The Atmosphere of an Extremely Low Density Super-Earth Mass Planet

0 Assigned ID: 378 ----- Attempting Submission 1 (Fri Apr 07 02:50:01 GMT 2017) ----- HST Phase I Proposal 378 (HSTprop0321.apt) successfully submitted. Receipt: # 378-1 LONG SU LIKELY TO INTERSECT THE SAA LONG SU LIKELY TO INTERSECT THE SAA 02/15/2018 update 2: We have modified the comments to visit 1 for clarity. We have altered the sequence of the first orbit to have 7 iterations of exposure 2. We have one value for zero phase for the transiting exoplanet for both visits. We corrected the orbital period as entered for visit 2 to the correct value 52.0908 days. 02/15/2018 update: The scan orient angle has been revised to 90 degrees forward for all spatial scans. This is within our tolerance to avoid light from the nearest source to our target landing on the detector. Long orbital period of 52.0908 days: The schedulability of these times is apparent on APT if we make each visit just 5 orbits, but APT restricts this and gives a schedulability error when we include the full 13 orbits per visit. SAA: We have 13 orbits allocated per visit. However, APT warns against more than 8 consecutive orbits because of the SAA. If the SAA requires a pause from observing of 3 orbits or less, we request to resume our observation trying to keep the in-transit baseline roughly equal to the out of transit baseline. However, if the SAA requires an interuption of 4 or more orbits, we will make do with a reduced number of orbits per visit. This will have a small but tolerable effect on our expected SNR and we are flexible about whether the orbits at the start or at the end of the ideal 17 hours are abandoned. Initial phase flexible: We have calculated the initial phase to begin at 0.99189 (one transit duration + one HST orbit) before mid-transit. Transiit_duration = 8.6388 hours, Orbit period = 1250.1792 hours. However, because of the long duration, we are flexible on this start time by ~3 hours and can observe out of transit baseline before ingress or after egress. TTVs: The TTVs will have no effect on schedulabulability since the ephemeris is known precisely. Orientation: The requirements below are calculated to avoid the spectrum of a field star KIC 8394725, 2.4 magnitudes fainter than Kepler-79 in J-band, at PA 160.26 degrees from Kepler-79, at a distance of 5.7 arcseconds. (This is using the Kepler Input Catalog, SIMBAD gives a closely consistent 158.2 degrees PA.) We calculated the scan tolerance assuming a minimum of 2 arcsec for the neighboring star. With NSAMP 14, and a scan length of 4.3 arcsec, a minimum of 2 arcsec for the nearby star gives a scan tolerance of acos(2/4.37) = 62.7 degrees. Orient and X,Y position: We calculated the orient to be 160.26 degrees for the position angle of the nearby star, plus 135 degrees for WFC3 from Table 7.4 in the manual = 295.26 degrees (293.6 degrees using the SIMBAD coordinates). We placed the (X, Y) of the target at (1,0) such that the scan would not reach the edge of the field. Our orient ranges include 295-180 degrees since it doesn't matter if the other star is above or below Kepler-79 on the detector. We have left 300s at the end of each sequence because of our use of spatial scanning, to allow a bias update on Gyro 2. -69866098 ----- Attempting Submission 1 (Tue Jul 18 00:05:13 GMT 2017) ----- HST Phase II Proposal 15138 (HST-Kep79phase2_0715.apt) successfully submitted. Receipt: # 15138-1 ----- Attempting Submission 2 (Thu Feb 15 15:52:08 GMT 2018) ----- HST Phase II Proposal 15138 (HST-Kep79phase2_2018_02_15.apt) successfully submitted. Receipt: # 15138-2 ----- Attempting Submission 3 (Thu Feb 15 22:07:11 GMT 2018) ----- Long orbital period of 52.0908 days: Only 3 transits appear schedulable and 2 visits are required. The three opportunities are on 9/16/2017 (midtransit at 2,458,013.0123), 11/7/2017 (2,458,065.1060), and 12/29/2018 (2,458,481.8279). Since the first one is so soon, and the last one is in a long time, we request first two opportunties. The schedulability of these times is apparent on APT if we make each visit just 5 orbits, but APT restricts this and gives a schedulability error when we include the full 13 orbits per visit. SAA: We have 13 orbits allocated per visit. However, APT warns against more than 8 consecutive orbits because of the SAA. If the SAA requires a pause from observing of 3 orbits or less, we request to resume our observation trying to keep the in-transit baseline roughly equal to the out of transit baseline. However, if the SAA requires an interuption of 4 or more orbits, we will make do with a reduced number of orbits per visit. This will have a small but tolerable