Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5707 Report Date: 18-Jul-95:17:52 Version: ********** Check-in Date: ********** 1.Proposal Title: MORPHOLOGY OF GALAXIES IN CLUSTERS AT Z = 0.5 - CONT OF 2373: CYCLE 4 CARRY-OVER ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO/CAR 2 Long Term yrs 3857 Sub Category GALAXY MORPHOLOGY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Alan Dressler CARNEGIE OBSERVATORIES USA 818-304-0245 ------------------------------------------------------------------------------------ 7. Abstract We outline a continuing program 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. We propose in Cycle 2 to continue our efforts by imaging with the Wide Field Camera two additional fields containing rich clusters of galaxies at z = 0.5 for which extensive photometry and spectroscopy already exist. The fields include a range of environments, from the dense cores of clusters to isolated field galaxies. These data will be used primarily to classify images according to traditional morphological categories and will be used, within the constraints implied by deconvolution techniques, to measure surface brightness distributions and bulge-to-disk ratios. A brief description is given of how the data are applicable to specific questions, like the cause of enhanced starburst activity found for high-z galaxies. NOTE: The portion of the program contained in this observing program ID 5707 consists of the unfinished portion of the CL1446 observations left over from Cycle 2 and is now being done with WFPC2 instead of WFPC-I. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 11.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5707 PI: Alan Dressler Proposal Title: MORPHOLOGY OF GALAXIES IN CLUSTERS AT Z = 0.5 - CONT OF 2373: CYCLE 4 CARRY-OVER ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ P.I. Alan Dressler CARNEGIE OBSERVATORIES USA Harvey Butcher KAPTEYN OBSERVATORY NETHERLANDS X Augustus, Jr. Oemler DEPARTMENT OF ASTRONOMY, YALE U. USA Page 3 ------------------------------------------------------------------------------------ 3. Description of proposed observations. NOTE: Q3 SECTIONS 1 & 2 BELOW DESCRIBE THE ORIGINAL WFPC-I OBS. SKIP TO GF Q3 SECTION 3 FOR CARRYOVER PROGRAM 5707 DESCRIPTION. Our original plan was to use the WFC to image 2 fields in each of 8 clusters 0.36 < z < 0.55 over a period of 2 years, fields selected from ground-based CCD images. For each cluster, multicolor photometry for several hundred objects, and low-resolution spectra for 30-50 representative galaxies in the fields covering a magnitude range 19 < m(r) < 23, are available. These fields typically contain field/cluster galaxies in the ratio of 1/2, so the sample covers a wide range of environments. Spectra have been classified according to "activity", as described in the text and the papers cited. The field centers were chosen to maximize the number of "active" galaxies. From our revised Cycle 1 allocation we have acquired 3 hrs on cluster CL0024+1654 and 6 hours on Cl0939+4713. These observations demonstrate that morphological information can be extracted from high-redshift galaxies despite the degraded imaging performance of HST. The 20% of the light concentrated in the small PSF core has made it possible to assess the salient features of morphological classification like bulge-to-disk ratio and strong spiral structure with of order 6 hours of exposure on clusters at z = 0.4. With our time in Cycle 2, we have scheduled approximately 6 hours on a third cluster CL1446+2621 and an additional 3 hours on CL0024+1654. These exposures will be coadded from single-orbit exposures, done in a single color with filter F702W, which roughly corresponds to a rest-frame color between B and V. Information on color distributions formed a promising though minor part of our original observing plan, but the prospect of restoring images of high photometric accuracy through deconvolution is sufficiently daunting that we will not attempt this unless experiments by others confirm its feasibility. NOTE: ALL GF Q3 TEXT ABOVE THIS POINT IS FROM THE OLD ORIGINAL CYCLE 2 PROGRAM, AND IS REFERRING TO THE PROGRAM AS IT WAS DESIGNED FOR THE WFPC-I OBSERVATIONS, WHICH ALSO INCLUDED PSF EXPOSURES OF NGC 188 FOR USE WITH DECONVOLUTIONS, ETC. THE SPECIFIC DETAILS PERTAINING TO THE CYCLE 4 CARRY-OVER PROGRAM GO/CAR 5707 ARE CONTAINED IN GF QUESTION 3 SECTION 3, BELOW. THIS SECTION DESCRIBES THE SPECIFIC DETAILS FOR IMPLEMENTATION OF THE CYCLE 4 CARRY-OVER PROGRAM GO/CAR 5707. This carry-over program consists of 2 exposures of the galaxy cluster GAL-CLUS-1446+2621. The first should be taken with the WFALL-FIX aperture chosen, and the special requirement POS TARG +10.0,+10.0 used to place the Fixed Target List coords at the apex. The second exposure should also use the WFALL-FIX aperture, but a small dither should be applied by use of the special requirement POS TARG +10.3,+10.3. This should place the second exposure 3" ( exactly 3 WFC pixels ) off in both x and y from the first, allowing us to deal effectively with hot pixels, etc. The use of NO GAP and SAME ORIENT special requirements will help us keep the offsets at a level of accuracy which will still allow us to register the two images well enough to do effective cosmic ray removal. The 3 pixel offset is small enough that field distortions and non-overlapping areas between