Deep, Broadband Spectral Line Surveys of Molecule-rich Interstellar Clouds

B1-b is a dark molecular cloud with an embedded prestellar core; we observed this source at the "core" position as designated by Öberg et al. (2010). A cold complex chemistry was discovered in B1-b via the detections of CH₃OH, HCOOCH₃, CH₃CHO, trans-HCOOH, C₄H, HNCO, and the H₂C₃O isomers (Sakai et al. 2009a; Öberg et al. 2010; López-Sepulcre et al. 2015; Cuadrado et al. 2016; Loison et al. 2016), and tentatively CH₃OCH₃ (Öberg et al. 2010), as well as CH₃O (Cernicharo et al. 2012). These previous detections were all reported at levels well below the noise level obtained in our observations. Therefore, in our survey, CH₃OH was the only COM detected. Several other diatomic and triatomic molecules were detected here, including CN, CS, and HCN. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was also detected. Dark molecular clouds are known to have deuterium enrichment (Bergin & Tafalla 2007). We detected N₂D⁺, DNC, and HDCO in B1-b, but not HDO. Other commonly detected deuterated molecules, such as DCN, DCO⁺, and H₂D⁺, do not have spectral lines within the spectral coverage of our survey.

GCM+0.693-0.027, located in the Sgr B2 complex, is a shocked region where COMs such as CH₃OH, C₂H₅OH, CH₃OCH₃, HCOOCH₃, and trans-HCOOH have previously been detected (Requena-Torres et al. 2006). The line shape is non-Gaussian and asymmetric, with strong absorption features at the higher frequency edge of the lines. GOBASIC can only treat Gaussian line shapes; therefore, the fit did not perfectly describe the source. Nevertheless, we could fit CH₃OH, CH₃CCH, CH₂NH, H₂CS, and OCS with some confidence. The temperatures of these molecules range from 15 to 63 K. The spectral lines are extremely wide, with FWHMs from 18 to 24 km s⁻¹. The velocities are also not consistent. OCS has a blueshift of 0.6 km s⁻¹, whereas all of the other molecules display redshifts. CH₃OH and CH₃CCH are redshifted by 4 km s⁻¹, followed by H₂CS at 3 km s⁻¹, and then CH₂NH at 2 km s⁻¹. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was detected and fit with one Gaussian profile.

HH 80–81 is a massive bipolar outflow where CH₃OH, CH₃CN, H₂CO, SO₂, SO, HCO⁺, and NH₃ were observed (Martí et al. 1993; Gómez et al. 2003; Qiu & Zhang 2009). In our survey, we reliably fit CH₃OH, CH₃CCH, H₂CS, SO, and SO₂. The molecules are cold, with the hottest one being SO₂ at 47 K. The other four molecules are within 15–25 K. The spectral lines are also narrow, with FWHMs from 1.5 to 3.1 km s⁻¹. The velocities are consistent within 1 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

The L1157 region is a bipolar outflow from the central star L1157 MM. We observed the B1 position in the outflow based on the interferometric study of Arce et al. (2008). Millimeter single-dish and interferometry studies on small molecules (CS, SiO, etc.), CH₃OH, and CH₃CN have revealed the outflow structure and molecular component (Avery & Chiao 1996; Codella et al. 2009; Flower et al. 2010; Gómez-Ruiz et al. 2013; Burkhardt et al. 2016). Additional observations were conducted in the submillimeter by the CHESS project on Herschel (Codella et al. 2010, 2012; Lefloch et al. 2010, 2012; Benedettini et al. 2012; Busquet et al. 2014). Bachiller & Gutiérrez (1997) and Bachiller et al. (2001) reported spectral lines from CH₃OH, H₂CO, SiO, HCN, CN, CS, SO, and SO₂ in the 1.3 mm band using the IRAM 30 m telescope. Another line survey reported the detection of HCOOCH₃, CH₃CN, HCOOH, and C₂H₅OH in its B1 shock region, which is in the blueshifted lobe of L1157 (Arce et al. 2008).

In our survey of the B1 region, we confirmed the detection of small molecules reported by Bachiller & Gutiérrez (1997) and Bachiller et al. (2001), except for the SO₂ lines, which were too weak to be observed. No spectral features, however, were found for any of the COMs reported by Arce et al. (2008). This is likely due to beam dilution, as the COM detections showed small spatial scales relative to the CSO beam. The spectral line shape in L1157 is asymmetric. We fit two velocity components to methanol and SO, one with a blueshift of 3.7–3.9 km s⁻¹ and a wider FWHM of 6 km s⁻¹, another one with a blueshift of 1 km s⁻¹ and a narrower FWHM of 3–3.6 km s⁻¹. The narrower component corresponds to the north region, where the lines are redshifted from the gas extending farther out from the star. The wider component corresponds to the south region toward the B1 and B2 blueshifted lobes. The molecules are extremely cold, with rotational temperatures below 15 K, and do not perfectly follow a Boltzmann intensity profile. Nevertheless, we can estimate the methanol column density to be $1.2\times {10}^{15}$ cm⁻², and the SO column density to be $1.8\times {10}^{14}$ cm⁻². The column density ratio between methanol and SO agrees well with that reported by Bachiller & Gutiérrez (1997). The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

The L1448 MM-1 source is a bipolar outflow. We observed the C(N) position. This source has been studied previously in the millimeter band (Bachiller et al. 1991; Gregersen et al. 1997; Maret et al. 2004; Jørgensen et al. 2005b, 2007; Maret et al. 2005; Requena-Torres et al. 2007). In these surveys, HCO⁺, H¹³CO⁺, HN¹³C, SiO, H₂CO, and CH₃OH were detected. Parise et al. (2006) studied the deuterated chemistry in detail using the HDCO, D₂CO, CH₂DOH, and CH₃OD lines. In the 3 mm band, the long carbon chain molecule C₄H was also observed (Sakai et al. 2009a). We confirmed the presence of CH₃OH and H₂CO lines in the 1.3 mm band. In addition to CH₃OH and H₂CO, we detected CS, CN, and HCN. We observed a high D/H ratio, indicated by strong lines from DNC, N₂D⁺, and HDCO.

The spectral lines are much narrower, compared to the outflow of L1157. An FWHM of 1.5 km s⁻¹ was found for CS, and line widths were narrower for the other detected molecules. CH₃OH has a rotational temperature of 17.7 K, slightly warmer than L1157. We only observed one main velocity component, which is redshifted from the central star rest velocity by 5–6 km s⁻¹. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was detected and fit with one Gaussian profile.

NGC 6334, also called the Cat's Paw nebula, is a H ii region that contains several massive protostars (Straw et al. 1989). Although it has been studied in the infrared and millimeter for its star formation processes (e.g., Persi et al. 2000; Hunter et al. 2006; Brogan et al. 2009), only a few molecular surveys are available for this source (Bisschop et al. 2007; Thorwirth et al. 2007; Walsh et al. 2010). In these surveys, COMs such as CH₃OH, ¹³CH₃OH, CH₃CCH, CH₃CN, ${\mathrm{CH}}_{3}^{13}\,\mathrm{CN}$, C₂H₅OH, HCOOCH₃, CH₃OCH₃, NH₂CHO, C₂H₅CN, and trans-HCOOH were detected. CH₃OH masers in the millimeter were also reported (Slysh et al. 2002).

