6406( 5) - 12/11/98 15:48 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6406 Version: 5 Check-in Date: 06-May-1998 10:55:11 1.Proposal Title: Intermediate Mass Stars and Unusual Stellar Mass Limits in a Starburst Galaxy ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 6 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Deidre Hunter Lowell Observatory ------------------------------------------------------------------------------------ 5. Abstract The dwarf irregular galaxy IC10 is the nearest example of the global starburst phenomenum. As such, it offers a unique opportunity to test ideas about the star formation process in such an environment. In particular it has been suggested that starburst galaxies, have unusually high lower stellar mass limits (up to 10 Msolar) and/or unusual IMF's. We propose to determine the IMF of intermediate mass stars and determine or constrain the lower stellar mass limit in IC10 through star counts. This will be the first direct examination of the intermediate stellar mass population in a starburst galaxy. H-alpha images obtained to subtract the gaseous contamination of the broad-band filters will also be used to examine the gaseous destruction caused by the concentrations of massive stars in the heart of the galaxy. ------------------------------------------------------------------------------------ 6406( 5) - 12/11/98 15:48 - [ 2] Observations Description ------------------------ IC10 has a reddening of E(B-V)=0.75 and a distance modulus of 24.9 (Massey & Armandroff 1995). Thus, a 5 Msolar star (M_V=-0.4) will have an apparent V magnitude of 27 in IC10. We have determined the exposure times necessary to reach this magnitude by scaling from images of IZw18 obtained by a previous program (Hunter & Thronson 1995). Taking reddening into account, we find that we will need 10*1400 s each in F555W and F814W. Experience with IZw18 showed that coincident cosmic rays were a sufficient problem that 3 long exposures was not adequate to remove cosmic rays. However, 10 will be fine. The F336W filter is used as a check on the reddening, and, because of the red leak, is only useful for the bluer, and hence brighter, stars. Therefore, the exposure in F336W is shorter: 3*800 s. An orbit for IC10 is approximately 58 minutes. With overheads, these exposures will fill 11 orbits. A 12th orbit is used for the H- alpha image, taken through F656N, with an exposure time of 3*800 s. The H-alpha image will be used to subtract gaseous emission contaminating the broad-band images. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 6406( 5) - 12/11/98 15:48 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 IC10 GALAXY, STARBURST RA=00H 20M 24.40S +/- 0.1S, 2000 V=-345 V = 27 DEC=+59D 17' 57.9" +/- 1", PLATE E(B-V) = 0.75 -ID=01MT U-V = -0.7 6406( 5) - 12/11/98 15:48 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENTation 264D TO 301D On Hold Comments: Additional Comments: TAC: "Should use the CVZ (hence 6 orbits allocated instead of 12). STScI should restore this to 12 orbits if CVZ or near-CVZ orbits cannot be scheduled." This file is for 12 orbits since the CVZ restriction severely restricts the scheduling and since it requires 6.5 CVZ orbits. To calculate ORIENT: Assumed rotation was around center of PC (PC1-FIX). Took position angle of +X PC axis and added 45. The position and orientation are chosen to avoid a 13.3 mag star, avoid the brightest Milky Way stars in and around the galaxy, and allow part of the FOV to extend to the edge of the galaxy. The 13.3 mag star will add background to part of the PC through stray light since it is inside the missing L, but there is no way to put it outside the L and prediction is for less than 1 DN/pixel. These requirements restrict the ORIENT which in turn severely restricts scheduling, but they are essential. Even so, there will also be some stars as bright as 16 in the WF chips which will saturate heavily. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IC10 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=NO,ATD-GAIN=7 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 2 IC10 WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO,ATD-GAIN=7 10 1400 S ------------------------------------------------------------------------------------------------------------------------------------ 6406( 5) - 12/11/98 15:48 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENTation AS 1 On Hold Comments: Additional Comments: I have broken these 12 orbits into 2 visits because of the SAA interruption after 8 orbits. However, I am after color information on stars, will be stacking all the images from each filter, and will be subtracting the Halpha image from the other filters. So, I need all of the images to be at the same orientation and position. THEREFORE, *PLEASE* USE THE EXACT SAME GUIDE STARS AND SET UP FOR VISIT 2 THAT WERE USED FOR VISIT 1. Thank you. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 IC10 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=NO,ATD-GAIN=7 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 4 IC10 WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO,ATD-GAIN=7 10 1400 S ------------------------------------------------------------------------------------------------------------------------------------ 6406( 5) - 12/11/98 15:48 - [ 6] Visit: 51 Visit Priority: Visit Requirements: ORIENTation 270.014270D TO 270.014270D On Hold Comments: Additional Comments: NOTE: THIS VISIT IS A REPEAT OF THE FAILED VISIT 01. A DIFFERENT GUIDE STAR MAY NEED TO BE USED, OR ELSE POSSIBLY A SINGLE INSTEAD OF A PAIR, BUT THE STARS USED IN VISIT 01 MAY BE SUSPECT AT ANY RATE UNLESS THE FAILURE WAS DUE TO AN FGS GLITCH INSTEAD. IT WAS INDETERMINATE AT THE TIME AS FAR AS WE KNOW. THE FOLLOWING COMMENTS APPLIED TO THE ORIGINAL VISITS 01 AND 02: TAC: "Should use the CVZ (hence 6 orbits allocated instead of 12). STScI should restore this to 12 orbits if CVZ or near-CVZ orbits cannot be scheduled." This file is for 12 orbits since the CVZ restriction severely restricts the scheduling and since it requires 6.5 CVZ orbits. To calculate ORIENT: Assumed rotation was around center of PC (PC1-FIX). Took position angle of +X PC axis and added 45. The position and orientation are chosen to avoid a 13.3 mag star, avoid the brightest Milky Way stars in and around the galaxy, and allow part of the FOV to extend to the edge of the galaxy. The 13.3 mag star will add background to part of the PC through stray light since it is inside the missing L, but there is no way to put it outside the L and prediction is for less than 1 DN/pixel. These requirements restrict the ORIENT which in turn severely restricts scheduling, but they are essential. Even so, there will also be some stars as bright as 16 in the WF chips which will saturate heavily. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IC10 WFPC2 IMAGE PC1-FIX F656N CR-SPLIT=NO,ATD-GAIN=7 3 800 S ------------------------------------------------------------------------------------------------------------------------------------ 2 IC10 WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO,ATD-GAIN=7 10 1400 S ------------------------------------------------------------------------------------------------------------------------------------ 6406( 5) - 12/11/98 15:48 - [ 7] Summary Form for Proposal 6406 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENTation 264D TO 301D SAME ORIENTation AS 1 ORIENTation 270.014270D TO 270.014270D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N F555W F336W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names IC10 ------------------------------------------------------------------------------------------------------------------------------------