9041( 8) - 09/18/01 09:30 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9041 Version: 8 Check-in Date: 18-Sep-2001 09:30:12 1.Proposal Title: Direct imaging of the progenitors of massive, core-collapse supernovae ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Stephen Smartt University of Cambridge CoI: Dr Gerry Gilmore Institute of Astronomy N CoI: Dr Simon Hodgkin Institute of Astronomy N CoI: Dr Neil Trentham Institute of Astronomy N CoI: Dr John Danziger University of Trieste N CoI: Dr Chris Tout Institute of Astronomy N ------------------------------------------------------------------------------------ 5. Abstract Recent surveys of starforming galaxies in the nearby Universe are discovering significant numbers of supernovae which have massive star progenitors (Types II, Ib and Ic). The extensive HST archive and high-resolution ground-based images of galaxies within ~20 Mpc enables us to resolve and quantify their individual bright stellar content. As massive, evolved stars are the most luminous single objects in a galaxy, the progenitors of core-collapse supernovae should be directly detectable on pre-explosion images. The site of the Type II supernova 1999gi (in NGC3184, ~8 Mpc distant) has been imaged in two colours by HST prior to explosion - it is a young star- forming region, with a resolved, massive stellar population. We request a post -explosion exposure to allow identification of the progenitor star, and its colours. We have deep, high- quality ground-based archive exposures of the pre-explosion region of 1999em (Type II in NGC1673, also at ~8 Mpc distant). We believe we have identified the progenitor as a mid-late G-type supergiant from its VRI colours, however a high-resolution HST image will indicate if this star really is coincident with the SN position at a more secure level. We are assimilating a database of all suitable exposures of nearby galaxies to allow similar future discoveries, and request similar follow-up exposures (as a TOO) if suitable pre- explosion material exists. ------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 2] Observations Description ------------------------ SN1999gi in NGC3184:, As discussed above, the supernova 1999gi (Type II) was discovered in December 1999 and there are two observations of this galaxy in the WFPC2 archive BEFORE explosion. We have identified the region on chip\#4 where the progenitor of the supernova is likely to be, however the absolute positional information in the WFPC2 header and the uncertainty in the exact position of 1999gi (combine to give ~1-2" uncertainty) will not allow the definite identification of the progenitor. Several short exposures with WFPC2 while this SN is still relatively bright will allow us to determine the position of the SN on the existing WFPC2 chips and hence identify the progenitor. We requested Directors Discretionary time for this observation in August 2000, however the Science Policies Division advised us that this was a not a ``true'' TOO, as observations could be taken as late as February next year when the SN should still be brighter than the stellar objects in the field. Hence D. Macchetto requested that we apply through the normal Cycle 10 TAC and advised us to add this sentence :, ``If the TAC selects your proposal, we will endeavor to observe the SN as soon as feasible, typically earlier than February 2001 (providing that its execution does not conflict with proposals approved in previous cycles) without waiting for the regular Cycle 10 to begin (~June 2001).'', The typical late-time Type II lightcurves suggest that SN1999gi would be V~20 in Feb 2001 (from Turatto et al. 1990). By June 2001, it may well be fainter than 21. We have already carried out photometry on the existing frames and the brightest stellar objects in the field have F606W/F300W magnitudes in the region 20-22 (Fig. 1), which could mean identification of the SN would be ambiguous. The SN could possibly then have the same magnitude as its progenitor, and identifying it definitively would not be straightforward. We believe that this is such a unique opportunity to definitely pin-point the progenitor star that the observations should be scheduled no later than April 2001, so that the SN is clearly seen. From their DD response, STScI are willing to schedule this quickly before the start of regular Cycle 10 observations. The pre- explosion exposures consist of 160s in F606W and 800s in F300W. We request repeat exposures to allow unambiguous SN identification. Apart from the possibility of variable stars in the field (e.g. very high mass red supergiants, LBVs, or Cepheids) the SN should be the only obvious object which has changed. Further we request supplementary observations in a set of other filters. This will allow the reddening of the surrounding stellar cluster to be determined. Also as we have a significant database of ground monitoring, we would use the multi-colour data to subtract the stellar components which are unresolved from the ground, but resolved with WFPC2, hence we request F555W, F814W, and F439W. The guide star acquisition overhead is 6min (and 5min in a second orbit), and we will have overheads of 5min per CR-split within an exposure. Hence we will design the exposure times per filter so that they do not saturate the SN, and their co-addition will provide total exposures of 800s in F300W and approximately 500s exposure in each of the other 4 requested filters. This will fit well into two orbits. We will be monitoring the magnitude of 1999gi between October and January and will inform STScI of any updates to the exposure times. noindent SN1999em:, The rationale behind the observations of SN1999em are slightly different. As we already have identified the progenitor site on the pre- explosion image, HST can't give any better accuracy to the position on the CFHT frame (as we are limited by the resolution of that exposure). However if the object (star\#66 in Fig. 2) is not a single source, but a compact cluster or multiple stellar objects, then an image of this at very late times should indicate this. We note that Kirshner et al. (GO 8243) had requested observations of this object for this year, however they appear to have been withdrawn from the Cycle. This would have been too early for our request anyway, as we want the SN to be as faint as possible to determine if star\#66 is still there or if there are other objects unresolved in the CFHT frame. Ideally we request the exposures in the period December 2001 - June 2002, when the SN will be V~21. We request exposures in well-calibrated WFPC2 filters close to the ground-based VRI (hence F555W, F675W, and F814W). A 600s exposure in each (each split into 2 separate shots), plus the usual WFPC2 overheads will fill one orbit. noindent Future SN:, If during the duration of Cycle 10 a bright supernova is discovered for which we have an image from our own data archive, then we will request a set of observations tailored to best match the pre-explosion material, and maximise our chances of identifying the progenitor. We loosely request a ToO observation as we clearly cannot name our targets, but our observations can be scheduled several weeks in advance so we need not disturb the telescope schedule. We certainly do not need a rapid turn around of HST, but we request 1 orbit as soon as it can be fitted into the schedule. During this 1 orbit, we will take a series of short and long exposures so that we get a measurement of the PSF centre of the SN, and good signal-to- noise of the surrounding fainter stars in the galaxy. The main problem is of course the dynamic range of WFPC2, and the fact that the supernova will saturate in exposures of the neighbouring stars. The PSF centres of the stars are required to pixel-map the post-explosion data to the pre- explosion data. We request observations in 1 filter in this orbit, matched to the pre-explosion archive data. We will design a series of observations, from short to long that will allow the unsaturated SN position to be placed firmly in the pixel reference frame of the background objects. The guiding of HST is easily good enough that drifts between exposures are generally less than 0.2 pixels. We are not attempting a monitoring campaign, or rapid turn around observations - this is being successfully done by the SINS group. Our proposal is totally geared towards exploiting the archive and identifying progenitors, as shown in the above two examples. We will only request observations if we already have a WFPC2/WFPC archive image which contains the SN position in the FOV. We suggest early observations to identify the progenitor, in order to give added impetus to the supernova monitoring community (and indeed our own ESO/Asiago/La Palma campaign). In addition, because this is such a novel project, we request imaging observations 1 year after explosion. By this time the supernovae will have faded to a magnitude close to that of the brightest surrounding stars (V~20-21 assuming 10 Mpc distance and typical Type II behaviour). There should be no problem with the dynamic range of WFPC2 at this epoch, and this extra observation will serve as a confirmation that we have identified the correct star. The observations would take a similar form to that of SN1999em or SN1999gi as detailed above. Again, the observations can be flexibly scheduled. How many total orbits we require will be determined by the discovery rate and the coincidence probability. If we assume the SN rates from Cappellaro et al. (1999), then the rate of core-collapse SN in typical Sbc-Sd spirals is 0.86+/-0.31 SN (100yr)^-1 (10^10L_odot^B)^-1. Within ~20 Mpc there are ~950 spirals with measured radial velocities of approximately this morphological type and luminosity (from the RC3 catalogue of de Vaucouleurs et al, 1991) Hence one would expect approximately 8 SN to occur within this sample. This maybe an underestimate as we are assuming our galaxies have a mean luminosity of 10^10L_odot^B, whereas the mean of this catalogue is likely to be a factor of ~2 brigther, but we assume the conservative value of 8 for this argument. The completion rate of discovery of SN in these galaxies by the combined efforts of various teams around the world has increased rapidly and is now certainly in the region 50-100 rate is dominated by the proportion of galaxies with archive material. We have submitted a companion SNAP proposal which aims to increase the number of WFPC2 galaxies with 3-colour photometry to >300. If we achieve this then we would expect to detect 2-3 possible progenitors per year. Without this SNAP proposal being successful however, we believe there is still a very strong case for awarding this proposal time to follow any coincidence that we do find, hence fully exploiting the HST archive with just a small investment of new time. Hence we request 3(targets)*2(orbits per target) = 6 orbits for Cycle 10. Real Time Justification ----------------------- noindent SN1999gi:, As specified above, we request that observations are taken before April 2001, and note the willingness of STScI to schedule these if the TAC approves the science. We have justified this in the preceding sections. We will update STScI with magnitdues when the RA of the target allows further monitoring (beginning October 2000). noindent SN1999em:, We have no special requirements for this target, other than it should be observed after December 2001. noindent Future SN:, We request that if future SN are discovered with already existing material in our assimilated data archive (from the ASTROVIRTEL project) then we are allocated time at a suitable date in the future. As explained in the previous sections we do not need rapid turn around at all, hence it is not a ``true TOO'' and can easily be scheduled into routine telescope observations at several weeks notice. