Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 6148 Report Date: 18-Jul-95:20:17 Version: ********** Check-in Date: ********** 1.Proposal Title: CROSS FILTER CALIBRATION ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID CAL/AST Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone William H. Jefferys UNIVERSITY OF TEXAS USA 512-471-1455 PROFESSOR ------------------------------------------------------------------------------------ 7. Abstract This CAL test attempts to determine values for the positional shift between the "clear" filter and the other filters in the astrometer FGS (FGS3) to one milliarcsecond rms or better. The calibrations are necessary to correct relative positions of targets measured with different filters within one observation set to within the measurement errors of of a single FGS setting. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 12.0 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FGS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 6148 PI: William H. Jefferys Proposal Title: CROSS FILTER CALIBRATION ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ William H. Jefferys TEXAS, UNIVERSITY OF USA Edmund P. Nelan TEXAS, UNIVERSITY OF USA George F. Benedict TEXAS, UNIVERSITY OF USA ------------------------------------------------------------------------------------ 2. Scientific Justification. When measuring relative star positions within the FGS field of view (pickle), changing filters between target settings within an observation set may produce offsets of several milliarcseconds. Unless these "cross filter" offsets are calibrated and removed, they will contribute significant systematic errors to the observed positions, and hence to the desired observed quantities such as separations, parallaxes, or proper motions. These systematic errors can be devastating to the end results: e.g. in cases where angular separations between bright and faint objects are observed, or in cases where the parallax of a bright object, observed using the F5ND, is measured with respect to faint reference stars (observed using F583W). When the pickle is rotated 180 deg from one side of the earth's orbit to the other, the cross filter affect is to add or subtract an unreal systematic component to the measured parallax. The nominal operating range of the FGS through the clear (F583W) filter is between 8th and 16th magnitude. In a typical observing scenario, the reference stars are observed using the F583W since this is the filter used to determine the primary calibrations for optical field angle distortions (OFAD) and plate scale are made through the clear filter. There are conditions which demand use of a different filter for a given object, such as a star of extreme color or brightness. In such cases, the cross filter calibration is required. ------------------------------------------------------------------------------------ 3. Description of proposed observations. The method of observation will be to point the telescope so that the calibration target field is positioned at the desired location in the pickle. The star will be observed as many times as possible, limited only by the visibility window, in the alternating sequence F583W/F5ND/F583W/F5ND,...etc. The test will be performed 3 times, once with the target field at pickle center, and once at each of the "football" ends, providing a field dependent sample of the cross filter effect at different pickle locations. A total of 3 orbits are required. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. At the moment, the program which makes the most use of a filter is the GO and GTO program to tie the Hipparcos Reference Frame to Extragalactic Objects (EGOs). To date, over 100 observation sets have been obtained. The stragety is to observe the separation of a Hipparcos Star and an EGO. When the Hipparcos star is brighter than about 8.2, the neutral density filter is required. The EGOs are always fainter than about 12.8 and are always measured using F583W, as are the reference stars. To date about 20% of the Hipparcos star observations required the ND filter. In order to measure the separations of bright Hipparcos stars with respect to faint EGOs with an accuracy that is comparable to the Hipparcos internal random accuracy (1.7 mas for individual stars, 0.2-0.3 mas systematically with respect to the Hipparcos reference frame) the FGS observations of the Hipparcos star that use the ND filter MUST be corrected for the position shift with respect to the FGS observations of the EGO, which is measured with F583W. We need to determine the cross filter calibration (F583W to F5ND or other filter) to 1 mas or better, if at all possible, so that the calibration will not be a major contributor to the error budget of an astrometric measurement. The internal precision of an FGS reading (averaged over one setting) may be as high as a few tenths of a milliarcsecond. The external accuracy of a single setting is around 2-3 milliarcseconds, based on global astrometric solutions and comparisons with ground-based data, for example. A cross filter calibration consists of differencing the measurements of a star with two filters. Thus, if we had a single measurement accuracy of 2mas, a single difference accuracy would be SQRT(2) larger or about 3mas. Therefore, to get to the 1 mas level formal error in the calibration, we need 9 single difference measurements. Because the 2 mas accuracy includes uncertainties in the local optical field angle distortion with respect to the global FGS frame, and because the cross filter measurements are all made within a tiny patch of the FGS, we expect the cross filter calibration to be better than that indicated using the 2mas number for the single setting formal rms error. However, the observations must be performed in such a manner that the FGS drift is removed at the same level of accuracy, and that will probably reduce the accuracy. The drift will be discussed below. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. We expect that the cross filter correction will show a slight rotation across the pickle with the positional dependence predicted by the theoretical model of the optics of the FGS. However, because of the complex OTA/FGS optical aberations the model is suspect, and since the Hipparcos observations are made with the Hipparcos star at various positions within the pickle, we need measure the field dependence of the cross filter calibration. We need to monitor the drift in such a way as to remove it at the level of accuracy we we are attempting to reach in the calibration. Analysis of the OFAD data indicates that the FGS reference frame drift is adequately modeled by simple second order polynomials with time in x,y. Therefore, the repeated measurement of a single star should suffice to give the drift in x and y in the pickle with high accuracy. By concentrating on one or two stars, with multiple measurements in any filter, the drift will be monitored at the location of the calibration measurements with a frequency and time span unequaled in any other FGS3 observation set. By alternating between filters, the cross filter measurements will give us the best statistical value because of the repeated settings. Therefore, with this proposed observation stragety, we will obtain more detailed drift information than we have had in the past, as well as obtain the best cross filter calibration. Page 4 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be processed through the standard astrometric pipelines and analyzed using the standard astrometric reduction software, including dejittering and drift correction software. The reduction and analysis will be performed at both STScI and Austin. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. The Fine Guidance Sensors have filter wheels with five filter positions. The Astrometer FGS (FGS 3) filter set comprises the following filters: F583W -- the "clear" filter F5ND -- the "neutral density" filter (with an intensity reduction equivalent to 5 magnitudes) F605 -- the "astrometry clear" filter F550W -- the "yellow" filter, and PUPIL -- an aperture stop "filter" with a clear circular aperture with a radius of 2/3 of the full "clear" filter. ------------------------------------------------------------------------------------ 11. Address Information Name: WILLIAM H. JEFFERYS Category: PI Institution: UNIVERSITY OF TEXAS Address: ASTRONOMY DEPARTMENT City: AUSTIN State: TX Zip Code: 78712 Country: USA Telephone: (512) 471-4461 Telex (or e-mail): TEXASTRO ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 6148 [ 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 XFILTER (GSC J,701 RA = 92.2354792D +/- 0.5", 2000 1 V = 8.08 +/- 0.1 509) DEC = 24.35992D +/- 0.5" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6148 [ 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 DEFINE # FGS POS 3 # DATA-RATE=32 1 20S 10 1 1 POSMODE ACQ-MODE=SEARCH Comments: FINE LOCK GUIDING ------------------------------------------------------------------------------------------------------------------------------------ 100.01 USE XFILTER F583W SEQ 100.01-100.23 POSMODE NON-INT POS TARG -290, -60 CYCLE 4/100.01- 300.23 Comments: THIS PROPOSAL MAY SPECIFY; MORE OBSERVATIONS THAN; CAN BE FIT INTO THE VISIBILITY; PERIOD. IF SO, STARS CAN BE ; DROPPED FROM THE END OF THE ; EXPOSURE LOG LIST ------------------------------------------------------------------------------------------------------------------------------------ 100.02 USE XFILTER F5ND SAME POS FOR POSMODE 100.02-100.23 AS 100.01 ------------------------------------------------------------------------------------------------------------------------------------ 100.03 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.04 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.05 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.06 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.07 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.08 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.09 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.1 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.11 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.12 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.13 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6148 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 100.14 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.15 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.16 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.17 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.18 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.19 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.2 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.21 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.22 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 100.23 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.01 USE XFILTER F583W SEQ 200.01-200.23 POSMODE NON-INT POS TARG 0,0 Comments: THIS PROPOSAL MAY SPECIFY; MORE OBSERVATIONS THAN; CAN BE FIT INTO THE VISIBILITY; PERIOD. IF SO, STARS CAN BE ; DROPPED FROM THE END OF THE ; EXPOSURE LOG LIST ------------------------------------------------------------------------------------------------------------------------------------ 200.02 USE XFILTER F5ND SAME POS FOR POSMODE 200.02-200.23 AS 200.01 ------------------------------------------------------------------------------------------------------------------------------------ 200.03 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.04 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.05 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6148 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 200.06 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.07 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.08 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.09 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.1 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.11 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.12 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.13 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.14 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.15 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.16 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.17 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.18 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.19 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.2 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.21 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 200.22 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6148 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 200.23 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.01 USE XFILTER F583W SEQ 300.01-300.23 POSMODE NON-INT POS TARG +290, -60 Comments: THIS PROPOSAL MAY SPECIFY; MORE OBSERVATIONS THAN; CAN BE FIT INTO THE VISIBILITY; PERIOD. IF SO, STARS CAN BE ; DROPPED FROM THE END OF THE ; EXPOSURE LOG LIST ------------------------------------------------------------------------------------------------------------------------------------ 300.02 USE XFILTER F5ND SAME POS FOR POSMODE 300.02-300.23 AS 300.01 ------------------------------------------------------------------------------------------------------------------------------------ 300.03 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.04 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.05 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.06 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.07 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.08 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.09 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.1 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.11 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.12 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.13 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.14 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6148 [ 10] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 300.15 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.16 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.17 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.18 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.19 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.2 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.21 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.22 USE XFILTER F5ND POSMODE ------------------------------------------------------------------------------------------------------------------------------------ 300.23 USE XFILTER F583W POSMODE ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 6148 [ 11] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DATA-RATE=32 ACQ-MODE ------------------------------------------------------------------------------------------------------------------------------------ Proposal for CAL/AST ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 12.0 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 100.01-100.23 NON-INT; POS TARG -290, -60; CYCLE 4/100.01-300.23; SAME POS FOR 100.02-100.23 AS 100.01; SEQ 200.01-200.23 NON-INT; POS TARG 0,0; SAME POS FOR 200.02-200.23 AS 200.01; SEQ 300.01-300.23 NON-INT; POS TARG +290, -60; SAME POS FOR 300.02-300.23 AS 300.01; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements # F583W F5ND ------------------------------------------------------------------------------------------------------------------------------------ Target Names XFILTER (GSC 509) ------------------------------------------------------------------------------------------------------------------------------------