16562

This program is aimed at obtaining NUV-MAMA flat-field observations for the construction of pixel-to-pixel flats (p-flats) with a SNR of virgul100 per binned pixel. The flats are obtained with the DEUTERIUM lamp and the MR grisms G230M. The actual choice of central wavelength and slit combination depends on the observed count level within each exposure. Note that STIS NUV-MAMA flats are taken every other cycles (i.e. during odd-number cycles) in order to preserve the DEUTERIUM lamp lifetime. In Cycle 27 comma a setup with aperture=52X0.5 and cenwave=2417A resulted in an adequate count rate of virgul1.8E5 counts-s. However comma the count rates keep decreasing and will be too low for Cycle 29 and previous observations with cenwave=2579A have increased comma being over the non-linearity limit. In Cycle 28 a special calibration program 16517 took multiple short exposures of the DEUTERIUM lamp at 9 different cenwaves. A setup with aperture=52x0.5d_comma and cenwave=2499A comma based on PID 16517 comma should yeild a count rate of virgul2.2E5 counts-s. The cenwave 2499A was not included in 16517 comma so Visit 01 is a test exposure with aperture=52x0.2d_comma and cenwave=2499 to verify the count rate is in the acceptable range.