a. o. h. olofsson et al- a spectral line survey of orion kl in the bands 486–492 and 541–577 ghz...

8/2/2019 A. O. H. Olofsson et al- A spectral line survey of Orion KL in the bands 486492 and 541577 GHz with the Odin sat

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A&A 476, 791806 (2007)DOI: 10.1051/0004-6361:20077229c ESO 2007

Astronomy&

Astrophysics

A spectral line survey of Orion KL in the bands 486492

and 541577 GHz with the Odin satellite

I. The observational data

A. O. H. Olofsson1,2, C. M. Persson1 , N. Koning3, P. Bergman1,4, P. F. Bernath5,6,7, J. H. Black1, U. Frisk8,W. Geppert9, T. I. Hasegawa3,10, . Hjalmarson1, S. Kwok3,11, B. Larsson12, A. Lecacheux13, A. Nummelin14,

M. Olberg1, Aa. Sandqvist12 , and E. S. Wirstrm1

1 Onsala Space Observatory (OSO), 43992 Onsala, Swedene-mail: [email protected]

2 LERMA, Observatoire de Paris, 61 Av. de lObservatoire, 75014 Paris, France3 Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4, Canada4 European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago, Chile5 Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA6 Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada7 Department of Chemistry, University of York, Heslington, York YO10 5DD, UK8 Swedish Space Corporation, PO Box 4207, 17104 Solna, Sweden9 Molecular Physics Division, Department of Physics, Stockholm University AlbaNova, 10691 Stockholm, Sweden

10 Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 106, Taiwan, R.O.C.11 Department of Physics, University of Hong Kong, Hong Kong, PR China12 Stockholm Observatory, AlbaNova University Center, 10691 Stockholm, Sweden13 LESIA, Observatoire de Paris, Section de Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France14 Computer science and engineering, Chalmers University of Technology, 41296 Gteborg, Sweden

Received 2 February 2007 /Accepted 30 August 2007

ABSTRACT

Aims. Spectral line surveys are useful since they allow identification of new molecules and new lines in uniformly calibrated datasets. The subsequent multi-transition analysis will provide improved knowledge of molecular abundances, cloud temperatures anddensities, and may also reveal previously unsuspected blends of molecular lines, which otherwise may lead to erroneous conclusions.Nonetheless, large portions of the sub-millimetre spectral regime remain unexplored due to severe absorptions by H2O and O2 inthe terrestrial atmosphere. The purpose of the measurements presented here is to cover wavelength regions at and around 0.55 mm regions largely unobservable from the ground.Methods. Using the Odin astronomy/aeronomy satellite, we performed the first spectral survey of the Orion KL molecular cloud corein the bands 486492 and 541576 GHz with rather uniform sensitivity (2225 mK baseline noise). Odins 1.1 m size telescope,equipped with four cryo-cooled tuneable mixers connected to broad band spectrometers, was used in a satellite position-switchingmode. Two mixers simultaneously observed different 1.1 GHz bands using frequency steps of 0.5 GHz (25 h each). An on-sourceintegration time of 20 h was achieved for most bands. The entire campaign consumed 1100 orbits, each containing one hour ofserviceable astro-observation.Results. We identified 280 spectral lines from 38 known interstellar molecules (including isotopologues) having intensities in therange 80 to 0.05 K. An additional 64 weak lines remain unidentified. Apart from the ground state rotational 11,010,1 transitions ofortho-H2O, H182 O and H172 O, the high energy 62,471,7 line ofpara-H2O (Eu = 867 K) and the HDO(20,211,1) line have been observed,as well as the 1001 lines from NH3 and its rare isotopologue 15NH3. We suggest assignments for some unidentified features, notablythe new interstellar molecules ND and SH. Severe blends have been detected in the line wings of the H182 O, H

172 O and

13CO lineschanging the true linewidths of the outflow emission.

Key words. ISM: individual: objects: Orion KL ISM: lines and bands ISM: molecules line: identification submillimeter surveys

Odin is a Swedish-led satellite project funded jointly by theSwedish National Space Board (SNSB), the Canadian Space Agency(CSA), the National Technology Agency of Finland (Tekes), and theCentre National dtudes Spatiales (CNES, France). The Swedish

Space Corporation (SSC) was the industrial prime contractor and is alsoresponsible for the satellite operation. Appendix B is only available at electronic form athttp://www.aanda.org

1. Introduction

Being the most popular target for spectral line surveys, in theOrion KL position OMC-1 has been the focal point of at least20 observational efforts in the mm and submm bands over

the last 20 years, starting with Johansson et al. (1984, 1985),and in the frequency range 7291 GHz. White et al. (2003)provide an extensive list of this earlier work in their intro-duction. Using the James Clerk Maxwell Telescope (JCMT),

Article published by EDP Sciences and available at http://www.aanda.org or http://dx.doi.org/10.1051/0004-6361:20077229
http://www.edpsciences.org/http://www.aanda.org/http://dx.doi.org/10.1051/0004-6361:20077229http://dx.doi.org/10.1051/0004-6361:20077229http://www.aanda.org/http://www.edpsciences.org/


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792 A. O. H. Olofsson et al.: A spectral line survey of Orion KL in the bands 486492 and 541577 GHz with the Odin satellite. I.

White et al. (2003) surveyed the bands 455469 and 492507 GHz, surrounding the lowest frequency range of ourOdin spectral scan (486492 GHz). The frequency range 607725 GHz, just above the Odin spectral scan band 542576 GHz,has been surveyed by Schilke et al. (2001) using the CaltechSubmillimeter Observatory (CSO).

More recent additions include 159.7164.7 GHz (Lee &Cho 2002), 795903 GHz (Comito et al. 2005), 260328 GHz(Yoshida & Phillips IAU 2311), and an IRAM 30 m survey(168 GHz in three windows between 80 and 281 GHz) byTercero et al. (IAU2311).

The first imaging line survey of Orion KL in the submmrange (337.2339.2 and 347.2349.2 GHz) was recently re-ported by Beuther et al. (2005), who used the SubmillimeterArray interferometer. They later employed the same instrumentto make measurements around 680 and 690 GHz with similarbandwidths (Beuther et al. 2006).

The luminous Orion Kleinmann-Low infrared nebula(Orion KL; L 105L), and its surrounding molecular cloud,

is the nearest (distance of 450 pc) and probably most studiedmassive star formation region in the sky. A very useful reviewhas been written by Genzel & Stutzki (1989); for reference up-dates see e.g., Olofsson et al. (2003), and Wirstrm et al. (2006).Here we summarise some source component designations anddynamical properties particularly relevant to the molecular lineidentification work in the current presentation of our Odin spec-tral scan data, which includes our molecular line assignments (inthe Online Table 6).

Odins circa 126 antenna beam is centred on the mostprominent infrared point source in the KL nebula, IRc2(RA05h35m14.s36, Dec. 052229.6 (J2000)). The Orion hotcore source, with a size of only 10 and centred only 2 Sof IRc2, is a warm (200 K, or even higher; cf. Sempere et al.

2000), dense (107 cm3) clump or rather collection of clumps,characterised by a spectral line width of 515 kms1 centredon vLSR = 36 km s1 and exhibiting emission from nitrogen-containing species at markedly enhanced abundances. The out-flowing gas, or theplateau source, with a size of 4060,maybecharacterised in terms of a bipolar high-velocity flow elongatedin the SE-NW direction (reaching velocities of100 km s1),and a SW-NE extended low-velocity flow (the 18 km s1 flow)of size 1530, centred on 10 and 5 km s1, respectively. Furtherdetails on the complex structure of the outflow such as a cen-tral jet and localised bullet type emission within the high ve-locity flow are nicely revealed by the IRAM 30-m CO J = 21maps by Rodrguez-Franco et al. (1999). Within the Odin 126

antenna beam there is also an N-S extended quiescent molecu-lar cloud structure (the ridge), with densities of 104106 cm3

and temperatures in the range 2060 K, and characterised byline widths of 35 km s1 and an abrupt velocity shift across theKL nebula from vLSR = 8 km s1 (in the south) to 10 km s1 (inthe north). The large-scale chemical structure of many importantridge molecules is outlined in Ungerechts et al. (1997).