We pointed to four Class 0 star-forming regions, NGC 6334–29, NGC 6334–38, NGC 6334–43, and NGC 6334-I(N), in this nebula. In general, rich chemistry was found in NGC 6334–29 and NGC 6334-I(N), whereas NGC 6334–38 and NGC 6334–43 have simpler chemistry.

In NGC 6334–29, we were able to fit 17 molecules with reliable temperatures, in addition to another 25 small molecules. For O-containing molecules, we detected CH₃OH, ¹³CH₃OH, CH₃OCH₃, H₂CCO, HCOOCH₃, and CH₃CHO. For N-containing molecules, we detected CH₃CN, ¹³CH₃CN, HCCCN (ground state and ${v}_{7}=1$), NH₂CHO, CH₂NH, and C₂H₅CN. For S-containing molecules, we detected H₂CS, OCS, SO, SO₂, and ³⁴SO₂. CH₃CCH is also abundant. CH₃OH has a cold component at 19 K and a warm component at 128 K. HCOOCH₃ is the warmest molecule detected, with a temperature of 285 K. The S-containing molecules in NGC 6334–29 are kinematically different from the rest of the COMs. Instead of having a Gaussian line shape with FWHMs of 4–6 km s⁻¹, S-containing molecules show broadening in their line shapes. We modeled this with a convolution of two Gaussian components, a narrow one of $\,4$ km s⁻¹, and a wide one of 8–13.5 km s⁻¹. The two components have similar temperatures for each molecule. SO₂, however, does not show these two components. Instead, it shows a cold component at 13 K, and a warm component at 138 K, similar to CH₃OH.

NGC 6334-I(N) is in an early cluster formation stage with molecular outflows but rather weak mid-IR emission (Megeath & Tieftrunk 1999). It contains seven submillimeter continuum sources in a roughly 15'' × 15'' region, with an estimated total gas mass of 39–145 ${M}_{\odot }$ (Hunter et al. 2006; Brogan et al. 2009). Walsh et al. (2010) acquired a low-resolution map toward a 5' × 5' region around NGC 6334-I(N) and found the peak fluxes of CH₃OH, CH₃CN, H₂CS, HCCCN, OCS, and SO on the source site. Spectral lines were also reported by Brogan et al. (2009) in the 1.3 mm band from their SMA maps. Detected molecules included CH₃OH, HCOOCH₃, C₂H₃CN, CH₃OCH₃, H₂CO, and HCCCN.

In our survey of NGC 6334-I(N), we were able to fit 15 molecules with reliable temperatures, in addition to another 21 small molecules. For O-bearing molecules, we only detected CH₃OH, ¹³CH₃OH, CH₃OCH₃, CH₃CHO, and H₂CCO. For N-bearing molecules, we only detected CH₃CN, CH₂NH, and HCCCN. For S-bearing molecules, we only detected H₂CS, OCS, SO, and SO₂. CH₃CCH is also abundant. Interestingly, despite the rich chemistry in NGC 6334-I(N), all molecules are cold. The temperature range is only 10–35 K, a temperature range more typical for prestellar cores. The reason for NGC 6334-I(N) having such a rich COM inventory at such a low temperature is not clear; it is possible there is an outflow driving shocks. The FWHMs are in the range of 3–9 km s⁻¹. We observed an asymmetric line shape, similar to NGC 6334–29, for SO, but not for other S-bearing molecules. Instead, CH₃OH in NGC 6334-I(N) shows a similar asymmetric line shape, with a narrow component at 3.4 km s⁻¹ and a wider component at 6.9 km s⁻¹. The temperature difference between these two CH₃OH components is only 4 K. The velocities range from 0.5 km s⁻¹ redshift to 2.2 km s⁻¹ blueshift.

In NGC 6334–38, we were able to fit nine molecules with reliable temperatures, in addition to another 26 small molecules. For O-bearing molecules, we only found CH₃OH and H₂CCO. For N-bearing molecules, we only found CH₃CN and HCCCN. For S-bearing molecules, we only found OCS and SO. CH₃CCH is also present. All molecules have temperatures within the range of 20–50 K, much colder than NGC 6334–29. The lines are 3–5 km s⁻¹ wide in FWHM, with a consistent redshift of 1.5–2.6 km s⁻¹ with respect to the source's v_lsr.

In NGC 6334–43, we were able to fit seven molecules with reliable temperatures, in addition to 18 other small molecules. For O-bearing molecules, we only found CH₃OH and H₂CCO. For N-bearing molecules, we only found CH₃CN and HCCCN. For S-bearing molecules, we only found OCS and SO. CH₃CCH is also present. All molecules have temperatures within the range of 10–35 K, even colder than NGC 6334–38. The lines are 3–4 km s⁻¹ wide in FWHM, with a consistent redshift of 1.9–2.6 km s⁻¹ with respect to the source v_lsr.

An asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was found in all four regions in NGC 6334. In NGC 6334–29, −38, and −43, it was modeled with two Gaussian components; in NGC 6334-I(N), it was modeled with three Gaussian components.

NGC 1333 is a fragmented molecular cloud with multiple low-mass protostars embedded. Intensive studies have focused on this low-mass star-forming region (Blake et al. 1995; Gregersen et al. 1997; Bachiller et al. 1998; Stark et al. 1999; Knee & Sandell 2000; Bottinelli et al. 2004, 2007; Jørgensen et al. 2004, 2005a, 2005b, 2007; Maret et al. 2004, 2005; Wakelam et al. 2005; Parise et al. 2006; Plume et al. 2007; Choi et al. 2010; Sakai et al. 2012, 2006; Coutens et al. 2013, 2015; Lyo et al. 2014; Taquet et al. 2015; De Simone et al. 2017). Numerous COMs, such as CH₃CN, CH₃OH, CH₂DOH, ¹³CH₃OH, trans-HCOOH, HCOOCH₃, CH₃OCH₃, C₂H₅OH, C₂H₅CN, and CH₂OCHO, were detected in the IRAS 2 and IRAS 4A regions in this cloud (Blake et al. 1995; Bachiller et al. 1998; Bottinelli et al. 2004, 2007; Jørgensen et al. 2004, 2005a, 2005b, 2007; Maret et al. 2005; Parise et al. 2006; Sakai et al. 2012; Coutens et al. 2015; Taquet et al. 2015; De Simone et al. 2017). (CH₂OH)₂ was also detected in IRAS 2 (Coutens et al. 2015). The IRAS 4B core has fewer COMs reported: CH₃CN, CH₃OH, CH₂DOH, CH₃OD, HCOOCH₃, and CH₂OHCHO (Jørgensen et al. 2005b; Maret et al. 2005; Parise et al. 2006; Sakai et al. 2006, 2012; De Simone et al.v2017).

In our survey, we observed three positions in NGC 1333: the IRAS 2A, 4A, and 4B regions. We also conducted observations on NGC 1333 IRAS 2B, but found after the observations were complete that the incorrect source position was used. Our survey revealed a relatively simple chemical composition of these sources, which is not surprising given that the COMs previously detected in these sources using single-dish observations were detected at signal intensities of ≤10 mK, which is our noise level (see Bottinelli et al. 2007 for an example). In the three regions observed, only CO, CS, cold CH₃OH, and the H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line were detected. We could only reliably fit the cold CH₃OH, which is 15–25 K, and has a non-Gaussian, asymmetric line shape. The total spectral flux of 4A and 4B is higher than that of 2A. In 4A and 4B, it is likely that they contain a warmer CH₃OH component, indicated by weak spectral features around the warm CH₃OH ${K}_{a}=3\to 2$ R-branch near 252 GHz. However, the signal-to-noise ratio is too low to generate a reliable LTE fit. In addition, two CH₃OH lines, ${8}_{-\mathrm{1,8}}\to {7}_{\mathrm{0,7}}({E}_{\mathrm{low}}\,=78\ {\rm{K}})$ at 229.76 GHz, and ${11}_{\mathrm{0,11}}\to {10}_{\mathrm{1,10}}({E}_{\mathrm{low}}=141\ {\rm{K}})$ at 250.51 GHz, present inconsistently high intensities which indicates the non-LTE environment of these sources. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with a single Gaussian in 2A, whereas 4A and 4B were modeled using two Gaussian components.

The weak intensity of COM lines in NCG 1333 sources is likely due to their small source sizes, which result in a heavy beam dilution effect. The warmer lines from other COMs are likely below the noise level. To study these hot corinos, telescopes with smaller beam size and higher spatial resolution are required.

GAL 75.58+0.34 is a massive star-forming region and a hypercompact H ii region (Kurtz 2005; Bisschop et al. 2007; Riffel & Lüdke 2010). CH₃OH, ¹³CH₃OH, CH₃CN, CH₃CCH, and SO₂ were detected in a 1.3 and 0.89 mm line survey (Hatchell et al. 1998b). CH₃OH and CH₃CN lines were also studied by Pankonin et al. (2001) and Sánchez-Monge et al. (2013). Bisschop et al. (2007) detected H₂CO, CH₃OH, ¹³CH₃OH, H₂CCO, CH₃OCH₃, HCOOCH₃, trans-HCOOH, CH₃CCH, CH₃CN, and NH₂CHO in this source with temperatures between 40 and 190 K. We reliably fit CH₃OH, CH₃CCH, CH₃CN, H₂CCO, H₂CS, HCCCN, OCS, SO, and SO₂. CH₃OH has a cold component at 15 K and a warm component at 160 K, and is the hottest molecule in this source. Other than the warm CH₃OH, the remaining molecules are below 100 K. Comparing GAL 75.78+0.34 and GAL 45.47+0.05, the former seems to be at a later stage in the star formation process, because of the presence of warm CH₃OH and CH₃CN (92 K). The FWHMs are 3–6 km s⁻¹, and the velocities are between −4 and −3 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

GAL 12.21–0.10 is a hot core embedded in an ultracompact H ii region (de la Fuente et al. 2010). A few line surveys in the 1.3 and 0.89 mm bands have been reported toward this source, where several COMs were detected (Hatchell et al. 1998a, 1998b; Pankonin et al. 2001). These COMs include CH₃OH and its isotopologue ¹³CH₃OH, CH₃CN, and CH₃CCH. Here, we present the detection of a handful of COMs at moderate temperatures, supporting the existence of a hot core. We reliably fit CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, H₂CCO, H₂CS, HCCCN, OCS, SO, and SO₂. CH₃OH has two temperatures, a cold component at 16 K and a warm component at 162 K. For other molecules, instead of clustering into cold and warm groups, their temperatures range widely from 20 to 150 K. CH₃OCH₃ and SO₂ are warm, whereas CH₃CCH and SO are cold. The FWHMs of these molecular lines are around 7–10 km s⁻¹, and the velocities are consistent within −1 to 1 km s⁻¹. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was detected and fit with one Gaussian profile.

NGC 2264 is a star-forming region with multiple millimeter continuum sources (Ward-Thompson et al. 2000). We pointed at the NGC 2264 C-MM3 source, where the peak CH₃OH intensity is located (Sakai et al. 2007; Saruwatari et al. 2011), and a rich chemistry was observed by combining extensive Nobeyama 45 m dish (4 and 3 mm) and ASTE 10 m dish (0.89 mm; Watanabe et al. 2015). CH₃OH, ¹³CH₃OH, CH₃CCH, HC₅N, CH₃CN, CH₃CHO, H₂CCO, CH₃OCH₃, HCOOCH₃, and NH₂CHO lines were detected in this survey. A 1.3 mm SMA map, however, reveals a C-MM4 core that has much higher continuum emission and more molecules than C-MM3 (Cunningham et al. 2016). C-MM4 is about 30'' away from C-MM3.

In our survey, we detected abundant CH₃OH, along with CH₃CCH, H₂CO, HDCO, H₂CS, and SO. More complex COMs, such as CH₃CHO, CH₃OCH₃, and HCOOCH₃, were not found. A consistent velocity component of 0–1 km s⁻¹ with 4–5 km s⁻¹ FWHM can be fit to the above molecules. The rotational temperature ranges from 20 to 50 K.

HCOOCH₃ was reported as a detection in NGC 2264 MMS3 (Sakai et al. 2007) in the 3 mm band using the Nobeyama 45 m radio telescope. The A/E lines from the ${8}_{\mathrm{1,8}}\to {7}_{\mathrm{1,7}}$ transition of HCOOCH₃ were observed at a main beam temperature intensity of 60–80 mK. The signal-to-noise ratio of that detection was only 2–3. In our 1.3 mm band survey, no HCOOCH₃ was detected. The peak-to-peak noise level of our survey is ∼50 mK. Considering a CSO beam ($30^{\prime\prime}$) that is larger than the Nobeyama beam ($19^{\prime\prime}$) and a higher frequency band, which in general means lines arising from warmer gas, it is likely that the HCOOCH₃ lines are below our detection limit. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was detected and fit with one Gaussian profile.

NGC 7538 is a high-mass star-forming region with massive protostars and outflows (Scoville et al. 1986; Kraus et al. 2006), the IRS 1 core being one of the protostars (Buizer & Minier 2005). H₂CO, CH₃OH, and CH₃CN were detected in the millimeter bands (Slysh et al. 1999; Kalenskii et al. 2000a, 2000b; van der Tak et al. 2000; Wirström et al. 2011), and one C₂H₅OH line was reported in the centimeter (Menten et al. 1986). Ikeda et al. (2001) detected c-C₂H₄O and CH₃CHO in this source. Bisschop et al. (2007) detected H₂CO, CH₃OH, ¹³CH₃OH, H₂CCO, HCOOCH₃, C₂H₅OH, CH₃CHO, trans-HCOOH, CH₃CCH, and NH₂CHO, and gave upper limits for CH₃CN, C₂H₅CN, and CH₃OCH₃. Among these molecules, the hottest ones are CH₃OH at 156 K, C₂H₅OH and NH₂CHO, both at 164 K, and HCOOCH₃ at 134 K. The rest of the molecules are below 100 K.

