8101( 3) - 06/21/99 13:42 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8101 Version: 3 Check-in Date: 19-Feb-1999 12:53:14 1.Proposal Title: High Resolution Imaging of the Core of Maffei 1, the Nearest Normal Massive Elliptical Galaxy ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Ronald Buta University of Alabama CoI: Prof. Marshall McCall York University N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain high resolution optical images of the center of the galaxy Maffei 1, which is the nearest normal intermediate to giant elliptical galaxy. Recent studies have shown that Maffei 1 is much larger (D_0 = 25^ ) and brighter (V_T^0 = 6.4) than previously thought, and that it is only 2.7 +/- 0.6 Mpc distant. This is one-sixth the distance to the Virgo and Fornax Cluster ellipticals, and 1 pixel in the Planetary Camera (PC) field covers only 0.5--0.7 pc. Thus, with HST, we have the opportunity of studying the core of a normal massive elliptical galaxy (M_V = -20.7) at sub-parsec spatial resolution. Besides revealing the profile of light in the core, which is invaluable for assessing the extent to which dissipation affected evolution, our images will be used to search for evidence of a central concentration of mass, including an accretion disk that might surround a supermassive black hole. Because of the proximity of Maffei 1, we will be able to identify a cen tr al black hole of considerably less mass ------------------------------------------------------------------------------------ 8101( 3) - 06/21/99 13:42 - [ 2] Observations Description ------------------------ Our I-band ground-based surface photometry has been used to deduce exposure time requirements as follows. We seek a high signal-to-noise over the pixels in the PC field, where the galaxy will be centered. The reference surface brightness we use is 19.3 mag arcsec^-2, which is an approximate value expected in the corners of the PC at r = 25^ . For a color excess E(B-V) = 1.5 mag, a total exposure time of 1250s would give a signal-to-noise ratio of 8 per pixel in filter F814W (HST I-band) and 4 per pixel in filter F675W (HST R-band) at these corners. Thus, observations for both filters could be obtained in a single orbit. For HAlpha observations, we use filter F656N and a reference flux of 1.0times10^-15 ergs cm^- 2 s^-1 arcsec^-2 based upon observations of the center of M87 by Ford et al. (1994), and after allowing for 4.1 mag of galactic extinction at HAlpha. In 6000s, we would achieve a signal-to-noise ratio of 2.0 per PC pixel against the bright galaxy background in the ce ntral few arcsecs, assuming that the background has an average surface brightness of 17.0 mag arcsec^-2 at I and E(B-V) = 1.5 mag. This signal-to-noise ratio is not high, but the inner parts of any disk could be much brighter than the average, so we could expect to detect the disk if its surface brightness characteristics are similar to those of M87's disk. Also, we should be able to detect a disk whose total HAlpha flux is more than 100 times fainter than that of M87. According to Ford et al. (1994), the total HAlpha+NII flux from the M87 disk within r = 1^ is 2.0times10^-13 ergs cm^-2 s^-1. Assuming half of of this is due to HAlpha alone, and with 4.1 mag of extinction, we would expect to see 7times10^-14 ergs cm^-2 s^-1 from the M87 disk viewed at Maffei 1's distance. A disk whose total flux is only 10^-17 ergs cm^-2 s^-1 would be detectable against the bright background with a signal-to-noise ratio of 2.6 in 6000s, treating it as a point source. To subtract the continuu m, we will use the image from filter F675W. (We note that Ford et al. (1994) used filter F547M for the continuum subtraction, but this choice is less desirable for Maffei 1 due to the heavy extinction and poor matching of the effective wavelength with the HAlpha filter.) The HAlpha imaging will require 2 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8101( 3) - 06/21/99 13:42 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 MAFFEI1 GALAXY, ELLIPTICAL RA=02H 36M 35.47S +/- 0.05", J2000 V = 0 V = 11.1+/-0.1 DEC=59D 39' 18.05" +/- 0.2", E(B-V) = 1.5+/-0.2 PLATE-ID=01MW SURF(I) = 19.3+/-0.1 8101( 3) - 06/21/99 13:42 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 80D TO 90D 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 MAFFEI1 WFPC2 IMAGE PC1-FIX F675W 6696 DITHER-TYPE=LINE,CR-SPLIT=0.5, 1 460 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 2 MAFFEI1 WFPC2 IMAGE PC1-FIX F656N 6564 DITHER-TYPE=LINE,CR-SPLIT=0.5, 1 1600 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 3 MAFFEI1 WFPC2 IMAGE PC1-FIX F814W 7921 CR-SPLIT=0.5,DITHER-TYPE=LINE, 2 400 S ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 8101( 3) - 06/21/99 13:42 - [ 5] Summary Form for Proposal 8101 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=LINE CR-SPLIT=0.5 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 80D TO 90D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F675W F656N F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names MAFFEI1 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6696 6564 7921 ------------------------------------------------------------------------------------------------------------------------------------