You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Circadian_rhythm

Context:
More-or-less independent circadian rhythms are found in many organs and cells in the body outside the suprachiasmatic nuclei (SCN), the "master clock". These clocks, called peripheral oscillators, are found in the adrenal gland,[citation needed] oesophagus, lungs, liver, pancreas, spleen, thymus, and skin.[citation needed] Though oscillators in the skin respond to light, a systemic influence has not been proven. There is also some evidence that the olfactory bulb and prostate may experience oscillations when cultured, suggesting that these structures may also be weak oscillators.[citation needed]

Question:
What is the SCN considered to be in comparison to the peripheral oscillators?

master clock