In our survey, we detected CH₃OH, H₂CCO, CH₃CCH, CH₃CN, H₂CS, HCCCN, SO, and SO₂. CH₃OH has two components, a cold one at 24 K and a warm one at 257 K. CH₃CN is the other warm molecule in this source, with a temperature of 244 K. Due to the low signal-to-noise ratio of the CH₃CN lines, its temperature is subject to a large uncertainty. Nonetheless, the value 244 K can be treated as an upper limit. The remaining molecules are between 13 and 66 K, which agrees with the result from Bisschop et al. (2007). The FWHMs are from 3 to 4.5 km s⁻¹. All of the lines are blueshifted within the range of 0–2.4 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

GAL 45.47+0.05 is an ultracompact H ii region (Cesaroni et al. 1992; Hofner et al. 1999) with outflows (Ortega et al. 2012). Remijan et al. (2004a) reported the detection of CH₃CN in the 3 mm band using BIMA, and the CH₃CN was further mapped by Hernández-Hernández et al. (2014). Other COMs, such as CH₃OH, ¹³CH₃OH, CH₃CCH, CH₃OCH₃, C₂H₅CN, and C₂H₃CN, were reported in several millimeter-band line surveys (Hatchell et al. 1998b; Fontani et al. 2007).

In our 1.3 mm band survey, we fit six molecules with reliable temperatures: CH₃OH, CH₃CCH, H₂CS, HNCO, SO, and SO₂. Among them, only two are COMs. We did not detect CH₃CN. The gas temperatures are low with SO₂ being the hottest one at 44 K. The FWHMs are between 4 and 6 km s⁻¹. The velocity shifts with respect to v_lsr span between 0 and 2.3 km s⁻¹. The H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was detected and fit with one Gaussian profile.

GAL 12.91–00.26 is a massive hot core. CH₃OH, CH₃CN, CH₃OCH₃, HCOOCH₃, and C₂H₅CN lines were reported by several line surveys across the millimeter bands (Slysh et al. 1999; van der Tak et al. 2000; Purcell et al. 2006; Reiter et al. 2011; He et al. 2012). Its rich chemistry was reported by Bisschop et al. (2007) using IRAM and JCMT. In their study, they detected CH₃OH, ¹³CH₃OH, C₂H₅OH, CH₃OCH₃, HCOOCH₃, H₂CO, NH₂CHO, and CH₃CN at elevated temperatures. In addition to these hot COMs, they also detected H₂CCO, trans-HCOOH, and CH₃CCH at cold temperatures. C₂H₅CN and CH₃CHO were reported as upper limits.

In our survey, we reliably fit CH₃OH, ¹³CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, CH₂NH, H₂CCO, H₂CO, HCCCN, HCOOCH₃, OCS, SO, and SO₂. We also detected lines from the ${v}_{7}=1$ vibrational excited state of HCCCN. CH₃OH has two temperature components, a cold one at 14 K and a warm one at 178 K. Similarly, CH₃OCH₃, CH₃CN, HCCCN, and HCOOCH₃ are warm, with temperatures above 100 K. The rest of the molecules, especially CH₃CCH and CH₂NH, are cold. This result agrees with that of Bisschop et al. (2007). The FWHM of these molecules are about 3–6 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

GAL 19.61–0.23 is identified as a hot molecular core by multiple line surveys. In the 3 mm band, CH₃OH, CH₃CN, C₂H₅CN, HCOOCH, and trans-HCOOH were detected (Remijan et al. 2004a; Furuya et al. 2005). In the 2 and 1.3 mm bands, C₂H₅CN, C₂H₃CN, CH₃OCH₃, CH₃CN, HCOOCH₃, CH₂NH and CH₂OHCHO (glycoaldehyde) were reported (Fontani et al. 2007; Calcutt et al. 2014; Favre et al. 2014; Suzuki et al. 2016). Wu et al. (2009) and Furuya et al. (2011) mapped the CH₃CN emission in the 890 μm band. Qin et al. (2010) compiled a list of molecules detected from a line survey in a 2 GHz window in the SMA 890 μm band. CH₃OH, ¹³CH₃OH, CH₃OCH₃, HCOOCH₃, C₂H₅OH, CO(CH₂OH)₂, NH₂CHO, and CH₃CN were reported with multiple unblended spectral lines observed. CH₃CHO, CH₂NH, ¹³CN₃CN, ${\mathrm{CH}}_{3}^{13}\,\mathrm{CN}$, C₂H₅CN, and trans-HCOOH were reported with either only one detected spectral line, or with multiple lines that are blended with other molecular lines.

Our 1.3 mm broadband line survey supports the rich chemistry discovered by previous line surveys. We reliably fit CH₃OH, ¹³CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, C₂H₃CN, C₂H₅CN, H₂CCO, H₂CS, HCCCN, HCOOCH₃, HNCO, OCS, SO, and SO₂. However, we did not find a reliable detection of CH₃CHO, CH₂NH, ¹³CN₃CN, ${\mathrm{CH}}_{3}^{13}\,\mathrm{CN}$, C₂H₅OH, and NH₂CHO. CO(CH₂OH)₂ was not included in the list of molecules that were analyzed in this source. CH₃OH has two components, a cold one at 14 K and a warm one at 177 K. This result is different from Qin et al. (2010), who fit a single temperature of 151 K in their Boltzmann diagram despite the fact that a cold CH₃OH line has a significantly higher $\mathrm{ln}({N}_{{\rm{u}}})/{g}_{{\rm{u}}}$ value than the rest of the warm CH₃OH lines. For most of the other detected molecules, our analysis shows a lower rotational temperature with smaller uncertainties. This is because the global analysis of GOBASIC is less likely to overpredict the spectral intensity from a single molecule in a blended line. Still, the trend is similar to that shown by Qin et al. (2010). N-bearing molecules, including CH₃CN, C₂H₅CN, and HNCO, are found to be at higher temperatures. The FWHM of these lines spans a wide range, from 4 to 14 km ${{\rm{s}}}^{-1}$. COMs are generally found to have FWHMs of 7–9 km ${{\rm{s}}}^{-1}$, with the exception of ¹³CH₃OH, which is 4.6 km ${{\rm{s}}}^{-1}$. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

