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Semester 2018B Instrument Restrictions and Target Accessibility

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This page provides best estimates, at the time of the Call for Proposals, of instrument restrictions and target (RA, DEC) accessibility for 2018B.

 

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Gemini North Instrument Availability and Target Accessibility

 

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

 

  • 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 11 nights in September 2018 (September 17 - September 27). 
  • 'Alopeke and POLISH-2 will be available, subject to demand, in 2018B semester. Targets are limited to RA defined by non-LGS instruments.

 

  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

**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 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.
  • A engineering shutdown is scheduled for 11 nights in August 2018 (August 20 - August 30).
  • Due to greater-than-average, repeatable, weather loss in August and September at Gemini South, the availability of time in the RA 18h - 20h range has been reduced by 15%, RA 21h - 23h by 8%, and RA 0h - 2h by 6%.
  • GMOS South will not be available from August 1 through August 31 for a planned instrument maintenance. Targets are limited to RA 19h - 12h (see Table).
  • DSSI Speckle Camera will be available, subject to demand, in the second half of 2018B semester; targets are therefore limited to RA 23h to 12h.
  • Phoenix will be available, subject to demand, in 2018B semester. Targets are limited to RA defined by non-LGS instruments.

 

  Accessible Restricted** Inaccessible
Declination (non-LGS) -87° to +22° -90° to -87°,
+22° to +28°
> +28°
Declination,
GeMS + GSAOI
-70° to +10° -75° to -70°,
+10° to +15°
< -75° and > +15°
Declination,
GPI
-70° to +10° -80° to -70°,
+10° to +20°
< -80° and > +20°
Right Ascension (non-LGS) 19h to 9h 16h to 19h,
9h to 12h
12h to 16h
Right Ascension (GMOS-S) 21h to 9h 19h to 21h,
9h to 12h
12h to 19h
Right Ascension,
GeMS + GSAOI
20h to 8h 19h to 20h,
8h to 11h
11h to 19h
Right Ascension,
DSSI
23h to 9h 21h to 22h,
9h to 12h
12h to 21h

**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.

 

 


 

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 up-looking port for other instrumentation. As more than three instruments are offered each semester, instrument swaps are required and not all instruments will be available for the entire semester. Instrument swaps are 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 above 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. Additionally, nights not scheduled for multi-instrument queue including classical and other observing modes, shutdowns, commissioning, etc., impose additional constraints on time-critical programs. Short observations (~1 hour) can often be accommodated during priority visitor periods. Programs with time-critical observations are asked 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.

 



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