J/ApJS/215/25ivo://CDS.VizieR/J/ApJS/215/25doi:10.26093/cds/vizier.22150025CDSFavre C.Carvajal M.Field D.Jorgensen J.K.Bisschop S.E.,Brouillet N.Despois D.Baudry A.Kleiner I.Bergin E.A.,Crockett N.R.Neill J.L.Margules L.Huet T.R.Demaison J.2015-03-25T11:28:40Z2015-02-27T10:35:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fratomic-physicsradio-astronomyinterstellar-mediumWe have surveyed a sample of massive star-forming regions located over a range of distances from the Galactic center for methyl formate, HCOOCH_3_, and its isotopologues H^13^COOCH_3_ and HCOO^13^CH_3_. The observations were carried out with the APEX telescope in the frequency range 283.4-287.4GHz. Based on the APEX observations, we report tentative detections of the ^13^C-methyl formate isotopologue HCOO^13^CH_3_toward the following four massive star-forming regions: Sgr B2(N-LMH), NGC 6334 IRS 1, W51 e2, and G19.61-0.23. In addition, we have used the 1mm ALMA science verification observations of Orion-KL and confirm the detection of the ^13^C-methyl formate species in Orion-KL and image its spatial distribution. Our analysis shows that the ^12^C/^13^C isotope ratio in methyl formate toward the Orion-KL Compact Ridge and Hot Core-SW components (68.4+/-10.1 and 71.4+/-7.8, respectively) are, for both the ^13^C-methyl formate isotopologues, commensurate with the average ^12^C/^13^C ratio of CO derived toward Orion-KL. Likewise, regarding the other sources, our results are consistent with the ^12^C/^13^C in CO. We also report the spectroscopic characterization, which includes a complete partition function, of the complex H^13^COOCH_3_ and HCOO^13^CH_3_species. New spectroscopic data for both isotopomers H^13^COOCH_3_and HCOO^13^CH_3_, presented in this study, have made it possible to measure this fundamentally important isotope ratio in a large organic molecule for the first time.2014ApJS..215...25Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/215/25CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/568/A58 : HCOO^13^CH_3_ rotational spectrum (Haykal+, 2014)J/A+A/538/A119 : ^18^O-methyl formate (HCO^18^OCH_3_) spectrum (Tercero+ 2012)J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)J/ApJS/190/315 : Rotational spectrum of H^13^COOCH_3_ (Carvajal+, 2010)J/ApJ/724/994 : Cyano- to methanol and ammonia observations (Braakman+, 2010)J/ApJ/714/1120 : Rotational spectrum and DCOOCH_3_ in Orion (Margules+, 2010)J/A+A/500/1109 : Rotational spectrum of HCOO^13^CH_3_ (Carvajal+, 2009)J/ApJS/169/28 : Rotational transitions of Methyl carbamate (Groner+, 2007)http://www.astro.uni-koeln.de/cdms : The Cologne database for molecularhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/215/25https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/215/25http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/215/25https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/215/25https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/215/25http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/215/25GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/ApJS/215/25/table12Transitions of ^12^C and ^13^C-methyl formate observed with the ALMA telescoperecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMolMolecule (HCOOCH_3_, HCOO^13^CH_3_ or H^13^COOCH_3_) (1)meta.noteFreq[213882/246623.2] FrequencyMHzem.freqdoublef_Freq[*] Flag on Freq (2)meta.codecharTransTransitionmeta.id;phys.atmol.transitionEup[99/504] Upper level energyKphys.energy;phys.atmol.levelintSmu2[10/74] S_{mu}_^2^ coefficientD**2spect.line.intensityint