The interaction between the bipolar high-velocity outflowand the surrounding ridge gas produces shock heating andshock enhanced chemistry, markedly visible in terms of brightH2 emission, strong high-J CO lines and uniquely strong emis-sion from abundant H2O (Melnick et al. 2000; Olofsson et al.2003). Also the roughly orthogonal low-velocity outflow com-ponent appears to interact with the ambient gas, creating density,

1 Poster contributions at Symposium No. 231 of The InternationalAstronomical Union, Asilomar 2005. Abstracts available athttp://asilomar.caltech.edu/

temperature and column density enhancements in the ridge gas.One such feature is the compact ridge cloud (v = 3 km s1;vLSR 8 km s1) situated only 1015 S of IRc 2, on the north-ern tip of the 8 kms1 ridge cloud, where complex oxygen-containing molecules have been observed to be abundant. Thehot core itself might also be a result of shock-induced compres-

sion. A recent finding along these lines is enhanced [CI] forbid-den line (3P23P1) emission north and south of IRc 2 (in a shellof radius 20, where the outflow encounters ambient gas), andproposed to result from CO dissociation in shocks (Pardo et al.2005).

Although the major source constituents are commonly dis-cussed in the literature as outlined above, we caution readersthat observations yielding higher spatial resolutions (e.g. Blakeet al. 1996; Wright et al. 1996; Beuther et al. 2005, all employ-ing aperture synthesis) reveal that the KL core composition is infact more complex and breaks down into further sub-structuresof sizes 103 AU.

We present here the observational results and line identifica-tions. Numerical analyses such as column density and rotationtemperature estimates are included in an accompanying paper inthis A&A issue (Persson et al. 2007, Paper II hereafter).

2. Observations

The present data-set was obtained in a four-part campaign run-ning over 1.5 years, starting in spring 2004(Feb.Apr.), followedby fall 2004 (Aug.Oct.) and continuing in the same mannerin 2005. This division naturally arises from the combination ofsource coordinates and Odins orbital plane (Sun-synchronouslow Earth orbit) leading to seasonal visiblilty constraints for low-declination sources such as the Orion nebula.

The dedicated observing period spanned over 1100 revo-

lutions with a very high success rate due to consistently stablespacecraft performance. Each orbit allows 61 min of astronomi-cal observations, whereas the source line-of-sight is occulted bythe Earth and its atmosphere for the remaining 35 min of theorbital period. We employed position switching (PSW) in orderto acquire cold sky reference spectra. This was implemented byregularly reorienting the entire spacecraft by 15 in RA witha cycle time of 1 min, carried out by the onboard momentumwheels. The resulting efficiency penalty for slew time was low(


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A. O. H. Olofsson et al.: A spectral line survey of Orion KL in the bands 486492 and 541577 GHz with the Odin satellite. I. 793

30003500 K with few exceptions as measured by switching be-tween the main beam and a hot load at room temperature. For agiven tuning, Tsys doesnot changein time by morethan a few per-cent due to the stable conditions and no interfering atmosphere.

The observing strategy was to tune the receivers in 0.5 GHzsteps and observe for 25 orbits. The resulting overlap in be-

tween adjacent tunings gives a net on-source integration timeof 50 61 0.8/2 20 h per channel. This commonly used ap-proach was adopted to reduce potential impacts of artificial spec-tral patterns/transients or baseline effects which could arise inone tuning but conceivably not in both.

Three spectrometers were used: one acousto-optical spec-trometer (AOS) and two hybrid autocorrelators (AC1/2). Theformer has a bandwidth of 1.1 GHz and a channel spacing of620 kHz, while the latter two can be used in several modes. Inthe low resolution mode used here, the bandwidth is 700 MHzwith 1 MHz channel spacing. The AOS and the ACs have ratherdifferent characteristics and therefore we have used slightly dif-ferent approaches in building the final spectra, hence the divisioninto two parts of the next section.

3. Data reduction

The data reduction has been performed in two parallell, indepen-dent efforts by members of the Odin Team situated at the OnsalaSpace Observatory and in the University of Calgary. The spec-tra presented in this paper are the products of the data reductionat Onsala. The very similar Calgary results have been used toverify the quality of the spectra shown here. Although a few dif-ferences were found for lines at a level below 0.1 K (or below 4in terms of the baseline noise), we are encouraged to believe thatthe majority of such weak lines are real.

3.1. AOS and data from RX549/RX555

3.1.1. Calibration and averaging

There were essentially three complicating factors that neededspecial consideration in these data sets.

Frequency correction: by using telluric ozone and water (andoccasionally rarer lines during the occultation phase, the ca-pability exists to check the frequency setting to a very highaccuracy, as is illustrated in Fig. 1. It was found that therewas an offset of 05 MHz from the commanded value lean-ing towards the upper value most of the time. Furthermore,

on a few occasions the off

set was seen to change instanta-neously by 23 MHz in mid-observation between two ap-parently stable offset levels. Thus it was deemed necessaryto register telluric frequency references at all times and cor-rect the astronomical spectra accordingly. If no atmosphericlines were present in a particular tuning, overlapping astro-nomical lines inherent to a different but adjacent tuning witha known frequency correction, were cross-correlated to findthe proper correction. This method gave consistently posi-tive results and we now believe that the absolute frequencyuncertainty is 1 MHz (0.5 km s1) at worst.

Channel dependent RMS: probably owing to the large band-width of the AOS, the system temperature profiles had rathersteep gradients towards the upper and lower edges, often

leading to noise temperatures in these portions twice themid-spectrum values. When averaging together two adjacenttunings, the low-noise central channels from one tuning willbe combined with the high-noise edge channels of the other.

17020 17025 17030

6

4

2

0AOS jump

Comb response

Offset[MHz]

Orbit number

Fig. 1. Tracing the frequency deviation using the telluric H172 O line. Asis evident, there was an early sudden shift of the line position, corre-sponding to an AOS laser mode jump during warming up a smallpenalty because of our shared astronomy/aeronomy mission. The timesof such shifts can be determined accurately since they a ffect the totalpower levels of the spectrometer. The gray dashed line shows the cor-rection applied to the data from this sample observation.

This has been taken into account in the weighting procedureby letting the most recently measured Tsys profile representthe formal noise in each channel of the the next spectrumto be included in the average. Provided that the integrationtimes and resolutions are all the same, and that we have agood linear correlation between Tsys and the channel RMS,this approach is easily justified.

Side-band suppression: In general, we have very good sup-pression of the undesired image band (20 dB in at least onetuning). In the RX555 tunings, there is one exception wherethe appearance of an image SO line indicates a suppressionof only 10 dB. Similarly poor SSB suppression was seen

more frequently in the RX549 data through the emergenceof telluric image ozone lines in occultation phase data. As isevident in the final result, we had in general more problemswith high Tsys and unexplained baseline ripples in this fron-tend/backend configuration, probably related to the poorerSSB performance. In those cases where image lines wereseen in the final average (almost exclusivelydue to the strongH2O and 13CO lines at 557 and 551 GHz, respectively),the appropriate channels were excluded to remove the inter-ference. The complementary tunings certified that no gapswere created in the total average, although the noise is vis-ibly higher in these portions due to less net observing time.Potential low-level image line intrusions are in general suffi-

ciently weakened not to be seen in our baseline noise, owingto the satellite motion Doppler correction which serves todisperse image band signals.

