Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3052o Report Date: 09-May-96:20:30 Version: ********** Check-in Date: ********** 1.Proposal Title: COSMIC ABUNDANCES AT Z=1.0 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID QUASARS & AGN SAT/FOS Sub Category QUASAR ABSORPTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone E. margaret Burbidge UC, SAN DIEGO USA (619) 534-4477 ------------------------------------------------------------------------------------ 7. Abstract We will use the FOS to measure the strengths of absorption lines in the UV in a QSO which has known absorption in the optical. This will enable us to determine the ability of the FOS to measure and deconvolve UV absorption lines in faint objects in the light of the degraded performance due to the slit losses, decreased resolution, possible increased scattered light and greater than expected particle-induced background. We will also make a precise test of the spectral resolution and scattered light properties of the FOS by measuring with the HST those lines previously measured from the ground. These observations will enable us to determine the relative abundance of the elements in a galaxy at z=1.0. ------------------------------------------------------------------------------------ 8. Scientific Key Words: UV SPECTROSCOPY, QUASAR, INTERGALACTIC ABSORPTION LINE, EMISSION LINE PROFILE, ABUNDANCE EVOLUTION, LYMAN ALPHA ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 3.06 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3052o PI: E. margaret Burbidge Proposal Title: COSMIC ABUNDANCES AT Z=1.0 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Edward Beaver UC, SAN DIEGO USA E. Margaret Burbidge UC, SAN DIEGO USA Bruce Margon WASHINGTON, UNIVERSITY OF USA J. Roger P. Angel ARIZONA, UNIVERSITY OF USA Frank Bartko MARTIN MARIETTA CORPORATION USA Arthur F. Davidsen JOHNS HOPKINS UNIVERSITY USA Richard J. Harms APPLIED RESEARCH CORPORATION USA Ralph Bohlin SPACE TELESCOPE SCIENCE USA INSTITUTE Holland C. Ford SPACE TELESCOPE SCIENCE USA INSTITUTE Page 3 ------------------------------------------------------------------------------------ 2. Scientific Justification. Observations of 0302-223 will characterize the ability of the FOS to measure absorption lines in faint objects as well as making a determination of the relative abundance of the elements in an object with z=1.0, at a look-back time of roughly 50% of the age of the universe. Determining the relative abundances of the elements over time is a key to understanding galaxy formation and evolution. These kinds of observations will allow us to determine the abundance of the elements at a critical range of look-back-times, where this measurement is impossible from the ground because of the absence of key absorption features. Because high resolution observations are available from the ground, a key problem with the curve of growth technique, the uncertainty in the number and velocity dispersion of individual components of the absorption lines, can be minimized. Because the abundance analysis, as well as a number of other key FOS programs, such as the evolution of the C IV absorption and Lyman alpha forest in quasars depend on accurate measurements of equivalent widths, it is necessary to demonstrate the accuracy with which we can do this. 0302-223 is the brightest object (see below) available to us within the proposed restrictions in right ascension which will enable us to perform this test. The test consists of two parts. The 6000s G270H observations will, in principal, determine equivalent widths to a 1 sigma limit of 0.071 Angstrom, assuming that the 0.5 arc second diameter FOS aperture transmits 23.5% of the incident light. However, the FOS performance is degraded from predicted in three ways. First, much less light gets through the aperture. Second, the (unresolved) absorption lines are broadened by a significant amount. Third, both of these problems are compounded by scattered light, which is probably increased over that predicted for the FOS both because much less light now goes through the entrance aperture and because much more light than predicted now grazes the edge of the aperture. This scattered light fills in the absorption lines and causes a systematic decrease in the measured equivalent widths. Finally, all measurements of faint objects are increased in difficulty because the FOS background is approximately .01 c/s/d, considerably greater than predicted based on ground based calibrations. With the G270H grating we can measure the strengths of several strong, low-ionization lines which must be present in the UV, based on what we know about the optical spectrum. Additionally, we know that the spectrum will not be cut off by any Lyman limit absorption long of the wavelengths of these lines. There may also be additional weaker features, including the C IV blend and Lyman alpha forest absorption lines. Additionally there will be a strong Lyman alpha emission line. Thus we will simultaneously test the ability of the FOS to make conduct several of its important scientific projects. With this test, we will first determine whether the FOS can detect absorption lines in a moderately faint object, although one which is considerably brighter than many that people will wish to observe. This is a qualitatively different test than measuring absorption lines in a bright star, for example. Second we can test deconvolution techniques on the type of data which people will obtain. If the object has C IV absorption (a closely spaced doublet), as it likely will have, this will provide a critical test of such techniques. Third, because of the high signal-to-noise of these observations, we can split them into pieces and compare the equivalent width measurements. This will allow us to test the accuracy of the (highly orbital position dependant) particle induced background subtraction. It may also allow us to test for other effects, such