12.9 Parallel Observing with STIS
The second Servicing Mission installed solid-state data recorders on HST. The volume capacity of these recorders is roughly ten times that of the mechanical tape recorders in use for Cycles 1 through 6. Coupled with changes to the ground system and the flight software of the second-generation instruments designed to fully exploit this capability, this translates into a greatly increased capability for parallel observing.
STIS can be used to observe simultaneously with ACS, COS, WFC3, or FGS. Figure 3.2 shows the HST field of view following the installation of COS and WFC3 during the HST Servicing Mission 4. STIS, ACS, COS, and WFC3 are shown, with their fields of view drawn to scale, in their relative focal plane positions. The three STIS cameras share a common field of view; only one can be used at a time.
The policy for proposing for parallel observations and technical advice on parallel observing are provided in the Call for Proposals/Phase II
Proposal Instructions. We remind you that there are two types of parallel observations:
- Coordinated parallels, in which you explicitly link the taking of exposures in parallel to your own prime scientific exposures.
- Pure parallels, in which exposures are taken in parallel with other observers' prime exposures. For Cycle 31 only pure parallel proposals using WFC3 or ACS CCDs will be considered by the TAC. See the HST Call for Proposals for more details.
Both coordinated and pure parallels must be explicitly proposed in Phase I
. Implementing parallels requires significant resources; only those recommended by the TAC process will be implemented. If you are considering coordinated parallels, you may wish to consider constraining the orientation of HST, to place an object of interest in the parallel instrument's field of view. ORIENT
constraints do affect observation scheduling, however, and should not be entered lightly (see Chapter 11).
12.9.1 Coordinated Parallels: Using STIS in Parallel with Other Instruments
Observations for which STIS is the parallel instrument are likely to be most useful when the full STIS field of view is used. If you wish to use a small slit, then STIS should be used as prime, and the other imaging instruments used in parallel with it.
If STIS is used as the secondary instrument in coordinated parallel observations, the STIS exposures cannot contain both external and internal exposures. Assuming the first exposure is external, all STIS exposures will be declared external. Therefore no internal exposures are allowed. This includes any user-specified internals, such as fringe flat fields, as well as automatic internals, such as auto-wavecals. If STIS is used as the prime instrument, this restriction does not apply.
For coordinated parallels where STIS is prime, automatic wavecals occur during the visibility period—not during occultation. Since many CCD observations request CR-SPLIT
s, in general, this is not an impact for STIS CCD coordinated parallels. However for long MAMA exposures, auto-wavecals that would have occurred during occultation in the absence of coordinated parallels are now shifted into the visibility period. This reduces the time available for science exposures. In addition, the buffer management overhead associated with the last MAMA science exposure now occurs prior to the auto-wavecal, further reducing the time available on target.
CCDFLATs for fringe correction of long wavelength CCD exposures can be taken in the same orbit as the coordinated parallel and forced into the occultation period when the prime STIS CCD exposures fill the visibility period. The CCDFLAT exposures are required to be specified outside the Prime + Parallel Group. However, they should be specified immediately after the last parallel exposure and they can be grouped as a non-interruptible sequence with the Prime + Parallel Group by highlighting both the Prime + Parallel Group and the CCDFLAT exposures then selecting Edit-Group-New Sequence in the APT menu toolbar and specifying that the CCDFLAT sub-exposures occur during the same orbit as the STIS observation they will correct.
The MAMA detectors cannot be used for pure parallel observing. For Cycle 31, coordinated parallels will not be allowed with STIS MAMA imaging modes and the STIS NUV-MAMA PRISM mode. However, coordinated parallels will be allowed with other STIS MAMA spectroscopic modes, provided that an explicit ORIENT is specified and precise RA and Dec coordinates for the parallel field are given.
The MAMA detectors are subject to bright object protection limits; see Section 2.8.
Three types of STIS exposures which have particular scientific utility with STIS as the parallel instrument are:
- Optical imaging taking advantage of the ability to go deep very fast with the
50CCD
wide-open mode. - Optical slitless spectroscopy.
- UV slitless spectroscopy (available only for coordinated parallels with exact
ORIENT
specification).