Other pre-averaging measures consisted of first linearising thereadouts of the AOS aided by internal frequency comb measure-ments, then resampling the AOS spectra to whole MHz to matchthe AC resolution.

The individual spectra each represent one on-source obser-vation in the PSW cycle which is equivalent to 24 s integrationtime. During one such observation, the variation of the projectedsatellite orbital velocity in the direction of the source is not takeninto account which introduces a slight spectral smearing of as-tronomical lines. However, the magnitude of the Doppler shift

change at most amounts to 200 ms

1 and is considerbly lessfor the major part of the orbit.The baseline stability was very good (Sect. 3.1.2) and no

fits were subtracted from the spectra in the averaging procedure.


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2004 2004.5 2005 2005.5

0

0.2

0.4

0.6

0.8

0.45 K

RX 555 RX 549

TA

[K

]

LEVELS

2004 2004.5 2005 2005.5

0.2

0

0.2

Observation date [yr]

[K/(0.5

GHz)]

SLOPES

Fig. 2. Baseline levels and slopes in 52 RX555 and RX549 observationsbefore any baseline subtractions. The error bars in the upper panel cor-respond to 3. The slopes are measured as the level difference of twohalves of the spectra whose centres are separated by 496 MHz. This fig-ure indeed highlights the stability of the receiver/AOS/calibration chain,but the upwards trends of the levels towards the ends of both spring ob-serving runs remain unexplained. There is also an observation that inex-plicably appears to lack continuum signal (while telluric spectral linescould still be detected).

However, to obtain accurate line property estimates for the veryweak features, we opted to subtract a piecewise linear fit fromthe broadband end products, putting the baseline level at zeroaround clearly detected emission lines.

3.1.2. Baseline stability/continuum level

We have estimated the dust continuum beam averaged antennatemperature around 550 GHz using the spectra from the RX549and RX555 receivers. One value was extracted for each tuningas shown in Fig. 2 and the average amounted to TA = 0.45 K(1800 Jy beam1).

Due to the crowding of strong lines in some tunings, this cal-culation relied on noise statistics and did notrequire that the po-sitions of lines were known beforehand. The assumptions madewere instead i) at least half the channels in a spectrum werelargely unaffected by emission lines, ii) the baselines are largelyflat compared to the noise scatter of the intensity in individualspectra, and iii) the noise is Gaussian and the RMS is well de-scribed by its formal value derived from the radiometer formula.

The simple procedure was then to sort all channels accord-ing to increasing intensity and select the bottom half of thedistribution (the top half is contaminated by emission lines).Statistically, the expectation value of the distribution is thenfound by adding 0.8RMSformal to the mean value of the se-lected low-intensity channels.

To further remove effects of baseline variations, and to geta handle on the baseline stability, each spectrum was dividedinto two 500 MHz subspectra on which the calculation describedabove were performed. The average difference between the two

halves in each tuning then additionally supplied an indication ofthe first order trend (or slope) of the baselines. Figure 2 also il-lustrates the results found here. Although it is obvious that a sys-tematic baseline pattern was present throughout the RX549 ob-servations, the RX555 baseline performanceis quite satisfactory.

3.2. ACs and data from RX495/RX572

The 700 MHz AC spectra are created by stitching together seven112 MHz portions. To achieve the double coverage of each fre-quency interval as we do with the AOS, one AC was split intotwo portions, 3+4 subbands, and placed on each side of the otherAC that covered the central 700 MHz in the passband.

Each such sub-band is typically well behaved in terms ofhaving Gaussian noise and a uniform gain curve. However, inthe PSW observing mode there is for unknown reasons a lin-ear falloff in channel intensity from the start of each on and offsequence. Due to the inescapable slight asymmetry between on

and offmeasurements, and to the fact that the drift rate changesgradually over the channels in one sub-band, the calibrated spec-tra end up with a low-level curved saw tooth-like appearancewith two sub-bands forming each tooth. This pattern has beenremoved by using high-order polynomials after careful compar-isons with the results obtained by calibrating each sub-band sep-arately. Around the extremely broad CO line at 576.3 GHz, thismethod failed and the corresponding two tunings were insteadcured by employing a corrective procedure that nullifies the ef-fects of the intensity drift mentioned above but is very time-consuming.

The uppermost 200 MHz of the RX495 spectrum wereacquired from a tuning that suffered instability; the LO alter-nated between being properly locked and oscillating betweenfrequencyoffsets of33 MHz. Using the recorded IF current andthe amplitudes of the [CI] forbidden line line at 491.7 GHz (vis-ible in individual spectra, TA 6 K) as guides, about ten minutesof integration was recovered. In spite of the higher noise levelthus obtained, we chose to include this spectral section since itcontains two strong lines, the [CI] and a low-energy methanoltransition (TA 1.2 K).

We did not find any evidence of image band lines interferingin the signal side band for these two receivers, nor did we findany significant frequency offsets (at most 1 MHz) from nomi-nal values in telluric line position controls in sample tunings.

4. Results

4.1. Summary

Table 1 lists some general figures and characteristics for the sur-vey as a whole. As is evident from this Table, our integrated in-tensity is dominated by the continuum emission by a ratio of 5:1(see Sect. 3.1.2 for details). The line-to-continuum ratio foundhere, 20%, is much lower than that at 350 GHz, 50%, but ratherclose to the 15% found at 650 GHz (Schilke et al. 2001). For alarger telescope (such as the Herschel Space Observatory) onecan expect this value to increase somewhat due to increased in-

tensity from the abundant lines from the compact line sources(


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Table 1. Survey overview.

Property ValueBandwidth covered 42 GHzNumber of lines detecteda 344Line density 8 GHz1 (range: 420)

Line intensity range 0.0580 KNumber of species detectedb 38Typical RMS reached 25 mK/1 MHz channelTotal

TA dv 2455c/2525d K k m s1

Total line luminositye,f 5 1026 WMean line-to-continuum ratiog 0.2

a Incl. U- and T-lines (see Sect. 4.4). b Including isotopologues and C i.c Over all lines detected. d Over all measured frequencies. e Using theexpression 2.65Tr/ where = 2.1 and is given in centimetres, tofind the flux density per beam. f Using a beam-filling correction factorof 1.25 for data near 490 GHz. g Near 550 GHz.

4.2. Spectra and identifications

The final spectral scan results from the four receivers can be seenin Figs. A.1A.4. The frequency scale is counted w.r.t. a sourcevelocity of vLSR = +8 km s1, and markers are placed at thelaboratory rest frequencies of the transitions attributed to the linefeatures.

The general method for identification was to select the mostplausible species after comparisons with available moleculardatabases2 (SLAIM03: Lovas 2003; CDMS: Mller et al. 2001;JPL: Pickett et al. 1998) of predicted/calculated or directlymeasured transition frequencies (SLAIM03 contains both kindswherever available). The selection criteria included: frequencycoincidence, expected abundance, line strength, line width, linevelocity, and upper state energy. Where possible we have also

used rotation diagram analysis (cf. Goldsmith & Langer 1999)to guide our identification, as discussed in Paper II.In the case of marginally detected line features suspected to

arise from more complex molecules such as dimethyl ether andmethyl formate, we also required that other lines of similar ex-pected emission characteristics be visible at other frequencieswithin the observed bands.

It is important to note that any conceivable artificial sharpfeatures produced in the radiometer would likely be stable inthe sky frequency rest frame and thus would be significantlysmeared here since the satellite motion Doppler correction ofeach spectrum varies between 7 and +7 km s1 over one orbit.

The line counts, upper state energy ranges and total inte-grated intensities for each detected molecule are listed in Table 2.

All identifications (molecule and laboratory rest frequency) canbe found in Table 6 (available on line).Also of interest here are the spectral offsets of the measured

lines relative to the laboratory frequencies. We have estimatedthese from the value found at the peak intensity channel of thelines (assuming a systemic emission velocity of+8 km s1) andthey are listed in full in Paper II. The average offset per moleculeis 0.6 MHz but this cannot be used as a quality measure of thedata fidelity nor the accuracy of tabulated rest frequencies sincedifferent molecules emit at different velocities (as is likely re-flected by the highdispersion, 3.2 MHz). In addition, these emis-sion velocities are often instrument-dependent due to varyingbeam fillings of the different source components. Nonetheless,

2 On line locations at http://www.cdms.de/ (CDMS) http://spec.jpl.nasa.gov/ (JPL) (SLAIM03 is not available on line butsome of its content is maintained under http://physics.nist.gov/PhysRefData/).

Table 2. Summary of all detected species.

Species Number Energy range

TA dv[K] [K k m s1]

CH3OCH3 47 106448 18.3SO2 42 75737 239.934SO2 5 79-457 2.6SO 5 71201 181.533SO 3 191199 6.534SO 2 191197 15.6CH3OH vt = 1 42 332-836CH3OH 34 38863 108.613CH3OH 21 37499 6.813CH3OH vt = 1 2 373670CH3CN 17 4101012 9.3NO 12 84232 11.1CN 8 54 8.5H2CS 5 138343 1.7H2CO 3 106133 38.5H132 CO 1 130 0.6HDCO 3 114141 2.8OCS 3 604658 1.3o-H2O 1 61 320.3p-H2O 1 867 2.2o-H172 O 1 61 9.4

o-H182 O 2 60430 16.2HDO 1 66 10.7HC3N 2 648799 0.6CO 1 83 110013CO 1 79 174.3C17O 1 81 6.0C18O 1 79 24.3C 1 24 38.7NH3 1 27 20.615NH3 1 27 0.7

HNC 1 91 10.7N2H+ 1 94 1.5H2S 1 166 4.4CS 1 129 2413CS 1 173 v blendSiO 1 190 17.629SiO 1 187 1.430SiO 1 185 0.5HCS+ 1 186 v blendNS 1 442 v blendU-line 28 9.1T-line 36 7.2

by choosing the 35 strongest lines of methanol (which conve-niently has narrow emission lines), we minimise this effect andget a dispersion of only 1.1 MHz. While this is slightly higherthan the stated estimated frequency uncertainty of our spectra,there are a number of possible remaining explanations asidefrom data error such as lab measurement/calculation error andline blending.

4.3. Important line blends

A means to identify and subsequently remove interferinglines is helpful, particularly in the detailed study of line shapes(where the signal-to-noise ratios of the lines are such that this is

feasible).It now seems convincingly clear that the line wings of therarer isotopologues of water and carbon monoxide are affectedby emission from SO2, 34SO2, CH3OH and CH3CN. Fortunately,


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the emission from these species can be accurately modelled dueto the wealth of other lines from these species present in ourband, allowing determinations of column densities and excita-tion temperatures. We have in the course of our analysis tried toreconstruct the true shapes of some lines by subtracting pollut-ing emissions from our spectra, and in Paper II one successful

example is demonstrated (H172 O).We caution that this approach is only useful in contexts

where the interfering lines emit in an optically thin portion ofthe main line (or if the gas is stratified so that the optically thinline arises in the near side of the gas column). For instance, wedo not find it likely that the SO2 line at 556.960 GHz signifi-cantly alters the profile of the main water line (at 556.936 GHz)since i) the optical depth towards the centre of the water lineis very large, and ii) according to the interpretation in Olofssonet al. (2003) the High Velocity Flow as seen in water is locatedin front of (or around) the Low Velocity Flow from which thesulphur oxide lines mainly originate, as evidenced by their linewidths and source size.

4.4. Unidentified line features

We have defined U-lines clearly detected lines well distin-guished from the baseline noise and T-lines, which are onlymarginally visible (T for Tentative) against the noise, or in anapparent line blend. The lines of both types are marked in thespectra and listed in Table 3.

We have in some cases found candidate species (Table 3)which have not fulfilled all our criteria for an unequivocal des-ignation and they are kept as U- or T-lines. Some of the moreinteresting scenarios are discussed below.

4.4.1. New SO+ lines?

Interstellar SO+ was first detected in the shocked clump IC443G,presumably being formed in the dissociative shock caused bythe supernova remnant (Turner 1992). Our weak unidentifiedlines at 486.845 and 487.209 GHz tentatively can be identifiedas the J = 21/219/2 e and f doublet of the reactive radical SO+

in its 21/2 ground state (JPL; Amano et al. 1991). The sug-gested assignment is consistent with the detection in Orion KLof lower energy SO+ lines at 115.804, 116.180, 208.590, and255.353 GHz (Turner 1994). Our assignment is further strength-ened by the U-line at 347.743 GHz observed by Schilke et al.(1997) which we identify here with the J = 15/213/2 e tran-sition of SO+ at 347.740 GHz. However, the corresponding f

transition at 348.115 GHz is hidden in a blend with 13CH3OHand 34SO2.

4.4.2. Other notable frequency coincidences:SH and ND

Our weak, slightly broad lines near 546.138 and 546.176 GHzcould be associated with the NJ = 1101 hyperfine transitioncluster of the ND radical in its X3 ground vibronic state(CDMS; Saito & Goto 1993; Takano et al. 1998). If so, thestrongest component is at a blue-shifted position closer to theHot Core velocity, in agreement to what is seen in other nitrogenhydrides such as NH2 (which we tentatively conclude to be blue-

shifted after studying the 900 GHz spectral survey of Comitoet al. 2005 in detail). NH3 on the other hand discussed furtherin Paper II has a 60% Hot Core contribution but this is heav-ily masked by its optical depth in both the Hot Core and in the

Table 3. Unidentified (U) and/or marginally detected (T) lines.

Frequency Type Sugg. Table[MHz] [U/T] ident. continued486 845 T SO+ 555 9 14 T 487 209 U SO+ 555 9 33 T

487 507 T CH3CHO 556 267 T 488 477 T 556 633 T 488 598 U CH3OCHO 559 239 U CH3OCHO488 633 U CH3CHO 559 816 T HDO489 193 T 559 861 U CH3OCHO489 709 T SiS 559 913 U 491 496 U CH3OCHO 560 753 T 491 892 U 561 971 U 541 926 T 562 118 T 541 981 U CH3OCHO 562 960 U 542 945 U 563 033 U 543 873 U 563 481 T HNCO544 016 T SiS 564 105 U

546 138 U ND 564 418 T SH

546 176 T ND 566 066 U 546 662 T 567 485 U 546 805 T 569 138 U HNCO547 080 T 570 303 U 547 162 T 570 335 T 547 262 T HNCO 570 790 T 549 142 T HNCO 570 814 T 549 199 T HNCO,H2CS 571 151 T HNCO549 449 U 571 217 T HNCO549 719 T SO2,(CH3)2O 571 477 T H2C18O550 132 T SO2 572 5 96 U 552 308 U 572 678 U

552 846 T 574 184 U 553 667 U CH3OCHO 575 397 T 553 716 U 576 446 U 555 312 T 577 160 T

Compact Ridge. Unfortunately, the predicted shape of the linebundle as a whole does not match the observation and one wouldneed to invoke non-LTE excitation to explain this difference.

A weak unidentified line at 564.418 GHz may originate inthe J= 10 rotational transition of SH in its X1+ ground state,measured to fall at the frequency 564.422 GHz (Civi et al.

