10214( 2) - 05/13/04 15:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10214 Version: 2 Check-in Date: 13-May-2004 19:48:18 1.Proposal Title: ACS/HRC imaging of two very bright ultra-luminous X-ray sources (ULXs) ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 13 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Roberto Soria University College London (UCL) CoI: Prof. Mark Cropper University College London (UCL) N CoI: Prof. Richard Mushotzky NASA Goddard Space Flight Center N CoI: Dr. Kinwah Wu University College London (UCL) N CoI: Prof. Manfred Pakull Universite de Strasbourg I N ------------------------------------------------------------------------------------ 6. Abstract We propose broad- and narrow-band ACS/HRC imaging of two very bright ultraluminous X-ray sources (ULXs) in NGC 4559. Our main objectives are: to identify the optical counterparts; to determine their masses and evolutionary stages; to determine the nature of mass transfer in the ULX systems; to determine the properties of the stellar population in the ULX fields (eg, metal abundance, age). With these observations, integrated with our Chandra, XMM-Newton, HST/WFPC2 and CHFT data, we will test the models for the nature and mechanisms of formation of the accreting black holes in ULXs. Moreover, one of the two ULXs is in a peculiar star-forming complex: we have suggested that it is an expanding wave of star-formation triggered by a dwarf galaxy plunging through the outer disk of NGC 4559. The ACS observation will also allow us to test this hypothesis. ------------------------------------------------------------------------------------ 10214( 2) - 05/13/04 15:50 - [ 2] Observations Description ------------------------ We shall observe two targets in the galaxy NGC4559, with ACS/HRC. The targets are two ultraluminous X-ray sources (known as X7 and X10) and their immediate environments. X7 is located at the outskirts of the galaxy, X10 is close to the nucleus. We have obtained 10 HST orbits (5 per target) in the Phase I allocation. We propose to observe each target 5 times: with the broad-band filters F435W, F555W, F814W, and with the narrow-band filters F502N and F658N; we shall use a combination of F555W and F814W to subtract the continuum from F658N. To achieve an optimal packing of the orbits, we shall observe each target for about 2400s with each filter. Each observation will be box-dithered: so, for each target, we shall have four 600s exposures, for each of the five filters. The relative position of the two targets is such that, when X10 is the prime HRC target (Visit 02 in our proposal), X7 can be in the WFC field of view, for an auto-parallel. To achieve this, we need an orientation angle between 205 and 230 deg in Visit 02. However, the converse is not true, ie we cannot have X10 in the WFC when X7 is the HRC prime target, in Visit 01 (absolute orientation constraints unsatisfied due to solar exclusion). So, in principle, the orientation angle in Visit 01 would not need to be constrained. However, in order to include most of the star-forming complex around the X-ray source, and to position the HRC finger in an empty part of the sky, the best orientation angles are between 230 and 250 deg. The angle constraints, particularly on Visit 02, are rather severe, but they would increase the science output (as also noted by the TAC report). Finally, a note on the pointing. When visiting X10, we choose to point a few arcsec west of the X-ray source, so that both X10 and the nucleus of the galaxy can be inside the HRC field of view, and not on or too close to the HRC finger. The coordinates of X10 are: 12:35:58.55, 27:57:41.8, but we choose to point at 12:35:58.10, 27:57:44.0. For similar reasons (in this case, to include most of the star- forming complex), when visiting X7, the target coordinates listed here are about 3 arcsec to the south-east of the real ULX position. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- We did not manage to pack the orbits completely, there are a few seconds left in each orbit. We thought of using individual exposures, instead of a fixed pattern, but we decided to leave the program as it is for the time being, after consulting the help desk. We are happy to modify the observing pattern if the panel thinks it is really necessary. We thought that using a pattern had other advantages which compensate the few seconds lost. ------------------------------------------------------------------------------------ 10214( 2) - 05/13/04 15:50 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4559-X7 EXT-CLUSTER, STAR RA=12H35M51.8S +/- 0.5", J2000 V = 23.0+/-0.5 FORMING REGION, OB DEC=+27D56'2.0" +/- 0.5" total flux V = 17.0 +/- 0.5 ASSOCIATION Coordinate Source: GSC_SURVEY_PLATE Comments: We are looking for a particular star inside an OB association/star-forming region. The individual star has V ~ 23, the total brightness of the association is V ~ 17 (about 300 OB stars spread over a circular region of radius 5.5 arcsec). 2 NGC4559-X10 EXT-STAR, X-RAY RA=12H35M58.1S +/- 0.5", J2000 V = 24.0+/-1.0 TRANSIENT DEC=+27D57'44.0" +/- 0.5" V ~ I ~ 17.5 +/- 0.5 Coordinate Source: GSC_SURVEY_PLATE Comments: The optical counterpart of the X-ray source X10 is faint, probably V ~ 24. However, the nuclear star cluster of this Sc galaxy is also in the same field of view. It has V ~ I ~ 17, and is the brightest point source in the requested ACS field. 10214( 2) - 05/13/04 15:50 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-HRC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.15 Line_Spacing 0.098 Coordinate_Frame POS-TARG Pattern_Orient 19.89 Angle_Between_Sides 63.5 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10214( 2) - 05/13/04 15:50 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 230.0D TO 250.0 D 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 NGC4559-X7 ACS/HRC ACCUM HRC F435W CR-SPLIT=NO 1 600 S PATTERN 1 1-5 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4559-X7 ACS/HRC ACCUM HRC F555W CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4559-X7 ACS/HRC ACCUM HRC F814W CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4559-X7 ACS/HRC ACCUM HRC F502N CR-SPLIT=NO 1 597 S ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC4559-X7 ACS/HRC ACCUM HRC F658N CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 1 none none none 1 tbd 01 1 2 none none none 2 tbd 01 1 3 none none none 3 tbd 01 1 4 none none none 4 tbd 01 2 1 none none none 1 tbd 01 2 2 none none none 2 tbd 01 2 3 none none none 3 tbd 01 2 4 none none none 5 tbd 01 3 1 none none none 1 tbd 01 3 2 none none none 2 tbd 01 3 3 none none none 4 tbd 01 3 4 none none none 5 tbd 01 4 1 none none none 1 tbd 01 4 2 none none none 3 tbd 01 4 3 none none none 4 tbd 01 4 4 none none none 5 tbd 01 5 1 none none none 2 tbd 01 5 2 none none none 3 tbd 01 5 3 none none none 4 tbd 01 5 4 none none none 5 tbd 10214( 2) - 05/13/04 15:50 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 205.0D TO 230.0 D 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 NGC4559-X10 ACS/HRC ACCUM HRC F435W CR-SPLIT=NO 1 600 S PATTERN 1 1-5 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4559-X10 ACS/HRC ACCUM HRC F555W CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4559-X10 ACS/HRC ACCUM HRC F814W CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4559-X10 ACS/HRC ACCUM HRC F502N CR-SPLIT=NO 1 597 S ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC4559-X10 ACS/HRC ACCUM HRC F658N CR-SPLIT=NO 1 600 S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 02 1 1 none none none 1 tbd 02 1 2 none none none 2 tbd 02 1 3 none none none 3 tbd 02 1 4 none none none 4 tbd 02 2 1 none none none 1 tbd 02 2 2 none none none 2 tbd 02 2 3 none none none 3 tbd 02 2 4 none none none 5 tbd 02 3 1 none none none 1 tbd 02 3 2 none none none 2 tbd 02 3 3 none none none 4 tbd 02 3 4 none none none 5 tbd 02 4 1 none none none 1 tbd 02 4 2 none none none 3 tbd 02 4 3 none none none 4 tbd 02 4 4 none none none 5 tbd 02 5 1 none none none 2 tbd 02 5 2 none none none 3 tbd 02 5 3 none none none 4 tbd 02 5 4 none none none 5 tbd 10214( 2) - 05/13/04 15:50 - [ 7] Summary Form for Proposal 10214 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 230.0D TO 250.0 D PATTERN 1 1-5 ORIENT 205.0D TO 230.0 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F435W F555W F814W F502N F658N ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4559-X7 NGC4559-X10 ------------------------------------------------------------------------------------------------------------------------------------