5992( 8) - 05/15/96 14:19 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5992 Version: 8 Check-in Date: 15-May-1996 14:09:10 1.Proposal Title: The Host Galaxies and Environments of , BL Lacertae Objects ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle AGN GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Buell T. Jannuzi National Optical Astronomy Observatories CoI: Brian Yanny Fermi National Accelerator, Laboratory N CoI: Chris Impey University of Arizona N ------------------------------------------------------------------------------------ 6. Abstract We proposed to obtain short (unsaturated) and deep PC images of 16 BL Lac objects selected from complete X-ray and radio- selected samples. We were given enough time to observe 4 objects. These high spatial resolution images will allow measurement of the luminosities of the host galaxies and provide basic morphological information about the hosts. They will allow the study of the inner regions (<4 Kpc) of BL Lacs in unprecedented detail and the determination of the degree of centering of the AGN with respect to the host. The longer exposures will allow the study of faint companion galaxies or other signs of interactions between the AGN and companions. All of this information is valuable for testing the current paradigms for the mechanism(s) responsible for the observed properties of BL Lacs and for identifying the parent population of these objects. The continuum properties might be affected by two distinct physical mechanisms: relativistic beaming and gravitational lensing. If beaming models are applicable, the data will yield a diagnostic for the parent population via the distribution of host galaxy luminosities and morphologies. In addition we will be able to test, again by comparison of the host galaxy properties, whether X-ray (less variable, greater fraction of their integrated light from stars) and radio-selected BL Lacs are drawn from the same population. If (micro)lensing is common, it will manifest itself as off-centered nebulosity around the AGN. ------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 2] Observations Description ------------------------ A sample of 4 X-ray and radio selected BL Lac objects will be imaged with the Planetary Camera using the I band (F814W) filter. We have chosen to observe in the I band in order to minimize the difference in AGN and host galaxy brightness. For each object we will take a series of exposures including short and long integrations. The first (or first few, depending on the object) exposure in each series will be short, designed to be unsaturated, usable in scaling PSF stars used to subtract the wings of the BL Lac point source in the longer exposures (see below), and to yield valuable data about the inner regions of these AGN. An example of the expected length of these exposures is that for MS2143.4+0704, for which an integration of 350 seconds will not be saturated (we will be using the 7 electron per ADU gain setting). All of the objects we are proposing to observe have been well monitored for periods as long as three years. We have calculated the length of the short exposures so that they will be unsaturated even if we happen to catch an object at the peak of its historical range of variability. It is worth noting that X-ray selected objects are not as variable as the radio selected objects -- none of the XSBLs in our program have been observed to change their brightness by more than a magnitude (Jannuzi et al. 1993). The short exposures will be immediately followed by longer exposures designed to yield information about the ``host'' galaxies at one to two effective radii. These images will also be used to search for faint companions. For this latter purpose it is not important that the central 0.1'' region will be saturated. Accurate subtraction of the unsaturated PSF wings can still be done using scaled measurements of PSF template stars (as was done in Cycle 4 imaging by Yanny et al), and the appropriate scale factor can be measured from the short (unsaturated) exposure and the relative exposure lengths. The mean redshift of the sample is z = 0.33, so the HST observations will obtain information that cannot be obtained from the ground. For example, the core radius of a brightest cluster elliptical at z = 0.3 corresponds to 7-10 pixels with the PC (H_0 = 50 kms^-1 Mpc^-1, q_0 = 0.5), which is why we will make use of the highest resolution available with the HST. If the host galaxy is a luminous elliptical of M_I = - 25. at z = 0.3, then the effective surface brightness is 22.8 I mag arcsec^-2 and the effective radius is 8.3 Kpc or 1.9'' (we assume B-V = 0.5, V-I=1.6, and use the models of Pritchett and Kline 1981, A.J., 86, 1859). This gives a signal to noise per pixel of 5 within the effective radius. If the host galaxy is a spiral of M_I = -21.9 at z = 0.3, then the central surface brightness is 22.3 I mag arcsec^-2 and scale length 5.1 kpc or 1.2'' (we assume a Mu = 0.3 evolutionary model of Bruzual and Kron 1980, Ap.J., 241, 29). Imaging with a limiting surface brightness of 26 I mag arcsec^-2 will cover 3-4 scale lengths of the host galaxy, sufficient for an accurate radial profile and some morphological information. The practical limit for surface photometry is not defined by the background but by the flat field; assuming flat fields to 1\\% of 26.7 I mag arcsec^-2. The proposed observations will also be sensitive to small, nearby companions to the BL Lac object. Real Time Justification ----------------------- One of our targets can make use of continuous-viewing- zone windows, allowing these images to be obtained more efficiently than most other observations. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS (2-day) Email: , ------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 OJ287 GALAXY,BL LAC RA=8H 51M 57.3S +/- 0.1S, DEC= 1950 Z=0.306 SURF(V) = 22.8 20D 17' 58.0" +/- 1" B-V = 0.5 V = 16.5 Comments: Radio Selected Quite Variable Can be as bright as V=14.0 2 MS1221+2452 GALAXY,BL LAC RA=12H 21M 53.5S +/- 0.1S, DEC= 1950 Z=0.218 SURF(V) = 22.8 24D 53' 01.0" +/- 1" B-V = 0.5 V = 17.3 Comments: X-ray Selected 3 MS1407+5954 GALAXY,BL LAC RA=14H 7M 50.8S +/- 0.1S, DEC= 1950 Z=0.495 SURF(V) = 22.8 59D 53' 49.0" +/- 1" B-V = 0.5 V = 17.1 Comments: X-ray Selected This is a CVZ Target. 