RELICS |
Phase II Design
IMAGING:
http://hstrelics.weebly.com/observations.html
We are observing 46 fields lensed by 41 galaxy clusters with WFC3/IR: 2 orbits, 4 filters per field. (For 5 clusters, we observe two WFC3/IR fields - sometimes adjoining, other times separated on the sky.)
We are also observing these fields with ACS as needed (minus existing archival imaging) to achieve 3 orbits, 3 filters per field (1 orbit per filter).
When all 3 ACS orbits are required (no archival ACS imaging), we obtain WFC3 imaging in parallel: 2 orbits IR (4 filters) and 1 orbit UVIS (F350LP).
We dither over the WFC3/IR death star and ACS chip gap. We also include smaller WFC3/IR dithers.
TIMING:
We split observations of each field into two epochs separated by ~40-60 days to enable a supernova search. For a few fields, we had to relax the 40 day minimum for schedulability.
Each epoch will have ACS imaging (if necessary: 0 - 2 orbits) followed by 1 orbit WFC3/IR imaging (per field). We split any ACS imaging between the two epochs (putting any odd orbits in Epoch 1).
Though we split the ACS and WFC3/IR imaging into separate visits for the APT file, we prefer they proceed in sequence when possible (with ACS orbit(s) followed immediately by WFC3/IR, in part to mitigate WFC3/IR persistence). We create these timing links using the "After Visit..." tools (which we also use for the supernova epoch timing).
POINTINGS AND ORIENTS:
http://hstrelics.weebly.com/hst-pointings.html
For many targets, we require precise orients to target interesting features and/or overlap with archival imaging. Sometimes we constrain our ACS and WFC3/IR observations to the same pointing coordinates and orient angle. Other times we point the two cameras independently, in which case we sometimes also allow them to be scheduled independently (without "After Visit" links between ACS and WFC3/IR).
SCHEDULABILITY:
We used SCHED 100 as required for a large program to ease schedule pressures. And all our epochs span 3 orbits or less, as requested (and desired).
Our timing and pointing constraints significantly restrict the schedulability of some observations. We have relaxed these constraints where necessary. We hope the remaining constraints will be acceptable.
http://hstrelics.weebly.com/observations.html
We are observing 46 fields lensed by 41 galaxy clusters with WFC3/IR: 2 orbits, 4 filters per field. (For 5 clusters, we observe two WFC3/IR fields - sometimes adjoining, other times separated on the sky.)
We are also observing these fields with ACS as needed (minus existing archival imaging) to achieve 3 orbits, 3 filters per field (1 orbit per filter).
When all 3 ACS orbits are required (no archival ACS imaging), we obtain WFC3 imaging in parallel: 2 orbits IR (4 filters) and 1 orbit UVIS (F350LP).
We dither over the WFC3/IR death star and ACS chip gap. We also include smaller WFC3/IR dithers.
TIMING:
We split observations of each field into two epochs separated by ~40-60 days to enable a supernova search. For a few fields, we had to relax the 40 day minimum for schedulability.
Each epoch will have ACS imaging (if necessary: 0 - 2 orbits) followed by 1 orbit WFC3/IR imaging (per field). We split any ACS imaging between the two epochs (putting any odd orbits in Epoch 1).
Though we split the ACS and WFC3/IR imaging into separate visits for the APT file, we prefer they proceed in sequence when possible (with ACS orbit(s) followed immediately by WFC3/IR, in part to mitigate WFC3/IR persistence). We create these timing links using the "After Visit..." tools (which we also use for the supernova epoch timing).
POINTINGS AND ORIENTS:
http://hstrelics.weebly.com/hst-pointings.html
For many targets, we require precise orients to target interesting features and/or overlap with archival imaging. Sometimes we constrain our ACS and WFC3/IR observations to the same pointing coordinates and orient angle. Other times we point the two cameras independently, in which case we sometimes also allow them to be scheduled independently (without "After Visit" links between ACS and WFC3/IR).
SCHEDULABILITY:
We used SCHED 100 as required for a large program to ease schedule pressures. And all our epochs span 3 orbits or less, as requested (and desired).
Our timing and pointing constraints significantly restrict the schedulability of some observations. We have relaxed these constraints where necessary. We hope the remaining constraints will be acceptable.
Description of Observations
For each cluster lacking ACS + WFC3/IR imaging, we will observe 3 orbits ACS (F435W, F606W, F814W) and 2 orbits WFC3/IR (F105W, F125W, F140W, F160W) (Figure 8). We reduce these requests where archival imaging exists as described in Table 2. We will obtain the ACS and WFC3/IR observations in 2 epochs separated by 40-60 days maintaining the same roll angle. We will perform combinations of small and large dithers to improve resolution and fill in blank regions such as the ACS chip gap and WFC3/IR "death star".
Coordinated Parallels
19 of our clusters require the 3 full orbits of ACS. For each of those 19 clusters, we will observe a field in parallel with WFC3 for an additional high-redshift / supernova search spread over two epochs (along with the prime ACS observations). We will observe 2 orbits WFC3/IR F105W, F125W, F140W, F160W and 1 orbit UVIS F350LP.
(We will also collect coordinated parallels with all of the SN follow-up ToO visits, providing imaging to enable parallel field SN searches and additional coverage for future weak lensing measurements)
(We will also collect coordinated parallels with all of the SN follow-up ToO visits, providing imaging to enable parallel field SN searches and additional coverage for future weak lensing measurements)
Current Phase 2 Plan
OLD Versions:
relics-2015.07.22.1800.apt | |
File Size: | 3095 kb |
File Type: | apt |
relics-2015.07.17.apt | |
File Size: | 423 kb |
File Type: | apt |
Dither Patterns
ACS Prime:
WFC3/UVIS Parallel:
WFC3/IR Parallel:
WFC3/IR Prime (revised 2015.07.21):
OLD:
relics.apt | |
File Size: | 14 kb |
File Type: | apt |
Orbit Packing : all filters in each epoch, 8 IR exposures in a single orbit. Requires SCHED60 for a generic target. Each exposure is NSAMP=8 to 11, SPARS25 or SPARS50.
Total exposure time per filter over 2 single-orbit epochs:
F140W (178+178)*2 = 712 sec = 88% of target 812
F105W (353+353)*2 = 1412 sec = 88% of target 1612
F160W (503+503)*2 = 2012 sec = 91% of target 2212
F125W (178+178)*2 = 712 sec = 88% of target 812
Total exposure time per filter over 2 single-orbit epochs:
F140W (178+178)*2 = 712 sec = 88% of target 812
F105W (353+353)*2 = 1412 sec = 88% of target 1612
F160W (503+503)*2 = 2012 sec = 91% of target 2212
F125W (178+178)*2 = 712 sec = 88% of target 812
Parallel Field IR orbit packing
For 19 clusters, when ACS is on the prime field, there will be IR parallels to enable a SN search and high-z galaxy search.
Epoch 1 : 1 orbit
prime field ACS = 4-5 exposures F606W
parallel field WFC3 = F140W and F350LP
Epoch 2 : 2 orbits
prime field ACS = 4-5 exposures F435W ; 4-5 exposures F814W
parallel field WFC3 = F160W + F350LP ; F105W + F125W
Epoch 1 : 1 orbit
prime field ACS = 4-5 exposures F606W
parallel field WFC3 = F140W and F350LP
Epoch 2 : 2 orbits
prime field ACS = 4-5 exposures F435W ; 4-5 exposures F814W
parallel field WFC3 = F160W + F350LP ; F105W + F125W