, Volume 1400 1400 ns within the emission (unpub- opkins University. 1400 2 d the Hopkins Ultra- 1300 1300 atio of nebular surface region as described by lar brightness to stellar llar flux near the central ervations, for example, a Proceedings of the SPIE Offset Pointing be coming from the region. tness to stellar flux ratio is Near HD 34078 hly excited states of molec- l. 2002). Measuring a limit horter wavelengths. lar offset position. The spec- wn in Figure 6). The most observations of the reflection d the offset pointing exhibits ) measure a roughly constant s result is in contrast with a ined as a decrease in the dust 1300 escent emission, and continued ncreasing flux from fluorescing lt is plotted on a log scale. , NGC 2023 (Burgh et al. s. fluorescence could be produced easing albedo. Another possible two orders of magnitude at shorter 2 1200 1200 ˚ ubmitted’. 1997, ApJ, 475, 835–842. A characteristic of H Kimble, R. A., & Durrance, S. T. 1993, ApJ, 408, dman, P. D. 2001. In 1200 flux rises by two orders of magnitude over the bandpass of , Roueff, E., Gry, C., Andersson, B.-G., & Le Brun, V. 2002, Wavelength (Å) Wavelength (Å) Wavelength (Å) 1100 1100 will be explored through further analysis of the flight Future Work REFERENCES 2 1100 1000 1000 fluorescence in the nebula. H 2

6 5 4 3 2 1 0

1000

* ) sr (x10

˚ S/F A. −1 6 emission will allow us to put a bound on the physical conditio 2 900 900 9 8 7 6 5 8 7 6 5 4 Ratio of Nebular Surface Brightness to Stellar Flux

10 10 10 10 10 10 10 10 10 10

* * ) (sr S/F ) (sr S/F

−1 −1 L97–L100. ApJ, ‘submitted’. 4498. Figure 8 shows the ratio of nebular surface brightness to ste We will look to explain the two order of magnitude rise in the r The possibility of fluorescent H The result is also in contradiction with Murthy et al. (1993) This work was supported by NASA grant NAG5-5122 to The Johns H by UV pumping, shockSternberg excitation, (1989). or formation pumping in the lished). Our initial result, Figurework will 6, allow does us not to put rule anThe out upper flight fluor limit on data what will emission be could comparedrecent FUSE with observation other of FUV HD and 34078 opticalular found obs hydrogen variability on in the hig timescaleon of the several UV months H (Boisse et a and at theinteresting offset aspect of pointing the ratio (spectra is the ofwavelengths. rise of these The approximately inner regions nebular sho regionthe shows a same clear trend, rise, despite an previous sounding the rocket decreased observation of signal-to-noise. another reflection 2002). Thi Observations of NGCflux 2023 (see show below). a constant Itplotted ratio should on be of a noted nebu linear scale that while the the flat more surface recent, ‘blue’, brigh resu brightness to stellar flux.absorption This cross-section ‘blue at nebula’ shorter could wavelengths be orexplanation expla an could incr be H nebula, namely the dust properties and excitation processe Sternberg, A. 1989, ApJ, 347, 863–874. Wolven, B. C., Feldman, P. D., Strobel, D. F., & McGrath, M. A. data. HUT, on Astro-2, observed a pointingtrum very near obtained our shows nebu the double peak near 1600 Æ Figure 8.the The instrument, ratio 900 of – nebular 1400 surface brightness to stellar Æ Boisse, P., Rollinde, E., Le Petit, F., Pineau des Forets, G. nebula NGC 7023. Usingviolet a Telescope combination (HUT), of aboard data Astro-1, Murthy fromratio et Voyager of 2 al. nebular an (1993 brightness tomolecular stellar hydrogen flux, balanced explained by as a an decreasing i dust albedo to s Burgh, E. B., McCandliss, S. R., & Feldman,Burgh, P. E. D. B., 2002, McCandliss, ApJ, S. R., ‘s Pelton, R., France, K., & Fel Murthy, J., Dring, A., Henry, R. C., Kruk, J. W., Blair, W. P., airglow. α 1400 1400 12, and SiC  O I ⊕ 1400 s to the aft end of the 1300 1300 al ratio of gh vacuum environments ular flux and instrumental ket experiment by allowing tion systems are expensive l. 2001). The collimator is ing of a vacuum ultraviolet provides mounts for several ments. Precise knowledge of pe and Spectrograph Sections. recently obtained a collimator ors, and overcome the strong simulation, an electron-impact etter understanding of detector H I orer (FUSE), and fitted it with ⊕ alibration, including LSF and flat- 1200 1200 violet Collimator. e central star. The top spectrum was obtained near s the spectrum measured at a pointing offset, a position overplotted with a modified Wolven model for fluorescent Wavelength (Å) Wavelength (Å)

