Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5432 Report Date: 18-Jul-95:17:22 Version: ********** Check-in Date: ********** 1.Proposal Title: HIGH SPATIAL RESOLUTION KINEMATICS OF THE DISK AROUND THE ACTIVE NUCLEUS OF NGC 4261 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO Sub Category NUCLEI/CORES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Holland C. Ford Johns Hopkins University USA (410) 516 8653 ------------------------------------------------------------------------------------ 7. Abstract HST F555W images of NGC 4261 (E3), the seventh brightest early type galaxy in Virgo, show a small (1".7 x 0".74), dusty disk with sharp edges and a point-like nucleus. The disk's minor axis is aligned with the axis of the large scale bi-directional radio jet which originates in the nucleus. The face-on optical depth of the dust is 0.3. The disk contains HI and CO, and the nucleus is a LINER with unusually strong and broad (FWZI ~ 4500 km/s) emission lines of \[NII\] and \[SII\]. We conclude that we are looking directly at the structure, i.e. the nuclear disk, which fuels the engine and determines the direction of the radio jet. WHT spectra show subtle but unmistakeable evidence for rotation of the narrow component of \[NII\] emission. Our models of the emission suggest, but by no means prove, that there is a ~ 4 x 10\*\*7 M black hole in the nucleus. Our models of the light and mass distribution show that the definitive signature of a massive black hole will be a transition from the solid body rotation observed from the ground to a rising Keplerian rotation curve for r < 0".3. We propose to use the FOS 0".09 aperture with G570H to map the rotation curve in the disk in the crucial region r < 0".3 which is unobservable from the ground. The observations of this nearly unique small nuclear disk provide an opportunity to make an unambiguous measurement of the mass of an active nucleus. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 7.59 par: 0.0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5432 PI: Holland C. Ford Proposal Title: HIGH SPATIAL RESOLUTION KINEMATICS OF THE DISK AROUND THE ACTIVE NUCLEUS OF NGC 4261 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Holland C. Ford 2380 USA Walter Jaffe 6870 Netherlands X Robert W. O'Connell 3730 USA Laura Ferrarese 2380 USA Frank C. Van Den Bosch 6870 Netherlands X ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to map the disk in NGC 4261 with the FOS 0.''1 aperture and grating G570H. The patter adopted includes a 3X3 grid centered on the nucleus and with axes aligned with the major and minor axes of the disk, plus 4 additional positions along the major and minor axes of the disk, on either side of the nucleus, placed just outside the 3X3 grid. We are aiming for a S/N between 10 and 30 in the peak of the [NII] lambda6584 emission line, corresponding to S/N between 6 and 17 in the adjacent continuum. Our models show that the analysis of the [NII]+Halpha emissions, for S/N ~ 16 and given the spatial sampling proposed here, will allow us to resolve a keplerian rise in the rotation curve due to a nuclear black hole with mass larger than 5X10^6 solar masses. The exposure times have been calculated using formula 1, page 25, of the FOS Instrument Handbook (Version 5.0), by neglecting the aperture throughput, as appropriate for an extended source. The flux at the [NII] peak has been derived from the WFPC2 H alpha images and the WHT spectra, and is reported in the parameter FLUXNUM_1 in the TARGET LIST for each individual position. The acquisition procedure includes an ACQ/BIN on an offset star located about 1 arcmin away from the nucleus, followed by a three stages ACQ/PEAK on the same star. The pointing accuracy for the star at the end of the acquisition procedure will be 0".03 (4 sigma measurement). The offset between the star and the nucleus is known with a 0".03 accuracy, and since the 1 sigma error associated with the slew is 0".08, the final 1 sigma pointing error on the nucleus will be 0".09. We therefore require that a one stage peak-up is executed on the nucleus using the 0".1 aperture and the G570 grating. Since the nucleus is bright in emission lines, we require that only the wavelenght region including Halpha, [NII] and [SII] is read out. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We have observed NGC 4261 at 21 cm with the VLA and at 1.3 mm with the James Clerk Maxwell Telescope in Hawaii. We detected HI and CO in absorption at the systemic velocity of the galaxy. We have obtained high signal-to-noise ratio NTT H-alpha on-band and off-band images of NGC 4261 during seeing with a FWHM ~ 0.''8. These observations detect the dust but do not resolve the disk. We obtained green and red spectra of the disk and nucleus of NGC 4261 with the William Herschel Telescope during 1.''1 seeing. The spectra show evidence for rotation (cf Figure 2), but cannot show if the rotation curve transitions from solid body decline to a rising Keplerian curve in the crucial region r < 0.''3. HST FOS spectra with a resolution of ~ 0.1'' are the only way to measure the rotation of the disk in the critical region close (r < 0.''3) to the nucleus. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. No special scheduling requirements are needed Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. No special calibration exposures are needed ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. We will derive a velocity map for the inner 0.3x0.3 arcsec of the galaxy. The continuum and emission lines of each of the FOS spectra will be fitted interactively by Chi-square minimization using a Simplex algorithm. This will allow us to derive the peak velocities of the emission lines. Our modeling shows that the S/N of the spectra and the spatial sampling will allow us to resolve a keplerian rise in the rotation curve due to a nuclear black hole with mass larger that 5 x 10^6 solar masses. The rotation curve will be modeled by assuming that the gas is embedded in the gravitational potential of the stellar component, plus the gravitational potential of the nuclear disk, and the central black hole. Since the mass of the disk is known to be 10^6 solar masses from radio observations (Jaffe and MacNamara 1993), the only two free parameters in the fit will be the stellar mass to light ratio and the mass of the central black hole. The shape of the gravitational potential of the stellar component has already been derived by fitting the brightness distribution obtained from HST/PC images with a double exponential law, and subsequently deprojecting the fit in order to otain a spatial luminosity density. For a black hole with mass a few times 10^7 solar masses (much larger masses are ruled out by our WHT spectrum), the expected velocity curve is given by the stellar potential at radii larger than 1-1.5 arcsec. The fit to the rotation curve in this region will allow us to constrain the range of possible values for the stellar mass to light ratio, so that a more precise estimate of the black hole mass is possible from the analysis of the inner 0.3 arcsec of the rotation curve. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. No additional comments ------------------------------------------------------------------------------------ 9. Description of previous HST work. H. Ford is the IDT-PI for the Following FOS GTO and GO Programs: 1034: M87's Jet, Nucleus, and Hot Corona. 1036: Imaging and Spectrophotometry of Seyfert Nuclei. 1038: Imaging and Spectrophotometry of Nuclear Activity in LINERs. 1040: Velocity Dispersions in the Nuclei of Giant Ellipticals. 1044: Stellar and Gas Dynamics in Normal Galaxies. 1046: Imaging and UV Spectrophotometry of Local Group Planetary Nebulae. 4668: FOS Spectroscopy of n1052 and n4258. H. Ford is a Co-I on the Following GO Programs: 2607: Black Holes, Stellar Dynamics and Populations in the Nuclei of a Complete Sample of Elliptical Galaxies. (PI Walter Jaffe) 2227: Determination of the Extragalactic Distance Scale (PI Jeremy Mould) 2266: Post-Asymptotic Giant Branch Evolution in the Magellanic Clouds (PI M Dopita). 4371: FOS Spectroscopy of Resolved Structure in the Nucleus of Markarian 3 (PI Zlatko Tsvetanov). ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Holland Ford and Laura Ferrarese at Johns Hopkins University will analyze and modelthe data using a cluster of Sun Workstations within the department. The workstations are part of a network, and are connected to printers, tape readers, etc. The Sun cluster is supported by a system manager. ------------------------------------------------------------------------------------ 11. Address Information Page 4 Name: Holland C. Ford Category: PI Institution: 2380 Address: Department of Physics and Astronomy Homewood Campus City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: (410) 516 8653 Telex (or e-mail): ford@stsci.edu ------------------------------------------------------------------------------------ Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5432 [ 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 NGC4261-OFF A,140 RA-OFF = +4.365S +/- 0.003S, 1 V = 15.7 +/- 0.3 DEC-OFF = +24.875" +/- 2 V-I = 1.1 0.05", FROM 2 Comments: OFFSET STAR FOR NUCLEAR POINTING ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4261-NUC E,303,315,317,910 RA = 12H 19M 23.145S +/- 2000.0 V = BKG 1 SURF(V) = 16.6 +/- 0.3 0.04S, +2282 2 F(6633) = 1.0 E-15 DEC = +5D 49' 30.059" +/- 3 SURF(4700) = 1.6 E-16 0.5" 4 SURF(2500) = 3.5 E-17 5 R = 19.2 +/- 0.3 Comments: POSITION DETERMINED FROM WFPC2 H ALPHA IMAGE ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4261-N1 E,303,315,317,910 XI-OFF = -0.026" +/- 0.003", V = 1 F(6633) = 4.4 E-16 ETA-OFF = +0.086" +/- +2282 0.001", FROM 2 Comments: 0.09 OFFSET ALONG MAJOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4261-N2 E,303,315,317,910 XI-OFF = -0.052" +/- 0.006", V = 1 F(6633) = 8.5 E-17 ETA-OFF = +0.172" +/- +2282 0.002", FROM 2 Comments: ALONG MAJOR AXIS 0.018 OFFSET ALONG MAJOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC4261-S1 E,303,315,317,910 XI-OFF = 0.026" +/- 0.003", V = 1 F(6633) = 4.4 E-16 ETA-OFF = -0.086" +/- +2282 0.001", FROM 2 Comments: 0.09 OFFSET ALONG MAJOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC4261-S2 E,303,315,317,910 XI-OFF = 0.052" +/- 0.006", V = 1 F(6633) = 8.5 E-17 ETA-OFF = -0.172" +/- +2282 0.002", FROM 2 Comments: ALONG MAJOR AXIS 0.018 OFFSET ALONG MAJOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC4261-W1 E,303,315,317,910 XI-OFF = -0.086" +/- 0.001", V = 1 F(6633) = 4.4 E-16 ETA-OFF = -0.026" +/- +2282 0.003", FROM 2 Comments: 0.09 OFFSET ALONG MINOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC4261-W2 E,303,315,317,910 XI-OFF = -0.172" +/- 0.002", V = 1 F(6633) = 8.5 E-17 ETA-OFF = -0.052" +/- +2282 0.006", FROM 2 Comments: ALONG MAJOR AXIS 0.018 OFFSET ALONG MINOR AXIS TARGET LIST a) Fixed Targets ID = 5432 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC4261-E1 E,303,315,317,910 XI-OFF = +0.086" +/- 0.001", V = 1 F(6633) = 4.4 E-16 ETA-OFF = +0.026" +/- +2282 0.003", FROM 2 Comments: 0.09 ALONG MINOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC4261-E2 E,303,315,317,910 XI-OFF = 0.172" +/- 0.002", V = 1 F(6633) = 8.5 E-17 ETA-OFF = 0.052" +/- 0.006", +2282 FROM 2 Comments: ALONG MAJOR AXIS 0.018 OFFSET ALONG MINOR AXIS ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC4261-NE1 E,303,315,317,910 XI-OFF = +0.060" +/- 0.004", V = 1 F(6633) = 2.3 E-16 ETA-OFF = +0.112" +/- +2282 0.002", FROM 2 Comments: OFF AXIS ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC4261-SE1 E,303,315,317,910 XI-OFF = +0.112" +/- 0.002", V = 1 F(6633) = 2.3 E-16 ETA-OFF = -0.060" +/- +2282 0.004", FROM 2 Comments: OFF AXIS ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC4261-NW1 E,303,315,317,910 XI-OFF = -0.112" +/- 0.002", V = 1 F(6633) = 2.3 E-16 ETA-OFF = +0.060" +/- +2282 0.004", FROM 2 Comments: OFF AXIS ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC4261-SW1 E,303,315,317,910 XI-OFF = -0.060" +/- 0.004", V = 1 F(6633) = 2.3 E-16 ETA-OFF = -0.112" +/- +2282 0.002", FROM 2 Comments: OFF AXIS ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5432 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE # FOS/RD ACCUM # G570H 4571- 1 1S # 1 CYCLE 4 SP 6820 # ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC4261-OFF FOS/RD ACQ/ 4.3 MIRROR BRIGHT=132000 1 11.8S 1 1 CYCLE 4 BINARY FAINT=330 SEQ 10-271 NO GAP ONBOARD ACQ FOR 190-271 Comments: BINARY ACQUISITION ON OFFSET STAR ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC4261-OFF FOS/RD ACQ/ 0.5- MIRROR SCAN-STEP- 1 10.0S 1 1 CYCLE 4 PEAK PAIR X=0.30 ONBOARD ACQ FOR SCAN-STEP- 190-271 Y=0.30 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 