G24.33+0.14 is listed as an outflow candidate in the Extended Green Objects catalog (Cyganowski et al. 2008). It is a high-mass young stellar object that has not yet formed a compact H ii region. This stellar core was mapped in the 890 μm band by the SMA using molecular lines from CH₃CN, ¹³CH₃CN, CH₃OH, CH₃OCH₃, SO, and ³⁴SO, and a few other COMs such as C₂H₅OH and NH₂CHO were tentatively detected (Rathborne et al. 2011). We pointed to the stellar core G24.33+00.11 MM1 at $\alpha =18$^h35^m0814, $\delta =-07^\circ 35$'01''1, which is offset from the nominal source position of α = 18^h35^m081, δ = −07°35'04''. The flux of G24.33+00.11 MM1 is weaker compared to that of other hot cores we observed. Nevertheless, it is one of the sources displaying the richest chemistry. In addition to the commonly detected CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, H₂CCO, H₂CS, HCCCN, HCOOCH₃, OCS, and SO, we reliably fit C₂H₅CN, C₂H₅OH, CH₂NH, ¹³CH₃OH, and CH₃CN (${v}_{8}=1$). Interestingly, we did not detect SO₂. The hottest molecules are CH₃CN (302 K), warm CH₃OH (233 K), CH₃OCH₃ (200 K), and HCOOCH₃ (124 K). CH₃OH also has a cold component at 14 K. Because we treated vibrational states as individual molecules, the CH₃CN (${v}_{8}=1$) temperature is 150 K, lower than the vibrational ground state. The rest of the COMs are below 100 K. The FWHMs of the lines are 3–5 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

GAL 24.78+0.08 is an embedded cluster with high-mass protostars (Furuya et al. 2002). It possesses a rotation toroid (Beltrán et al. 2005) and gas infall accompanied by outflows (Cesaroni et al. 2003; Beltrán et al. 2006, 2011). In these observations, CH₃OH, H₂CCO, CH₃OCH₃, C₂H₅CN, C₂H₃CN, C₂H₅OH, and HCOOCH₃ lines were reported, and CH₃CN and ${\mathrm{CH}}_{3}^{13}\,\mathrm{CN}$ were used as kinematic tracers. Molecular lines from CH₃OH, CH₃OD, CH₃CN, HCOOCH₃, and C₂H₅CN were also reported in other surveys in the centimeter and millimeter bands (Purcell et al. 2006; Vig et al. 2008; Ratajczak et al. 2011; Calcutt et al. 2014; Favre et al. 2014). Bisschop et al. (2007) reported the detection of H₂CO, CH₃OH, C₂H₅OH, NH₂CHO, CH₃CN, C₂H₅CN, HCOOCH₃, CH₃OCH₃, H₂CCO, CH₃CCH, and trans-HCOOH. The rotational temperature of these molecules ranges from 39 to 261 K. Specifically, glycolaldehyde (CH₂OHCHO) was reported as a detection in this source (Beltrán et al. 2005; Calcutt et al. 2014).

In our analysis, we reliably fit CH₃OH, ¹³CH₃OH, CH₃OCH₃, CH₂NH, CH₃CCH, CH₃CN, H₂CS, HCCCN, HCOOCH₃, OCS, SO, and SO₂. CH₃OH has a cold component at 17 K and a warm component at 141 K. We also detected the HCCCN ${v}_{7}=1$ vibrational excited state. The temperatures of CH₃OH, CH₃OCH₃, HCOOCH₃, HCCCN (${v}_{7}=1$), and CH₃CN are above 100 K. CH₃CN is the hottest molecule, with a temperature of 204 K. This temperature of CH₃CN is slightly lower than the 261 K reported by Bisschop et al. (2007), but higher than the 132 K reported by Beltrán et al. (2005), who combined the lines from the normal species, the ¹³C isotopologue, and the ${v}_{8}=1$ vibrational state in their analysis. The FWHMs of the lines are 5–9 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

DR21(OH), located in the Cygnus X complex, is a giant, fragmented molecular cloud with multiple emission cores (Minh et al. 2012; Girart et al. 2013). Small molecules such as CS, OCS, H₂CO, HDCO, H₂CS, and c-C₃H₂ (cyclopropenylidene) have been observed in the centimeter band toward this cloud (Angerhofer et al. 1978; Goldsmith & Linke 1981; Madden et al. 1989; Chandler et al. 1993; Richardson et al. 1994; Mehringer et al. 1995; Wootten & Mangum 2009). Numerous COMs, such as CH₃OH, CH₃CN, CH₃CHO, c-C₂H₄O, CH₃CCH, CH₃OCH₃, C₂H₅CN, and CH₂NH, were detected in multiple line surveys in the 3, 2, 1.3, and 0.89 mm bands (Kalenskii et al. 1997, 2000a, 2000b; Slysh et al. 1999, 2002; van der Tak et al. 2000; Ikeda et al. 2001; Alakoz et al. 2002; Charnley 2004; Kalenskii & Johansson 2010a; Wirström et al. 2011; Zapata et al. 2012; Girart et al. 2013; Suzuki et al. 2016). Kalenskii & Johansson (2010a) found low to moderate rotational temperatures, 9–56 K, for most molecules detected. The evidence for the existence of an embedded hot core is the hot rotational temperature of CH₃OH at 252 K and SO₂ at 186 K.

Our results agree well with those of Kalenskii & Johansson (2010a) and Minh et al. (2012) in the type of molecules detected. In brief, two methanol temperature components were observed, indicated by the coexistence of the cold methanol branch at 242 GHz and the warm methanol branch between 250 and 253 GHz. The temperature of the warm methanol, however, is 93 K and significantly lower than the value reported by Kalenskii & Johansson (2010a). It is possible that heavy beam dilution diminished the weaker lines of the methanol branch into the noise, which led to our lower estimation of the rotational temperature. Other detected COMs include CH₃CN, CH₃CCH, CH₃CHO, CH₃OCH₃, H₂CCO, HCCCN, and HCOOCH₃. No rigorous detections of trans-HCOOH, NH₂CHO, and C₂H₃CN were found, despite being reported by Kalenskii & Johansson (2010a). The two tentative detections reported by Kalenskii & Johansson (2010a), CH₂NH and C₂H₅OH, were also not found. The LTE temperatures of the COMs we detected are all below 150 K, with CH₃CHO being the warmest one at 139 K. The FWHMs of these molecular lines are consistent within the range of 4–7 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with three Gaussian components.

Multiple methanol masers have been observed in the DR21 complex (Plambeck & Menten 1990; Araya et al. 2009; Fish et al. 2011). Similarly, we also observed non-LTE methanol emission at 229.76 GHz (${8}_{-\mathrm{1,8}}\to {7}_{\mathrm{0,7}}$) and 250.5 GHz (${11}_{\mathrm{0,11}}\to {10}_{\mathrm{1,10}},{A}^{+}$), as the total flux of these two methanol lines considerably exceeds the LTE emission at 93 K. These two lines may be associated with the same physical environment that drives the methanol masers at lower frequencies. The rest of the molecular lines can be modeled with the LTE model.

W75N is an ultracompact H ii region associated with high-mass star formation (Persi et al. 2003). Watson et al. (2002) mapped CH₃CN, and more recently, three compact cores, MM1, MM2, and MM3, were found in the 1.3 mm continuum map (Minh et al. 2010). The largest core, MM1, is about 3'' × 6'', and all three cores are covered by the CSO beam. The MM1 core was further resolved into two emission peaks, MM1a and MM1b, which present different chemical compositions (Minh et al. 2010). SO, SO₂, HCCCN, NH₂CHO, and HCOOH were detected in MM1a, whereas MM1b exhibits more COMs such as CH₃OH, HCOOCH₃, and C₂H₅OH. Other studies also reported COMs such as CH₃OH, CH₃CN, C₂H₅OH, HCOOCH₃, and trans-HCOOH (Menten et al. 1986; Pankonin et al. 2001; Minier & Booth 2002; Remijan et al. 2004a; Reiter et al. 2011).

