0 Assigned ID: 628 ----- Attempting Submission 1 (Fri Apr 10 18:06:24 GMT 2015) ----- HST Phase I Proposal 628 (APT_Stingray.apt) successfully submitted. Receipt: # 628-1 Use of available instrument mode BLAE=A for the short 1 second wide band exposures (F555W, F625W, F438W) was approved on July 13th via email inquiry. We calculated that only the long exposure F658N and F487N are necessary (since these filters won't reach saturation), therefore, we reallocated that time to an extra exposure, H_alpha (F656N) -130953743 ----- Attempting Submission 1 (Wed Jul 22 16:57:07 GMT 2015) ----- HST Phase II Proposal 14126 (APT_Stingray.apt) successfully submitted. Receipt: # 14126-1 ----- Attempting Submission 2 (Thu Jul 23 20:41:33 GMT 2015) ----- The Stingray Nebula provides the unique opportunity to watch the ionization of a planetary nebula, a helium shell flash, and the evolution of the central star. Importantly, before 1980 the Stingray's spectrum was characteristic of a B1 I star, then in 1990 the Stingray's spectrum was dominated by bright emission lines characteristic of a young planetary nebula, indicating the fast evolution of this system. Despite its fast evolution, the Stingray has not been imaged for 15 years. We propose to use 2 orbits of HST, using WFC3, to define the evolution of this planetary nebula and its central star. These observation will address three science goals: First, measure the differential expansion of the shell from 1992 to present. Second, detect brightening from the fast wind of the 1980s ionization event impacting the inside of the planetary nebula shell. Third, define the motion of the central star through the HR diagram to provide quantitative measures for comparison to theory. This program cannot be done from ground-based observatories since it requires HST's angular resolution to detect expansion, and resolve the central star from the surrounding nebula. We propose to take WFC3 images of the Stingray to answer three main science questions: First, we will measure the differential expansion of the shell from 1992 to present. Second, we will detect the collision of the fast stellar wind from the 1980s with the PN shell. Third, we will define the current position of the central star on the HR diagram so as to follow its fast and startling evolution. All three goals can be accomplished with just two HST orbits of imaging with WFC3-UVIS. We will take exposures through narrow band filters F502N ([O III]), F487N (H_beta), and F658N ([N II]) as to nearly match the exposures from the first epoch images. Indeed, these first epoch images provide the proof that our exposure times will produce good S/N and not be saturated in the nebula. We will also take short and long exposures through the F438W (B), F555W (V), and F625W (SDSS r') filters. To accomplish the first two science goals, we will use our narrow band images in 2015 as second epoch images, for direct comparison with first epoch HST images variously from 1992, 1996, and 2000. Our analysis is to make a direct comparison to measure the expansion and to difference the images to seek the collisional brightening. Within two HST orbits, we have time for three narrow-band filters, and these must be F502N ([O III]), F487N (H_beta), and F658N ([N II]). These three filters have the highest S/N in the nebula, and they have the most first epoch images. (The 1992 data set has both [O III] and H_beta, the 1996 set has all three, while the 2000 images include [O III] and [N II].) The three sets of old first epoch images will provide multiple time baselines of 23 years, 19 years, and 15 years. Our original observing plan was to take short exposures in F487N and F658N to protect against overstaturation due to unexpected brigthening. After calculating the expected counts, the long exposures are far from overstaturation and thus we do not require the short observations. Therefore, we are reallocating the time orignially used for the F487N and F658N filters to take an exposure in the F656N filter. This provides yet another filter with high S/N to accomplish our first two stated science goals. In addition, we are left with ~5 minutes of unused orbital visability. Thus, in addition our proposed program, we will get a long exposure in [SII] (F673N). This additional filter (providing a 19 year baseline) will allow us to a 5th measure of the shell expansion as well as provide another spectral element to detect any collisional brightening. HOT STARS 12 false false false false AVAILABLE STAR EMISSION LINE NEBULA PLANETARY NEBULA CENTRAL STAR YES This object was generated by the target selector and retrieved from the SIMBAD database. V839ARA SAO244567 J2000 J2000 WFC3/UVIS Imaging No No F502N WFC3/UVIS Imaging No No F487N WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F658N WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F625W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false 1437671855392 /Users/zachary/Documents/Research/HST_Proposals/Stingray/OP-cache/APT_Stingray-v01.xml The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. 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