the two images should be minimized, yet large enough to allow us to identify and deal with hot pixels and most chip defects, etc. Both exposures should be of the same duration, in this case 2200s each. Each exposure is intended to essentially fill an orbit ( or most of one ) but to still be of equal exposure time. An absolute ORIENT of 305.356D +/- 0.01D is given in order to match as much as possible the field of view of the previous data taken with WFPC-I. A SUMMARY OF THE CURRENT GO/CAR 5707 CARRY-OVER REQUIREMENTS FOLLOWS: 1). WFALL-FIX aperture with POS TARG +10.0,+10.0 ( FTL coords at apex ) for the first exposure, and POS TARG +10.3,+10.3 for the second exposure, yielding a 3-WFC-pixel dither in both x and y between the first and second exposures. We should be able to align the two frames well enough to do effective cosmic ray removal during the data reduction, provided the two exposures are tied together with a NO GAP special requirement in order to keep the offset well registered, using the same guide stars on the same pointing during the observations. 2). SAME ORIENT for both exposures 3). SEQ NO GAP ( do both together, one after another ) 4). 2x2200s exposures ( 2 orbits, with 1 exposure / orbit ), and without a CR-SPLIT ( i.e. CR-SPLIT = NO ) 5). ORIENT=305.356D +/- 0.01D in order to cover richest field of cluster in previous WFPC-I data. Opposite and orthogonal angles may be OK as well, but we prefer and request that we be consulted if any such change is necessary. ( Please consult with the PI, Alan Dressler, and/or Ray Lucas, at STScI, if an alternate ORIENT is needed. ) NOTE THAT THE ORIGINAL ORIENT ANGLE IN GO 3857 WAS U3=125.356D, BUT THE ORIENT ANGLE IN THIS CARRYOVER PROGRAM WAS TAKEN FROM THE CHANGE THAT WAS MADE TO 3857 IN AN ATTEMPT TO DO THE SECOND HALF AT 180D OFF WITH WFPC-I BEFORE THE REFURBISHMENT MISSION. ( CONT'D, BELOW.) DOING THE CARRYOVER AT 180D FROM THE ORIGINAL ALSO APPEARS TO HAVE THE ADVANTAGE OF CAUSING FEWER GALAXIES TO BE LOST OFF THE MISSING WF1 THAN IF THE ORIGINAL U3 ORIENT=125.356D HAD BEEN USED IN THIS PROGRAM. DOING THE CARRYOVER PROGRAM AT U3 ORIENT=305.356D MEANS THAT THE OLD WF4 FIELD WILL NOW FALL ON THE NEW WF2, THE OLD WF1 WILL NOW FALL ON THE NEW WF3, THE OLD WF2 WILL NOW FALL ON THE NEW WF4, AND WHAT APPEARS TO HAVE BEEN THE SPARSEST FIELD, THE OLD WF3, WILL NOW FALL ON ( AND OFF OF ) THE NEW PC1. Page 4 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. NOTE: THIS IS TEXT FOR THE NEW CYCLE 4 CARRY-OVER PROGRAM. See the summary in GF Question 3, Sections 3, 4, and 5 ( immediately above ) for a summary of our scheduling requirements for the Cycle 4 carry-over program GO/CAR 5707. ------------------------------------------------------------------------------------ 9. Description of previous HST work. We are presently involved in analyzing our first WFC images, of cluster CL0024+1654 and CL0939+4713, as described in the above text. NOTE: QUESTION 9 TEXT IS OLD TEXT. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Dressler and Oemler each have access to a MicroVAX computer with image display capability. Each MicroVAX is part of a VAX system, supplied and maintained individually by Carnegie Observatories and Yale which includes a variety of I/O devices and access to BITNET and other communication networks. NOTE: QUESTION 10 TEXT IS OLD TEXT. ------------------------------------------------------------------------------------ 11. Address Information Name: ALAN DRESSLER Category: PI Institution: CARNEGIE OBSERVATORIES Address: 813 SANTA BARBARA ST. City: PASADENA State: CA Zip Code: 91101 Country: USA Telephone: 818-304-0245 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5707 [ 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- F,404 RA= 14H47M16.5S +/-0.1S, 1950.0 Z=0.37 1446+2621 DEC= +26D20'20.0" +/-1" Comments: CLUSTER OF GALAXIES AT Z=0.37. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5707 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 1 2200S 1 POS TARG +10.0, 1446+2621 FIX +10.0 ORIENT 305.356D +/ - 0.01D SAME ORIENT FOR 2 AS 1 Comments: DO BOTH EXPOSURES AT THE SAME SEQ 1-2 NO GAP ORIENT ANGLE, BUT DITHER BY 3" CYCLE 4 (3 WFC PIXELS) IN X AND Y BETWEEN THEM. DO IN SEQUENTIAL ORDER WITH NO GAP IN BETWEEN. POS TARG +10,+10 PLACES FTL COORDS AT PYRAMID APEX FOR THIS EXP. ------------------------------------------------------------------------------------------------------------------------------------ 2 GAL-CLUS- WFPC2 IMAGE WFALL- F702W CR-SPLIT=NO 1 2200S 1 POS TARG +10.3, 1446+2621 FIX +10.3 CYCLE 4 Comments: DITHER BY USING POS TARG +10.3, +10.3 WHICH PLACES FTL COORDS 3" (3 WFC PIXELS) OFF THE APEX IN X AND Y FOR THIS SECOND EXPOSURE. ALTERNATE ORIENT ANGLES OF 215.356D, 125.356D, AND 36.356D MAY BE ACCEPTABLE IF NEEDED. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5707 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 11.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category GALAXY MORPHOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG +10.0,+10.0; ORIENT 305.356D +/- 0.01D; SAME ORIENT FOR 2 AS 1; SEQ 1-2 NO GAP; CYCLE 4; POS TARG +10.3,+10.3; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F702W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-CLUS-1446+2621 ------------------------------------------------------------------------------------------------------------------------------------