ISPI Quick reference guide

General information

The Infrared Side Port Imager ISPI (eye-spy) is a facility imager at the CTIO Blanco 4-m telescope, serving a broad range of science programs through the following capabilities:

  • 1-2.4 micron imaging with 2K x 2K HgCdTe HAWAII-2 array
  • 0.3 arcsec/pixel sampling matched to f/8 IR image quality of ~0.6 arcsec
  • 10.25 x 10.25 arcmin field of view,
  • broad band J,H and Ks, as well as a set of narrow band filters.
  • A list of available filters can be found on the ISPI filter page.


During the January 2003 engineering night weather permitted us to measure the throughput of ISPI at the telescope, see table. The ISPI throughput is very similar to the throughput of Flamingos at the Kitt Peak 4m. Exposure times and signal-to-noise ratios can be estimated using the exposure time calculator on the CTIO Infrared Instrument web page .

ISPI performancebased on data taken on Jan. 19, 2003
Band Background Flux
per pixel
Integrated Flux
for m=15 star
point source detection limit
5 sigma in
60 sec
J 310 4000 19.6
H 1560 5000 18.9
K' 2160 3300 18.3

The HAWAII-2 array in ISPI

The array, as set-up in ISPI since May 2003, has the following performance characteristics:

  • Gain: 4.25 e-/ADU
  • Well depth: 150,000 e-
  • Linearity: 1% full frame linear range is ~13,000 ADU's
  • Minimum exposure time: 3.227s

NOTE: For data taken prior to May 2003 please consult the ISPI support staff.

Observing with ISPI

ISPI is run through a Graphical User Interface, in which all array control parameters, such as exposure time, number of co-adds, as well as filter, telescope focus and telescope off-set can be set.

The GUI can also initiate a series of observations, to conduct for example a dither sequence, a focus sequence, or a sequence of darks. These sequences are simple ASCII text files, which can be prepared in advance. Examples of such observing sequences are in the following links in H, J and K.

February 13, 2007