8880( 2) - 10/10/00 14:22 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8880 Version: 2 Check-in Date: 10-Oct-2000 14:21:44 1.Proposal Title: EV Lac ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Rachel Osten University of Colorado at Boulder CoI: Dr. Alex Brown CASA N CoI: Dr. Thomas Ayres CASA N CoI: Dr. Carol Ambruster Villanova N CoI: Dr. Steve Drake GSFC N CoI: Dr. Travis Rector NOAO N CoI: Dr. Nick White GSFC N CoI: Dr. Jeffrey Linsky JILA N ------------------------------------------------------------------------------------ 5. Abstract We will carry out four orbits of STIS E140M spectroscopy in TIME-TAG mode of the active red dwarf star EV Lac, in conjunction with a 100 ks Chandra HETGS pointing. EV Lac is an excellent candidate for dispersed X-ray spectroscopic studies owing to its brightness and propensity for frequent and extreme variability. EV Lac is the second brightest M dwarf X-ray source (the other, AU Mic, already has been observed by both Chandra and HST/STIS). HETG observations record coronal dynamics; and constrain key physical parameters--abundances, temperatures, and densities--leading to improved understanding of coronal structure. The coordinated observations with HST/STIS will extend the investigation into the cooler subcoronal atmosphere of the active red dwarf star. ------------------------------------------------------------------------------------ 8880( 2) - 10/10/00 14:22 - [ 2] Observations Description ------------------------ The STIS FUV observations are straightforward. First, the target is acquired with the CCD, and then a PEAK-UP is performed using one of the very narrow ND- filtered apertures. The E140M/FUV-MAMA observations are carried out with the 0.2X0.2 "photometric" aperture in TIME-TAG mode. Based on simulations with the STIS exposure time calculator, we estimate a typical global count rate (during quiescence) of 75 cps, completely dominated by the 1215 A hydrogen Lyman alpha feature (peak count rate ~ 0.1 cps/px). During a flare, the H I flux might triple, but the count rate at the line peak would still be less than 1 cps/px, and the global rate would be only about 200 cps. The C IV doublet might brighten substantially more than Lyman alpha, but even a 10X flux increase would still yield a peak count rate of less than 1 cps/px, and only a minimal increase in the global count rate. Given these estimates, the appropriate BUFFER-TIME would be 10, 000 S, well in excess of the maximum exposure time of 3015 S, so we set BUFFER-TIME= exp time in each orbit. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- It is essential to have the STIS observation scheduled to fall sometime during, and entirely within, the long Chandra exposure, which will last for more than a day. The Chandra observation has been tentatively scheduled for the week of Sept. 17, 2001. ------------------------------------------------------------------------------------ 8880( 2) - 10/10/00 14:22 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 EV-LAC STAR, M V-IV, CORONA RA=22H 46M 49.73S +/- 0.05S, 2000 V = 0 V = +10.29+/-0.1 DEC=+44D 20' 2.4" +/- 1" B-V = +1.54+/-0.1 F-LINE(1215)=50+/-15e-13 W-LINE(1215)=1.6 F-LINE(1548)=8+/-1e-13 W-LINE(1548)=0.25 TYPE=M4V Coordinate Source: OTHER_SOURCE Comments: Positions & Proper Motions from Hipparcos Catalogue; FUV fluxes from IUE spectra; FWHMs from STIS spectra of similar object (AU Mic); the fluxes are ergs/cm^2/s/A at the line peak. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0657 -0.459 0.198 8880( 2) - 10/10/00 14:22 - [ 4] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Essential to schedule observation entirely within the ~1D duration of the Chandra X-ray Observatory pointing on the same target Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 EV-LAC STIS/C ACQ F25ND3 MIRROR 1 1 S CD Comments: S/N=68, 3000 e- ------------------------------------------------------------------------------------------------------------------------------------ 2 EV-LAC STIS/C ACQ/PEA 0.2X0.0 MIRROR 1 1 S CD K 5ND Comments: S/N=79, 4000 e- ------------------------------------------------------------------------------------------------------------------------------------ 3 EV-LAC STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=1875. 1 1875 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 40 EV-LAC STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=3015. 1 3015 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 41 EV-LAC STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=3015. 1 3015 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 42 EV-LAC STIS/F TIME-TA 0.2X0.2 E140M 1425 BUFFER-TIME=3015. 1 3015 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 8880( 2) - 10/10/00 14:22 - [ 5] Summary Form for Proposal 8880 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F25ND3 0.2X0.05ND 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1875. BUFFER-TIME=3015. ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names EV-LAC ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 ------------------------------------------------------------------------------------------------------------------------------------