Using this form investigators can estimate the integration time, magnitude, or signal-to-noise ratio (SNR) for a stellar observation for a given telescope, CCD or IR imager, and filter combination at specified seeing/airmass/sky conditions at CTIO, SOAR, or KPNO. Simply fill in the appropriate information below and press the

**
CCDTIME is intended to provide an approximate exposure guide; the treatment
of sky brightness is based upon Walker (1987 NOAO Newsletter No. 10, 16); see
also discussion in Elias (NOAO Newsletter No. 37, 29).**

In the form below, leave either the integration time, the magnitude, or the signal-to-noise ratio field set to INDEF, or leave it blank, to compute this value based on the other parameters. Investigators may select instruments for one or both observatories using the same parameter input.

Additional information about the imaging instruments at these observatories can be found at the Web sites for KPNO, CTIO, and SOAR.

An Excel spreadsheet for estimating DECam exposures can be found on the CTIO DECam page.

Please use the CTIO Infrared Imager Exposure Time Calculator for CT-4m observations with ISPI.

Information for estimating exposure times for the CT-1.3m telescope can be found on the OSU Andicam Page.

The instrument scientist maintains a page for estimating exposure times for the WIYN-0.9m telescope with HDI.

webmaster@noao.edu

29 Mar 2017