Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4885o Report Date: 09-May-96:20:33 Version: ********** Check-in Date: ********** 1.Proposal Title: LONG PERIOD VARIABLES OF M81: CYCLE3MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO 2 Long Term yrs Sub Category STELLAR POPULATIONS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Shaun M Hughes PALOMAR OBSERVATORY USA ------------------------------------------------------------------------------------ 7. Abstract This is part of a very long term project to identify Long-Period Variables (LPVs) in external galaxies. Most LPVs are members of the Asymptotic Giant Branch (AGB), and hence one of the main reasons for studying the LPVs will be to understand the AGB, and how it varies in nearby galaxies. So far the only AGB LPVs to be identified in external galaxies are those in the Magellanic Clouds. Ground based programs are currently underway to identify the AGB LPVs in M31, and using HST to identify the LPVs in a galaxy beyond the local group will tell us how important a part galactic environment plays in the formation of AGB progenitor stars (ie initial main sequence masses of between ~0.8 and 9 solar masses). An important bonus of studying LPVs is that they possess a precise PL relation, which will be a very useful check against the distance derived from Cepheids in the H_0 key project (Program No. 2227). ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.00 par: 0 10. Num targs pri: 2 par: 2 ------------------------------------------------------------------------------------ 11. Instruments requested: FOC WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4885o PI: Shaun M Hughes Proposal Title: LONG PERIOD VARIABLES OF M81: CYCLE3MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Shaun M Hughes PALOMAR OBSERVATORY USA Jeremy R Mould PALOMAR OBSERVATORY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Cycle 2: 1 epoch of 25.9m I May 1993 M81 disk field : 1 epoch of 25.9m I May 1993 M81 V30 field Cycle 3: 2 epochs of 25.9m I July 1993 M81 disk field : 2 epochs of 25.9m I July 1993 M81 V30 field : 2 epochs of 25.9m I Nov 1993 M81 disk field : 2 epochs of 25.9m I Nov 1993 M81 V30 field : 1 epoch of 25.9m I Jan 1994 M81 disk field : 1 epoch of 25.9m I Jan 1994 M81 V30 field Cycle 1 Primary Hours: Parallel Hours: Exposures: Cycle 2 Primary Hours: 0.9 Parallel Hours: 0 Exposures: 2 Cycle 3 Primary Hours: 4.3 Parallel Hours: 0 Exposures: 10 Cycle 4 Primary Hours: 1.0 Parallel Hours: 0 Exposures: 12 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. So far the only AGB LPVs to be identified in external galaxies are those in the Magellanic Clouds. Ground based programs are currently underway to identify the AGB LPVs in M31, which is at the limit of current ground-based observations. Using HST to identify the LPVs in a galaxy beyond the local group will tell us how important a part galactic environment plays in the formation of AGB progenitor stars (ie initial main sequence masses of between ~0.8 and 9 solar masses). An important bonus of studying LPVs is that they possess a precise P-L relation, which will be a very useful check against the distance derived from Cepheids in the H_0 key project (Program No. 2227). In order to obtain accurate periods, we shall need 18 epochs. As part of Program No. 2227, there already exists four F785LP exposures in each of the two fields from cycle 1, and an additional two exposures will be taken in each field in cycle 2. The Cepheid surveys have established that a cycle 3 HST can reliably reach magnitudes of 23.5 in I in 1800 sec. Due to spacecraft overheads, the amount of spacecraft time allocated in cycle 3 phase I is sufficient for 12 exposures (6 epochs) of 1610 sec, a reduction of 0.12 mag, which should not reduce the numbers of recovered LPVs too severely. In order to obtain near-continuous light curves (see below) one epoch is requested for the end of cycle 2, and five epochs in cycle 3. The remaining six epochs required to finish the project will be requested in cycle 4, for which the WFPC2 refurbishment should mean that we can reduce the required exposure times by a factor of 6. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Time-critical observations: Because the periods of some LPVs change from cycle to cycle, and in order to avoid severe period aliases, we will need to obtain well-sampled continuous light curves. The existing data are concentrated over a period of 42 days (4 epochs) in cycle 1, with 2 epochs in cycle 2. Hence it is important to obtain one epoch at the end of cycle 2, to light-curve continuity, with the remaining epochs well-spread over the rest of maintain the sampling time. However, because the pulsation periods are so long (100-1000 days), we can tolerate a reasonably large scatter (+/- 5 days) about the ideal sampling times listed below. Special orientation: because of undersampling, and to ensure good phase coverage for the maximum number of stars, it is very important to expose on the same area for each observation in a sequence. This means the position and orientation (+/- Nx90 deg) must be kept fixed for the maximum number of exposures. We have obtained output from the RUN-ORIENT program to determine the allowable dates for the correct orientation for each exposure. This gives us 4 windows per year (one for each orientation), two of which last 60 days, and the other two lasting only 10 days. Future Cycles: Although we have been allocated only 1.5 hours of spacecraft time in `Future Cycles', enough for only 3x5 min exposures plus overheads, we hope to be allocated more time when cycle 4 proposals are solicited. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. A preliminary calibration of the HST Program No. 2227 data (Cepheids in M81) shows that the ALLFRAME photometry package (based on DAOPHOT) is well able to produce accurate photometry (to I ~ 23.5) from the Science Images produced by the standard STSDAS pipeline. We shall therefore be using the same package on the LPV data. The added advantage of using ALLFRAME is that it also provides the light curve of every detected image in the frame, and so it is a relatively easy matter of analysing each light curve to search for variability and periodicity, in a similar manner to Hughes (1989 AJ 97, 1634), which will also enable completeness estimates to be made, and which can be applied to the final results to obtain reasonable LPV luminosity functions and period distributions. Ground- based (Palomar 200-inch) photometry of the brightest stars already exists and will be used to calibrate the data onto the Cousins I system. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. It would be highly desirable for the data to be reserved for our exclusive use until one year after the cycle 4 data have been acquired, as a premature analysis of a partial light curve sample will only produce misleading results. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. 2227GO: The Extragalactic Distance Scale I. M81. 3905GO: The Extragalactic Distance Scale II. M81 & M101. These programs are aimed at finding Cepheids in galaxies beyond the local group, and eventually out to the Virgo group. The first and nearest galaxy to be observed is M81, and in cycle 1, 12 and 4 epochs were obtained in F555W and F785LP, in two fields of M81, while in cycle 2 a further 6 and 2 epochs will be obtained. The F785LP frames will be used as part of the data for this LPV proposal. From the cycle 1 data, 37 Cepheid candidates have been identified. More epochs being obtained in cycle 2 will be used to obtain accurate periods. The entire data set is now being calibrated against ground-based photometry (Palomar 200-inch) of the brightest stars in each of the fields. The Cepheid colors will then be used to estimate internal extinction, and when combined with the re-calibrated data will provide an accurate distance to M81, the first step in measuring H_0 to better than 10%. Cepheids in Nearby Galaxies, Freedman, W. in IAU Colloquium 139, in press, 1992 Faint Stellar Photometry with HST, Hughes, S., in IAU Coll. 136, in press, 1992 Stellar Populations in Neighboring Galaxies, Mould, J., in Science with the Hubble Space Telescope, in press, 1992. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). A computer workstation will be used to reduce and analyse the data. ------------------------------------------------------------------------------------ 11. Address Information Name: SHAUN M HUGHES Category: PI Institution: Palomar Observatory Address: CALTECH MS 105-24 City: PASADENA State: CA Zip Code: 91125 Country: USA Telephone: 818 356 4023 Telex (or e-mail): 675425 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4885o [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC3031- E,301 RA=09H 51M 02.6S +/- 2", 1950 V=80 1 SURF(V)=25 FIELD DEC=+69D 23' 15" +/- 2" 2 SURF(I)=25 Comments: DISK FIELD ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC3031-V30 E,301 RA=09H 52M 03.5S +/- 2", 1950 V=80 1 SURF(V)=25 DEC=+69D 21' 18" +/- 2" 2 SURF(I)=25 Comments: V30 FIELD ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4885o [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 23 DEFINE # WFC IMAGE WFALL F785LP CR-SPLIT=NO 1 1610S 10 1 # BEFORE 35 BY ILONG PRE-FLASH=NO 260.0D +/- 5.0D POS TARG +10, -10 ORIENT 270D +/- 0.02D FROM 35 CYCLE 2 / 23 Comments: THIS IS AN EXACTLY 270 DEG GUID TOL 0.010" ROTATED EXPOSURE. I.E. -90 DEGREES FROM 35 ------------------------------------------------------------------------------------------------------------------------------------ 31 DEFINE # WFC IMAGE WFALL F785LP CR-SPLIT=NO 1 1610S 10 2 # BEFORE 35 BY ILONG PRE-FLASH=NO 179.0D +/- 5.0D POS TARG +10, -10 ORIENT 180D +/- 0.02D FROM 35 CYCLE 3 / 31 Comments: THIS IS AN EXACTLY INVERTED GUID TOL 0.010" EXPOSURE I.E. 180 DEGREES FROM 35 ------------------------------------------------------------------------------------------------------------------------------------ 32 DEFINE # WFC IMAGE WFALL F785LP CR-SPLIT=NO 1 1610S 10 1 # BEFORE 35 BY 97.0D ILONG PRE-FLASH=NO +/- 5.0D POS TARG +10, -10 ORIENT 90D +/- 0.02D FROM 35 CYCLE 3 / 32 Comments: THIS IS AN EXACTLY 90 DEG GUID TOL 0.010" ROTATED EXPOSURE. I.E. +90 DEGREES FROM 35 ------------------------------------------------------------------------------------------------------------------------------------ 33 DEFINE # WFC IMAGE WFALL F785LP CR-SPLIT=NO 1 1610S 10 1 # BEFORE 35 BY 74.0D ILONG PRE-FLASH=NO +/- 5.0D SAME POS FOR 33 AS 32 SAME ORIENT FOR 33 AS 32 Comments: SAME GUIDE STARS FOR 33 AS 32 CYCLE 3 / 33 (RETURNING TO THE SAME POSITION GUID TOL 0.010" AND SAME ORIENTATION IS CRUCIAL) EXPOSURE +90 DEGREES FROM 35 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4885o [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 34 DEFINE # WFC IMAGE WFALL- F785LP CR-SPLIT=NO 1 1610S 10 1 # BEFORE 35 BY 51.0D ILONG FIX PRE-FLASH=NO +/- 5.0D SAME POS FOR 34 AS 32 SAME ORIENT FOR 34 AS 32 Comments: SAME GUIDE STARS FOR 34 AS 32 CYCLE 3 / 34 (RETURNING TO THE SAME POSITION GUID TOL 0.010" AND SAME ORIENTATION IS CRUCIAL) EXPOSURE +90 DEGREES FROM 35 ------------------------------------------------------------------------------------------------------------------------------------ 35 DEFINE # WFC IMAGE WFALL F785LP CR-SPLIT=NO 1 1610S 10 1 # AT 19-JAN-94 +/- ILONG PRE-FLASH=NO 4D POS TARG +10, -10 CYCLE 3 / 35 GUID TOL 0.010" Comments: THIS POSITION PUTS TARGET ON APEX ------------------------------------------------------------------------------------------------------------------------------------ 301 USE NGC3031- 1 CYCLE 2 / 23 ILONG FIELD CYCLE 3 / 31 - 35 ------------------------------------------------------------------------------------------------------------------------------------ 302 USE NGC3031-V30 2 CYCLE 2 / 23 ILONG CYCLE 3 / 31 - 35 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4885o [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 35 BY 260.0D +/- 5.0D; POS TARG +10, -10 ; ORIENT 270D +/- 0.02D FROM 35 ; CYCLE 2 / 23; GUID TOL 0.010" BEFORE 35 BY 179.0D +/- 5.0D; ORIENT 180D +/- 0.02D FROM 35 ; CYCLE 3 / 31; BEFORE 35 BY 97.0D +/- 5.0D; ORIENT 90D +/- 0.02D FROM 35 ; CYCLE 3 / 32; BEFORE 35 BY 74.0D +/- 5.0D; SAME POS FOR 33 AS 32; SAME ORIENT FOR 33 AS 32; CYCLE 3 / 33; BEFORE 35 BY 51.0D +/- 5.0D; SAME POS FOR 34 AS 32; SAME ORIENT FOR 34 AS 32; CYCLE 3 / 34; AT 19-JAN-94 +/- 4D; CYCLE 3 / 35; CYCLE 2 / 23; CYCLE 3 / 31 - 35; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F785LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC3031-FIELD NGC3031-V30 ------------------------------------------------------------------------------------------------------------------------------------