1998). A new interstellar anion would be of utmost interest sinceonly one has been found previously, namely the discovery ofC6H which was recently reported by McCarthy et al. (2006).Thus although our line is not strong enough to claim a detec-tion (3.5 relative to the local noise) we chose to perform avery simple column density calculation (or an upper limit thereofif the line turned out false). By employing the LTE assumptionwith full beamfilling, an excitation temperature of 100 K, anda dipole moment of 0.273 D (adopted from the ab initio cal-culations of Senekowitsch et al. 1985), we arrive at a figure ofNSH = 2 1013 cm2. The scenario used would be consistentwith SH residing in the extended OMC-1/M42 face-on PDR(discussed in Wirstrm et al. 2006). Should the origin of the line(if real) be any of the smaller Orion KL components as indeed

the observed line width (vFWHM = 11 kms1) seems to indi-cate the column density rises by a factor of200. We deemat least the PDR column density to be a reasonably low valuein light of the rather unknown chemistry of similar hydrides in


7/21


the interstellar medium. The SH radical, for instance, has onlybeen found in the atmosphere of a Mira variable through mid-IR transitions (Yamamura et al. 2000). Nevertheless, a possiblecontribution from SH in a C3 spectrum towards Sgr B2 has beenreported by Cernicharo et al. (2000). We also note that a for-mation pathway exists involving H2S (via dissociative electron

attachment), a molecule observed by Odin in the present surveyand treated in Paper II.Both these candidates (marked by gray arrows in the spec-

tra figures) can be confirmed or ruled out by the forthcomingHerschel mission (discussed further in Sect. 5). For the case ofND, the triplets of NH at 947 and 1000 GHz are also relevant.

4.5. Non-detections

Two notable non-detections have been indicated by gray arrowsin our spectra: the PH and O2 molecules. The PH line (a hyper-fine transition within the NJ = 1101 group at 553.363 GHz) hasalso been searched for in IRC + 10216 by Odin to a much higher

sensitivity by Bernath et al. (2007), and we refer to them for de-tails on the PH physical and chemical properties and its role inthe circum- and interstellar medium.The O2 line at 487.249 GHzhas previously been searched for by the SWAS satellite (havinga larger beam size) down to a sensitivity of 6.4 mK (Goldsmithet al. 2000) without success. Both O2 non-detections are consis-tent with the Odin upper limit from the ground state transition at118.750 GHz by Pagani et al. (2003).

4.6. Improvements of existing spectroscopic data

In the case of our rather weak H2CS lines, we did at first findfrequency offsets between 6 and 14 MHz systematically red-

wards of the expected values (as given in the JPL database whichindeed stated high uncertainties for these calculated H2CS fre-quencies). Prompted by private communication, an entry for thismolecule was subsequently inserted into CDMS and the new cal-culated rest frequencies found there gave very good agreementswith our measured positions in all but one line. This is an en-couraging result proving that large measured frequency offsetsare likely not to be spurious and may in some cases indicate thatthe existing tabulated spectroscopy data are offthe mark.

In the case of H2CS, new extensive laboratory spectroscopywork has kindly been performed by Eric Herbst and his collabo-rators. The resulting H2CS database will be crucial for HerschelSpace Observatory.

In general, we hope that our measured line parameters (listed

in bulk in Paper II) may be useful for accurate determination ofmolecular data such as rotational constants.

5. Discussion of future observations

No further Odin observations of this kind are currently plannedand the observation time cost for significant noise reductionwould in any case be prohibitive. However, the spectral portionspresented here will be reobserved by the Herschel space observa-tory3 and is of interest to briefly discuss what they could obtain.Herschel is a European Space Agency (ESA) satellite missionaimed at launching a 3.5 m telescope equipped with very lownoise submm/far-IR heterodyne receivers in 2008.

Most of the identified lines in this survey belong to speciesalready observed at other transitions (at both lower and higher

3 http://www.esa.int/science/herschel

frequencies) and source size estimates for the correspondingemission components are available in the literature (e.g. refer-ences in Sect. 1 and Paper II). A rough Herschel beam-filling es-timate based on these source sizes reveals that those lines will be110 times stronger in the Herschel spectrum, with the majorityleaning towards the higher end. Assuming further an observation

time of only one hour in combination with recent figures for theHerschel receiver system sensitivity, one finds that the signal-to-noise ratio will be increased by up to a factor of 20 in such a case.This will be particularly useful for the weakest lines (510)seen in the Odin survey which will be possible to study in somedetail in the Herschel spectrum. It is in this group we find nearlyall the unidentified lines and the potential for new discoveriesamong them is obvious. The interesting frequency coincidencesof SH and ND described earlier are good examples. The inter-pretation of these and even weaker lines runs, however, the riskof being hampered by line crowding and blending (already up to20 lines/GHz in our spectrum) due to the plethora of lines thatwill emerge from the noise compared to the Odin spectrum. Thisin turn will put high demands on the system baseline stability inorder to correctly disentangle the emissions. The pollutive con-tributions in the key water isotopologue lines discussed abovewill also be worsened (due to differential beam-fillings) and ona side note one can predict that this problem will arise in mostsources where Herschel observes these species.

6. Conclusions

We have conducted a spectral survey in two submillimetre win-dows largely inaccessible from the ground due to atmosphericopacity. The frequency ranges covered are: 486.4492.3 and541.5577.6 GHz. This was achieved using the Odin submmsatellite.

The spacecraft performance was generally excellent in termsof high observing efficiency and good sideband suppressionmost of the time (within the SSB receivers).

The baseline stability has been shown to be satisfactory, al-beit high-order polynomials being required in about 50% of thedata to remove a fixed pattern arising in the autocorrelators inthis particular observation setup.

Careful attention has been paid to the frequency alignmentof our data resulting in an estimated frequency error of1 MHz.

Thus, high confidence is warranted in the fidelity of the re-duced spectra. To ascertain the calibration accuracy, some lineshave also been compared to previous or later targeted Odin ob-servations using markedly different instrumental setups.

We found a total of 280 identified emission lines (some ofwhich include multiple transitions), and 28 unidentified lines.We have also pointed out a further 36 borderline detected fea-tures which in some cases have interesting candidate assign-ments such as SH and SO+.

Among the 38 detected molecules, we have four water iso-topologues seen in at least five emssion lines. These data areused in Paper II to make a water abundance analysis.

Column density estimates for all species are presented inPaper II, as well as abundance, source size, and rotation tem-perature estimates for a selection of molecules.

Acknowledgements. Generous financial support from the Research Councils andSpace Agencies in Sweden, Canada, Finland and France is gratefully acknowl-edged. We sincerely thank Frank Lovas for a CD containing his molecular spec-troscopy database SLAIM03, and the dedicated scientists at Cologne (CDMS)and at JPL for undertaking the all-important work of providing spectroscopicdata through the internet.


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Appendix A: Spectra

490.4 490.6 490.8 491 491.2 491.4 491.6 491.8 492 492.2 492.4 492.60.5

0

0.5

1

1.5

HDO

(CH

3)2O

HC

3N

CH

3OH

13CH

3OH

13CH

3OH

13CH

3OH

CH

3OH

SO

2

HD

CO

H2

CO

CI

CH

3OH

U U

Frequency [GHz]

An

tenna

tempera

ture1

.25

[K]

488.4 488.6 488.8 489 489.2 489.4 489.6 489.8 490 490.2 490.4 490.60.5

0

0.5

1

1.5

H2

O

CH

3OH*

CH

3OH

H21

8O

CH

3OH

CS

13CH

3OH

U UT T T

486.4 486.6 486.8 487 487.2 487.4 487.6 487.8 488 488.2 488.4 488.60.5

0

0.5

1

1.5

CH

3OH

CH

3OH

H2

CS

SO

13CH

3OH

13CH

3OH

H2

O

UT T T

O2

SO+

? SO+

?

