Interstellar formaldehyde
![A rotational spectrum of H2CO at the ground state vibrational level at 30 K.](/Images/godic/202501/20/H2CO_rot_spec4433.png")
![The rotational energy level diagram of H2CO at 30 K shown with ortho/para splitting.](/Images/godic/202501/20/H2co_energydiagram4434.png")
Interstellar formaldehyde (a topic relevant to astrochemistry) was first discovered in 1969 by L. Snyder et al. using the National Radio Astronomy Observatory. Formaldehyde (H2CO) was detected by means of the 111 - 110 ground state rotational transition at 4830 MHz. On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON).