Cahill Rooftop Observatory

Check-Out Procedures

To check out the telescopes or binoculars, you need to get authorized, pick a date, and inform us about your plans. We have several tools to help you plan your session. Finally, we have some suggestions for people who don't know how to use these telescopes, but want to do some stargazing.

Before Check-Out

Caltech students, staff, and faculty may reserve CRO equipment for observing labs or personal use, subject to the following restrictions:

Checking Out Equipment

To check out a telescope:

This is a shared resource, and thus falls under the precepts of the Caltech Honor Code. Take good care of the equipment entrusted to you, and return it to the observatory in a timely fashion so that others have an equal opportunity to use it. Repeated failure to follow these simple rules will result in a curse being placed upon you so that it is never clear when you want to observe.


CRO equipment may be handled only by individuals ("authorized users") who have demonstrated that they are sufficiently knowledgeable and responsible to use them in the proper fashion. Any member of the Caltech community can become authorized. JPL staff can access the telescopes by special arrangement.

Each telescope has its own peculiarities, so you must be authorized separately for each instrument. Just because you've been checked out on the C-14 does not mean you know how to use the C-10 (although they are similar enough that it will be easy to learn the latter). In addition, you must be separately authorized for solar observing, for use of binoculars, and for each individual CCD model. We will keep track of who has been trained on which instruments.

Caltech's rooftop access policies prohibit us from granting card access to every authorized user. We will be happy to let you on to the roof when you need to access equipment. In very rare cases, we may be able to make an exception and grant rooftop access to very frequent observers.

Caltech students, staff, or faculty who wish to become authorized users should follow these steps: