Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 16 Report Date: 18-Jul-95:15:58 Version: ********** Check-in Date: ********** 1.Proposal Title: MORPHOLOGY OF GALAXIES IN CLUSTERS AT Z = 0.5: FUTURE- CYCLE OBSERVATIONS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO 2 Long Term yrs 2373 Sub Category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Alan Dressler THE OBSERVATORIES OF THE CAR USA 818-304-0245 ASTRONOMER ------------------------------------------------------------------------------------ 7. Abstract Our program is intended to study galaxy evolution through the investigation of galaxy morphology as a function of lookback time. The development of disks and bulges, the role of mergers, interactions, and other environmental influences, are expected to be visible over the range 0 < z < 1 as judged by the spectrophotometric evolution already observed over this redshift range. Over this first year of our two year program, we will image with the Wide Field Camera 5 fields in four rich clusters of galaxies at z = 0.35 - 0.55 for which extensive photometry and spectroscopy already exist. The fields include a wide range of environments from the dense cores of clusters to isolated field galaxies. These data will be used to classify images according to traditional morphological categories and will be used to determine quantitative measures of surface brightness distributions and bulge-to- disk ratios. The images will be obtained in two colors in order to map the distribution of star formation in comparison with low-z galaxies in similar clusters. The data are applicable to specific questions, like the cause of enhanced starburst activity found for high-z galaxies. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GALAXY MORPHOLOGY, EVOLUTION, GALAXY CLUSTER ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 28.50 par: 0 10. Num targs pri: 5 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 16 PI: Dr. Alan Dressler Proposal Title: MORPHOLOGY OF GALAXIES IN CLUSTERS AT Z = 0.5: FUTURE- CYCLE OBSERVATIONS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Prof. Harvey Butcher KAPTEYN OBSERVATORY NETHERLANDS X Prof. James E. Gunn ASTROPHYSICAL SCIENCES, USA PRINCETON UNIVERSITY Prof. Augustus, Jr. Oemler DEPARTMENT OF ASTRONOMY, YALE USA UNIVERSITY P.I. Alan Dressler THE OBSERVATORIES OF THE USA CARNEGIE INSTITUTION OF WASHINGTON ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will use the WFC to image 5 fields in 4 clusters 0.36 < z < 0.55 in the first year of our two-year program. Ground-based CCD images of these fields were used to select a WFC field which includes an area for which multicolor photometry for most objects and low resolution spectroscopy for some objects are already in hand. A typical field will contain 1 contaminating field galaxy for every 2 cluster galaxies, so the sample covers a wide range of environments. The spectra have been classified according to "activity", related to star formation or an active nucleus. The fields centers are chosen to maximize the number of "active" galaxies. Observations will be coadded single-orbit exposures of 7,500 s or 10,000 s in each of two broad-band colors. roughly corresponding to rest-frame V and a band between U and B. Color maps will be constructed to study the distribution of star formation. The two colors will be coadded for the morphological classification, producing an effective wavelength near the center of the B band. This will be directly comparable to morphological classification at low redshift which is traditionally done in this color. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Morphology is the missing component in our attempts to study galaxy evolution for 0 < z < 1. At the distance of our intended targets, 1 arcsecond = 7 1/h kpc, so morphological classification is extremely crude with ground-based seeing of FWHM = 0.5-1.0 arcseconds. No meaningful comparisons can be made with low-z classification systems. The HST with the WFC, with its field of 2.7 x 2.7 arcminutes and 0.1 arcsecond pixels, affords us the only opportunity to fundamentally correct this deficiency. In his study of 55 rich clusters, Dressler (1980 Ap. J. Suppl. 