8606( 8) - 07/10/01 13:23 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8606 Version: 8 Check-in Date: 10-Jul-2001 13:21:58 1.Proposal Title: Determining the Nature of the Variable Absorption in AGN: Monitoring NGC 3783 with HST and Chandra ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: D. Crenshaw Catholic University of America CoI: Dr. Joseph Shields Department of Physics and Astronomy, Ohio N University CoI: Dr. Smita Mathur Ohio State University N CoI: Dr. Ian George Laboratory for High Energy Astrophysics, N NASA's Goddard Space Flight Center CoI: Dr. Fred Hamann University of Florida, Gainsville N CoI: Dr. Anuradha Koratkar Space Telescope Science Institute N CoI: Dr. Steven Kraemer Catholic University of America, STIS N Science Team CoI: Dr. Gerard Kriss Space Telescope Science Institute N CoI: Dr. Smita Mathur Smithsonian Institution Astrophysical N Observatory CoI: Dr. Richard Mushotzky Laboratory for High Energy Astrophysics, N NASA's Goddard Space Flight Center CoI: Dr. Paul Nandra Laboratory for High Energy Astrophysics, N NASA's Goddard Space Flight Center CoI: Dr. Hagai Netzer Wise Observatory, Tel-Aviv University N CoI: Dr. Bradley Peterson Department of Astronomy, The Ohio State N University ------------------------------------------------------------------------------------ 5. Abstract About 60% of Seyfert 1 galaxies show intrinsic UV absorption lines, characterized by high ionization (C IV, N V), moderate widths (30 -- 300 km s^-1), significant outflow velocities (up to 2500 km s^-1), and variability on time scales as small as days. Seyferts with UV absorption also show variable X-ray ``warm absorbers'', characterized by O VII and O VIII absorption edges, which suggests a common origin. Variability monitoring is the key to understanding the absorbers, by providing their radial locations, densities, and evolution in ionization, column density, velocity, and coverage of the inner active nucleus. HST/STIS and Chandra are ideal instruments for this pursuit, and NGC 3783 is an ideal target, because it shows extremely variable absorption and rapid continuum variability in both the UV and X-rays. ------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 2] Observations Description ------------------------ We have chosen a monitoring sequence that will characterize th e continuum and absorption variations on time scales of days, weeks, and months. Comparison with previous GHRS and STIS observations will allow us to monitor the UV variations on a time scale of years. During each visit, we will obtain STIS E140M spectra through the 0.2X0.2 slit over two orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Five HST observations will be coordinated with Chandra observations. ------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC3783 GALAXY, SEYFERT RA=11H 39M 1.7S +/- 0.05S, DEC=- J2000 Z = V = 13.0 37D 44' 19" +/- 0.5", PLATE- 0.009 ID=00JJ Coordinate Source: GSC_SURVEY_PLATE 8606( 8) - 07/10/01 13:23 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 01-Aug-2000 AND 15-Aug-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 15-Nov-2000 AND 01-Dec-2000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 6] Visit: 03 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 15-Jan-2001 AND 01-Feb-2001 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 7] Visit: 04 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 25-Feb-2001 AND 26-Feb-2001:01:00:00.0 On Hold Comments: Additional Comments: Simultaneous with Chandra observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 8] Visit: 05 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 28-Feb-2001 AND 01-Mar-2001:01:00:00.0 On Hold Comments: Additional Comments: Simultaneous with Chandra observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 9] Visit: 06 Visit Priority: Visit Requirements: SCHED 100% AFTER 05 BY 2.6 D TO 3.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 10] Visit: 07 Visit Priority: Visit Requirements: SCHED 100% AFTER 16 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 11] Visit: 08 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 11-Mar-2001 AND 12-Mar-2001:01:00:00.0 On Hold Comments: Additional Comments: Coordinated with Chandra observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 12] Visit: 09 Visit Priority: Visit Requirements: SCHED 100% AFTER 08 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 13] Visit: 10 Visit Priority: Visit Requirements: SCHED 100% AFTER 09 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 14] Visit: 11 Visit Priority: Visit Requirements: SCHED 100% AFTER 10 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 15] Visit: 12 Visit Priority: Visit Requirements: SCHED 100% AFTER 11 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 16] Visit: 13 Visit Priority: Visit Requirements: SCHED 100% BETWEEN 31-Mar-2001 AND 01-Apr-2001:01:00:00.0 On Hold Comments: Additional Comments: Coordinated with Chandra observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 17] Visit: 14 Visit Priority: Visit Requirements: SCHED 100% AFTER 13 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 18] Visit: 15 Visit Priority: Visit Requirements: SCHED 100% AFTER 14 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 19] Visit: 16 Visit Priority: Visit Requirements: SCHED 100% AFTER 15 BY 3.6 D TO 4.4 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 20] Visit: 17 Visit Priority: Visit Requirements: SCHED 100% On Hold Comments: Additional Comments: Coordinated with Chandra observations. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 21] Visit: 53 Visit Priority: Visit Requirements: SCHED 100% On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC3783 STIS/C ACQ F28X50L MIRROR 1 0.3 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC3783 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8606( 8) - 07/10/01 13:23 - [ 22] Summary Form for Proposal 8606 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 100% BETWEEN 01-Aug-2000 AND 15-Aug-2000 SCHED 100% BETWEEN 15-Nov-2000 AND 01-Dec-2000 SCHED 100% BETWEEN 15-Jan-2001 AND 01-Feb-2001 SCHED 100% BETWEEN 25-Feb-2001 AND 26-Feb-2001 01 00 00.0 SCHED 100% BETWEEN 28-Feb-2001 AND 01-Mar-2001 01 00 00.0 SCHED 100% AFTER 05 BY 2.6 D TO 3.4 D SCHED 100% AFTER 16 BY 3.6 D TO 4.4 D SCHED 100% BETWEEN 11-Mar-2001 AND 12-Mar-2001 01 00 00.0 SCHED 100% AFTER 08 BY 3.6 D TO 4.4 D SCHED 100% AFTER 09 BY 3.6 D TO 4.4 D SCHED 100% AFTER 10 BY 3.6 D TO 4.4 D SCHED 100% AFTER 11 BY 3.6 D TO 4.4 D SCHED 100% BETWEEN 31-Mar-2001 AND 01-Apr-2001 01 00 00.0 SCHED 100% AFTER 13 BY 3.6 D TO 4.4 D SCHED 100% AFTER 14 BY 3.6 D TO 4.4 D SCHED 100% AFTER 15 BY 3.6 D TO 4.4 D SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC3783 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------