4 MS2143+0704 GALAXY,BL LAC RA=21H 43M 23.0S +/- 0.1S, DEC= 1950 Z=0.237 SURF(V) = 22.8 7D 05' 36.0" +/- 1" B-V = 0.5 V = 17.7 Comments: X-ray Selected 5992( 8) - 05/15/96 14:19 - [ 5] Visit: 01 Visit Requirements: 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 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 11 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 12 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 13 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 14 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 15 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 6] Visit: 02 Visit Requirements: ORIENT 7D TO 10D FROM 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 16 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 17 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 18 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 19 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 20 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 21 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 7] Visit: 03 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 31 MS1221+2452 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 200S ------------------------------------------------------------------------------------------------------------------------------------ 32 MS1221+2452 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 200S ------------------------------------------------------------------------------------------------------------------------------------ 33 MS1221+2452 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 34 MS1221+2452 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 35 MS1221+2452 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 8] Visit: 04 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 41 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 160S ------------------------------------------------------------------------------------------------------------------------------------ 42 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 160S ------------------------------------------------------------------------------------------------------------------------------------ 43 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 160S ------------------------------------------------------------------------------------------------------------------------------------ 44 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 900S ------------------------------------------------------------------------------------------------------------------------------------ 45 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 900S ------------------------------------------------------------------------------------------------------------------------------------ 46 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 900S ------------------------------------------------------------------------------------------------------------------------------------ 47 MS1407+5954 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 900S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 9] Visit: 05 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 51 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 350S ------------------------------------------------------------------------------------------------------------------------------------ 52 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 350S ------------------------------------------------------------------------------------------------------------------------------------ 53 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 350S ------------------------------------------------------------------------------------------------------------------------------------ 54 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 350S ------------------------------------------------------------------------------------------------------------------------------------ 55 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 350S ------------------------------------------------------------------------------------------------------------------------------------ 56 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 1100S ------------------------------------------------------------------------------------------------------------------------------------ 57 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 1100S ------------------------------------------------------------------------------------------------------------------------------------ 58 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 40S ------------------------------------------------------------------------------------------------------------------------------------ 59 MS2143+0704 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 40S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 10] Visit: 06 Visit Requirements: ORIENT 227D TO 230D 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 ------------------------------------------------------------------------------------------------------------------------------------ 60 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 61 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO 1 30S ------------------------------------------------------------------------------------------------------------------------------------ 62 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 63 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 64 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 65 OJ287 WFPC2 IMAGE PC1 F814W CLOCKS=NO,CR-SPLIT=NO 1 500S ------------------------------------------------------------------------------------------------------------------------------------ 5992( 8) - 05/15/96 14:19 - [ 11] Summary Form for Proposal 5992 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CLOCKS=NO CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category AGN ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 7D TO 10D FROM 1 CVZ ORIENT 227D TO 230D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names OJ287 MS1221+2452 MS1407+5954 MS2143+0704 ------------------------------------------------------------------------------------------------------------------------------------