42) assigned Revised Hubble types to about 6000 galaxies. The more distant clusters in his sample have an average redshift z = 0.05, for which the 1 arcsecond FWHM seeing obtained by Dressler gave a resolution of approximately 0.7 1/h kpc. Though not as detailed as the classification of galaxies within the Local Supercluster, where resolutions of order 100 pc can be obtained, such imaging has thus been shown to be sufficient to distinguish between the major classes in the Hubble or de Vaucouleurs schemes. With HST imaging, nearly the same resolution of 0.7 1/h kpc can be obtained for galaxies in clusters at z = 0.5. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. From CCD images of low-z cluster spirals we have simulated HST observations and concluded that, for clusters at z = 0.4, exposures of 15,000 s (6 x 2500 s single -orbit) exposures are required for a S/N = 20, necessary for even rudimentary classification. The more distant clusters at z = 0.55 in our sample will require at least 20,000 seconds (8 x 2500 s single-orbit) exposures. We have arrived at these numbers by obtaining CCD images of spiral galaxies in low-redshift clusters and using them to simulate exposures with the HST WFC, taking into account telescope and detector efficiency, dark current, readout noise, resolution, and sampling. We have found that at z = 0.5 the fine detail of spiral structure, particularly for early-type spirals, is only marginally discernible in the 10,000 s exposures obtained in each color. By coadding the two colors we should achieve a S/N and resolution comparable to that of Dressler's 1980 morphological classification of 6000 galaxies in 55 low-redshift clusters (z = 0.05). Should this still be insufficient, we have the option of repeating the first year's 5 fields in the second year. We have not included the possibility that evolution may make such features easier to detect. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. In order to accomplish our scientific objectives we must develop methods of moving from images to parametrized data. Traditionally this has been accomplished by using the image processing capabilities of the human eye plus brain, in order to assign morphological classes, estimate bulge-to-disk ratios, and describe distributions of color, dust, non-axisymmetric structures, etc. These classifications are semi-quantitative at best, and useful results regarding the evolution of galaxy morphology will depend on having an equivalent sample of observations at low redshift for which the same subjective criteria can be applied. With this in mind, Dressler and Gunn have begun to obtain CCD images of low redshift clusters 0.02 < z < 0.04 in seeing of FWHM < 1 arcsecond. With suitable processing, such data can be used to simulate the HST observations (similar sampling, S/N, and resolution) in order to provide calibration images. Thus, although the criteria will be remain subjective in this initial step, it can be applied so that redshift is the only significant variable, and a good assessment of differential morphology can be made. This procedure will be useful in applying traditional classification schemes like the Hubble or de Vaucouleurs systems. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Dressler, Oemler, and Gunn each have access to a MicroVAX computer with image display capability. Each MicroVAX is part of a VAX system, supplied and maintained individually by MWLCO, Yale, and Princeton, which includes a variety of I/O devices and access to BITNET and other communication networks. Partial support for students will be provided Yale University and Princeton University. ------------------------------------------------------------------------------------ 11. Address Information Name: ALAN DRESSLER Category: PI Institution: THE OBSERVATORIES OF THE CARNEGIE Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ Page 4 Name: ALAN DRESSLER Category: PI Institution: THE OBSERVATORIES OF THE CARNEGIE Address: 813 SANTA BARBARA ST. City: PASADENA State: CA Zip Code: 91101 Country: USA Telephone: 818-304-0245 Telex (or e-mail): 1561318 OCIW UT ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 