C.M. (Ka?e) Gosmeyer, P.R. McCullough, S. BaggeK, E. Sabbi Space Telescope Science Ins.tute, Bal.more, MD
Poster 416.14
cgosmeyer @stsci.edu
New Mid-‐Cycle Proposal Scheme
Abstract We provide a summary of new Wide Field Camera 3 (WFC3) capabilities and updates to the Hubble Space Telescope (HST) proposal process of interest to exoplanet observers. In particular, we discuss recent studies on high precision photometry with spatial scanning that show up to 0.1% photometric repeatability for the UVIS channel and 0.5% for the IR channel. We describe a new IR sample sequence, SPARS5, which may open up more orient ranges and scheduling opportunities for exoplanet targets. Finally we present a new mid-cycle proposal scheme for HST that will allow observers to apply for up to 5 orbits outside the standard annual call for proposals; this will be especially advantageous for observers of recently discovered exoplanets.
High Precision Photometry with UVIS and IR Spa?al Scanning Absolute Photometry
Differential Photometry (referred to star C) σ = 0.19%
σ = 0.36%
Scanning rationale: More pixels (than staring mode): = more photons per exposure (and per HST orbit) = less Poisson noise = less uncalibrated systematics
ETC Now Supports Spa?al Scanning Modes
C
C
B O M
σ = 0.32%
M
C
σ = 0.21%
C
B
B
O
O M
M
IR finder chart. The 1st and 4th scans of each visit are shown, for horizontal scans (top) and vertical scans (bottom). Note that we purposefully shifted each scan to expose “fresh” pixels to the star light; this was to avoid self-persistence effects. IR: Flux ratios of stars (colors) to their respective means versus visit number. There are 4 visits and 4 exposures per visit. We scanned both horizontally (top) and vertically (bottom), and present both Absolute and Differential results (columns). Stars C, B, M, and O (see finder chart) are known to vary less than 0.1% from the K2 photometry of Vanderberg (2015). The rms (sigma) of points is indicated, excluding the values for the reference star (1.00 by definition) in the differential photometry. We continue to investigate the systematic variations in the absolute photometry, both inter-visit (jumps) and intra-visit (slopes).
References & Resources
McCullough, P.R, & Gosmeyer, C.M. 2015, WFC3 ISR-xx, in progress McCullough, P. R. 2015, A New Infrared Sample Sequence: SPARS5, WFC3 STAN Issue 20 Vanderburg, A. 2015, private communication
§ The WFC3 Exposure Time Calculator (ETC) will include spatial scanning modes for both UVIS and IR imaging, and IR grisms. § Will go live by the Cycle 24 Call for Proposals. § See etc.stsci.edu § If you find problems, please contact the STScI Help Desk
[email protected]
B
O
Help Desk:
[email protected]
§ The new Mid-Cycle program will enable a quick turn-around for high-impact, but not necessarily time-critical proposals. Newly discovered exoplanets are an ideal case in this scheme. § This is unlike Director’s Discretionary Time (DDT), which is often used for time-critical events such as comets and supernovae. § Mid-Cycle GO proposal criteria (in short): • Provide explanation why proposal could not be submitted for the standard annual Call for Proposals. (I.e., target exoplanet was discovered after annual proposal deadline.) • Provide description of scientific urgency of the observations. • Limited to 5 orbits or less. • Minimal constraints to maximize scheduling flexibility. • Propriety period of no more than 3 months. § Submission period for Mid-Cycle is between August 2015 and 31 January 2016. Submissions after 1 February 2016 will be considered in the Cycle 24 TAC review. § For more detailed information, see handout or use QR code.
UVIS results (not shown) are easier to report: Poisson limited performance of absolute photometry down to a systematic noise floor of ~0.1% caused by unknown effect(s). (We suspect shutter timing jitter but this is unproven at this time.)
Mid-Cycle Proposals: http://www.stsci.edu/hst/proposing/mid-cyclesubmission WFC3 Main Page: http://www.stsci.edu/hst/wfc3 WFC3 Instrument Handbook: http://www.stsci.edu/hst/wfc3/documents/handbooks/ currentIHB/wfc3_cover.html
WFC3 Data Handbook: http://www.stsci.edu/hst/wfc3/documents/handbooks/ currentDHB/wfc3_cover.html
SPARS5 Sample Sequence § Intermediate between RAPID and SPARS10. § Short cadence to better isolate a target exoplanet from a stellar companion in spatially scanned IR grism observations, allowing a wider range of orients and increased scheduling opportunities. § Ideal for G141 and G102 grism observations of stars brighter than ~7 mag in H band, scanned at >1 arcsec/ sec. § First science observations successfully implemented in September 2015.
GRISM256
GRISM512
Readout
RAPID
SPARS5
SPARS10
RAPID
SPARS5
SPARS10
0
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
1
0.2805
0.2805
0.2805
0.8605
0.8530
0.8605
2
0.5610
2.6294
7.6296
1.7210
3.7745
8.7896
3
0.8414
4.9784
14.9788
2.5814
6.6960
16.7188
4
1.1219
7.3274
22.3279
3.4419
9.6175
24.6479
5
1.4024
9.6763
29.6771
4.3024
12.5391
32.5771
6
1.6829
12.0253
37.0262
5.1629
15.4606
40.5062
7
1.9634
14.3742
44.3754
6.0234
18.3821
48.4354
8
2.2438
16.7232
51.7245
6.8838
21.3036
56.3645
9
2.5243
19.0722
59.0737
7.7443
24.2251
64.2937
10
2.8048
21.4211
66.4228
8.6048
27.1466
72.2228
11
3.0853
23.7701
73.7720
9.4653
30.0681
80.1520
12
3.3658
26.1190
81.1212
10.3258
32.9896
88.0812
13
3.6462
28.4680
88.4703
11.1862
35.9111
96.0103
14
3.9267
30.8170
95.8195
12.0467
38.8326
103.9395
15
4.2072
33.1659
103.1686
12.9072
41.7541
111.8686
Comparison of readout times (sec) of different sample sequences for the subarray apertures most used in exoplanet spectroscopy (GRISM256 and GRISM512). Adapted from McCullough (2015).
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