Fig.A.1. The Odin spectral survey between 486.4 and 492.1 GHz (RX495). Note the intensity scaling factor of 1.25 to approximately deconvolvethe spectrum to the beam size near 557 GHz (assuming a point source). Empty markers at the intensity level of 1.25 K denote CH 3OCHO lines.


10/21


545 545.2 545.4 545.6 545.8 546 546.2 546.4 546.6 546.8 5470.5

0

0.5

1

1.5

CH

3OH

SO

2

HC

3N

SO

2

CH

3OH*

CH

3OH*

CH

3OH

SO

2

(CH

3)2O

OCS

U T T T T

ND?

Frequency [GHz]

Antennatemperatu

re[K]

543 543.2 543.4 543.6 543.8 544 544.2 544.4 544.6 544.8 5450.5

0

0.5

1

1.5

CH

3OH

SO

2

CH

3OH*

SO

2

(CH

3)2O

HNC

13CH

3OH*

13CH

3OH

CH

3OH*

CH

3OH

CH

3OH

U U T

541 541.2 541.4 541.6 541.8 542 542.2 542.4 542.6 542.8 5430.5

0

0.5

1

1.5

SO

2

SO

2

CH

3OH

CH

3OH

34SO

2

CH

3OH*

34SO

2

(CH3)2O

34SO2

CH

3OH

U UT

Fig.A.2. The Odin spectral survey between 541.4 and 547.1 GHz (RX549). Empty markers at the intensity level of 1.25 K denote CH 3OCHOlines. A star denotes a transition within a vibrationally excited state: vt = 1 for methanol, and 2 = 1 for SO2.


11/21


551 551.2 551.4 551.6 551.8 552 552.2 552.4 552.6 552.8 5530.5

0

0.5

1

1.5

13CO

SO

2

NO

*

CH3CN

(CH3)2O

NO

SO

2

*

34SO

2

H217O

SO

2

SO

2

*

(CH

3)2O

33SO

*

CH3CN

8=1

HDCO

13CH

3OH*

*

33SO

2

U T

Frequency [GHz]

Antennatemperatu

re[K]

549 549.2 549.4 549.6 549.8 550 550.2 550.4 550.6 550.8 5510.5

0

0.5

1

1.5

34SO

13CH

3OH*

SO

2

*

H2

CS

H2

CS

(CH

3)2O

SO

2

*

30SiO

*

CH

3CN

13CO

SO

2

UT T T T

547 547.2 547.4 547.6 547.8 548 548.2 548.4 548.6 548.8 5490.5

0

0.5

1

1.5

34SO

(CH3)2O

H2

CS

13CH

3OH

34SO

2

H21

8O

*

SO

2

34SO

H21

3CO

*

SO

2

C18O

SO

2

T T T

Fig.A.3. The Odin spectral survey between 546.9 and 563.1 GHz (RX555). Unlabelled markers at intensity levels 0.1, 0.5, 0.9, and 1.25 K, belongto SO2, (CH3)2OH, CH3OH, and CH3OCHO, respectively. A star denotes a transition within a vibrationally excited state: vt = 1 for methanol, and2 = 1 for SO2. Two sets of markers immediately below the spectrum baseline belong to ground state and vibrationally excited CH 3CN.


12/21


557 557.2 557.4 557.6 557.8 558 558.2 558.4 558.6 558.8 5590.5

0

0.5

1

1.5

H2

O

SO

2

*

H2

CS

**

29SiO

SO

2

* *

SO

SO

2

*

SO

2

SO

2

34SO

2

SO

2

****

N2

H+

OCS

Frequency [GHz]

Antennatemperatu

re[K]

555 555.2 555.4 555.6 555.8 556 556.2 556.4 556.6 556.8 5570.5

0

0.5

1

1.5

*

SO

2

(CH

3)2O

SO

2

*

(CH

3)2O

SO

2

*

13CH

3OH

(CH3)2O

*

(CH

3)2O

*

H2

O

SO

2

T TT T T

553 553.2 553.4 553.6 553.8 554 554.2 554.4 554.6 554.8 5550.5

0

0.5

1

1.5

*

33SO

2

SO

2

*

CH3CN

8=1

*

*

33SO

* * *

SO

2

*

33SO

HCS+

(CH

3)2O

*

34SO

2

13CS

(CH

3)2O

*

U U

PH

Fig.A.3. continued.


13/21


561 561.2 561.4 561.6 561.8 562 562.2 562.4 562.6 562.8 5630.5

0

0.5

1

1.5

*

SO

2

13CH

3OH

SO

2

SO

2

SO

2

SO

2

SO

2SO

2

34SO

C17O

*

H2

CO

U U UT

559 559.2 559.4 559.6 559.8 560 560.2 560.4 560.6 560.8 5610.5

0

0.5

1

1.5

**

N2

H+

OCS

SO

SO

2

*

SO

2

SO

*

SO

2

34SO

2

SO

2

(CH

3)2

O

SO

2

*

SO

2

U U UT T

Fig.A.3. continued.


14/21


567 567.2 567.4 567.6 567.8 568 568.2 568.4 568.6 568.8 5690.5

0

0.5

1

1.5

CN

NO

H2

S

SO

2

CH

3OH

H2

S

(CH

3)2O

CH

3OH

(CH

3)2O

SO

CH

3OH

CH

3CN

34SO

2

U

Frequency [GHz]

Antennatemperatu

re[K]

565 565.2 565.4 565.6 565.8 566 566.2 566.4 566.6 566.8 5670.5

0

0.5

1

1.5

13CH

3OH

(CH

3)2O

13CH

3OH

13CH

3OH

13CH

3OH

HDCO

13CH

3OH

13CH

3OH

13CH

3OH

13CH

3OH

(CH

3)2O

13CH

3OH

(CH3)2O

13CH

3OH

CN

CH

3OH*

13CH

3OH

CN

NO

H2

S

U

563 563.2 563.4 563.6 563.8 564 564.2 564.4 564.6 564.8 5650.5

0

0.5

1

1.5

CH

3OH*

13CH

3OH

SiO

CH

3OH

U U UT T

SH

?

Fig.A.4. The Odin spectral survey between 562.9 and 577.6 GHz (RX572). Empty markers at the intensity level of 1.25 K denote CH3OCHO lines.


15/21


573 573.2 573.4 573.6 573.8 574 574.2 574.4 574.6 574.8 5750.5

0

0.5

1

1.5

CH

3OH

34SO

2

CH

3OH

(CH

3)2O

H2

CS

SO

2

34SO

2

SO

2

CH

3OH

U

Frequency [GHz]

Antennatemperatu

re[K]

571 571.2 571.4 571.6 571.8 572 572.2 572.4 572.6 572.8 5730.5

0

0.5

1

1.5

OCS SO

2

SO

2

15NH

3

NH

3

CH

3OH

CH

3OH

U UT T T

569 569.2 569.4 569.6 569.8 570 570.2 570.4 570.6 570.8 5710.5

0

0.5

1

1.5

CH

3CN

34SO

2

CH

3OH

CH

3CN

CH

3CN

CH

3CN

CH

3CN

CH

3CN

(CH3)2O

CH3OH C

H3

OH

13CH

3OH

U U T T T

Fig.A.4. continued.


16/21


577 577.2 577.4 577.6 577.8 578 578.2 578.4 578.6 578.8 5790.5

0

0.5

1

1.5

T

575 575.2 575.4 575.6 575.8 576 576.2 576.4 576.6 576.8 5770.5

0

0.5

1

1.5

CH

3OH*

SO

2

CO

H2

CO

NS

UT

577 577.2 577.4 577.6 577.8 578 578.2 578.4 578.6 578.8 5790.5

0

0.5

1

1.5

T

575 575.2 575.4 575.6 575.8 576 576.2 576.4 576.6 576.8 5770.5

0

0.5

1

1.5

CH

3OH*

SO

2

CO

H2

CO

NS

UT

Fig.A.4. continued.


17/21

A. O. H. Olofsson et al.: A spectral line survey of Orion KL in the bands 486492 and 541577 GHz with the Odin satellite. I. , Online Material p 1

Online Material


18/21


Appendix B: Electronic table on lines

Table B.1. Lines detected towards Orion KL listed in order of laboratory frequency.

Frequency Molecule[MHz] or U/T-line486845 T-line486940.9 CH3OH487 2 09 U-line487507 T-line487531.9 CH3OH487663.4 H2CS487708.5 SO488 153.5 13CH3OH488 302.6 13CH3OH488477 T-line488 491.1 para-H2O488 5 98 U-line488 6 33 U-line488945.5 CH3OH489037.0 CH3OH

489 054.3 ortho-H18

2 O489193 T-line489224.3 CH3OH489709 T-line489751.1 CS490 299.4 13CH3OH490 596.7 HDO490795.3 CH3OCH3490795.3 CH3OCH3490797.5 CH3OCH3490798.3 CH3OCH3490801.3 CH3OCH3490804.3 CH3OCH3490804.7 CH3OCH3490810.3 CH3OCH3

490811.4 CH3OCH3490812.1 CH3OCH3490864.4 CH3OCH3490869.8 CH3OCH3490871.5 CH3OCH3490877.2 CH3OCH3490877.6 CH3OCH3490878.3 CH3OCH3490955.7 HC3N490960.0 CH3OH491 170.0 13CH3OH491 201.3 13CH3OH491 310.1 13CH3OH491 4 96 U-line491550.9 CH3OH

491 8 92 U-line491934.7 SO2491 937.0 HDCO491968.4 H2CO492160.7 C492278.7 CH3OH541750.9 SO2541810.6 SO2

Frequency Molecule[MHz] or U/T-line541 926 T-line541 9 81 U-line542 000.9 CH3OH542 081.9 CH3OH542 097.7 34SO2542 163.0 CH3OH542 177.4 34SO2542 233.5 34SO2542 257.7 CH3OCH3542 257.7 CH3OCH3542 260.1 CH3OCH3542 262.4 CH3OCH3542 270.1 34SO2542 291.7 34SO2542 302.3 34SO2

542 9 45 U-line543 076.1 CH3OH543 413.5 SO2543 457.3 CH3OH543 467.7 SO2543 753.9 CH3OCH3543 753.9 CH3OCH3543 756.9 CH3OCH3543 759.8 CH3OCH3543 8 73 U-line543 897.6 HNC544 016 T-line544 140.5 13CH3OH544 206.7 13CH3OH544 653.1 CH3OH

544 820.5 CH3OH545 034.8 CH3OH545 318.5 SO2545 417.1 HC3N545 517.3 SO2545 755.6 CH3OH546 1 38 U-line546 176 T-line546 226.8 CH3OH546 239.0 CH3OH546 579.8 SO2546 662 T-line546 805 T-line546 827.8 CH3OCH3546 829.2 CH3OCH3

546 831.5 CH3OCH3546 834.5 CH3OCH3546 859.8 OCS547 080 T-line547 119.6 34SO547 162 T-line547 262 T-line547 284.8 CH3OCH3

Frequency Molecule[MHz] or U/T-line547286.2 CH3OCH3547287.8 CH3OCH3547290.1 CH3OCH3547308.2 H2CS547 457.8 13CH3OH547 613.5 34SO2547 676.4 ortho-H182 O547698.9 CH3OH547802.2 SO2548 389.8 34SO548475.2 H132 CO548548.7 CH3OH548734.3 SO2548831.0 C18O548838.9 SO2

549142 T-line549199 T-line549 278.7 34SO549 297.1 13CH3OH549303.3 SO2549322.8 CH3OH549402.4 H2CS549447.5 H2CS549 4 49 U-line549504.7 CH3OCH3549504.7 CH3OCH3549504.9 CH3OCH3549505.2 CH3OCH3549543.8 CH3OCH3549546.5 CH3OCH3

549547.4 CH3OCH3549547.7 CH3OCH3549550.4 CH3OCH3549550.6 CH3OCH3549550.8 CH3OCH3549551.7 CH3OCH3549566.4 SO2549719 T-line550025.2 CH3OH550132 T-line550 605.2 30SiO550659.3 CH3OH550671.7 CH3CN550850.0 CH3CN550 926.3 13CO

550946.7 SO2551007.4 CH3CN551143.9 CH3CN551187.3 NO551187.5 NO551188.8 NO551228.6 CH3OH551259.6 CH3CN


19/21


Table B.1. continued.

Frequency Molecule[MHz] or U/T-line551270.8 CH3OCH3551273.6 CH3OCH3

551275.1 CH3OCH3551275.1 CH3OCH3551276.5 CH3OCH3551276.5 CH3OCH3551277.9 CH3OCH3551279.4 CH3OCH3551354.2 CH3CN551427.9 CH3CN551480.6 CH3CN551512.2 CH3CN551522.7 CH3CN551531.5 NO551534.0 NO551534.1 NO551622.9 SO2

551736.2 CH3OH551 767.4 34SO2551968.8 CH3OH552 021.0 ortho-H172 O552069.4 SO2552078.9 SO2552184.8 CH3OH552258.9 CH3OCH3552258.9 CH3OCH3552261.4 CH3OCH3552264.0 CH3OCH3552 3 08 U-line552 429.8 33SO552577.2 CH3OH552646.6 CH3CN

552 740.9 HDCO552 835.1 13CH3OH552846 T-line552915.4 CH3OH552970.8 CH3CN553007.8 CH3CN553029.1 CH3CN553146.3 CH3OH553164.9 SO2553201.6 CH3OH553240.3 CH3CN553362.2 CH3CN553437.5 CH3OH553570.9 CH3OH553624.5 CH3OH

553 6 67 U-line553 681.3 33SO553707.6 CH3CN553 7 16 U-line553763.7 CH3OH554052.7 CH3OH

Frequency Molecule[MHz] or U/T-line554055.5 CH3OH554202.9 CH3OH

554212.8 SO2554402.5 CH3OH554555.6 33SO554 576.6 HCS+

554619.8 CH3OCH3554619.8 CH3OCH3554621.0 CH3OCH3554621.5 CH3OCH3554622.1 CH3OCH3554622.6 CH3OCH3554622.6 CH3OCH3554623.2 CH3OCH3554650.9 CH3OH554708.2 34SO2554726.0 13CS

554811.5 CH3OCH3554811.5 CH3OCH3554812.7 CH3OCH3554813.4 CH3OCH3554813.9 CH3OCH3554814.6 CH3OCH3554814.6 CH3OCH3554815.3 CH3OCH3554888.3 CH3OCH3554888.3 CH3OCH3554890.4 CH3OCH3554892.5 CH3OCH3554947.4 CH3OH554979.1 CH3OCH3554979.1 CH3OCH3

554980.4 CH3OCH3554981.2 CH3OCH3554981.7 CH3OCH3554982.5 CH3OCH3554982.5 CH3OCH3554983.3 CH3OCH3555121.5 SO2555124.5 CH3OCH3555124.5 CH3OCH3555125.9 CH3OCH3555126.8 CH3OCH3555127.3 CH3OCH3555128.2 CH3OCH3555128.2 CH3OCH3555129.1 CH3OCH3

