Characterization activities for NASA's Spitzer Space Telescope continue, a process that began after its cryogen ran out on May 15. These activities are part of NASA's plan to operate Spitzer in a "warm" mode, with two infrared channels still functioning.

Using Spitzer's infrared array camera, sample calibration observations were obtained on Friday, June 4, with the temperature of the 3.6-micron array at 23 Kelvin (-418 degrees Fahrenheit or -250 degrees Celsius) and the 4.5-micron array at 26 Kelvin (-413 degrees Fahrenheit or -247 degrees Celsius). Scientists have examined the data and found no change in the noise properties from either array compared with data taken before the cryogen was depleted. This is an important step in establishing that the instrument has about the same level of sensitivity as it did during the "cold" mission.

Development of a software patch to adjust the temperature of the arrays around the expected equilibrium temperature of the observatory continues, and engineers and scientists plan to test the patch next week.

Meanwhile, the observatory continues to warm towards the expected equilibrium temperature of 28 to 30 Kelvin. All systems on the spacecraft are healthy and functioning normally.