Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5631 Report Date: 18-Jul-95:17:46 Version: ********** Check-in Date: ********** 1.Proposal Title: A NEW SIZE CONSTRAINT ON LYMAN ALPHA CLOUDS: HOPR #202 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS AND AGN GO 5320 Sub Category QUASAR ABSORPTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Craig B. Foltz MULTIPLE MIRROR TELESCOPE USA 602-621-1269 ------------------------------------------------------------------------------------ 7. Abstract Although they have been the target of extensive ground- and space-based investigations as well as intense theoretical modelling, the physical nature of the absorbing clouds responsible for the Lyman alpha forest of absorption seen shortward of 1215 A in the rest frame of all QSOs remains elusive. Optical and UV data have yielded column density, Doppler parameter, and redshift distributions, but the determination of gas density and ionization fractions requires a knowledge of the size of the absorber. Ground-based constraints derived from observations of gravitationally-lensed and projected pairs of QSOs allow for a wide range of sizes: 10 kpc < r < 1 Mpc. We propose to observe three relatively bright, intermediate- redshift pairs of QSOs, with separations on the sky of roughly an arcminute to search for common Lyman alpha forest lines in the redshift range from 0.35 to 1.7. Numerical simulations show that these observations will be sensitive to cloud sizes greater than about 100 kpc. If the characteristic size of the clouds is in the range from 100 kpc to 1 Mpc an estimate of the size will result from the fraction of absorption lines common along two nearby lines of sight. In the case of no common features, the upper limit on the size of the clouds will be reduced by more than a factor of 4. This is a HOPR (#202) REPEAT FOR for PKS0254-344,Q0254-344,LB9605(V1) only. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 16.96 par: 0 10. Num targs pri: 6 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5631 PI: Craig B. Foltz Proposal Title: A NEW SIZE CONSTRAINT ON LYMAN ALPHA CLOUDS: HOPR #202 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Craig B. Foltz 1216 USA Chris D. Impey 1212 USA Nadine Dinshaw 1212 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Three pairs of quasars will be observed with the red side of the FOS. The G190H and G270H gratings will give spectral coverage from 1650-3280 A, corresponding to 0.35 < z < 1.7 for Lyman-alpha absorbers. The two high redshift pairs will be observed with both the G190H and G270H gratings, and the lower redshift pair with just the G190H grating. All three targets can be acquired in ACQ/BINARY mode with the large 4.3 arcsecond aperture and the observations will be made in the 0.9 arcsecond circular aperture. One internal wavelength calibration frame will be acquired at both gratings for the high-z quasars and at only the G190H grating for the lower-z quasars. The integration times are scaled to yield a SNR per diode of about 50 which gives a better than 5 sigma equivalent width limit for unresolved absorption lines of 0.3 A at 2300 A for the G190H observations and at 2650 A for G270H. A 0.3 A equivalent width line will be detected at greater than 3 sigma everywhere in the G270H spectra and longward of 1650 A in the G190H spectra. Shortward of 1650 A in the G190H spectra, such a line will fall below 3- sigma significance. The quoted SNRs are estimated from the observed V magnitudes by assuming a power law slope of nu^-1. This is a HOPR (#202) repeat for PKS0254- 344,Q0254-344,LB9605(VISIT1) only. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. This observation requires the ultraviolet spectroscopic capability of the HST. Ground-based observations of Lyman-alpha absoprtion lines are only possible for redshifts above z = 1.7. Since the quasars have redshifts up to z = 2, we plan ground-based spectroscopy using the Multiple Mirror Telescope to augment the HST data (the ground-based data will also be essential in weeding out metal lines from the relatively small number of Lyman-alpha lines). However, most of the path length to absorption, and most of the expected absorbers, are at wavelengths below 3200 Angstroms that can only be studied by HST. Also, it is by no means clear that the high and low redshift Lyman-alpha absorbers represent the same kind of object. There is some indication that the slope of dN/dz flattens below z = 1.5. Therefore a new constraint on the sizes of low redshift Lyman-alpha clouds is desirable independent of ground-based data. We also note that this observation is complementary to the scientific goals of the Quasars Key Project. The Key Project will eventually have enough absorbers to calculate whether Lyman- alpha clouds cluster in the same way as galaxies at low redshift. The use of pairs, however, gives size information that cannot be obtained either from a 2- point correlation function or from an autocorrelation function along a single line of sight. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. The success of this proposal relies on whether the absorption features of one quasar can be unambiguously identified as being common (or not) to those of the other quasar in a pair. This demands accurate calibration of the zero point of the wavelength scale within a pair. According to Papers I and II of the HST Quasar Absorption Line Key Project, the rms scatter in the zero point is about 0.5 A in the G190H and G270H gratings. The offsets can be determined from the Galactic absorption lines, however in calibrating the G190H spectra only the Al II 1670 line is suitable and is not always well detected (Paper II, preprint, p9). Therefore one wavelength calibration frame following an exposure at each grating for each of the quasars is required. We will not need a calibration frame for every exposure because the relative zero-point shifts between exposures of a given quasar can be calculated by cross-correlating the individual exposures of that quasar. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Previous HST observing time awarded us is as follows: GO Program 2524 "Spectropolarimetry of Bright Quasars" - IMPEY GO Program 3732 "Spectropolarimetry of Bright Quasars" - IMPEY GO Program 3648 "Imaging of BL Lac Host Galaxies and Environments" - IMPEY GO Program 4402 "A Study of the Gravitational Lens 1422+321" - IMPEY, FOLTZ Papers on the results of GO Programs 2524 and 3732 are in preparation. The data from GO Program 3648 have been received and are being reduced. The observations for GO Program 4402 have not yet been made. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The University of Arizona will provide central computing services (hard disks, networks, tape drives) in support of this project. One undergraduate will be able to work on this project. We will also be supported by the University of Arizona and the Smithsonian Institution in follow-up ground-based spectroscopy spectroscopy of the quasar pairs using the Multiple Mirror Telescope. ------------------------------------------------------------------------------------ 11. Address Information Name: CRAIG B. FOLTZ Category: PI Institution: 1216 Address: MMT OBSERVATORY UNIVERSITY OF ARIZONA City: TUCSON State: AZ Zip Code: 85721 Country: USA Telephone: 602-621-1269 Telex (or e-mail): 602-670-5740 ------------------------------------------------------------------------------------ Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5631 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 PKS0254-334 E,313 PLATE-ID = 02IV, J2000.0 Z=1.915 1 V=17.0 Q0254-334A RA = 02H 56M 42.60S +/- 1.0", DEC = -33D 15' 22.6" +/- 1.0" Comments: COMPONENT A OF QUASAR PAIR Q0254-334A AND B ------------------------------------------------------------------------------------------------------------------------------------ 2 Q0254-334 E,313 PLATE-ID = 02IV, J2000.0 Z=1.863 1 V=16.5 Q0254-334B RA = 02H 56M 47.85S +/- 1.0", DEC = -33D 15' 26.3" +/- 1.0" Comments: COMPONENT B OF QUASAR PAIR Q0254-334A AND B ------------------------------------------------------------------------------------------------------------------------------------ 5 LB9605 E,313 PLATE-ID = 027J, J2000.0 Z=1.834 1 V=18.4 RA = 15H 19M 13.41S +/- 1.0", DEC = +23D 46' 57.4" +/- 1.0" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5631 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 PKS0254-334 FOS/RD ACQ/ 4.3 MIRROR 1 13.9S 20 