12501( 4) - 02-Apr-2012 18:33:19 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12501 Version: 4 Check-in Time: 02-Apr-2012 18:33:19 STScI Edit Number: 1 Title COS G140L CENWAV = 800, a gapless low astigmatism mode for observations to the Lyman Limit ------------------------------------------------------------------------------------ Type Cycle CAL/COS 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Stephan Robert McCandliss The Johns Hopkins University CoI: Mr. Brian Fleming The Johns Hopkins University N CoI: Dr. Steven Osterman University of Colorado at Boulder N CoI: Prof. J. Christopher Howk University of Notre Dame N CoI: Dr. Wei Zheng The Johns Hopkins University N CoI: Prof. Scott F. Anderson University of Washington N CoI: Prof. Boris T. Gaensicke The University of Warwick N CoI: Dr. Kevin France University of Colorado at Boulder N ------------------------------------------------------------------------------------ Abstract The demonstrated sensitivity of COS to wavelengths below 1150 Angstroms has opened a new window to the universe, enabling a number of unique science investigations in a bandpass hitherto inaccessible to Hubble. Here we propose to calibrate a new operating mode for G140L with a central wavelength setting CENWAV = 800 Angstroms, which will place the entire spectrum, from the Lyman edge (near 912 Angstroms) to the CsI cutoff (near 1850 Angstroms), onto Segment A. The proposed new mode moves the 900 Ð 1100 Angstrom region into the low astigmatism portion of the spectral coverage and will produce an unprecedented improvement in sensitivity to low flux objects observed in this bandpass. Most importantly it will enable the efficient utilization of Hubble orbits for executing exciting new science programs that are currently background limited. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program will determine the best focus position for a new operating mode for G140L at the central wavelength setting of CENWAV = 800 Angstroms. It will be carried out in a single visit consisting of 3 orbits and sixteen exposures. The target, AV243 an O6V star in the LMC, was chosen for four reasons: 1) It has a good density of narrow interstellar atomic molecular features with which to assess focus; 2) It is faint enough to so as not to exceed the local and global count rate restrictions for COS; 3) It is bright enough to use for an efficient high s/n focus sweep in three orbits; and 4) It has been observed previously by FUSE, COS (in G130M only), FOS and IUE, so that a rudimentary flux calibration can be performed. In Phase I we presented evidence that the expected integrated count rate for AV243 on Segment A in the CENWAV = 800 position is 14327 counts s^-1, which does not exceed the 15000 count s^-1 buffer limit nor the Global Bright Object 12501( 4) - 02-Apr-2012 18:33:19 - [ 2] Protection (BOP) limit. We also showed that the local count rate is not expected to exceed the local BOP limit of 0.67 counts s^-1 pixel^-1. Our calculations, covering the entire wavelength regime from 900 - 2300 Angstroms, were based on effective area measurements from early SMOV, which were a splice of a Segment A CENWAV = 1105 calibration to a Segment B calibration for CENWAV = 1250. We have confirmed our expectations with a recent run of the ETC cos.sp.185838, which returned a global rate of about 13000 counts s^-1 and a local rate below 0.67 counts s^-1 pixel^-1 for a Segment A setting in CENWAV = 1105. Our Phase I calculation, which is 10% large than the current ETC, can be taken as a conservative upper limit to the count rate because the most recent effective area calibration used in the current ETC is lower than that derived during the early SMOV stage and because we include counts from the region below 1105. However, our calculation shows that inclusion of the counts below 1105 Angstroms produces only a minor, ~ 1%, increase in the count rate. We have two special command requirements, rotating the Optics Select Mechanism 1 (OSM1) to the CENWAV = 800 position and preforming a focus sweep. These command options cannot be accessed under the General Observer Proposal Category, so we have built this Phase II proposal using APT in -mode STScI and invoked the CAL/COS Proposal Category. The coordinates of AV243 are known to better than 0.4 arcseconds and it has been observed previously using G130M, so we have elected todo a dispersed light target accquistion in G140L CENWAV = 1105 using PeakXD followed by PeakD (5 steps of 1.0 arcsec) in exposures 1 and 2. Exposure 3 is a Special Command that redefines the STEP rotational position of the OSM1, and the Main Electronics Box 1 and 2 (MEB1 and MBE2) coarse resolver positions RES1 and RES2 for a G140L CENWAV = 1105 call to that appropriate to CENWAV = 800. The new values for the STEP = 1615 for CENWAV =800 were offset by +17 from the 1105 position of 1598 given in the pcmech.c flight software file. The new resolver positions were linear extrapolations to the new position using known values of step for G140L taken from the pcmech.c file. The following even Exposures from 4 through 14 are on target timetag acquisitions using FP-POS = ALL. The odd Exposures from 5 through 13 are Special Commands identical to Exposure 3 excepting the absolute focus step settings of -370, -770, -870, -970, -1070, and -1170. The first two sets of timetag exposures are for 192 seconds at each FP-POS, while final four are 264 seconds for each FP-POS. In the Phase I proposal we estimated that an expose time of 1000 seconds would yield a signal-to-noise of 10 per 0.48 Angstrom resel in the 900 - 1000 Angstrom region. The final Exposure 15 restores the rotational STEP, and resolver positions to those appropriate to G140L CENWAV = 1105. Real Time Justification ----------------------- Realtime observations are not required. Calibration Justification ------------------------- The new mode will position the entire spectrum, from the Lyman edge (near 912 Angstroms) to the CsI cutoff, onto Segment A, placing the 900 Ð 1100 Angstrom region into the low astigmatism portion of the spectral coverage to lower the 12501( 4) - 02-Apr-2012 18:33:19 - [ 3] effects of detector background in the low efficency portion of the bandpass. There are three principal advantages to the new mode: 1) It lowers the background by a factor of 2 by reducing astigmatism at the short wavelength end where the effective area is lowest, thus boosting the S/N for objects with fluxes at or below the background limit. 2) Contiguous spectral coverage on a single detector segment simplifies the tracking of flux, wavelength and flat-field calibrations. 3) It provides more efficient use of observing time for science investigations seeking full wavelength coverage from 900 Ð 1850 Angstroms by eliminating the need for a grating change. Additional Comments ------------------- We are working closely with the COS instrument teams at STScI and CU to craft a calibration program that places the safety of the instrument at the highest priority while significantly enhancing the G140L performance to the benefit of the community, from which we have strong support for this calibration program. The Special Commanding sections in Exposures 3 and 15 should be closely check by the CS, PC and support staff to see that the code is correct. The Special Commanding sections were created under the guidance of the CS, PC and support staff following a face-to-face meeting. These Special Commands follow closely those used by CAL/COS Proposal 12505 (Penton - PI). ------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AV243 CALIBRATION, FOCUS RA=01H00M6.7800S +/- 0.4", J2000 V = 147 V = 13.87 +/- 0.04 f(960)=5e-13, TEST, INSTRUMENT DEC=-72D47'18.70" +/- 0.4" f(1060)=5e-13, f(1160)=4.5e-13, SENSITIVITY TEST, f(1260)=4e-13, f(1600)=3e-13, THROUGHPUT TEST, erg/cm2/s/ang WAVELENGTH Reference Frame: ICRS Comments: Target coordinates taken from proposal 11625. Flux from FUSE+FOS+IUE. Target previously observed in FUV with COS G130M so there should be no BOT issues. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 5] Visit: 01 Visit Requirements: PCS MODE FINE On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 AV243 COS/FUV ACQ/PEA PSA G140L 1105 SEGMENT=A 1 0.2 S KXD Comments: Coordinates for AV243 were taken from Proposal 11625 (Hubeny - PI) ------------------------------------------------------------------------------------------------------------------------------------ 2 AV243 COS/FUV ACQ/PEA PSA G140L 1105 SEGMENT=A, CENTER=FLUX-WT-FLR, 1 0.2 S KD STEP-SIZE=1.0, NUM-POS=5 ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -370 Comments: Special Commanding to overwrite the G140L/1105 settings with the G140L/800 settings. OSM1 should be set to position of 1615, which is +17 steps from the G140L-1105A position of 1598. Segment B should be turned off to avoid issues with zero-order. The cos handbook (figure 14.10) says the wavelength coverage for FP-POS=3 in the CENWAV=1105 setting is 1118 to 2251. In the CENWAV=800 setting the wavelength coverage for FP-POS=3 will then be shifted by -333.2Angstroms = 17 STEP * 19.6 Angstroms/STEP, ie 785 to 1918 Angstroms. ------------------------------------------------------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=99, EXTENDED=NO, 1 190 S G SEGMENT=A, FLASH=S0045D010, see below FP-POS=ALL Comments: Zeroth spectrum at the nominal focus for the redefined G140L CENWAV=1105, which has uses STEP = 1615 to produce CENWAV = 800 and FOCUS -370 absolute. SEGMENT = A to avoid zero issues on the B side. Flash is set to S0045D010, ie every 45 sec flash for 10 sec, which will yield 4 flashes for nominal 190 second exposure per FP-POS. This is included to monitor grating settling after focus shifts in subsequent observations. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 5 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -770 Comments: As before but with FOCUS = -770 absolute. ------------------------------------------------------------------------------------------------------------------------------------ 6 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=99, EXTENDED=NO, 1 190 S G FP-POS=ALL, SEGMENT=A, see below FLASH=S0045D010 Comments: First spectrum from nominal focus for G140L CENWAV=1105, -770 absolute. Exposures are same as previous. The 190 seconds was chosen to fit all four FP-POS for these first two exposures into a single orbit. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -870 Comments: As before but with FOCUS = -870 absolute. ------------------------------------------------------------------------------------------------------------------------------------ 8 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=150, EXTENDED=NO, 1 250 S G FP-POS=ALL, SEGMENT=A, see below FLASH=S0060D010 Comments: Second spectrum from nominal focus for G140L CENWAV=1105, -870 absolute. Flash is now set to S060D010, ie every 60 sec flash for 10 sec, which will yield 4 flashes for nominal 250 exposure per FP-POS. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 9 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -970 Comments: As before but with FOCUS = -970 absolute. ------------------------------------------------------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=150, EXTENDED=NO, 1 250 S G FP-POS=ALL, SEGMENT=A, see below FLASH=S0060D010 Comments: Third spectrum from nominal focus for G140L CENWAV=1105, -970 absolute. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 11 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -1070 Comments: As before but with FOCUS = -1070 absolute. ------------------------------------------------------------------------------------------------------------------------------------ 12 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=150, EXTENDED=NO, 1 250 S G FP-POS=ALL, SEGMENT=A, see below FLASH=S0060D010 Comments: Forth spectrum from nominal focus for G140L CENWAV=1105, -1070 absolute. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 12501( 4) - 02-Apr-2012 18:33:19 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 13 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QASISTATES COS SI OBSERVE OBSERVE; QASISTATES COS FUV HVSEGA HVSEGA; QESIPARM ACTION TEST; QESIPARM GRATING G140L; QESIPARM CENTWAVE 800; QESIPARM STEP 1615; QESIPARM RES1 35182; QESIPARM RES2 39803; QESIPARM FOCUS -1170 Comments: As before but with FOCUS = -1170 absolute. ------------------------------------------------------------------------------------------------------------------------------------ 14 AV243 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=150, EXTENDED=NO, 1 250 S G FP-POS=ALL, SEGMENT=A, see below FLASH=S0060D010 Comments: Fifth spectrum from nominal focus for G140L CENWAV=1105, -1170 absolute. SQL is required to set qelogsheet.minwave to 800. Pipeline processing of this unsupported mode is not possible, so calibrations should be bypassed. ------------------------------------------------------------------------------------------------------------------------------------ 15 DARK S/C DATA NONE 1 10 S SPEC COM INSTR ELOSMTEST; QESIPARM ACTION RESTORE Comments: Restore G140L CENWAV = 1105 default parameters for STEP, RES1, RES2, and FOCUS. