7207( 3) - 06/25/96 09:46 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7207 Version: 3 Check-in Date: 25-Jun-1996 09:44:14 1.Proposal Title: Sakurais novalike variable in Sagittarius: ejecta and light echoes ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle INTERSTELLAR MEDIUM GO/DD 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: HOWARD E. BOND SPACE TELESCOPE SCIENCE INSTITUTE ------------------------------------------------------------------------------------ 6. Abstract One orbit of HST time will be devoted to imaging the novalike variable in Sagittarius discovered by Sakurai, believed to be a planetary-nebula nucleus undergoing a final helium shell flash. Broad-band V,I and narrow-band [O III] images will be obtained. These initial observations will allow us to follow the evolution of this object, and in future years, HST observers will subtract these baseline images from their images, in order to detect expanding ejecta and light echoes. ------------------------------------------------------------------------------------ 7207( 3) - 06/25/96 09:46 - [ 2] Observations Description ------------------------ Our goals are as follows: (1) Obtain a set of V, I, and [O III] frames in which the central star just avoids saturation in its central pixel. Assuming that the star will have reached V=10.7 in the summer of 1996, and cutting the exposures to 40% of the calculated time for an extra margin of safety, we get exposure times of 0.14, 0.16, and 10 sec, respectively. These are for imaging of the region immediately surrounding the central star. (2) Obtain a second set of V, I, and [O III] frames in which the central pixel from the star reaches about 100,000 electrons. These exposures are 1.2, 1.6, and 100 sec. These are for deeper imaging of the immediate surroundings. (3) Fill out the single orbit with longer V, I, and [O III] frames. We can accommodate 3 x 40 sec in V, 3 x 40 sec in I, and 2 x 260 sec in [O III]. These are for imaging fainter light echoes and nebular features at somewhat larger radii from the central star, as well as perhaps showing some details of the old planetary nebula surrounding the star. The central star is placed 1/2 way between the center of the PC chip and the apex, in order to cover more area around the central star (including the large surrounding planetary nebula) which still maintaining the high spatial resolution of the PC. Real_Time_Justification Due to the sudden outburst of this object, it MUST be observed in the summer of 1996. This is essential in order to search for outwardly propagating light echoes, and nebular material ejected during the outburst. The observation should be done as soon as possible, preferably before Sept 1, 1996, and definitely before the target goes behind the Sun at the end of October 1996. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 7207( 3) - 06/25/96 09:46 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI- Star, nova-like, RA=17H 52M 32.69S +/- 1", DEC=- J2000 V=+115 V = 10.7 NOVALIKE-VAR planetary nebula 17D 41' 07.7" +/- 1", PLATE- B-V = 0.81 central star; ISM, ID=060B planetary nebula Comments: The target flux level refers to the central star, and is the expected brightness extrapolated to late summer 1996. 7207( 3) - 06/25/96 09:46 - [ 4] Visit: 01 Visit Requirements: BEFORE 01-SEP-96 On Hold Comments: Additional Comments: This is a Director's Discretion observation which should be done as soon as possible, and if at all possible be done before 1996 Sept 1. It must, in any case, be done in 1996 before the target goes behind the Sun at the end of October 1996. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 10 S POS TARG -8.75, -8.75 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 2 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 1 0.16 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 1 0.14 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 1 1.2 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 5 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 1 1.6 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 6 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 100 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 7 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 2 230 S SAME POS AS 1 EXPAND ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 8 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 3 40 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 9 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 3 40 S SAME POS AS 1 END ORBIT ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 7207( 3) - 06/25/96 09:46 - [ 5] Summary Form for Proposal 7207 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 01-SEP-96 POS TARG -8.75, -8.75 SAME POS AS 1 SAME POS AS 1 EXPAND SAME POS AS 1 END ORBIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F502N F814W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SAKURAI-NOVALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------