1 1 CYCLE 4 / 1-7 BINARY ONBOARD ACQ FOR 2- 7 ------------------------------------------------------------------------------------------------------------------------------------ 2 PKS0254-334 FOS/RD ACCUM 1.0 G190H 1565- 1 35M 50 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 3 PKS0254-334 FOS/RD ACCUM 1.0 G190H 1565- 1 35M 50 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 4 WAVE FOS/RD ACCUM 1.0 G190H 1565- 1 DEF 1 CALIB FOR 3 NO 2312 SLEW GROUP 3-4 NO GAP Comments: DO NOT CHANGE GRATING POSITION BETWEEN EXPOSURES 3 AND 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 PKS0254-334 FOS/RD ACCUM 1.0 G270H 2223- 1 24M 50 1 1 3278 ------------------------------------------------------------------------------------------------------------------------------------ 6 PKS0254-334 FOS/RD ACCUM 1.0 G270H 2223- 1 24M 50 1 1 3278 ------------------------------------------------------------------------------------------------------------------------------------ 7 WAVE FOS/RD ACCUM 1.0 G270H 2223- 1 DEF 1 CALIB FOR 6 NO 3278 SLEW GROUP 6-7 NO GAP Comments: DO NOT CHANGE GRATING POSITION BETWEEN EXPOSURES 6 AND 7 ------------------------------------------------------------------------------------------------------------------------------------ 8 Q0254-334 FOS/RD ACQ/ 4.3 MIRROR 1 8.8S 20 1 1 CYCLE 4 / 8-13 BINARY ONBOARD ACQ FOR 9- 13 ------------------------------------------------------------------------------------------------------------------------------------ 9 Q0254-334 FOS/RD ACCUM 1.0 G190H 1565- 1 23M 50 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 10 Q0254-334 FOS/RD ACCUM 1.0 G190H 1565- 1 23M 50 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 11 WAVE FOS/RD ACCUM 1.0 G190H 1565- 1 DEF 1 CALIB FOR 10 NO 2312 SLEW GROUP 10-11 NO GAP Comments: DO NOT CHANGE GRATING POSITION BETWEEN EXPOSURES 10 AND 11 ------------------------------------------------------------------------------------------------------------------------------------ 12 Q0254-334 FOS/RD ACCUM 1.0 G270H 2223- 1 28M 50 1 1 3278 ------------------------------------------------------------------------------------------------------------------------------------ 13 WAVE FOS/RD ACCUM 1.0 G270H 2223- 1 DEF 1 CALIB FOR 12 NO 3278 SLEW GROUP 12-13 NO GAP Comments: DO NOT CHANGE GRATING POSITION BETWEEN EXPOSURES 12 AND 13 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5631 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 35 LB9605 FOS/RD ACQ/ 4.3 MIRROR 1 50.3S 20 1 1 CYCLE 4 / 35-42 BINARY ONBOARD ACQ FOR 36 -42 ------------------------------------------------------------------------------------------------------------------------------------ 36 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 37 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 38 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 39 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 40 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 41 LB9605 FOS/RD ACCUM 1.0 G190H 1565- 1 37M 45 1 1 2312 ------------------------------------------------------------------------------------------------------------------------------------ 42 WAVE FOS/RD ACCUM 1.0 G190H 1565- 1 DEF 1 CALIB FOR 41 NO 2312 SLEW GROUP 41-42 NO GAP Comments: DO NOT CHANGE GRATING POSITION BETWEEN EXPOSURES 41 AND 42 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5631 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 16.96 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS AND AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 1-7 ; ONBOARD ACQ FOR 2-7 CALIB FOR 3 NO SLEW ; GROUP 3-4 NO GAP CALIB FOR 6 NO SLEW ; GROUP 6-7 NO GAP CYCLE 4 / 8-13 ; ONBOARD ACQ FOR 9-13 CALIB FOR 10 NO SLEW ; GROUP 10-11 NO GAP CALIB FOR 12 NO SLEW ; GROUP 12-13 NO GAP CYCLE 4 / 35-42 ; ONBOARD ACQ FOR 36-42 CALIB FOR 41 NO SLEW ; GROUP 41-42 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G190H G270H ------------------------------------------------------------------------------------------------------------------------------------ Target Names PKS0254-334 Q0254-334A Q0254-334 Q0254-334B LB9605 ------------------------------------------------------------------------------------------------------------------------------------