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AV243 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD AV243 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD DARK 3 S/C DATA NONE none none none none 1 N/A AV243 4 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 192.0 S G AV243 4 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 192.0 S G 12501( 4) - 02-Apr-2012 18:33:19 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ AV243 4 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 192.0 S G AV243 4 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 192.0 S G DARK 5 S/C DATA NONE none none none none 1 N/A AV243 6 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 192.0 S G AV243 6 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 192.0 S G AV243 6 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 192.0 S G AV243 6 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 192.0 S G DARK 7 S/C DATA NONE none none none none 1 N/A AV243 8 COS/FUV TIME-TA PSA G140L 1105 none none none 1 2 264.0 S G AV243 8 COS/FUV TIME-TA PSA G140L 1105 none none none 2 2 264.0 S G AV243 8 COS/FUV TIME-TA PSA G140L 1105 none none none 3 2 264.0 S G AV243 8 COS/FUV TIME-TA PSA G140L 1105 none none none 4 2 264.0 S G DARK 9 S/C DATA NONE none none none none 2 N/A AV243 10 COS/FUV TIME-TA PSA G140L 1105 none none none 1 2 264.0 S G AV243 10 COS/FUV TIME-TA PSA G140L 1105 none none none 2 2 264.0 S G AV243 10 COS/FUV TIME-TA PSA G140L 1105 none none none 3 2 264.0 S G AV243 10 COS/FUV TIME-TA PSA G140L 1105 none none none 4 2 264.0 S G DARK 11 S/C DATA NONE none none none none 2 N/A AV243 12 COS/FUV TIME-TA PSA G140L 1105 none none none 1 3 264.0 S G AV243 12 COS/FUV TIME-TA PSA G140L 1105 none none none 2 3 264.0 S G AV243 12 COS/FUV TIME-TA PSA G140L 1105 none none none 3 3 264.0 S G AV243 12 COS/FUV TIME-TA PSA G140L 1105 none none none 4 3 264.0 S G DARK 13 S/C DATA NONE none none none none 3 N/A AV243 14 COS/FUV TIME-TA PSA G140L 1105 none none none 1 3 264.0 S G AV243 14 COS/FUV TIME-TA PSA G140L 1105 none none none 2 3 264.0 S G AV243 14 COS/FUV TIME-TA PSA G140L 1105 none none none 3 3 264.0 S G 12501( 4) - 02-Apr-2012 18:33:19 - [ 11] 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 | ------------------------------------------------------------------------------------------------------------------------------------ AV243 14 COS/FUV TIME-TA PSA G140L 1105 none none none 4 3 264.0 S G DARK 15 S/C DATA NONE none none none none 3 N/A 12501( 4) - 02-Apr-2012 18:33:19 - [ 12] Summary Form for Proposal 12501 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures NONE, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, S/C ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, DATA, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=150, BUFFER-TIME=99, CENTER=FLUX-WT-FLR, EXTENDED=NO, FLASH=S0045D010, FLASH=S0060D010, FP-POS=ALL, NUM-POS=5, SEGMENT=A, STEP-SIZE=1.0 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE, QASISTATES COS FUV HVSEGA HVSEGA, QASISTATES COS SI OBSERVE OBSERVE, QESIPARM ACTION RESTORE, QESIPARM ACTION TEST, QESIPARM CENTWAVE 800, QESIPARM FOCUS -1070, QESIPARM FOCUS -1170, QESIPARM FOCUS -370, QESIPARM FOCUS -770, QESIPARM FOCUS -870, QESIPARM FOCUS -970, QESIPARM GRATING G140L, QESIPARM RES1 35182, QESIPARM RES2 39803, QESIPARM STEP 1615, SPEC COM INSTR ELOSMTEST ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names AV243, DARK ------------------------------------------------------------------------------------------------------------------------------------