The list of Investigators does not match the STScI records for this program. FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser First submission. 432170194 ----- Attempting Submission 1 (Tue Nov 15 20:11:22 GMT 2022) ----- We are using "nonstandard" backgrounds because this is the goal of the calibration program, namely to explore how the recovery of faint sources varies with background. I added a couple of co-I's to the program, since they did not make it on when the program was instantiated after it was approved by the HST Mission Office. This program is a follow-on to CAL-16441 (PI-Anderson), which examined how faint sources near the background are impacted by CTE (charge-transfer efficiency) losses. See WFC3/ISR 2021-09 for a description of CAL-16441's findings. Many WFC3/UVIS programs involve taking multiple long exposures of fields in order to find extremely faint sources that cannot be detected reliably in single exposures. It is unclear how well the pixel-based CTE-correction algorithm is able to correct for CTE losses when the sources are very close to the background. We need to assess this directly so that we can help observes plan and interpret their observations. The previous program --- CAL-16441 --- explored backgrounds from 0e to 30e, spanning the levels that users get when they post-flash low-background images (or when they neglect to use a proper post-flash). CTE continues to improve beyond 30e, and observations with wide-band filters often get natural backgrounds higher than 30e, so it is useful to extend the CAL-16441 analysis to backgrounds from 30e all the way up to 100e. In particular, users often decide whether to take 3 exposures per orbit or 2 exposures per orbit (or even one exposure per orbit) based on CTE considerations. CTE improves in two ways with fewer longer exposures: (1) the source flux per exposure is larger, and (2) the natural background per exposure is larger. The downside is that cosmic rays impact more pixels in longer exposures. This 1-orbit external program will help users better weigh their options. We will take backgrounds of 20e, 35e, 50e, 70e, and 100e. The 20e background is so that we can have a more direct tie-in at the current epoch to the "recommended" level. We will take two deep exposures to provide the "truth" against which the short 1s exposures are compared. We will take five short 1-s exposures with post-flashed backgrounds of 20e, 35e, 50e, 70e, and 100e, and two deep 350-s exposures of the same field with no dither. The deep exposures can be combined to show us the true astronomical scene present in the short exposures. The survival of flux in the variously post-flashed short exposures will tell us about how CTE impacts faint sources near background levels from 20e up to 100e. The medium post-flash gives about 85e per second (from FIg 16 of WFC3/ISR 2013-12, Biretta & Baggett) . So: 25e = 0.3s * 85 e/s 34e = 0.4s * 85 e/s 51e = 0.6s * 85 e/s 76e = 0.9s * 85 e/s 105e = 1.2s * 85 e/s Anderson has been working on CTE issues for ACS/WFC and WFC3/UVIS for over 12 years and has devised many of the mitigation/analysis strategies for these instruments. Kuhn is in charge of the CTE monitor. Baggett is the branch lead for WFC3 and has played a large role in writing documentation to help users take the best possible observations in light of CTE challenges. 0 false false RESTRICTED EXT-CLUSTER GLOBULAR CLUSTER J2000 1668542840257 /private/var/folders/_d/p5sz3s3n6tsf5mjyrwch42zc000496/T/OPVisit3522999434074375465.xml The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. Take five short 1-s exposures with various postflash and two long 350-s exposures. The long exposures can be scaled down by x350 (6.3 mags), such that a star near saturation with 70000 counts in the deep exposure will have 200 counts in the central pixel in the short 1s images. And marginally detectable stars with 5e in their central pixels in the short exposures will have 1750 counts in their central pixels in the deep exposures. We use "medium" flash for all these exposures for consistency. The medium flash gets about 85e/s. Thus (Tic-Visit :proposal-id 17262 :visit-id "01" :proposal-version -1 :trans-version "20220630" :date "15-Nov-2022 15:07:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2021216 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17262 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17262 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2851 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) true 1 0