region is possible, but restricted. See text, and values in the Gemini North Table above.

 

GS Target Accessibility

Figure 2: Schematic representation of target accessibility at Gemini South during semester 2015B. Green regions offer unrestricted access, red regions are inaccessible. Hatched areas indicate the more restricted GeMS regions. The yellow region is possible, but restricted. See text, and values in the Gemini South Table above.