Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2698c Report Date: 09-May-96:17:17 Version: ********** Check-in Date: ********** 1.Proposal Title: LYMAN-ALPHA IMAGING OF YOUNG AND FORMING GALAXIES AT LARGE REDSHIFTS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone P.i. S. Djorgovski CALTECH USA (818)-356-4415 ASSOCIATE PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract A number of the recently discovered optical counterparts of powerful radio sources such as 3C 326.1 at z ~= 1.8 have properties which can be interpreted as those of giant galaxies or cluster cores in the process of formation. Among these are the galaxies' large size, clumpy appearance, strong Ly alpha emission, low continuum surface brightness, large velocity fields, and estimated star formation rates of several hundred Mo/yr. While the presence of strong radio lobes marks these objects as atypical, they are the best candidates for primeval galaxies now known. UV imaging with the HST can check this hypothesis, and provide further insights into their nature. We propose to do imaging in intermediate width bands containing the Ly alpha line of 3C 326.1, our primary primeval galaxy candidate, and 3C 256, a radio galaxy with comparable redshift which shows a strong Ly alpha, bright and compact stellar continuum, and is an excellent example of the radio-optical alignment effects. The initial burst of star formation in 3C 256 may be over, but it is still very young and actively evolving. Ly alpha imaging will reveal the distribution of star formation in these galaxies, and constrain estimates of star formation rate, jet-galaxy interaction, and and gas ionization mechanisms. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GALAXIES: FORMATION-GALAXIES: RADIO-GALAXIES:EMISSION LINE-COSMOLOGY. ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 16.10 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2698c PI: P.i. S. Djorgovski Proposal Title: LYMAN-ALPHA IMAGING OF YOUNG AND FORMING GALAXIES AT LARGE REDSHIFTS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ H. Spinrad CALIFORNIA, UNIVERSITY OF, USA BERKELEY M. Dickinson CALIFORNIA, UNIVERSITY OF, USA BERKELEY M. Strauss CALTECH USA N. Weir CALTECH USA D. Thompson CALTECH USA J. Smith CALTECH USA W. Van Breugel CALIFORNIA, UNIVERSITY OF, USA BERKELEY P.I. S. Djorgovski CALTECH USA P. Mccarthy OCIW USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. This revised proposal reflects our reassessment and suggested modifications of the original proposal, and resulting recommendations by the TAC. The changes in the scope of the proposal are as follows: The original (phase 1) version of this proposal had eight targets; per the TAC request, this list was pared down to four objects in phase 2. Since one must now increase the integration times by a factor of a few in order to compensate for the OTA problems, we believe that the best course at this point is to reduce the number of targets and the diversity of exposure types, and to invest more integration time in fewer objects and filters. Thus, we decided to devote an approximately equal net observing time to the two most interesting objects, 3C 326.1 and 3C 256, and to do them well. We also decided to eliminate any FOC/96 exposures, and replace them with the closest PC equivalents (in terms of the bandpasses). This is motivated by the desire to include some PSF stars in the fields, and thus help any image restoration attempts, and to simplify the operational requirements. Since the PC exposures provide more signal per unit time than the FOC/96 exposures, and there is no instrument setup change (all of our new proposed exposures are with PC), there is some time saving. (The FOC was originally proposed in part because of its better sampling, an issue which is now practically irrelevant.) The details of filters, etc., are given in the answer to Question 5 below. According to the RPSS resource estimator, our total exposure time is 14.14 hours, the spacecraft time is 16.09 hours, and the efficiency is thus 87.9 %. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We have pursued the optical imaging from the ground of the four 3CR galaxies mentioned above as far as is practical with 3 to 5-m class telescopes. We also have high-quality VLA maps, and will be obtaining more spectra and near-IR images in the future. However, high-resolution imaging with HST is essential to determine the kpc-scale structure of these systems, especially in the light of Ly alpha; recall that it is the morphology of these systems, and their strong Ly alpha emission which make them interesting and good primeval galaxy candidates in the first place. