7260( 3) - 06/30/97 17:13 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7260 Version: 3 Check-in Date: 30-Jun-1997 17:11:29 1.Proposal Title: NICMOS Observations of PKS1413+135 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle AGN/QUASARS GO 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: IAN MCHARDY SOUTHAMPTON UNIVERSITY CoI: Roberto Abraham Institute of Astronomy, Cambridge N CoI: Andrew Newsam University of Southampton N CoI: Michael Merrifield University of Southampton N CoI: Carolin Crawford Institute of Astronomy, Cambridge N ------------------------------------------------------------------------------------ 6. Abstract In deep ground based CCD observations we discovered that the BL Lacertae object, PKS1413+135 apparently lies in a disc host galaxy. In cycle 2 HST observations we showed that the `host' was a type Sa spiral galaxy. In the conventional `unified schemes' for active galaxies this result is extremely surprising as the parent population of BL Lac objects are thought to be low power radio galaxies which almost all lie in large elliptical galaxies. No similar radio source has yet been found in a spiral galaxy. One way around this problem is to suppose that the BL Lac does not lie in the `host' galaxy, but is a background quasar which is being gravitationally lensed by the apparent host. If the BL Lac does live in the host galaxy then we expect it to be exactly centered. However, a background lensed object will typically lie a fraction of an arcsecond from the center of the lensing galaxy. The BL Lac core has a very steep spectrum and dominates the galaxy in ground based K-band images but is undetectable in the cycle 2 V band image (or ground based R and I band images). We ask, therefore, for a deep H band image which will detect both the galaxy and core well, to determine the precise location of the BL Lac object relative to the underlying galaxy. If we find the BL Lac to be exactly centred on the underlying galaxy, the conventional `unified schemes' will have to be re- thought. ------------------------------------------------------------------------------------ 7260( 3) - 06/30/97 17:13 - [ 2] Observations Description ------------------------ Given the size of the galaxy (>= 10'' diameter in the optical bands), we might miss some of the outer isophotes of the galaxy if we use Camera 1 (11''x11'') and so we prefer camera 2 (19''x19''). Thus we must observe in H band. We need to define the morphology of the galaxy well if we are to define its centre accurately and so must detect outer isophotes. Based on our optical images, and assuming an SED appropriate to an Sa galaxy at the redshift of PKS1413+135, we calculate that R-H = 2.52 mag. Assuming no strong colour gradients then, again based on the optical images which show a surface brightness of R=25 mag arcsec^2 at 6'' radius and which allow us to define the center of the galaxy accurately, we have to reach surface brightness levels of 22.5 mag arcsec^2 in H. In 2000s we reach a S/N of 0.46 per pixel and in 6500s we reach a S/N of 1. At the expense of spatial resolution we can bin up pixels to improve the S/N and so do not require 3 Sigma significance in individual pixels. Thus we request only a 2 orbit observation. Obtaining a good S/N observation of the galaxy is the difficult task here; determining the core position is very easy. However we must take account of core saturation as we require an unsaturated image to accurately define the core position. Here we find that the MULTIACCUM mode provides the perfect solution, providing excellent dynamic range. We estimate (based on fig 2) that the core will saturate in 400s. Therefore we will use the STEP256 observing strategy, giving a good range of shorter exposure times to enable good definition of the PSF of the central core, while keeping the readout overheads to a minimum on the longer exposure. This is repeated for the second orbit rather than using, say, the SPARS256 mode in case any small (eg sub-pixel) shifts in the pointing have modified the detailed shape of the PSF. Real Time Justification ----------------------- None Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7260( 3) - 06/30/97 17:13 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PKS1413+135 GALAXY,BL RA=14H 13M 58.80S +/- J2000 Z = 0.26 V = 19.4+/-0.1 LAC,SPIRAL,DUST LANE .05S,DEC=13D 20' 24.2" +/- .1",PLATE-ID=01US 2 OFF- GALAXY,BL XI-OFF=1.125"+/- 0.005",ETA- J2000 Z = 0.26 V = 19.4+/-0.1 PKS1413+135 LAC,SPIRAL,DUST LANE OFF=1.125"+/- 0.005",FROM 1,PLATE-ID=01US Comments: Offset from main PKS1413 position in case there are transient bad pixels. 7260( 3) - 06/30/97 17:13 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: The Primary target is PKS1413+135 using NIC2. Parallels for NIC1 and NIC3 are given in Nos 21,61 and 31,71 respectively, although no scientific justification can be given for these w.r.t PKS1413+135. Therefore, no ORIENT is specified. Any modifications to 21, 61, 31 and 71 that are desired should be made. OFF-PKS1413+135 is simply PKS1413+135 with a 15x15 pixel offset to avoid any possible problems with the transient bad-pixel regions found in NIC2 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 PKS1413+135 NIC2 MULTIAC NIC2-FI F160W SAMP-SEQ=STEP256,NSAMP=20, 1 DEF PAR 21-31 WITH 11 CUM X PATTERN=NONE Comments: Primary observation. Parallels (21, 31) are Attached Parallels with no scientific justification for this proposal. ------------------------------------------------------------------------------------------------------------------------------------ 21 PKS1413+135 NIC1 MULTIAC NIC1 F160W SAMP-SEQ=SPARS256,NSAMP=12 1 DEF CUM Comments: Any modifications (eg SAMP-SEQ, Filter, Aperture etc) that do not affect exposure 11 can be made. ------------------------------------------------------------------------------------------------------------------------------------ 31 PKS1413+135 NIC3 MULTIAC NIC3 F160W SAMP-SEQ=SPARS256,NSAMP=12 1 DEF CUM Comments: Any modifications (eg SAMP-SEQ, Filter, Aperture etc) that do not affect exposure 11 can be made. ------------------------------------------------------------------------------------------------------------------------------------ 51 OFF-PKS1413 NIC2 MULTIAC NIC2-FI F160W SAMP-SEQ=STEP256,NSAMP=21, 1 DEF PAR 61-71 WITH 51 +135 CUM X PATTERN=NONE Comments: Primary observations. Parallels (61, 71) are Attached Parallels with no scientific justification for this proposal. ------------------------------------------------------------------------------------------------------------------------------------ 61 OFF-PKS1413 NIC1 MULTIAC NIC1 F160W SAMP-SEQ=SPARS256,NSAMP=13 1 DEF +135 CUM Comments: Any modifications (eg SAMP-SEQ, Filter, Aperture etc) that do not affect exposure 51 can be made. ------------------------------------------------------------------------------------------------------------------------------------ 71 OFF-PKS1413 NIC3 MULTIAC NIC3 F110W SAMP-SEQ=SPARS256,NSAMP=13 1 DEF +135 CUM Comments: Any modifications (eg SAMP-SEQ, Filter, Aperture etc) that do not affect exposure 51 can be made. ------------------------------------------------------------------------------------------------------------------------------------ 7260( 3) - 06/30/97 17:13 - [ 5] Summary Form for Proposal 7260 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 NIC1 NIC3 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP256 NSAMP=20 PATTERN=NONE NSAMP=12 SAMP-SEQ=SPARS256 NSAMP=21 NSAMP=13 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category AGN/QUASARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PAR 21-31 WITH 11 PAR 61-71 WITH 51 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PKS1413+135 OFF-PKS1413+135 ------------------------------------------------------------------------------------------------------------------------------------