We fitted CH₃OH, H₂CCO, CH₃CCH, CH₃CN, HCCCN, H₂CS, OCS, SO, and SO₂. Two CH₃OH temperature components are found, a cold one at 19 K and a warm one at 207 K. CH₃CN and SO₂ are above 100 K, and the rest of the molecules are below 100 K. The widths of the lines show two categories: CH₃CCH, cold CH₃OH, H₂CS, and SO are narrow, between 4.2 and 5.5 km s⁻¹; CH₃CN, warm CH₃OH, H₂CCO, HCCCN, OCS, and SO₂ are wide, between 7.4 and 10.2 km s⁻¹. The velocities are consistent within 1 km s⁻¹. No detection was found for HCOOCH₃, C₂H₅OH, NH₂CHO, and HCOOH, likely due to the heavy beam dilution effect. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

W51 has two molecular cores, e1 and e2, and two extended continuum emission regions, IRS 1 and IRS 2 (Ho & Young 1996). We pointed to the center of e1, but also covered the entire e2 core with our CSO beam. Edges from IRS 1 may also be included in the beam. A spectral line survey of the e1 and e2 cores in the 3 mm band was reported by Kalenskii & Johansson (2010b), who detected COMs such as CH₃OH, CH₃CN, CH₃OCHO, C₂H₅OH, CH₃OCH₃, CH₃CH₂CN, CH₃COCH₃, and C₂H₅OOCH. They found that O-bearing molecules dominate the e2 core whereas N-bearing molecules dominate the e1 core. Other observations across the millimeter bands have detected multiple COMs, including CH₃OH, CH₃CN, CH₃CCH, HCOOCH₃ (g.s. and v_t = 1), HCOO¹³CH₃, C₂H₅OH, CH₃CHO, c-C₂H₄O, trans-HCOOH, CH₃COOH, C₂H₅CN (g.s., v_t = 1, and v_b = 1), C₂H₃CN, and, tentatively, (CH₂OH)₂ (Dickens et al. 1997; Slysh et al. 1999; Kalenskii et al. 2000a, 2000b, 2002; Ikeda et al. 2001; Alakoz et al. 2002; Minier & Booth 2002; Remijan et al. 2002, 2008; Demyk et al. 2008; Jordan et al. 2008; Wirström et al. 2011; Favre et al. 2014; Hernández-Hernández et al. 2014; Lykke et al. 2015; Suzuki et al. 2016). The rotational temperatures of CH₃OH, CH₃CN, C₂H₅OH, and C₂H₃CN were derived to be above 150 K, whereas those of CH₃CHO and HCOOCH₃ were below 100 K (Ikeda et al. 2001; Remijan et al. 2002, 2004b).

We detected CH₃OH, ¹³CH₃OH, CH₃OCH₃, HCOOCH₃, H₂CCO, CH₃CCH, CH₃CN, CH₂NH, HCCCN, H₂CS, OCS, SO, and SO₂. Due to limited spectral sampling, the noise level above 259.5 GHz is noticeably higher than the rest of the spectrum. To avoid the unrealistic temperature simulations of large COMs from overfitting the noise in this spectral region, we truncated the molecular catalogs of CH₃OCH₃, HCOOCH₃, and H₂CCO at 259.5 GHz. Visual examinations confirmed that fits better matched the actual observed lines after this adjustment. The temperatures of the molecules in this source span a wide range from 14 to 472 K. The 472 K HCOOCH₃, in contrast to the result of Ikeda et al. (2001), appears to be much hotter than the rest of the molecules. Warm CH₃OH and CH₃CN are above 200 K, and CH₃OCH₃, ¹³CH₃OH, and SO₂ are above 100 K. The CH₃CN rotational temperature, 226 K, is slightly higher than that found by Remijan et al. (2002), which is not surprising because the 3 and 2 mm lines of CH₃CN showed a larger intensity scattering in the analysis of Remijan et al. (2002), likely due to the inconsistency of beam sizes. The cold CH₃OH component is at 23 K. The FWHMs of the molecules range from 7.5 to 11.4 km s⁻¹, and the velocities range from 1 to 4 km s⁻¹, redshifted. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

W3 is a massive star-forming region with a hot core, W3(H₂O), indicated by the H₂O maser (Alcolea et al. 1993; Wilner et al. 1999), and an ultracompact H ii region, W3(OH), which is indicated by the OH maser (Wyrowski et al. 1997). The OH maser is located 6'' to the west of W3(H₂O) (Turner & Welch 1984; Wilner et al. 1995). CH₃OH masers are also present in this region (Slysh et al. 1999). Our CSO beam covered both sources, but was centered on W3(H₂O).

Both cores have a rich inventory of COMs, revealed by extensive line surveys across the millimeter bands (Helmich et al. 1994; Helmich & van Dishoeck 1997; Kalenskii et al. 1997, 2000a; Wyrowski et al. 1999a; van der Tak et al. 2000; Ikeda et al. 2001; Alakoz et al. 2002; Charnley 2004; Sutton et al. 2004; Kim et al. 2006; Bisschop et al. 2007; Fontani et al. 2007; Ratajczak et al. 2011; Reiter et al. 2011; Li et al. 2012; Gerner et al. 2014; Hernández-Hernández et al. 2014; Ligterink et al. 2015; Qin et al. 2015). Detected COMs include CH₃OH, ¹³CH₃OH, C₂H₅OH, NH₂CHO, CH₃CN, ${\mathrm{CH}}_{3}^{13}\,\mathrm{CN}$, C₂H₅CN, C₂H₃CN, HCOOCH₃, CH₃OCH₃, H₂CCO, CH₃CHO, CH₃CCH, and trans-HCOOH, as well as ground state and vibrationally excited HCCCN. The rotational temperature of most COMs ranges between 100 and 250 K (Helmich & van Dishoeck 1997; Fontani et al. 2007; Qin et al. 2015), and CH₃OH has two temperature components (Qin et al. 2015). Cold CH₃OH, CH₃CCH, C₂H₅OH, and CH₃CHO lines were also observed at low frequency (3 mm and centimeter; Menten et al. 1986; Alakoz et al. 2002; Charnley 2004; Kim et al. 2006).

CH₃CN lines in the 1.3 mm band have been imaged to reveal the binary rotational structure of W3(H₂O) (Chen et al. 2006). The CH₃CN lines in W3(H₂O) have wide velocity range from −55 to −43 km s⁻¹ (i.e., −8 to 4 km s⁻¹ with respect to our v_lsr), whereas the CH₃CN lines in W3(OH) are more concentrated in the velocity channels from −48 to −43 km s⁻¹ (−1 to 4 km s⁻¹ with respect to our v_lsr).

In our survey, we fit CH₃OH, ¹³CH₃OH, CH₃OCH₃, H₂CCO, HCOOCH₃, CH₃CCH, CH₃CN, C₂H₅CN, HCCCN (both ground state and ${v}_{7}=1$), H₂CS, OCS, SO, and SO₂. The line shapes of the warm O-bearing molecules, including CH₃OH, ¹³CH₃OH, CH₃OCH₃, and HCOOCH₃, are asymmetric, and can be modeled with two velocity components. For each of these molecules, one component is redshifted from 1.7 to 2.5 km s⁻¹ with a narrower FWHM between 4 and 5.8 km s⁻¹, while another component is blueshifted from 0 to 3.2 km s⁻¹ with a wider FWHM between 5.4 and 9.7 km s⁻¹. Comparing this kinematic information to Chen et al. (2006), it is likely that the wide, blueshifted components arise from the W3(H₂O) region, and the redshifted, narrow components arise from the W3(OH) region. We found that the narrow components of CH₃OH, ¹³CH₃OH, CH₃OCH₃, and HCOOCH₃ are all hot, with rotational temperatures of 100–162 K. CH₃OH and CH₃OCH₃ from the W3(H₂O) region, on the other hand, have both hot (150–156 K) and cold (17–23 K) components. The SO₂ line profile is more complicated; it can be modeled with three components, each of which has a distinct rotational temperature (17, 70, and 148 K), velocity, and line width. It is difficult to attribute these components definitively to either the W3(H₂O) or the W3(OH) regions. These temperatures are comparable to the results from Helmich et al. (1994) and Bisschop et al. (2007). The temperatures of N-bearing molecules are slightly colder than the warm O-bearing molecules, ranging between 83 and 152 K. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with three Gaussian components.

GAL 034.3+00.2 is a high-mass, chemically rich star-forming region with ultracompact H ii regions (Benson & Johnston 1984) and embedded hot cores (Garay & Rodriguez 1990; Carral & Welch 1992). Numerous small molecules are present in this region (Macdonald et al. 1996), and multiple COMs have also been detected across the millimeter bands. The detected COMs include common interstellar O-bearing and N-bearing molecules such as CH₃OH, CH₃CCH, CH₃CN, C₂H₃CN, C₂H₅CN, NH₂CHO, C₂H₅OH, CH₃OCH₃, HCOOCH₃, HCOOCH₃, trans-HCOOH, CH₃CHO, and CH₃COOH (MacDonald et al. 1995; Millar et al. 1995; Macdonald et al. 1996; Mehringer & Snyder 1996; Dickens et al. 1997; Hatchell et al. 1998b; Nummelin et al. 1998b; Slysh et al. 1999; Watt & Mundy 1999; Kalenskii et al. 2000a, 2000b; Kim et al. 2000, 2001; Ikeda et al. 2001; Alakoz et al. 2002; Remijan et al. 2003; Charnley 2004; Mookerjea et al. 2007; Reiter et al. 2011; Rosero et al. 2013; Lykke et al. 2015; Fu & Lin 2016; Suzuki et al. 2016). Istopologues such as CH₂DCN and ¹³CH₃OH are also observed (Gerin et al. 1992; Macdonald et al. 1996; Hatchell et al. 1998b).

GAL 034.3+00.2, is an incredibly rich source in chemistry. We were able to derive reliable rotational temperatures and densities for 22 molecules, in addition to the detection of spectral lines from 22 other small molecules and their isotopologues. In addition to the commonly detected CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, H₂CCO, H₂CS, HCCCN, HCOOCH₃, OCS, SO, and SO₂, we found C₂H₃CN, C₂H₅CN, C₂H₅OH, CH₃CHO, CH₃COCH₃, NH₂CHO, CH₂NH, HCCCN (${v}_{7}=1$), and trans-HCOOH. ¹³CH₃OH and ¹³CH₃CN are both detected. We did not analyze CH₃COOH because the available molecular catalog was incomplete. CH₃OH was fitted to two components, a cold one at 16 K and a warm one at 190 K. On the other hand, one component at 155 K was sufficient to describe ¹³CH₃OH. Other COMs have temperatures spanning 25 to 160 K. Surprisingly, CH₃OH, instead of CH₃CN, is the hottest molecule in GAL 034.3+00.2. The FWHMs are between 4 and 8 km s⁻¹. The velocities are consistent in the range of −1 and 1 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with three Gaussian components.

GAL 31.41+0.31 is a high-mass star-forming region (Cesaroni et al. 1994) with embedded hot cores (Osorio et al. 2009; Cesaroni et al. 2011) and outflows (Maxia et al. 2001; Beltrán et al. 2004; Araya et al. 2008; Moscadelli et al. 2013). CH₃CN was used as a tracer for the structure and kinematics and extensively mapped in the millimeter (Olmi et al. 1995; Walmsley et al. 1995; Olmi et al. 1996a, 1996b; Pankonin et al. 2001; Beltrán et al. 2004, 2005; Araya et al. 2005; Purcell et al. 2006; Hernández-Hernández et al. 2014). Numerous COMs have been detected in this region via multiple millimeter and submillimeter line surveys. The detected COMs include CH₃OH, ¹³CH₃OH, CH₃CN, CH₃CCH, CH₃OCH₃, HCOOCH₃, C₂H₅OH, CH₃CHO, c-C₂H₄O, trans-HCOOH, C₂H₃CN, C₂H₅CN, and CH₃COCH₃ (Hatchell et al. 1998b; Nummelin et al. 1998b; Ikeda et al. 2001; Fontani et al. 2007; Araya et al. 2008; Jordan et al. 2008; Beltrán et al. 2009; Reiter et al. 2011; Isokoski et al. 2013; Calcutt et al. 2014; Ligterink et al. 2015; Suzuki et al. 2016). It is one of the sources where CH₂OHCHO (glycolaldehyde), a sign of complex chemistry, was reported (Beltrán et al. 2009; Beltràn et al. 2010; Calcutt et al. 2014).

GAL 31.41+0.31 is one of the chemically richest sources in our list. We were able to derive reliable rotational temperature and density for 22 molecules, in addition to the detection of spectral lines from 19 other small molecules and their isotopologues. In addition to the commonly detected CH₃OH, CH₃OCH₃, CH₃CCH, CH₃CN, H₂CCO, H₂CS, HCCCN, HCOOCH₃, OCS, SO, and SO₂, we found C₂H₃CN, C₂H₅CN, C₂H₅OH, CH₃CHO, CH₃COCH₃, NH₂CHO, CH₂NH, and CH₃SH. ¹³C isotopologues of CH₃OH and CH₃CN are also detected. The ¹³CH₃OH:CH₃OH ratio is 0.16, whereas the ¹³CH₃CN:CH₃CN ratio is 0.05. The temperatures of the COMs span 20 to 320 K. Both ¹³CH₃OH and CH₃OH have two components, a cold one at ∼40 K and a warm one above 200 K. The temperature of ¹³CH₃CN is lower than that of CH₃CN, with the former at 105 K and the latter at 321 K. Additionally, CH₃CN (${v}_{8}=1$) is detected at 180 K. The FWHMs of the lines are between 5 and 10 km s⁻¹. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with three Gaussian components.

