12092( 3) - 09-Nov-2010 14:57:43 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12092 Version: 3 Check-in Time: 09-Nov-2010 14:57:43 STScI Edit Number: 1 Title UVIS Stray Light Characterization ------------------------------------------------------------------------------------ Type Cycle CAL/WFC3 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Larry D. Petro Space Telescope Science Institute CoI: Ms. Tiffany Borders Space Telescope Science Institute N CoI: Mr. Abhijith Rajan Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract This on-orbit test will characterize the extent of scattering surfaces outside the WFC3/UVIS detector FOV. During SMOV, diffuse, structured, linear streaks were noted in several images. Depending upon the specific image, the streaks were approximately perpendicular to either the CCD rows, or columns. The features move in proportion to small dithers. The source of the stray light is, apparently, an external target, although the nature of the scattering process, nor the scattering surface has been identified. Similar features have been observed in GO exposures. The stray light is more commonly found in red filter images. This proposal will repeat exposures of the targets observed to cause stray light, but substantially expand the range of dithers to better limit the extent of the scattering surface. ------------------------------------------------------------------------------------ Observations Description ------------------------ The test will be comprised of horizontal and vertical step-and-dwell scans of exposures of two targets in the F814W. That filter favors the brightness of a stray light image. The science targets are selected from SMOV and GO exposures that have presented horizontal and vertical linear stray light feature. For both targets, a step and dwell pattern is executed in the X and Y POSTARG directions. The positions range from -32 arcsec to +32 arcsec, in a geomeric progression of step sizes (2, 4, 8, 16, and 32 arcsec from the default pointing). The CR-SPLIT=NO/50-second exposures are read out with BIN=3. On-chip binning reduces data volume, while allowing full-detector readouts, maintaining adequate spatial resolution of the diffuse streaks, and improving S/N for these low surface brightness features. The first orbit obtains the horizontal and vertical scans of the horizontal stray light target. The second and third orbits obtain the scans of the vertical stray light target. The readout of the horizontal subarray is faster than of the vertically oriented subarray, which accounts for the greater time required to observe the vertically oriented stray light. Real Time Justification ----------------------- Not applicable. Calibration Justification 12092( 3) - 09-Nov-2010 14:57:43 - [ 2] ------------------------- Knowledge of stray light from sources outside the detector FOV will benefit planning science observations in crowded fields, or in the vicinity of bright targets. Dither patterns used in the discovery observations cover approximately 1 arcsecond, so these will observations will explore the arc-minute scale. A census of GO and Calibration images has identified exposures in 11 GO VISITs and 5 Calibration VISITs with stray light streaks. Additional Comments ------------------- ------------------------------------------------------------------------------------ 12092( 3) - 09-Nov-2010 14:57:43 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HOR-TARGET STAR, DA RA=03H09M27.1737S +/- 0.1", J2000 V = 13.3 DEC=+61D35'33.39" +/- 0.1" Reference Frame: ICRS Comments: Target from SM4/COS 11515, Visit 01, WFC3 data set iacs01tq. Coordinates taken from header RA_APER & DEC_APER for aperture UVIS-CENTER. ------------------------------------------------------------------------------------------------------------------------------------ 2 VER-TARGET-C GALAXY, RADIO GALAXY RA=14H59M24.7000S +/- 0.1", J2000 V = 13.3 OPY DEC=-16D41'36.00" +/- 0.1" Reference Frame: ICRS Comments: Target from GO 11832, Visit 01, WFC3 data set ib8t01030. Coordinates taken from header RA_APER & DEC_APER for aperture UVIS-FIX. ------------------------------------------------------------------------------------------------------------------------------------ 12092( 3) - 09-Nov-2010 14:57:43 - [ 4] Visit: 01 Visit Requirements: ORIENT 261.872513D TO 261.872513 D On Hold Comments: Additional Comments: ORIENT is the same as SM4/COS 11515 (Post-SM4 Cross-Instrument Light Leak Test) PA_V3+180. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -60, 0; GS ACQ S ER SCENARIO BASE1B3; SEQ 1-11 NON-INT Comments: These 10 sequential exposures explore translation along X of a target that produces a horizontal stray light streak. ------------------------------------------------------------------------------------------------------------------------------------ 2 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -48, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 3 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -36, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 4 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -24, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 5 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG -12, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 6 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 0, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 7 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 12, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 8 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 24, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 9 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 36, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 10 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 48, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 11 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 60, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 12 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -60, 0; SEQ S ER 12-22 NON-INT Comments: These 10 sequential exposures explore translation along Y of a target that produces a horizontal stray light streak. 