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN1999GI EXT-STAR, SUPERNOVA RA=10H 18M 16.7S +/- 1.0", J2000 R = 18.1+/-1 TYPE II, GALAXY, SPIRAL DEC=41D 26' 28.5" +/- 1.0" Coordinate Source: HST_IMAGE 2 SN1999EM EXT-STAR, SUPERNOVA RA=04H 41M 27.04S +/- 1", DEC=- J2000 V = 20+/-0.2 TYPE II, GALAXY, SPIRAL 02D 51' 45.2" +/- 1" Coordinate Source: IMAGE_TIED_TO_GSC_FRAME 3 SN2001DU EXT-STAR, SUPERNOVA RA=03H 33M 29.11S +/- 5", DEC=- J2000 V = V = 15.3+/-0.2 TYPE II, GALAXY, SPIRAL 36D 8' 32.5" +/- 5" +1652 Coordinate Source: OTHER_SOURCE 9041( 8) - 09/18/01 09:30 - [ 4] TARGET LIST Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 4 CP1-SN200X2 EXT-STAR, SUPERNOVA OTHER: FUTURE SUPERNOVA V = 16+/-3 ------------------------------------------------------------------------------------------------------------------------------------ 5 CP1-SN200X3 EXT-STAR, SUPERNOVA OTHER: FUTURE SUPERNOVA V = 16+/-3 ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 5] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Previous ORIENT=92D(u3hy2901r) Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 SN1999GI WFPC2 IMAGE WF4 F606W 5767 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 160 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 20 SN1999GI WFPC2 IMAGE WF4 F606W 5767 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 160 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 30 SN1999GI WFPC2 IMAGE WF4 F300W 2892 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 800 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 40 SN1999GI WFPC2 IMAGE WF4 F300W 2892 CR-SPLIT=NO,CR-TOLERANCE=0.0, 1 400 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 50 SN1999GI WFPC2 IMAGE WF4 F555W 5202 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 160 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 60 SN1999GI WFPC2 IMAGE WF4 F675W 6714 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 160 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 70 SN1999GI WFPC2 IMAGE WF4 F439W 4283 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 600 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 80 SN1999GI WFPC2 IMAGE WF4 F814W 8203 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 600 S ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 6] Visit: 02 Visit Priority: Visit Requirements: AFTER 01-Dec-2001 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 SN1999EM WFPC2 IMAGE PC1 F555W 5202 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 500 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 20 SN1999EM WFPC2 IMAGE PC1 F675W 6714 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 500 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 30 SN1999EM WFPC2 IMAGE PC1 F814W 8203 CR-SPLIT=0.5,CR-TOLERANCE=0.0, 1 500 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 7] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 22-NOV-2001 AND 02-DEC-2001 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 SN2001DU WFPC2 IMAGE PC1 F555W 5202 CR-SPLIT=0.5,ATD-GAIN=15, 1 40 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 20 SN2001DU WFPC2 IMAGE PC1 F555W 5202 CR-SPLIT=0.5,ATD-GAIN=15, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 30 SN2001DU WFPC2 IMAGE PC1 F555W 5202 CR-SPLIT=0.5,ATD-GAIN=15, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 40 SN2001DU WFPC2 IMAGE PC1 F555W 5202 CR-SPLIT=0.5,ATD-GAIN=15, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 50 SN2001DU WFPC2 IMAGE PC1 F814W 8203 CR-SPLIT=0.5,ATD-GAIN=15, 1 40 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 60 SN2001DU WFPC2 IMAGE PC1 F814W 8203 ATD-GAIN=15,CR-SPLIT=0.5, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 70 SN2001DU WFPC2 IMAGE PC1 F814W 8203 ATD-GAIN=15,CR-SPLIT=0.5, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 80 SN2001DU WFPC2 IMAGE PC1 F814W 8203 ATD-GAIN=15,CR-SPLIT=0.5, 1 200 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 90 SN2001DU WFPC2 IMAGE PC1 F336W 3317 CR-SPLIT=0.5,ATD-GAIN=15, 1 100 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 100 SN2001DU WFPC2 IMAGE PC1 F336W 3317 ATD-GAIN=15,CR-SPLIT=0.5, 1 500 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 110 SN2001DU WFPC2 IMAGE PC1 F675W 6714 ATD-GAIN=15,CR-SPLIT=0.5, 1 400 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 120 SN2001DU WFPC2 IMAGE PC1 F439W 4283 ATD-GAIN=15,CR-SPLIT=0.5, 1 400 S CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 8] Visit: 04 Visit Priority: Visit Requirements: ON HOLD On Hold Comments: Target of Opportunity Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 SN200X2 WFPC2 IMAGE PC1 F555W 5202 1 400 S ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 9] Visit: 05 Visit Priority: Visit Requirements: ON HOLD On Hold Comments: Target of Opportunity Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 SN200X3 WFPC2 IMAGE PC1 F555W 5202 1 400 S ------------------------------------------------------------------------------------------------------------------------------------ 9041( 8) - 09/18/01 09:30 - [ 10] Summary Form for Proposal 9041 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF4 PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.0 ATD-GAIN=15 ATD-GAIN=7 CR-SPLIT=NO CR-TOLERANCE=0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01-Dec-2001 BETWEEN 22-NOV-2001 AND 02-DEC-2001 ON HOLD ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W F300W F555W F675W F439W F814W F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN1999GI SN1999EM SN2001DU SN200X2 SN200X3 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 5767 2892 5202 6714 4283 8203 3317 ------------------------------------------------------------------------------------------------------------------------------------