Comments: CRITICAL PEAK-UP ON STAR FIRST OF THREE STAGES ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC4261-OFF FOS/RD ACQ/ 0.25- MIRROR SCAN-STEP- 1 10.0S 1 1 CYCLE 4 PEAK PAIR X=0.17 ONBOARD ACQ FOR SCAN-STEP- 190-271 Y=0.17 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 Comments: CRITICAL PEAK-UP ON STAR SECOND OF THREE STAGES ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC4261-OFF FOS/RD ACQ/ 0.1- MIRROR SCAN-STEP- 1 10.0S 1 1 CYCLE 4 PEAK PAIR-B X=0.05 ONBOARD ACQ FOR SCAN-STEP- 190-271 Y=0.05 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 Comments: CRITICAL PEAK-UP ON STAR THIRD OF THREE STAGES ------------------------------------------------------------------------------------------------------------------------------------ 45 NGC4261-NUC FOS/RD ACQ/ 0.25- G570H 6500- SCAN-STEP- 1 66.0S 5 1 CYCLE 4 PEAK PAIR 6820 X=0.17 ONBOARD ACQ FOR SCAN-STEP- 190-271 Y=0.17 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 Comments: CRITICAL PEAK-UP ON NUCLEUS FIRST OF TWO STAGES ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5432 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 46 NGC4261-NUC FOS/RD ACQ/ 0.1- G570H 6500- SCAN-STEP- 1 50.0S 5 1 CYCLE 4 PEAK PAIR-B 6820 X=0.052 ONBOARD ACQ FOR SCAN-STEP- 190-271 Y=0.052 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 Comments: CRITICAL PEAK-UP ON NUCLEUS SECOND OF TWO STAGES ------------------------------------------------------------------------------------------------------------------------------------ 190 USE SP NGC4261-NUC 0.1- X2030.0 35 2 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 191 WAVE FOS/RD ACCUM 0.1- G570H 1 DEF 1 CYCLE 4 PAIR-B Comments: WAVECAL FOR LINE 190 ------------------------------------------------------------------------------------------------------------------------------------ 200 USE SP NGC4261-N1 0.1- X2030.0 23 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 205 USE SP NGC4261-N2 0.1- X2030.0 10 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 210 USE SP NGC4261-S1 0.1- X2030.0 23 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 215 USE SP NGC4261-S2 0.1- X2030.0 10 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 220 USE SP NGC4261-W1 0.1- X2030.0 23 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 225 USE SP NGC4261-W2 0.1- X2030.0 10 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 230 USE SP NGC4261-E1 0.1- X2030.0 23 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5432 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 235 USE SP NGC4261-E2 0.1- X2030.0 10 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 240 USE SP NGC4261-NW1 0.1- X2030.0 17 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 250 USE SP NGC4261-SW1 0.1- X2030.0 17 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 260 USE SP NGC4261-SE1 0.1- X2030.0 17 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 270 USE SP NGC4261-NE1 0.1- X2030.0 17 1 PAIR-B Comments: S/N AT THE PEAK OF THE [NII] LINE ------------------------------------------------------------------------------------------------------------------------------------ 271 WAVE FOS/RD ACCUM 0.1- G570H 1 DEF 1 CYCLE 4 PAIR-B Comments: WAVECAL FOR LINE 270 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5432 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ACQ/BINARY ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=132000 FAINT=330 SCAN-STEP-X=0.30 SCAN-STEP-Y=0.30 SEARCH-SIZE-X=3 SEARCH-SIZE-Y=3 SCAN-STEP-X=0.17 SCAN-STEP-Y=0.17 SCAN-STEP-X=0.05 SCAN-STEP-Y=0.05 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-X=0.052 SCAN-STEP-Y=0.052 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 7.59 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category NUCLEI/CORES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 CYCLE 4; SEQ 10-271 NO GAP; ONBOARD ACQ FOR 190-271 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G570H MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4261-OFF NGC4261-NUC NGC4261-N1 NGC4261-N2 NGC4261-S1 NGC4261-S2 NGC4261-W1 NGC4261-W2 NGC4261-E1 NGC4261-E2 NGC4261-NE1 NGC4261-SE1 NGC4261-NW1 NGC4261-SW1 ------------------------------------------------------------------------------------------------------------------------------------