GAL 10.47+00.03 is an ultracompact H ii region with an embedded hot core (Cesaroni et al. 1992; Pascucci et al. 2004). It is surprising that GAL 10.47+00.03 has chemical complexity comparable to that of Orion-KL. Hot cores have been identified in this UC H ii region (Pascucci et al. 2004), and methyl cyanide (CH₃CN) (Olmi et al. 1993, 1995,1996a, 1996b; Araya et al. 2005; Hernández-Hernández et al. 2014) has been used to map this source. The molecular line surveys were conducted by a few groups (Hatchell et al. 1998b; Nummelin et al. 1998b; Ikeda et al. 2001; Pankonin et al. 2001; Hatchell & van der Tak 2003; Purcell et al. 2006; Fontani et al. 2007; Jordan et al. 2008; Rolffs et al. 2011). Detections of several COMs, including O-bearing molecules CH₃OH, ¹³CH₃OH, CH₃CCH, CH₃CHO, CH₃OCH₃, HCOOCH₃, CH₃CHO, CH₃COCH₃, trans-HCOOH, C₂H₅CN, C₂H₃CN, and NH₂CHO were reported in these surveys. Sulfur chemistry, probed by H₂CS, SO, and SO₂ emissions, was studied by Hatchell et al. (1998a). Suzuki et al. (2016) detected CH₂NH in this source as well.

In our survey, we report the rigorous detection of 13 COMs, in addition to 29 smaller molecules. For O-bearing molecules, we detected CH₃OH with a cold and a warm component, as well as ¹³CH₃OH, CH₃OCH₃, H₂CCO, HCOOCH₃, trans-HCOOH, C₂H₅OH, CH₃CHO, and CH₃COCH₃. For N-bearing molecules, we detected CH₃CN (both ground state and ${v}_{8}=1$), ¹³CH₃CN, C₂H₃CN, C₂H₅CN, CH₂NH, HCCCN, and NH₂CHO. Because of heavy line blending, the FWHMs of C₂H₅OH, CH₃CHO, and CH₃COCH₃ were fixed to 10 km s⁻¹ for the fit to converge. Our result of detected COMs agrees well with previous line surveys. The cold CH₃OH component is at 21 K, while the warm component is at 258 K. All CH₃OH emission features could be modeled well with LTE. HCOOCH₃ is slightly colder than the warm CH₃OH at 233 K. Other O-bearing COMs are slightly colder than the warm CH₃OH, with ¹³CH₃OH at 179 K, and CH₃OCH₃, H₂CCO, and trans-HCOOH all between 130 and 150 K, agreeing with the result for CH₃OCH₃ from Ikeda et al. (2001). The temperatures of N-bearing COMs span a wide range. Methyl cyanide is one of the hottest: the main species is at 668 K, the ${v}_{8}=1$ state is at 733 K, and the ¹³C isotopologue is at 298 K. N-bearing COMs also suffer from a large temperature uncertainty due to heavy line blending. The methyl cyanide temperature is found to be much higher than the literature value of 148 K (Olmi et al. 1996b). In our survey, we observed emission features from methyl cyanide lines up to K = 12 in the $J=12\to 11,J=13\to 12$, and $J=14\to 13$ ladders. The higher K lines observed as compared to Olmi et al. (1996b) cause the higher rotational temperature of methyl cyanide in our analysis. CH₂NH is at 654 K, but with a large temperature uncertainty because of line blending. C₂H₃CN is much hotter than C₂H₅CN, the former being at 507 K, and the latter being at 177 K. NH₂CHO is at 248 K. For S-bearing molecules, we detected H₂CS, OCS, SO, and SO₂. They are significantly colder than the N-bearing species, with the hottest SO₂ at 162 K. CH₃CCH is also present in large abundance at a moderate temperature of 59 K.

The FWHMs of these molecular lines are relatively wide, spanning 7 to 12 km s⁻¹. The line shape is symmetric, agreeing with Olmi et al. (1993, 1996b). The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with two Gaussian components.

The molecular lines and chemistry in Orion-KL have been extensively studied by numerous groups (Sutton et al. 1985, 1995; Menten et al. 1986; Blake et al. 1987; Turner 1989, 1991; Mangum et al. 1990; Minh et al. 1993; Groesbeck 1995; Dickens et al. 1997; Schilke et al. 1997, 2001; Slysh et al. 1999; Ikeda et al. 2001; Lee et al. 2001; Liu et al. 2001, 2002; Alakoz et al. 2002; Minier & Booth 2002; White et al. 2003; Beuther et al. 2004, 2006; Charnley 2004; Comito et al. 2005; Friedel et al. 2005; Persson et al. 2007; Friedel & Snyder 2008; Remijan et al. 2008; Goddi et al. 2009; Crockett et al. 2010; Gupta et al. 2010; Margulès et al. 2010; Favre et al. 2011a, 2011b; Zapata et al. 2011; Friedel & Widicus Weaver 2012; Brouillet et al. 2013; Crockett et al. 2014; Favre et al. 2014; Frayer et al. 2015; Morris et al. 2016; Suzuki et al. 2016; Tahani et al. 2016). We observed this source with a pointing centered on the Orion Hot Core as described by Blake et al. (1986). Due to the extreme complexity of the kinematics of Orion-KL, the line shapes are asymmetric and non-Gaussian. Our global fit for Orion-KL required more manual configuration for the fitting parameter space, and the overall fit residual was not as clean as the other sources we analyzed. For several molecules such as HCCCN, HCCCN (${v}_{7}=1$), and CH₂NH, Gaussian components with fixed FWHM and $\delta v$ were necessary to constrain the overall line shape of the transitions. There were also numerous lines that could not be modeled or were only partially modeled. Nonetheless, as a benchmark source, our detection of many COMs, including CH₃OH, ¹³CH₃OH, CH₃OCH₃, HCOOCH₃, CH₃COCH₃, trans-HCOOH, C₂H₃CN, C₂H₅CN, and CH₃CN, agrees with the previous literature. The asymmetric H₂CO ${3}_{\mathrm{1,2}}\to {2}_{\mathrm{1,1}}$ line was modeled with three Gaussian components.

Sgr B2(N-LMH) is by far the most chemically complex source observed. A large portion of reported COMs were first detected in Sgr B2(N), which is known to harbor the largest number of COMs of any sightline investigated thus far. There are numerous literature studies of both comprehensive broadband line surveys and detailed studies for individual molecules for Sgr B2(N): to list a few, for example, Goldsmith & Linke (1981), Miao & Snyder (1997), Mehringer et al. (1997), Nummelin et al. (1998a, 2000), Cernicharo et al. (1999), Hollis et al. (2000, 2006), Liu et al. (2001), Snyder et al. (2002), Remijan et al. (2002), Halfen et al. (2006, 2011, 2013), Apponi et al. (2006), Requena-Torres et al. (2006), Belloche et al. (2007, 2008, 2009, 2013), Leigh et al. (2007), Halfen & Ziurys (2008), Remijan et al. (2008), Martín-Pintado et al. (2001), Friedel et al. (2004), Favre et al. (2014), and Neill et al. (2014). Because of the extreme spectral complexity and numerous previous studies that have targeted this source, we only provide the deconvolved spectrum of Sgr B2 (N-LMH) without performing a global spectral analysis.