16 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 GAL-CLUS- Z = 0.54 CLUSTER OF RA= 00H15M58.4S +/-0.1S, 1950.0 Z=0.54 001558+1609- GALAXIES DEC= +16D09'07" +/-1" FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 2 GAL-CLUS- Z = 0.54 CLUSTER OF RA= 00H16M00.0S +/-0.1S, 1950.0 Z=0.54 001558+1609- GALAXIES DEC= +16D10'42" +/-1" FLD2 ------------------------------------------------------------------------------------------------------------------------------------ 3 GAL-CLUS- Z = 0.39 CLUSTER OF RA= 00H23M56.9S +/-0.1S, 1950.0 Z=0.39 002400+16530 GALAXIES DEC= +16D53'10" +/-1" 0-FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 4 GAL-CLUS- Z = 0.39 CLUSTER OF RA= 00H23M53.8S +/-0.1S, 1950.0 Z=0.39 002400+16530 GALAXIES DEC= +16D54'50" +/-1" 0-FLD2 ------------------------------------------------------------------------------------------------------------------------------------ 5 GAL-CLUS- Z = 0.37 CLUSTER OF RA= 02H37M21.1S +/-0.1S, 1950.0 Z=0.37 ABELL370- GALAXIES DEC= -01D47'12" +/-1" FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 6 GAL-CLUS- Z = 0.37 CLUSTER OF RA= 02H37M31.2S +/-0.1S, 1950.0 Z=0.37 ABELL370- GALAXIES DEC= -01D45'27" +/-1" FLD2 ------------------------------------------------------------------------------------------------------------------------------------ 7 GAL-CLUS- Z = 0.43 CLUSTER OF RA= 03H03M27.0S +/-0.1S, 1950.0 Z=0.43 030330+1706- GALAXIES DEC= +17D07'07" +/-1" FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 8 GAL-CLUS- Z = 0.43 CLUSTER OF RA= 03H03M16.1S +/-0.1S, 1950.0 Z=0.43 030330+1706- GALAXIES DEC= +17D07'07" +/-1" FLD2 ------------------------------------------------------------------------------------------------------------------------------------ 9 GAL-CLUS- Z = 0.40 CLUSTER OF RA= 09H39M42.0S +/-0.1S, 1950.0 Z=0.40 093942+4713- GALAXIES DEC= +47D12'34" +/-1" FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 10 GAL-CLUS- Z = 0.40 CLUSTER OF RA= 09H39M56.5S +/-0.1S, 1950.0 Z=0.40 093942+4713- GALAXIES DEC= +47D12'34" +/-1" FLD2 ------------------------------------------------------------------------------------------------------------------------------------ 11 GAL-CLUS- Z = 0.46 CLUSTER OF RA = 14H09M33.3S +/-0.1S, 1950.0 Z=0.46 3C295-FLD1 GALAXIES DEC= +52D26'12" +/-1" ------------------------------------------------------------------------------------------------------------------------------------ 12 GAL-CLUS- Z = 0.46 CLUSTER OF RA = 14H09M49.7S +/-0.1S, 1950.0 Z=0.46 3C295-FLD2 GALAXIES DEC= +52D28'42" +/-1" ------------------------------------------------------------------------------------------------------------------------------------ 13 GAL-CLUS- Z = 0.37 CLUSTER OF RA= 14H47M16.5S +/-0.1S, 1950.0 Z=0.37 144642+2621- GALAXIES DEC= +26D20'20" +/-1" FLD1 Comments: THESE POSITIONS MAY BE SLIGHTLY IN ERROR; UPDATES WILL BE PROVIDED. ------------------------------------------------------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 16 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 14 GAL-CLUS- Z = 0.37 CLUSTER OF RA= 14H47M33.1S +/-0.1S, 1950.0 Z=0.37 144642+2621- GALAXIES DEC= +26D22'50" +/-1" FLD2 Comments: THESE POSITIONS MAY BE SLIGHTLY IN ERROR; UPDATES WILL BE PROVIDED. ------------------------------------------------------------------------------------------------------------------------------------ 15 GAL-CLUS- Z = 0.53 CLUSTER OF RA= 16H01M27.7S +/-0.1S, 1950.0 Z=0.53 160134+4254- GALAXIES DEC= +42D53'50" +/-1" FLD1 ------------------------------------------------------------------------------------------------------------------------------------ 16 GAL-CLUS- Z = 0.53 CLUSTER OF RA= 16H01M38.7S +/-0.1S, 1950.0 Z=0.53 160134+4254- GALAXIES DEC= +42D54'50" +/-1" FLD2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 16 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 DEFINE # WFC IMAGE ALL # CR-SPLIT=NO # 2100S # MEXP PRE-FLASH=NO Comments: THIS SEQUENCE IS INTENDED TO FIT EACH EXPOSURE INTO 1 ORBIT. ADJUST EXPOSURE TIME +/- 20 PERCENT TO ACCOMPLISH. THIS IS THE CYCLE 2 VERSION OF THIS PROPOSAL: AD/RAL 91/04/16 ------------------------------------------------------------------------------------------------------------------------------------ 