ular flux, one notices the prominent hydrogen Ly- 1100 1100

1300

O I O ⊕

H I H ⊕

Far-UV Nebular Spectra

O I O 1000 ⊕ 1000 and Eric B. Burgh (UW - Madison) Windowless Vacuum Ultraviolet Collimator

900 900 5 4 3 2 1 0 8 6 4 2 0

10 ) Å s cm ergs 10 x ( Flux

) Å s cm ergs 10 x ( Flux −1 −1 −2 −12 −12

−1 −1 −2 −13 −13 . Errors are plotted in red. 2 1200 FUV instrumentation requires testing and calibration in hi The collimator vacuum skin tapers to 17.26 inches and couple Figure 6.HD Spectra 34078 were during also target acquisitionpreviously obtained observed and for by maneuvering. regions the Below Hopkins awayemission i Ultraviolet of from Telescope H th , a Cassegrain telescope, with a 381 mm primary diameter, a foc optical system has traditionally been challenging. We have vacuum skins provided by Wallops Flight Facility (Burgh et a instrument section where it shares a vacuum with the Telesco Æ Æ Figure 7. JHU Sounding Rocket Group Windowless Vacuum Ultra to avoid contamination, operateatmospheric microchannel attenuation plate of detect FUVto light. build and Large maintain, vacuum calibra and as a consequence,used end-to-end in test calibrating the Far Ultraviolet Spectroscopic Expl This allows for full end-to-end pre/postflight testing and c us to clearly distinguish between the profile of extended neb field determination. A computer controlled motorized stage the LSF has enhanced the capabilities of the JHU sounding roc scattered light (Burgh et al. 2001).non-uniformities Flat and permits fielding gives a us more a complete b calibration. light sources: a gas discharge pinholelamp lamp and for a point Bayard-Alpert source ion gauge for filled aperture experi coated optics for improved FUV reflectance. ent, and detector effects. In addition to the stellar and neb Wavelength (Å) mi- torr). 5 Control lectronics. 10 1400 1100 projected on ¢ is sealed by a JHU/NASA 36.198 UG - IC 405

few 200 C II C ¢ < am, with a focal ratio pider’ that is fastened P riate time in flight. The lses (three 16-bit words (12 1300 adout by a double delay- he spectrograph achieves torr, and isolated from the emetry section. 8

10 H I H 

1200 C III C a, after corrections for maneuvering, spectrograph alignm ˚ A. riment. – Error plotted as red broken line. tar in IC 405, overplotted with a Kurucz stellar model 1000 3 Rocket Observations of IC 405  atomic and molecular hydrogen absorption (using a column Wavelength (Å) 1100 2 H Far-UV Stellar Spectrum 1000 Sounding Rocket Experiment contains an evacuated Rowland Circle spectrograph, using a consists of the Faint Object Telescope (FOT) and an Attitude 900 is passively evacuated and houses all the experiment flight e 0 50

