Context. IRC +10216 is the prototypical carbon star exhibiting an extended molecular circumstellar envelope. Its spectral properties are therefore the template for an entire class of objects. Aims. The main goal is to systematically study the λ ∼ 1.3 cm spectral line characteristics of IRC +10216. Methods. We carried out a spectral line survey with the Effelsberg-100 m telescope toward IRC +10216. It covers the frequency range between 17.8 GHz and 26.3 GHz (K-band).Results. In the circumstellar shell of IRC +10216, we find 78 spectral lines, among which 12 remain unidentified. The identified lines are assigned to 18 different molecules and radicals. A total of 23 lines from species known to exist in this envelope are detected for the first time outside the solar system and there are additional 20 lines first detected in IRC +10216. The potential orgin of "U" lines is also discussed. Assuming local thermodynamic equilibrium (LTE), we then determine rotational temperatures and column densities of 17 detected molecules. Molecular abundances relative to H 2 are also estimated. A non-LTE analysis of NH 3 shows that the bulk of its emission arises from the inner envelope with a kinetic temperature of 70 ± 20 K. Evidence for NH 3 emitting gas with higher kinetic temperature is also obtained, and potential abundance differences between various 13 C-bearing isotopologues of HC 5 N are evaluated. Overall, the isotopic 12 C/ 13 C ratio is estimated to be 49 ± 9. Finally, a comparison of detected molecules in the λ ∼ 1.3 cm range with the dark cloud TMC-1 indicates that silicate-bearing molecules are more predominant in IRC +10216.

The Milky Way Imaging Scroll Painting (MWISP) project is an unbiased Galactic plane CO survey for mapping regions of l = −10 • to +250 • and |b| < ∼ 5. • 2 with the 13.7 m telescope of the Purple Mountain Observatory. The legacy survey aims to observe the 12 CO, 13 CO, and C 18 O (J=1-0) lines simultaneously with full-sampling using the nine-beam Superconducting SpectroScopic Array Receiver (SSAR) system with an instantaneous bandwidth of 1 GHz. In this paper, the completed 250 deg 2 data from l = +25. • 8 to +49. • 7 are presented with a grid spacing of 30 ′′ and a typical rms noise level of ∼ 0.5 K for 12 CO at the channel width of 0.16 km s −1 and ∼ 0.3 K for 13 CO and C 18 O at 0.17 km s −1 . The high-quality data with moderate resolution (∼50 ′′ ), uniform sensitivity, and high spatial dynamic range, allow us to investigate the details of molecular clouds (MCs) traced by the three CO isotope lines. Three interesting examples are briefly investigated, including distant Galactic spiral arms traced by CO emission with V LSR <0 km s −1 , the bubble-like dense gas structure near the H ii region W40, and the MCs distribution perpendicular to the Galactic plane.