The night “Comisión de Asignación de Tiempos” (CAT) evaluates the observing proposals that guarantee to the Spanish community access to the majority of the night telescopes at the “Observatorios de Canarias” (OOCC): GTC, WHT, INT, TNG, NOT, Mercator, and Liverpool on La Palma, and Stella, TTT on Tenerife, and TCS since 2024A. Likewise, the CAT distributes the time allotted to Spain on the GTC, in the same way that it jointly manages, together with the University of Florida, the 1.5% of GTC time in collaboration with this international partner.
Telescope time is offered and allocated twice a year in periods of 6 months. Detailed information will be provided in the Call for Proposals. Allocation periods run differently depending on the telescope as indicated next:
| Semester | Telescope | Period |
|---|---|---|
|
Semesters A Due date: 2 Oct 2026, 12.00pm WEST (2027A) |
Liverpool, TTT* INT, Stella, TCS GTC NOT, TNG, Mercator WHT |
January – August* February – July March – August April – September May – October |
|
Semesters B Due date: 7 Apr 2026, 21:59 UT (2026B) CAT meeting: mid or end of May. |
Liverpool, TTT* INT, Stella, TCS GTC NOT, TNG, Mercator WHT |
July – February* August – January September – February October – March November – April |
*A two month overlap period is adopted at the start and end of each period, when proposals from both semesters may be observed, in order to reduce problems with under-filled observation queues.
The night-time CAT is composed by three panels with five well-known astrophysicists each, one President (that represents the Director of the IAC), and one Vice-President.
There are different schemes to apply for observing time. They are all described in the menu on the left: Ordinary proposals (including regular and Large programs), DDT, Service Time, and various international agreements (Note: starting from 2026B, Service and DDT time on NOT and TNG have been substituted with the introduction of a Fast Track channel for those proposals that fullfil certain characteristics, see news, while the rest will have to be submitted as regular programs).
The IAC80 is no longer offered through CAT since semester 2013A. Any interested potential users must directly contact the Head of Telescope Operations at the IAC [aoscoz at iac.es], or visit this web site.
The President and vice-President of the night CAT can be contacted by email to catiac@iac.es.
Page updated: 9 March 2026.