Mission Planning Updates Chandra Users Committee Meeting 092617

Mission Planning Updates Chandra User’s Committee Meeting (09/26/17) P. Slane (Chandra Mission Planning)

Thermal Balance: A Reminder Maximum Dwell for Sample S/C Component (~today) Brown: maximum exposure before exceeding temperature limit (heavy is composite for all components). -Z Blue: minimum cooling time required to return to state from which another max dwell possible +X +Y Complete Science Orbit -Z cooling limited by ACIS DPA Multi-layer Insulation (MLI) Rad. Zone Temperature Prediction (deg. F) Obs. ID • Scheduling is a balance of heating and cooling multiple s/c components - Observations often split to accommodate temperature limits Chandra User’s Committee Meeting (09/26/17) 2 P. Slane (Chandra Mission Planning)

ACIS DPA/FP Constraints • At tail-sun attitudes, where -Z side of s/c cools, ACIS warms up. - Heating rate is slower with fewer CCDs • Maximum dwells in tail-sun region <50 ks at perihelion; less than –Z cooling time. - Overall hot/cold budget difficult, but feasible in principle. Chandra User’s Committee Meeting (09/26/17) ACIS Observations: Cycle 19 Req. CCDs Tpcold (Ms) % TCycle 19 1 2. 0 10. 1 2 0. 3 1. 5 3 0. 6 3. 0 4 7. 1 35. 8 5 1. 0* 5. 0* * Under discussion P. Slane (Chandra Mission Planning)

Constraints: Sky View CDF-N +60 ACA hot zone e COSMOS SDSS Stripe 82 tic p ipti c lan Instantaneous ACA cold region ecl Ga lac Declination Galactic anticenter Galactic center CDF-S ACA hot zone -60 24 h Right Ascension LMC SMC 0 h • Sometimes-cold ACA (-Z) region covers large sky area. Ecliptic Plane - Many well-known fields can provide some cooling (e. g. , Galactic Center, COSMOS field, SDSS Stripe 82). - Others (e. g. , CDF-N, LMC, SMC) difficult for long exposures. • Very Large Programs currently limited to <2 Ms within 30˚ Ecliptic Pole of ecliptic pole. (And 2 Ms is what we got in Cycle 19…) Chandra User’s Committee Meeting (09/26/17) 4 P. Slane (Chandra Mission Planning)

Target Distribution: Cycle 19 +60 ACA hot zone ecl pla ne Instantaneous ACA cold region ipti c lac tic Declination Galactic anticenter Ga Galactic center ACA hot zone -60 LMC 24 h Chandra User’s Committee Meeting (09/26/17) Right Ascension 5 SMC 0 h P. Slane (Chandra Mission Planning)

Sample of Significant Planning Efforts Completed in Cycle 18: • Venus - Eight 6 ks observations. - Very significant effort due to Sun proximity and star monitoring. • Sgr A* - Simultaneous uninterrupted 24 -hr observation with Spitzer. - Tight windows coordinated with EHT and Nu. STAR. (Also M 87) • Jupiter, coordinated w/ Juno, XMM, Nu. STAR, HST. - Tightly windowed at Juno apojoves and perijoves. • CDWFS – 1. 025 Ms at ecliptic latitude of 60∘- e. Coming up in Cycle 19: • Sgr A* (see above; rinse and repeat). • 3. 8 Ms near ecliptic poles (including 2 Ms on Abell 2146). • 750 ks of HETG observations w/ 5 chips. • Comet 46 P/Wirtanen: Two visits (4 x 5 ks and 10 x 2 ks), each with pre/post observation of comet position in sky. Chandra User’s Committee Meeting (09/26/17) 6 P. Slane (Chandra Mission Planning)

Actions CUC 2016 MP Action: “The CUC… endorses the steps that they are taking to manage thermal balance of the spacecraft [and] also endorses the expanded IPPS procedure that is now part of the observation planning and approval for flight process. ” • MP now carries out post-IPPS review of constraints/preferences in remarks. • MP continues to work with flight team and thermal engineers to manage scheduling with thermal constraints. Chandra User’s Committee Meeting (09/26/17) 7 P. Slane (Chandra Mission Planning)

Recent Activities • Modified operational schemes in response to large(r than expected) attitude errors following maneuvers, caused by gyro bias and/or ACA tracking hot pixels instead of stars. - Established brighter magnitude requirement for stars (10. 3 @ -11. 5 C, with additional temperature scaling). - Implemented larger ACQ search box sizes (from 120” to 160 -180”). - Require minimum of 20 minutes in “normal pointing mode” following maneuvers. - Reduced offset threshold for stars used in attitude determination (from 20” to 5”). • Additional large effort by ACA team to simulate ACA temperature-dependent performance, pursuing mitigations that will guard against star acquisition and tracking failures. • Continued work to incorporate thermal constraints into efficient planning and scheduling scheme. - Carried out study of Cycle 19 targets for thermal feasibility; looks ok. - Updated/Improved use of thermal models in constructing long-term schedule. - Temperature limit increases in past year: ACA (1 + pending), OBA (1), TCYLAFT (3). Chandra User’s Committee Meeting (09/26/17) 8 P. Slane (Chandra Mission Planning)

Observation Scheduling From 10/1/2015 -9/22/2016: SCS 107 (NSM) - 849 observations (21. 0 Ms) • Executed: - 41 TOO observations (1047 ks) SCS 107 (BSH) • Scheduled: - 31 DDT observations (888 ks) ✧ interrupted 12 operating loads for TOO/DDT support • Coordinated Observations: - Constraints: 16 observations (706 ks) + - Preferences: 20 observations (553 ks) HST, VLA, Nu. STAR, SWIFT, XMM, Spitzer, Astronaut, Juno, NOAO, EHT, Keck, GBT, EVN, ATCA, INTEGRAL - Non-specified/Unoffical: 18 (551 ks) - TOO/DDT coordinations: 19 (407 ks) Chandra User’s Committee Meeting (09/26/17) 9 P. Slane (Chandra Mission Planning)

Constraints and Preferences Constraints 600 Met Total 300 500 Number Preferences 350 250 400 200 300 150 200 100 50 0 0 2 4 6 8 10 12 14 16 2 Cycle 4 6 8 10 12 14 16 Cycle • Continue to successfully meet observing constraints with high observing efficiency. • Continue to support significant number of observing preferences. - Ability to meet these is decreasing due to spacecraft constraints. - Crucial Chandra User’s Committee Meeting (09/26/17) 10 P. Slane (Chandra Mission Planning)