Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014...
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Transcript of Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014...
![Page 1: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/1.jpg)
Page 1
Kepler – Best Performance and Best Practices
JWST Transit Planning MeetingMarch 11, 2014
Jessie [email protected]
![Page 2: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/2.jpg)
Page 2
How to build an exquisite photometer
![Page 3: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/3.jpg)
Page 3
Pointing
• Pre-launch requirement of 3mas (~1 millipixel) pointing jitter in 15 mins
• Measured month to month drift 10-15 millipixels
• Largely eliminated the requirement for absolute flatfielding (large scale flat a geometric model derived from optics)
• Tweaks/sudden impulses are substantially more difficult to cotrend/detrend after the fact (we modified the ADCS to eliminate the drift)
• This will be more of an issue with K2
![Page 4: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/4.jpg)
Page 4
Focus
• We’re building an $8b thermometer• Ideally, separate temperature change timescales from scientific
timescales• As much thermal ancillary data as possible (reaction wheel
heaters! etc)• Tailor photometry method to capture flux – either large apertures
or PRF-fitting• L2/sun shade = excellent
Too quantized
![Page 5: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/5.jpg)
Page 5
Calibration
• Test early, test often• Don’t scrimp on calibration pixels
- Undershoot was 10x worse when found, but was found early enough in testing that some patches were able to be made- Moire pattern (resonance in the LDE amplifier circuit), not so much
![Page 6: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/6.jpg)
Page 6
Reaction wheels
• Better pointing jitter achieved with higher RPM (Kepler was more stable with three wheels at high RPM than four wheels at low RPM)
• Zero crossings degraded pointing and flux time series – if timing is negotiable, try to keep them away from transits
![Page 7: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/7.jpg)
Page 7
Saturation
• Don’t be afraid of saturation!
• (If you have a handle on your non-linearity and you have the ability to capture the spilled charge).
• Theta Cyg (4.5th mag),
• CH Cyg (8th mag)
• Bright TESS and K2 targets should be on the table
![Page 8: Page 1 Kepler – Best Performance and Best Practices JWST Transit Planning Meeting March 11, 2014 Jessie Christiansen jessie.christiansen@caltech.edu.](https://reader036.fdocuments.us/reader036/viewer/2022062417/551c00db550346a84f8b4bec/html5/thumbnails/8.jpg)
Page 8
Gotchas
• Provide multiple levels of processing/calibration
• Time system – Kepler AND EPOXI both had trouble
• Accumulation of high-energy particle hits on the detectors (SPSDs, CMEs…)
• Try not to use variable stars as guide stars
• Don’t forget about Jupiter! (And solar system objects in general…)