9511( 3) - 04/26/02 11:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9511 Version: 3 Check-in Date: 26-Apr-2002 11:13:11 1.Proposal Title: Connecting the UV and X-ray Warm Absorbers in NGC 5548 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Jelle Kaastra Space Research Organization Netherlands CoI: Dr. Nahum Arav UC Davis N CoI: Prof. D. Michael Crenshaw Georgia State University Y CoI: Prof. Kirk Korista Western Michigan University N ------------------------------------------------------------------------------------ 5. Abstract In the last Chandra cycle, we were awarded a joint Chandra/HST proposal to study the warm absorber in NGC 5548 and to obtain a definitive answer about the connection between the warm absorber and the UV absorber in this object. We are confident that the deep Chandra observation (500 ksec) will allow for an unprecedented determination of the kinematic components in the warm absorber as well as accurate column density measurements from several line series. However, two new lines of investigation that appeared after the submission of the Chandra/HST proposal, suggest that the original modest request for HST time will not suffice to obtain reliable column density measurements for the UV absorber. In view of the new evidence, we need a a higher S/N in the proposed observations to allow for accurate UV column densities determination. Absorption features in both the UV and warm absorbers are known to be variable. Therefore, it will be highly unfortunate if the large investment of Chandra time will not be accompanied by enough simultaneous HST time to ensure an accurate measurements of the UV absorber. Without these it will be very difficult to draw conclusions concerning the relationship between the two absorbers. We therefore ask for 20 additional STIS E140M Echelle orbits. ------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 2] Observations Description ------------------------ We propose 20 orbits observation using the STIS E140M. Our S/N requirements are driven by the C IV\ trough. An exposure that will satisfy the needed C IV\ S/N will be more than adequate to analyze the N V\ and \Ly\ troughs (and put excellent limits on [S II]v, [S II]I\ and \cii, which are not detected in the existing data). When dealing with saturated troughs the relevant S/N is at the bottom of the trough. We look at a conservative case where the UV flux is only half of what is shown in figures ref5548stis and refghrs_cover. In the available data, roughly 90\ 0.5times10^-13 (flux units are in ergs s^-1 cm^-2 AA^-1), therefore our conservative benchmark flux level is 0.25times10^-13. Based on our optical-depth/covering-factor analysis (see Fig. refghrs_cover), we determine that the difference between the normalized flux levels of the blue and red doublet components is 20\ across most of the trough. To be able to ascertain such a saturation level to 50\ This must be the total error after we add in quadrature errors from both doublet components and uncertainties in the unabsorbed emission model. After a short iterative process (since higher S/N also lowers the uncertainties in the unabsorbed emission model), we determined that a S/N=15 at F=0.25times10^-13 is needed. This S/N will allow us to determine the unabsorbed emission model above the troughs to 5\ of the deep trough. Adding these errors in quadrature yield the required 10 Calculator we calculate that to reach a S/N=15 at F=0.25times10^-13 with the E140M grating at 1570 Angstrom and a 0.2''*0.2'' aperture, requires 67 ksec which yields 26 orbits of exposure time for NGC 5548 (taking into account the need for ~six separate visits due to the south Atlantic anomaly). If the flux level drops below our conservative limits we should still be able to reach most of our goals by binning the data proportionally. The trade off is of course losing velocity resolution, which is highly undesirable, but it will allow for a reasonable analysis even if the flux level drops by another factor of two (a very low state for NGC 5548). We note that while our requirement to ascertain the saturation level to 50\ over a width of 20--30 resolution elements for the trough, so our results will be considerably better. However, we cannot afford a lower accuracy since then more and more resolution elements will give rise to very large optical depth values due to noise fluctuations. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5548 GALAXY, SEYFERT RA=14H 17M 59.57S +/- 0.05S, J2000 V = 13.5 DEC=25D 8' 12.3" +/- 0.5", PLATE -ID=01TM Coordinate Source: GUIDE_STAR_CATALOG 9511( 3) - 04/26/02 11:14 - [ 4] Visit: 01 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 NGC5548 STIS/C ACQ F28X50L MIRROR 1 1.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 5] Visit: 02 Visit Priority: Visit Requirements: AFTER 01 BY 1 D TO 14 D 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 NGC5548 STIS/C ACQ F28X50L MIRROR 1 1.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 6] Visit: 03 Visit Priority: Visit Requirements: AFTER 01 BY 1 D TO 14 D 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 NGC5548 STIS/C ACQ F28X50L MIRROR 1 1.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 7] Visit: 04 Visit Priority: Visit Requirements: AFTER 01 BY 1 D TO 14 D 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 NGC5548 STIS/C ACQ F28X50L MIRROR 1 1.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2200 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5548 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2700 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 9511( 3) - 04/26/02 11:14 - [ 8] Summary Form for Proposal 9511 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% AFTER 01 BY 1 D TO 14 D SCHED 100% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5548 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------