900 8 6 4 2 0

−50

) Å s cm ergs

Flux ( x 10 x ( Flux −100

−1 −1 −2 −11 −11 Arcseconds 16 and SiC coated optics. The aft end of the telescope section  vacuum door. crochannel plate stack detector with aline anode. KBr The photocathode, spectrograph re is kept at a vacuum of A mirrored slitjaw lies at the telescope focus and a long slit the sky) defines the entrance aperturea to pointing the limited spectrograph. spectral resolution T of spectrograph section by a gatevalvespectrograph that and opens telescope at sections the share approp a common vacuum ( of System (ACS) startracker mounted aftto of an the invar heat telescope shield. on The a FOT is ‘s a 40 cm diameter Dall-Kirkh per event) and directs them to a parallel interface on the tel An onboard telemetry interface collects the raw detector pu Spectrograph Section extincted by a Fitzpatrick anddensity Massa of parameterization, 21.15, and dominated by T = 80 K) along the line of sight Telescope Section Figure 3. Flux calibrated spectrum of HD 34078, the central s Æ Figure 4. Raw flight data of HD 34078 and the surrounding nebul Æ Figure 5. A schematic diagram of the JHU sounding rocket expe Æ Avionics Section Kevin France, Stephan R. McCandliss, Paul D. Feldman (JHU), ) = R 12 ned by ¢ stellar flux 100 10-15 at  Brant IX sounding g slit (200 ce HD 34078 into the to experiment turn-off e Range, New Mexico rocket mission (36.198 (HD 34078 – O9.5 Ve) 50 pointing was adjusted to 6.0 and mildly extincted, ˚ A. This is in contrast with ditional nebular pointings having been ejected from es a setting to study a star = raviolet Telescope showing camera imaging the slit jaw the nominal target, and this ime ACS command uplinks ows absorption from molec- bula. The flux at the second 00 quality (S/N 600 ˚ A wavelength region. Several , V nd Figure 3 shows the spectrum ground. cloud and star are approximately a prior sounding rocket observa- us and ), then reorienting 400 0 airglow). Postflight determination of the instrument α ayed and East in the negative x direction (courtesy of 200 e extension of the nebula beyond the stellar peak. LSF he dashed lines represent the portion of the spectrograph g Ly- Arcseconds 0 −50 Abstract Arcseconds −200 −400 −100 Spectral Flight Profile Postflight Measurement Sounding Rocket Observations 0 −600 500

1000 −500 ). Observations of the nebula reveal a surface brightness to

4 North), on 09 February 2001 at 21:00 MST. The target is obtai 2 Arcseconds 53 . Æ : 0 : −150 fluorescent emission. −1 −2 −3 −4 −5 0

10 2

10 10 10 10 10 = slit of length over Histogram µ V 3 West, 32

This experiment was launched aboard a Mark 70 Terrier-Black Æ : field-of-view). Fine adjustments are performed with real-t Data was obtained of IC 405 from our arrival at the target field We present the preliminary results from a NASA/JHU sounding B ´ IC 405 is a diffuse nebula in whose central star, AE Aur two previously defined offsets tooffset sample position other was parts not of appreciably the different than ne the back of HD 34078 measured by the experiment. During the flight, the to argon jets. (T +150 – T +490 seconds).slit. The The star command was uplinks in were the used spectrograph to slit for pla 106 seconds, a rocket (NASA flight number 36.198(106 UG) from White Sands Missil Æ spectrum of the reflection nebula IC 405 in the 900 – 1400 Æ Figure 1. 0.9m KPNOTravis Rector, image NRAO). of IC 405, with slit positions overl is passing through the nebula with a highinteracting proper with motion a nebula after not associated withcospatial its at birth. a distance The of 446 pc. HD 34078 is visually bright the roughly 2.5 million years ago. IC 405 provid E UG), launched on 09 February 2001 at 21:00 MST, to obtain a lon 300) spectrum of the central star, HD 34078, which clearly sh ular hydrogen (H pointings within the nebula were obtained, including a high measurement discussed below. slit unaffected by instrumental vignetting. One notices th line-spread-function (LSF) reproduces the flight profile. T referencing the startracker to twoto bright the guide target. The (Siri obtainedfield field is is relayed to within the a ground few in arcminutes real-time of through a Xybion TV (20 Figure 2. Spatial profile of the flight data in black (excludin ratio that rises by two orders of magnitude between 1400 and 9 tion of the reflection nebula NGCwithin 2023. IC 405, We including will a also region presentevidence observed of ad by H the Hopkins Ult the relatively flat nebular dust scattering observed during Fig. 1.—

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