555204.1 SO2555249.8 CH3OCH3555249.8 CH3OCH3555251.3 CH3OCH3555252.3 CH3OCH3555252.7 CH3OCH3

Frequency Molecule[MHz] or U/T-line555253.8 CH3OCH3555253.8 CH3OCH3

555254.9 CH3OCH3555291.1 CH3OH555312 T-line555356.8 CH3OCH3555356.8 CH3OCH3555358.3 CH3OCH3555359.5 CH3OCH3555359.9 CH3OCH3555361.1 CH3OCH3555361.1 CH3OCH3555362.3 CH3OCH3555417.7 CH3OH555418.5 CH3OH555447.3 CH3OCH3555447.3 CH3OCH3

555448.9 CH3OCH3555450.2 CH3OCH3555450.6 CH3OCH3555451.9 CH3OCH3555451.9 CH3OCH3555453.1 CH3OCH3555522.9 CH3OCH3555522.9 CH3OCH3555524.6 CH3OCH3555526.0 CH3OCH3555526.4 CH3OCH3555527.8 CH3OCH3555527.8 CH3OCH3555529.2 CH3OCH3555585.3 CH3OCH3


555666.3 SO2555676.3 CH3OCH3555676.3 CH3OCH3555678.3 CH3OCH3555679.9 CH3OCH3555680.3 CH3OCH3


20/21



Frequency Molecule[MHz] or U/T-line555681.0 CH3OH555681.9 CH3OCH3

555681.9 CH3OCH3555683.6 CH3OCH3555 700.1 13CH3OH555707.6 CH3OCH3555707.6 CH3OCH3555709.7 CH3OCH3555711.4 CH3OCH3555711.8 CH3OCH3555713.5 CH3OCH3555713.5 CH3OCH3555715.2 CH3OCH3555731.2 CH3OCH3555731.2 CH3OCH3555733.4 CH3OCH3555735.2 CH3OCH3


555764.0 CH3OCH3555764.4 CH3OCH3555766.3 CH3OCH3555766.3 CH3OCH3555766.8 CH3OCH3555766.8 CH3OCH3555768.2 CH3OCH3555769.2 CH3OCH3555771.2 CH3OCH3555771.6 CH3OCH3555773.5 CH3OCH3555773.5 CH3OCH3555775.5 CH3OCH3555914 T-line555933 T-line

556115.8 CH3OH556179.4 CH3OCH3556179.4 CH3OCH3556179.4 CH3OCH3556179.5 CH3OCH3556212.0 CH3OCH3

Frequency Molecule[MHz] or U/T-line556 212.0 CH3OCH3556 212.1 CH3OCH3

556 212.2 CH3OCH3556 267 T-line556 594.4 CH3OH556 603.7 CH3OH556 633 T-line556 936.0 ortho-H2O556 959.9 SO2557 115.2 CH3OH557 123.2 H2CS557 147.0 CH3OH557 147.0 CH3OH557 184.4 29SiO557 283.2 SO2557 676.6 CH3OH558 004.6 CH3OH

558 087.7 SO558 101.2 SO2558 276.8 CH3OH558 344.5 CH3OH558 390.9 SO2558 555.8 SO2558 606.4 CH3OH558 717.5 34SO2558 812.5 SO2558 890.2 CH3OH558 890.2 CH3OH558 904.6 CH3OH558 914.0 CH3OH558 966.6 N2H+

558 990.5 OCS

559 2 39 U-line559 319.8 SO559 500.4 SO2559 586.1 CH3OH559 816 T-line559 8 61 U-line559 882.1 SO2559 9 13 U-line560 178.7 SO560 291.0 CH3OH560 318.9 SO2560 590.2 34SO2560 613.5 SO2560 648.9 CH3OCH3560 648.9 CH3OCH3

560 649.0 CH3OCH3560 649.0 CH3OCH3560 753 T-line560 891.0 SO2561 026.4 CH3OH561 094.8 SO2

Frequency Molecule[MHz] or U/T-line561 138.5 13CH3OH561265.6 SO2

561269.1 CH3OH561361.4 SO2561392.9 SO2561402.9 CH3OH561490.5 SO2561560.3 SO2561608.6 SO2561639.3 SO2561656.7 SO2561664.2 SO2561 700.4 34SO561712.8 C17O561789.7 CH3OH561899.3 H2CO561 9 71 U-line

562118 T-line562 9 60 U-line563 0 33 U-line563481 T-line564 1 05 U-line564221.6 CH3OH564 223.7 13CH3OH564 249.2 SiO564418 T-line564759.8 CH3OH565 245.2 13CH3OH565262.1 CH3OCH3565262.8 CH3OCH3565265.2 CH3OCH3565267.9 CH3OCH3

565 527.813

CH3OH565 737.4 13CH3OH565 737.4 13CH3OH565857.5 HDCO565 895.0 13CH3OH565 914.4 13CH3OH565 946.2 13CH3OH566046.6 CH3OCH3566047.3 CH3OCH3566049.3 CH3OCH3566051.7 CH3OCH3566 0 66 U-line566 411.9 13CH3OH566606.7 CH3OCH3566606.7 CH3OCH3

566608.5 CH3OCH3566610.4 CH3OCH3566 662.8 13CH3OH566729.9 CN566730.7 CN566730.8 CN


21/21



Frequency Molecule[MHz] or U/T-line566 840.7 13CH3OH566946.8 CN

566946.9 CN566947.2 CN566962.0 CN566963.7 CN567064.2 NO567069.6 NO567073.4 NO567077.9 NO567079.6 H2S567082.7 NO567086.6 NO567 4 85 U-line567592.7 SO2567942.6 CH3OH568050.7 H2S

568430.6 CH3OCH3568432.6 CH3OCH3568433.9 CH3OCH3568435.3 CH3OCH3568436.3 CH3OCH3568437.2 CH3OCH3568437.7 CH3OCH3568439.2 CH3OCH3568566.1 CH3OH568690.1 CH3OCH3568690.1 CH3OCH3568690.3 CH3OCH3568690.4 CH3OCH3568741.6 SO568783.6 CH3OH

568999.3 CH3CN569 091.6 34SO2569 1 38 U-line569324.5 CH3OH569486.9 CH3CN569606.3 CH3CN569704.0 CH3CN569780.1 CH3CN569834.5 CH3CN569867.1 CH3CN569878.0 CH3CN570219.1 CH3OCH3570221.9 CH3OCH3570223.3 CH3OCH3570223.3 CH3OCH3

570224.7 CH3OCH3570224.7 CH3OCH3570226.1 CH3OCH3570227.5 CH3OCH3570261.5 CH3OH570264.0 CH3OH

Frequency Molecule[MHz] or U/T-line570 3 03 U-line570335 T-line

570619.0 CH3OH570624.2 13CH3OH570790 T-line570814 T-line571 119.7 OCS571151 T-line571217 T-line571477 T-line571 532.6 SO2571 553.3 SO2572112.8 15NH3572 498.2 NH3572 5 96 U-line572676.2 CH3OH572 6 78 U-line

572898.8 CH3OH573471.1 CH3OH573527.3 34SO2573912.7 CH3OH574090.9 CH3OCH3574090.9 CH3OCH3574093.3 CH3OCH3574095.7 CH3OCH3574140.0 H2CS574 1 84 U-line574 587.8 SO2574797.9 34SO2574 807.3 SO2574868.5 CH3OH575397 T-line

575547.2 CH3OH576 042.1 SO2576267.9 CO576 4 46 U-line576708.3 H2CO576 720.2 NS577160 T-line

a. o. h. olofsson et al- a spectral line survey of orion kl in the bands 486–492 and 541–577 ghz...

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