effect on our expected SNR and we are flexible about whether the orbits at the start or at the end of the ideal 17 hours are abandoned. The Atmosphere of an Extremely Low Density Super-Earth Mass Planet Kepler-79 d provides a unique opportunity to study the atmosphere of a low-mass low density planet among compact multi-transiting systems. It has the largest estimated atmospheric scale-height for a planet in a known compact system of four or more transiting exoplanets and has the highest expected atmospheric annulus depth for any exoplanet unobserved by HST. Its extremely low density, and its low mass places it among a small number of exoplanets that challenge atmospheric mass loss models. Other planets of similarly low density are likely young in age and may still be cooling and constracting. With an age of ~3.4 Gyr, however, Kepler-79 d is unlikely to be contracting and is the best candidate for atmospheric retrieval among low density planets in compact formation. Whether such compact multi-transiting systems formed in situ or beyond the snow-line before migrating to within 1AU is the subject of a high profile debate in planet formation theory, motivating the search for atmospheric water. Kepler-79 d occupies a unique space in temperature, surface gravity and stellar type which will provide an important constraint on the formation of clouds and hazes, although a cloud-free atmosphere is expected for a wide range of compositions. Spectroscopy of transiting exoplanet. Two visits. Observations occur at specific times of transit, according to known ephemerides. Planets and Planet Formation 6 false false false false false false SUPPORTED STAR EXTRA-SOLAR PLANETARY SYSTEM This object was generated by the targetselector and retrieved from the SIMBAD database. KOI-152 KIC8394721 J2000 J2000 WFC3/IR Spectroscopic No No G141 1518730378142 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. /Users/danielj/Documents/Proposals/2017/HST/StepII/OP-cache/HST-Kep79phase2_2018_02_15b-v01.xml Long orbital period of 52.0908 days: The schedulability of these times is apparent on APT if we make each visit just 5 orbits, but APT restricts this and gives a schedulability error when we include the full 13 orbits per visit. SAA: We have 13 orbits allocated per visit. However, APT warns against more than 8 consecutive orbits because of the SAA. If the SAA requires a pause from observing of 3 orbits or less, we request to resume our observation trying to keep the in-transit baseline roughly equal to the out of transit baseline. However, if the SAA requires an interuption of 4 or more orbits, we will make do with a reduced number of orbits per visit. This will have a small but tolerable effect on our expected SNR and we are flexible about whether the orbits at the start or at the end of the ideal 17 hours are abandoned. Initial phase flexible: We have calculated the initial phase to begin at 0.99189 (one transit duration + one HST orbit) before mid-transit. Transiit_duration = 8.6388 hours, Orbit period = 1250.1792 hours. However, because of the long duration, we are flexible on this start time by ~3 hours and can observe out of transit baseline before ingress or after egress. TTVs: The TTVs will have no effect on schedulabulability since the ephemeris is known precisely. Orientation: The requirements below are calculated to avoid the spectrum of a field star KIC 8394725, 2.4 magnitudes fainter than Kepler-79 in J-band, at PA 160.26 degrees from Kepler-79, at a distance of 5.7 arcseconds. (This is using the Kepler Input Catalog, SIMBAD gives a closely consistent 158.2 degrees PA.) We calculated the scan tolerance assuming a minimum of 2 arcsec for the neighboring star. With NSAMP 14, and a scan length of 4.3 arcsec, a minimum of 2 arcsec for the nearby star gives a scan tolerance of acos(2/4.37) = 62.7 degrees. Orient and X,Y position: We calculated the orient to be 160.26 degrees for the position angle of the nearby star, plus 135 degrees for WFC3 from Table 7.4 in the manual = 295.26 degrees (293.6 degrees using the SIMBAD coordinates). We placed the (X, Y) of the target at (1,0) such that the scan would not reach the edge of the field. Our orient ranges include 295-180 degrees since it doesn't matter if the other star is above or below Kepler-79 on the detector. We have left 300s at the end of each sequence because of our use of spatial scanning, to allow a bias update on Gyro 2. 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CASM was run in Phase II mode. /private/var/folders/kh/t28bvsf12p33qjc_6cmfdbpc0000gn/T/OPVisit4334178615135439280.xml Same as for Visit 01. 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