as an increase in sky background near the limb of the earth. We stress that this is the best available candidate for this test; it is bright, will have light in the UV, and will have known absorption, (A few brighter objects have the interesting absorption at wavelengths where the FOS is less efficient.) while at the same time it is similar to other objects that people will wish to observe. In addition, it is scientifically interesting. The G570H measurements do not test the UV capabilities of the FOS, and thus do not directly test capabilities that anyone will wish to use, except for observations of closely spaced objects which the FOS may no longer be able to observe better than can be done from the ground. However, because of the presence of very precisely measured lines in this region, including a closely spaced doublet, we can critically measure the scattered light, deconvolution techniques and orbital positional effects. For example, based on the published ground based data, we can simulate the originally predicted FOS data, and see how close we can mimic it with deconvolution techniques, on data which is similar in signal-to-noise to that which will be used for real observations. Because all problems will probably be worse in the UV, this observation will provide a limiting test of the UV capabilities of the FOS in a way which is not possible in the UV, because no such accurate comparison measurements exist for a faint object. While a few brighter QSOs with known optical absorption do exist which are brighter in the optical than 0302, we felt that for comparison purposes and observing efficiency it would be better to stick with the same object. This observation will observe down to a limiting equivalent width of 0.15 Angstroms. Depending on what kind of test you want, you can decrease the observing time or throw this observation out altogether. A proposal without the G570H observation has already been prepared. Page 4 ------------------------------------------------------------------------------------ 3. Description of proposed observations. This proposal contains 1 object which will be observed with G270H and G570H and the Red Detector of the FOS. S/N will be 40 per diode allowing us to measure absorption as well as as emission lines. All exposures are cycle 0. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The main point of this program is to determine the effects of the actual HST and FOS performance on the abilities of the FOS to carry out some of its unique observations. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. The signal-to-noise calculation assumed transmission through the 0.5 arc second diameter of 23.5% and a total HST+FOS efficiency of 4.8% with G270H and 2.3% with G570H. The equivalent width limits will permit us to measure moderately strong lines to 10%. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. The OV prerequisite programs for all observations are: Prop ID 2188, 2189, 1441, 1442, and 1443 The SV prerequisite program for all observations is: Prop ID 2195 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. To characterize the performance of the HST + FOS, we will measure the equivalent widths of absorption lines, in the total observation as well as in shorter segments of the total integration. We will compare the flux levels in portions to check the particle-induced background subtraction. We will do spectral deconvolution and simulations to determine the effect of the decreased spectral resolution of the FOS on our observations ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We will schedule ground-based observations at Lick Observatory as close to the HST observations in time as possible to provide an estimate of the absolute flux to test the HST flux calibration and to provide additional scientific input. ------------------------------------------------------------------------------------ 11. Address Information Name: E. MARGARET BURBIDGE Category: PI Institution: UC, SAN DIEGO Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ Name: ROSS D. COHEN Category: CON Institution: UNIVERSITY OF CALIFORNIA, SAN DIE Address: CASS DEPT., C-011 City: LA JOLLA State: CA Zip Code: 92093 Country: USA Telephone: (619) 534-2664 Telex (or e-mail): FAX: (619) 534-6316 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3052o [ 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 1E0302-223 QUASAR RA = 03H 04M 49.823S +/- 2000 Z=1.40 1 V=16.3 +/- 0.5 1.0", DEC = -22D 11' 51.91" +/- 1.0", PLATE-ID = 025C ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3052o [ 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 1E0302-223 FOS/RD ACQ/ 4.3 MIRROR BRIGHT=700000 1 11S 1 1 ONBOARD ACQ FOR 2- BINARY 4 CYCLE 0 / 1-4 ------------------------------------------------------------------------------------------------------------------------------------ 2 ^ ^ ACQ ^ ^ 1 11S 1 ^ ------------------------------------------------------------------------------------------------------------------------------------ 3 ^ ^ ACCUM 0.5 G270H 2700 STEP- 1 6000S 40 ^ PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 4 ^ ^ ACCUM 0.5 G570H 5700 STEP- 1 5000S 40 ^ PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3052o [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ^ ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT STEP-PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Proposal for SAT/FOS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 3.06 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category QUASARS & AGN ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category QUASAR ABSORPTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2-4; CYCLE 0 / 1-4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR ^ G270H G570H ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1E0302-223 ------------------------------------------------------------------------------------------------------------------------------------