12092( 3) - 09-Nov-2010 14:57:43 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 13 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -48, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 14 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -36, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 15 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -24, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 16 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG -12, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 17 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 0, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 18 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 12, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 19 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 24, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 20 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 36, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 21 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 48, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ 22 HOR-TARGET WFC3/UVI ACCUM UVIS-CENT F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 60, 0 S ER ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HOR-TARGET 1 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 2 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 3 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 4 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 5 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER 12092( 3) - 09-Nov-2010 14:57:43 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ HOR-TARGET 6 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 7 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 8 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 9 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 10 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 11 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 12 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 13 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 14 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 15 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 16 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 17 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 18 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 19 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 20 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 21 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER HOR-TARGET 22 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER 12092( 3) - 09-Nov-2010 14:57:43 - [ 7] Visit: 02 Visit Requirements: ORIENT 105.283203D TO 105.283203 D On Hold Comments: Additional Comments: ORIENT is the same as GO 11832 (The Structure and Physics of the Youngest Radio Galaxies) PA_V3+180. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -60, 0; GS ACQ COPY S SCENARIO BASE1B3; SEQ 1-11 NON-INT Comments: These 10 sequential exposures explore translation along X of a target that produces a horizontal stray light streak. ------------------------------------------------------------------------------------------------------------------------------------ 2 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -48, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 3 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -36, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 4 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -24, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 5 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG -12, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 6 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 0, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 7 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 12, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 8 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 24, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 9 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 36, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 10 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 48, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 11 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 60, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 12092( 3) - 09-Nov-2010 14:57:43 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 12 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -60, 0; SEQ COPY S 12-22 NON-INT Comments: These 10 sequential exposures explore translation along Y of a target that produces a horizontal stray light streak. ------------------------------------------------------------------------------------------------------------------------------------ 13 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -48, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 14 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -36, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 15 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50. S POS TARG -24, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 16 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG -12, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 17 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 0, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 18 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 12, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 19 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 24, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 20 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 36, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 21 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 48, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ 22 VER-TARGET- WFC3/UVI ACCUM UVIS F814W CR-SPLIT=NO, BIN=3 1 50 S POS TARG 60, 0 COPY S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ VER-TARGET-COPY 1 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 2 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S 12092( 3) - 09-Nov-2010 14:57:43 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ VER-TARGET-COPY 3 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 4 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 5 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 6 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 7 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 8 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 9 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 10 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 11 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 12 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 13 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 14 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 15 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 16 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 17 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 18 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 19 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 20 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 21 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S VER-TARGET-COPY 22 WFC3/UVI ACCUM UVIS F814W none none none none 1 N/A S 12092( 3) - 09-Nov-2010 14:57:43 - [ 10] Summary Form for Proposal 12092 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS, UVIS-CENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BIN=3, CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1B3, ORIENT 105.283203D TO 105.283203 D, ORIENT 261.872513D TO 261.872513 D, POS TARG -12, 0, POS TARG -24, 0, POS TARG -36, 0, POS TARG -48, 0, POS TARG -60, 0, POS TARG 0, 0, POS TARG 12, 0, POS TARG 24, 0, POS TARG 36, 0, POS TARG 48, 0, POS TARG 60, 0, SEQ 1-11 NON-INT, SEQ 12-22 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names HOR-TARGET, VER-TARGET-COPY ------------------------------------------------------------------------------------------------------------------------------------