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. For both targets, we wish to obtain images using PC8 (it has the highest UV sensitivity), and filters F336W (which includes the redshifted Ly alpha line near the peak of its transmission, for both objects), and F413M (which samples the line-free continuum). The former replaces the originally proposed FOC exposures; the latter is the same as originally proposed. For 3C326.1, we wish to obtain 2 exposures of 600 sec, and 6 exposures of 1800 sec with F413M (which samples the line-free continuum), and 2 exposures of 600 sec, one of 1100 sec, and 9 of 1800 sec with F336W (which samples the Lyman alpha line and some continuum). For 3C256, we wish to obtain 2 exposures of 600 sec, and 4 exposures of 1800 sec with F413M, and 2 exposures of 600 sec, and 6 of 1800 sec with F336W. For this integration time, our estimates of the S/N, using the Handbook, the Preliminary Report on HST Performance for Cycle 1 GO's, and the materials provided at the recent STScI workshop, with the increase factor of 5, give the range S/N =~ 10 - 30 for individual bright regions in these galaxies, or S/N =~ 20 - 40 for the entire objects (or slightly higher in F336W, due to the large equivalent widths of the Ly alpha lines). ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. We have working image processing and data analysis packages at our home institutions, including a superb Maximum Entropy image restoration package, which was exported to the STScI, and assorted other software (Lucy, Wiener, and other methods). We have done extensive image restoration experiments, using both real and simulated HST data. We are confident that we can restore the effective angular resolution of the HST images comparable to those proposed here down to the angular resolution of about 0.1 arcsec, with the photometric distortions well understood. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Our institutions have extensive computing and other research facilities (libraries, etc.), and there is no shortage of additional graduate students which can participate in this project. Along with the support requested with the present proposal, we should have quite adequate resources to analyse the data and publish the results very rapidly. ------------------------------------------------------------------------------------ 11. Address Information Name: S. DJORGOVSKI Category: PI Institution: CALTECH Address: ASTRONOMY, MS 105-24 CALTECH City: PASADENA State: CA Zip Code: 91125 Country: USA Telephone: 818-356-4415 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2698c [ 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 3C326.1 GALAXY; RADIO GALAXY RA = 15H 53M 57.3S +/- 1", 1950 Z = 1 V = 23 +/- 0.5 DEC = +20D 13' 00" +/- 1" 1.825 Comments: WE WISH TO USE PC8, AS IT HAS THE HIGHEST UV SENSITIVITY, BUT ALSO TO AVOID THE BAUM SPOT (SEE OUR POS TARG REQUIREMENTS). IF THIS IS TOO DIFFICULT TO SCHEDULE, PC6 CCD WITH THE DEFAULT (MIDDLE) POINTING MAY BE ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 2 3C256 GALAXY; RADIO GALAXY RA = 11H 18M 04.15S +/- 1950 Z = 1 V = 22.5 +/- 0.3 0.5", 1.819 DEC = +23D 44' 21.2" +/- 0.5" Comments: WE WISH TO USE PC8, AS IT HAS THE HIGHEST UV SENSITIVITY, BUT ALSO TO AVOID THE BAUM SPOT (SEE OUR POS TARG REQUIREMENTS). IF THIS IS TOO DIFFICULT TO SCHEDULE, PC6 CCD WITH THE DEFAULT (MIDDLE) POINTING MAY BE ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2698c [ 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 3C326.1 PC IMAGE P8 F413M CR-SPLIT=NO 2 600S 1 1 CYCLE 1 POS TARG 8.4, -8.4 Comments: WE WISH TO USE PC8, SINCE HIGHEST UV SENSITIVITY, BUT ALSO WISH TO AVOID THE BAUM SPOT (SEE POS TARG REQUIREMENTS). IF TOO DIFFICULT TO SCHEDULE, PC6 WITH THE DEFAULT (MIDDLE) POINTING MAY BE ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 2 3C326.1 PC IMAGE P8 F413M CR-SPLIT=NO 6 1800S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 3 3C326.1 PC IMAGE P8 F336W CR-SPLIT=NO 2 600S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 4 3C326.1 PC IMAGE P8 F336W CR-SPLIT=NO 1 1100S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 5 3C326.1 PC IMAGE P8 F336W CR-SPLIT=NO 9 1800S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 6 3C256 PC IMAGE P8 F413M CR-SPLIT=NO 2 600S 1 1 CYCLE 1 POS TARG 8.4, -8.4 Comments: WE WISH TO USE PC8, SINCE HIGHEST UV SENSITIVITY, BUT ALSO WISH TO AVOID THE BAUM SPOT (SEE POS TARG REQUIREMENTS). IF TOO DIFFICULT TO SCHEDULE, PC6 WITH THE DEFAULT (MIDDLE) POINTING MAY BE ACCEPTABLE. ------------------------------------------------------------------------------------------------------------------------------------ 7 3C256 PC IMAGE P8 F413M CR-SPLIT=NO 4 1800S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 8 3C256 PC IMAGE P8 F336W CR-SPLIT=NO 2 600S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ 9 3C256 PC IMAGE P8 F336W CR-SPLIT=NO 6 1800S 1 1 CYCLE 1 POS TARG 8.4, -8.4 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2698c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 16.10 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 1 ; POS TARG 8.4, -8.4 ; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F413M F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 3C326.1 3C256 ------------------------------------------------------------------------------------------------------------------------------------