2 USE GAL-CLUS- F622W 3 1 CYCLE 2 / 2-3 MEXP 001558+1609 GROUP 2-3 WITHIN -FLD1 1D SAME POS FOR 3 AS 2 SAME ORIENT FOR 3 AS 2 POS TARG 0,0 / 2- 11 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 3 ^ ^ F725LP 3 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 4 USE GAL-CLUS- F555W 2 1 CYCLE 2 / 4-5 MEXP 093942+4713 GROUP 4-5 WITHIN -FLD1 1D SAME POS FOR 5 AS 4 SAME ORIENT FOR 5 AS 4 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 5 ^ ^ F814W 2 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 6 GAL-CLUS- WFC IMAGE ALL F555W CR-SPLIT=NO 2 2100S 1 CYCLE 2 / 6-7 ABELL370- PRE-FLASH=NO GROUP 6-7 WITHIN FLD2 1D SAME POS FOR 7 AS 6 SAME ORIENT FOR 7 AS 6 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 7 GAL-CLUS- WFC IMAGE ALL F814W CR-SPLIT=NO 2 2100S 1 COND IF TAC OK ABELL370- PRE-FLASH=NO FLD2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 16 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 8 USE GAL-CLUS- F555W 2 1 CYCLE 2 / 8-9 MEXP 144642+2621 GROUP 8-9 WITHIN -FLD1 1D SAME POS FOR 9 AS 8 SAME ORIENT FOR 9 AS 8 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 9 ^ ^ F814W 2 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 10 USE GAL-CLUS- F622W 3 1 CYCLE 2 / 10-11 MEXP 160134+4254 GROUP 10-11 WITHIN -FLD1 1D SAME POS FOR 10 AS 11 SAME ORIENT FOR 10 AS 11 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 11 ^ ^ F725LP 3 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 12 USE GAL-CLUS- F622W 3 1 CYCLE 2 / 12-13 MEXP 001558+1609 GROUP 12-13 WITHIN -FLD2 1D SAME POS FOR 13 AS 12 SAME ORIENT FOR 13 AS 12 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 13 ^ ^ F725LP 3 1 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 16 USE GAL-CLUS- F555W 2 1 CYCLE 2 / 16-17 MEXP ABELL370- GROUP 16-17 WITHIN FLD1 1D SAME POS FOR 17 AS 16 SAME ORIENT FOR 17 AS 16 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 17 ^ ^ F814W 2 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 18 USE GAL-CLUS- F555W 3 1 CYCLE 2 / 18-19 MEXP 030330+1706 GROUP 18-19 WITHIN -FLD1 1D SAME POS FOR 19 AS 18 SAME ORIENT FOR 19 AS 18 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 16 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 19 ^ ^ F814W 2 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 20 USE GAL-CLUS- F555W 2 1 CYCLE 2 / 20-21 MEXP 093942+4713 GROUP 20-21 WITHIN -FLD2 1D SAME POS FOR 21 AS 20 SAME ORIENT FOR 21 AS 20 COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ 21 ^ ^ F814W 2 ^ COND IF TAC OK ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 16 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 28.50 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 2 / 2-3; GROUP 2-3 WITHIN 1D; SAME POS FOR 3 AS 2; SAME ORIENT FOR 3 AS 2; POS TARG 0,0 / 2-11; COND IF TAC OK; CYCLE 2 / 4-5; GROUP 4-5 WITHIN 1D; SAME POS FOR 5 AS 4; SAME ORIENT FOR 5 AS 4; CYCLE 2 / 6-7; GROUP 6-7 WITHIN 1D; SAME POS FOR 7 AS 6; SAME ORIENT FOR 7 AS 6; CYCLE 2 / 8-9; GROUP 8-9 WITHIN 1D; SAME POS FOR 9 AS 8; SAME ORIENT FOR 9 AS 8; CYCLE 2 / 10-11; GROUP 10-11 WITHIN 1D; SAME POS FOR 10 AS 11; SAME ORIENT FOR 10 AS 11; CYCLE 2 / 12-13; GROUP 12-13 WITHIN 1D; SAME POS FOR 13 AS 12; SAME ORIENT FOR 13 AS 12; CYCLE 2 / 16-17; GROUP 16-17 WITHIN 1D; SAME POS FOR 17 AS 16; SAME ORIENT FOR 17 AS 16; CYCLE 2 / 18-19; GROUP 18-19 WITHIN 1D; SAME POS FOR 19 AS 18; SAME ORIENT FOR 19 AS 18; CYCLE 2 / 20-21; GROUP 20-21 WITHIN 1D; SAME POS FOR 21 AS 20; SAME ORIENT FOR 21 AS 20; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements # F622W F725LP F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-CLUS-001558+1609-FLD1 GAL-CLUS-001558+1609-FLD2 GAL-CLUS-002400+165300-FLD1 GAL-CLUS-002400+165300-FLD2 GAL-CLUS-ABELL370-FLD1 GAL-CLUS-ABELL370-FLD2 GAL-CLUS-030330+1706-FLD1 GAL-CLUS-030330+1706-FLD2 GAL-CLUS-093942+4713-FLD1 GAL-CLUS-093942+4713-FLD2 GAL-CLUS-3C295-FLD1 GAL-CLUS-3C295-FLD2 GAL-CLUS-144642+2621-FLD1 GAL-CLUS-144642+2621-FLD2 GAL-CLUS-160134+4254-FLD1 GAL-CLUS-160134+4254-FLD2 ------------------------------------------------------------------------------------------------------------------------------------