-
STIS Instrument Handbook
- • Acknowledgments
- Chapter 1: Introduction
-
Chapter 2: Special Considerations for Cycle 32
- • 2.1 STIS Repair and Return to Operations
- • 2.2 Summary of STIS Performance Changes Since 2004
- • 2.3 New Capabilities for Cycle 32
- • 2.4 Use of Available-but-Unsupported Capabilities
- • 2.5 Choosing Between COS and STIS
- • 2.6 Scheduling Efficiency and Visit Orbit Limits
- • 2.7 MAMA Scheduling Policies
- • 2.8 Prime and Parallel Observing: MAMA Bright-Object Constraints
- • 2.9 STIS Snapshot Program Policies
- Chapter 3: STIS Capabilities, Design, Operations, and Observations
- Chapter 4: Spectroscopy
- Chapter 5: Imaging
- Chapter 6: Exposure Time Calculations
- Chapter 7: Feasibility and Detector Performance
-
Chapter 8: Target Acquisition
- • 8.1 Introduction
- • 8.2 STIS Onboard CCD Target Acquisitions - ACQ
- • 8.3 Onboard Target Acquisition Peakups - ACQ PEAK
- • 8.4 Determining Coordinates in the International Celestial Reference System (ICRS) Reference Frame
- • 8.5 Acquisition Examples
- • 8.6 STIS Post-Observation Target Acquisition Analysis
- Chapter 9: Overheads and Orbit-Time Determination
- Chapter 10: Summary and Checklist
- Chapter 11: Data Taking
-
Chapter 12: Special Uses of STIS
- • 12.1 Slitless First-Order Spectroscopy
- • 12.2 Long-Slit Echelle Spectroscopy
- • 12.3 Time-Resolved Observations
- • 12.4 Observing Too-Bright Objects with STIS
- • 12.5 High Signal-to-Noise Ratio Observations
- • 12.6 Improving the Sampling of the Line Spread Function
- • 12.7 Considerations for Observing Planetary Targets
- • 12.8 Special Considerations for Extended Targets
- • 12.9 Parallel Observing with STIS
- • 12.10 Coronagraphic Spectroscopy
- • 12.11 Coronagraphic Imaging - 50CORON
- • 12.12 Spatial Scans with the STIS CCD
-
Chapter 13: Spectroscopic Reference Material
- • 13.1 Introduction
- • 13.2 Using the Information in this Chapter
-
13.3 Gratings
- • First-Order Grating G750L
- • First-Order Grating G750M
- • First-Order Grating G430L
- • First-Order Grating G430M
- • First-Order Grating G230LB
- • Comparison of G230LB and G230L
- • First-Order Grating G230MB
- • Comparison of G230MB and G230M
- • First-Order Grating G230L
- • First-Order Grating G230M
- • First-Order Grating G140L
- • First-Order Grating G140M
- • Echelle Grating E230M
- • Echelle Grating E230H
- • Echelle Grating E140M
- • Echelle Grating E140H
- • PRISM
- • PRISM Wavelength Relationship
-
13.4 Apertures
- • 52X0.05 Aperture
- • 52X0.05E1 and 52X0.05D1 Pseudo-Apertures
- • 52X0.1 Aperture
- • 52X0.1E1 and 52X0.1D1 Pseudo-Apertures
- • 52X0.2 Aperture
- • 52X0.2E1, 52X0.2E2, and 52X0.2D1 Pseudo-Apertures
- • 52X0.5 Aperture
- • 52X0.5E1, 52X0.5E2, and 52X0.5D1 Pseudo-Apertures
- • 52X2 Aperture
- • 52X2E1, 52X2E2, and 52X2D1 Pseudo-Apertures
- • 52X0.2F1 Aperture
- • 0.2X0.06 Aperture
- • 0.2X0.2 Aperture
- • 0.2X0.09 Aperture
- • 6X0.2 Aperture
- • 0.1X0.03 Aperture
- • FP-SPLIT Slits 0.2X0.06FP(A-E) Apertures
- • FP-SPLIT Slits 0.2X0.2FP(A-E) Apertures
- • 31X0.05ND(A-C) Apertures
- • 0.2X0.05ND Aperture
- • 0.3X0.05ND Aperture
- • F25NDQ Aperture
- 13.5 Spatial Profiles
- 13.6 Line Spread Functions
- • 13.7 Spectral Purity, Order Confusion, and Peculiarities
- • 13.8 MAMA Spectroscopic Bright Object Limits
-
Chapter 14: Imaging Reference Material
- • 14.1 Introduction
- • 14.2 Using the Information in this Chapter
- 14.3 CCD
- 14.4 NUV-MAMA
-
14.5 FUV-MAMA
- • 25MAMA - FUV-MAMA, Clear
- • 25MAMAD1 - FUV-MAMA Pseudo-Aperture
- • F25ND3 - FUV-MAMA
- • F25ND5 - FUV-MAMA
- • F25NDQ - FUV-MAMA
- • F25QTZ - FUV-MAMA, Longpass
- • F25QTZD1 - FUV-MAMA, Longpass Pseudo-Aperture
- • F25SRF2 - FUV-MAMA, Longpass
- • F25SRF2D1 - FUV-MAMA, Longpass Pseudo-Aperture
- • F25LYA - FUV-MAMA, Lyman-alpha
- • 14.6 Image Mode Geometric Distortion
- • 14.7 Spatial Dependence of the STIS PSF
- • 14.8 MAMA Imaging Bright Object Limits
- Chapter 15: Overview of Pipeline Calibration
- Chapter 16: Accuracies
-
Chapter 17: Calibration Status and Plans
- • 17.1 Introduction
- • 17.2 Ground Testing and Calibration
- • 17.3 STIS Installation and Verification (SMOV2)
- • 17.4 Cycle 7 Calibration
- • 17.5 Cycle 8 Calibration
- • 17.6 Cycle 9 Calibration
- • 17.7 Cycle 10 Calibration
- • 17.8 Cycle 11 Calibration
- • 17.9 Cycle 12 Calibration
- • 17.10 SM4 and SMOV4 Calibration
- • 17.11 Cycle 17 Calibration Plan
- • 17.12 Cycle 18 Calibration Plan
- • 17.13 Cycle 19 Calibration Plan
- • 17.14 Cycle 20 Calibration Plan
- • 17.15 Cycle 21 Calibration Plan
- • 17.16 Cycle 22 Calibration Plan
- • 17.17 Cycle 23 Calibration Plan
- • 17.18 Cycle 24 Calibration Plan
- • 17.19 Cycle 25 Calibration Plan
- • 17.20 Cycle 26 Calibration Plan
- • 17.21 Cycle 27 Calibration Plan
- • 17.22 Cycle 28 Calibration Plan
- • 17.23 Cycle 29 Calibration Plan
- • 17.24 Cycle 30 Calibration Plan
- • 17.25 Cycle 31 Calibration Plan
- Appendix A: Available-But-Unsupported Spectroscopic Capabilities
- • Glossary